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Sample records for desynchronizing control schemes

  1. Event-based minimum-time control of oscillatory neuron models: phase randomization, maximal spike rate increase, and desynchronization.

    PubMed

    Danzl, Per; Hespanha, João; Moehlis, Jeff

    2009-12-01

    We present an event-based feedback control method for randomizing the asymptotic phase of oscillatory neurons. Phase randomization is achieved by driving the neuron's state to its phaseless set, a point at which its phase is undefined and is extremely sensitive to background noise. We consider the biologically relevant case of a fixed magnitude constraint on the stimulus signal, and show how the control objective can be accomplished in minimum time. The control synthesis problem is addressed using the minimum-time-optimal Hamilton-Jacobi-Bellman framework, which is quite general and can be applied to any spiking neuron model in the conductance-based Hodgkin-Huxley formalism. We also use this methodology to compute a feedback control protocol for optimal spike rate increase. This framework provides a straightforward means of visualizing isochrons, without actually calculating them in the traditional way. Finally, we present an extension of the phase randomizing control scheme that is applied at the population level, to a network of globally coupled neurons that are firing in synchrony. The applied control signal desynchronizes the population in a demand-controlled way. PMID:19911192

  2. Brain State-Dependent Closed-Loop Modulation of Paired Associative Stimulation Controlled by Sensorimotor Desynchronization

    PubMed Central

    Royter, Vladislav; Gharabaghi, Alireza

    2016-01-01

    Background: Pairing peripheral electrical stimulation (ES) and transcranial magnetic stimulation (TMS) increases corticospinal excitability when applied with a specific temporal pattern. When the two stimulation techniques are applied separately, motor imagery (MI)-related oscillatory modulation amplifies both ES-related cortical effects—sensorimotor event-related desynchronization (ERD), and TMS-induced peripheral responses—motor-evoked potentials (MEP). However, the influence of brain self-regulation on the associative pairing of these stimulation techniques is still unclear. Objective: The aim of this pilot study was to investigate the effects of MI-related ERD during associative ES and TMS on subsequent corticospinal excitability. Method: The paired application of functional electrical stimulation (FES) of the extensor digitorum communis (EDC) muscle and subsequent single-pulse TMS (110% resting motor threshold (RMT)) of the contralateral primary motor cortex (M1) was controlled by beta-band (16–22 Hz) ERD during MI of finger extension and applied within a brain-machine interface environment in six healthy subjects. Neural correlates were probed by acquiring the stimulus-response curve (SRC) of both MEP peak-to-peak amplitude and area under the curve (AUC) before and after the intervention. Result: The application of approximately 150 pairs of associative FES and TMS resulted in a significant increase of MEP amplitudes and AUC, indicating that the induced increase of corticospinal excitability was mediated by the recruitment of additional neuronal pools. MEP increases were brain state-dependent and correlated with beta-band ERD, but not with the background EDC muscle activity; this finding was independent of the FES intensity applied. Conclusion: These results could be relevant for developing closed-loop therapeutic approaches such as the application of brain state-dependent, paired associative stimulation (PAS) in the context of neurorehabilitation. PMID

  3. Electroencephalography (EEG)-based brain-computer interface (BCI): a 2-D virtual wheelchair control based on event-related desynchronization/synchronization and state control.

    PubMed

    Huang, Dandan; Qian, Kai; Fei, Ding-Yu; Jia, Wenchuan; Chen, Xuedong; Bai, Ou

    2012-05-01

    This study aims to propose an effective and practical paradigm for a brain-computer interface (BCI)-based 2-D virtual wheelchair control. The paradigm was based on the multi-class discrimination of spatiotemporally distinguishable phenomenon of event-related desynchronization/synchronization (ERD/ERS) in electroencephalogram signals associated with motor execution/imagery of right/left hand movement. Comparing with traditional method using ERD only, where bilateral ERDs appear during left/right hand mental tasks, the 2-D control exhibited high accuracy within a short time, as incorporating ERS into the paradigm hypothetically enhanced the spatiotemoral feature contrast of ERS versus ERD. We also expected users to experience ease of control by including a noncontrol state. In this study, the control command was sent discretely whereas the virtual wheelchair was moving continuously. We tested five healthy subjects in a single visit with two sessions, i.e., motor execution and motor imagery. Each session included a 20 min calibration and two sets of games that were less than 30 min. Average target hit rate was as high as 98.4% with motor imagery. Every subject achieved 100% hit rate in the second set of wheelchair control games. The average time to hit a target 10 m away was about 59 s, with 39 s for the best set. The superior control performance in subjects without intensive BCI training suggested a practical wheelchair control paradigm for BCI users. PMID:22498703

  4. An adaptive Cartesian control scheme for manipulators

    NASA Technical Reports Server (NTRS)

    Seraji, H.

    1987-01-01

    A adaptive control scheme for direct control of manipulator end-effectors to achieve trajectory tracking in Cartesian space is developed. The control structure is obtained from linear multivariable theory and is composed of simple feedforward and feedback controllers and an auxiliary input. The direct adaptation laws are derived from model reference adaptive control theory and are not based on parameter estimation of the robot model. The utilization of feedforward control and the inclusion of auxiliary input are novel features of the present scheme and result in improved dynamic performance over existing adaptive control schemes. The adaptive controller does not require the complex mathematical model of the robot dynamics or any knowledge of the robot parameters or the payload, and is computationally fast for online implementation with high sampling rates.

  5. Practical scheme for error control using feedback

    SciTech Connect

    Sarovar, Mohan; Milburn, Gerard J.; Ahn, Charlene; Jacobs, Kurt

    2004-05-01

    We describe a scheme for quantum-error correction that employs feedback and weak measurement rather than the standard tools of projective measurement and fast controlled unitary gates. The advantage of this scheme over previous protocols [for example, Ahn et al. Phys. Rev. A 65, 042301 (2001)], is that it requires little side processing while remaining robust to measurement inefficiency, and is therefore considerably more practical. We evaluate the performance of our scheme by simulating the correction of bit flips. We also consider implementation in a solid-state quantum-computation architecture and estimate the maximal error rate that could be corrected with current technology.

  6. Configuration-Control Scheme Copes With Singularities

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Colbaugh, Richard D.

    1993-01-01

    Improved configuration-control scheme for robotic manipulator having redundant degrees of freedom suppresses large joint velocities near singularities, at expense of small trajectory errors. Provides means to enforce order of priority of tasks assigned to robot. Basic concept of configuration control of redundant robot described in "Increasing The Dexterity Of Redundant Robots" (NPO-17801).

  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. Chaotic desynchronization of multistrain diseases

    NASA Astrophysics Data System (ADS)

    Schwartz, Ira B.; Shaw, Leah B.; Cummings, Derek A. T.; Billings, Lora; McCrary, Marie; Burke, Donald S.

    2005-12-01

    Multistrain diseases are diseases that consist of several strains, or serotypes. The serotypes may interact by antibody-dependent enhancement (ADE), in which infection with a single serotype is asymptomatic, but infection with a second serotype leads to serious illness accompanied by greater infectivity. It has been observed from serotype data of dengue hemorrhagic fever that outbreaks of the four serotypes occur asynchronously. Both autonomous and seasonally driven outbreaks were studied in a model containing ADE. For sufficiently small ADE, the number of infectives of each serotype synchronizes, with outbreaks occurring in phase. When the ADE increases past a threshold, the system becomes chaotic, and infectives of each serotype desynchronize. However, certain groupings of the primary and secondary infectives remain synchronized even in the chaotic regime.

  9. Chaotic desynchronization of multistrain diseases

    NASA Astrophysics Data System (ADS)

    Shaw, Leah; Billings, Lora; McCrary, Marie; Schwartz, Ira

    2005-03-01

    Dengue fever, a multi-strain disease, has four distinct co-existing serotypes (strains). The serotypes interact by antibody-dependent enhancement (ADE), in which infection with a single serotype is asymptomatic, but contact with a second serotype leads to serious illness accompanied by greater infectivity. It has been observed from serotype data that outbreaks of the four serotypes occur asynchronously (Nisalak et al., Am. J. Trop. Med. Hyg. 68: 192). We developed a compartmental model and did bifurcation analysis for multiple serotypes with ADE. Both autonomous and seasonally driven versions were studied. For sufficiently small ADE, we find that the number of infectives of each serotype synchronizes, with outbreaks occurring in phase. However, when the ADE increases past a threshold, the system becomes chaotic, and infectives of each serotype desynchronize.

  10. EEG Event-Related Desynchronization of patients with stroke during motor imagery of hand movement

    NASA Astrophysics Data System (ADS)

    Tabernig, Carolina B.; Carrere, Lucía C.; Lopez, Camila A.; Ballario, Carlos

    2016-04-01

    Brain Computer Interfaces (BCI) can be used for therapeutic purposes to improve voluntary motor control that has been affected post stroke. For this purpose, desynchronization of sensorimotor rhythms of the electroencephalographic signal (EEG) can be used. But it is necessary to study what happens in the affected motor cortex of this people. In this article, we analyse EEG recordings of hemiplegic stroke patients to determine if it is possible to detect desynchronization in the affected motor cortex during the imagination of movements of the affected hand. Six patients were included in the study; four evidenced desynchronization in the affected hemisphere, one of them showed no results and the EEG recordings of the last patient presented high noise level. These results suggest that we could use the desynchronization of sensorimotor rhythms of the EEG signal as a BCI paradigm in a rehabilitation programme.

  11. Desynchronization and spatial effects in multistrain diseases

    NASA Astrophysics Data System (ADS)

    Shaw, Leah; Billings, Lora; Schwartz, Ira

    2006-03-01

    Dengue fever, a multistrain disease, has four distinct co- existing serotypes (strains). The serotypes interact by antibody- dependent enhancement (ADE), in which infection with a single serotype is asymptomatic, but contact with a second serotype leads to serious illness accompanied by greater infectivity. We present a compartmental model for multiple serotypes with ADE, and consider autonomous, seasonally driven, and stochastic versions of the model. Spatial effects are included in a multipatch model. We observe desynchronization between outbreaks of the different serotypes, as well as desynchronization between spatially distinct regions.

  12. An adaptive control scheme for coordinated multimanipulator systems

    SciTech Connect

    Jonghann Jean; Lichen Fu . Dept. of Electrical Engineering)

    1993-04-01

    The problem of adaptive coordinated control of multiple robot arms transporting an object is addressed. A stable adaptive control scheme for both trajectory tracking and internal force control is presented. Detailed analyses on tracking properties of the object position, velocity and the internal forces exerted on the object are given. It is shown that this control scheme can achieve satisfactory tracking performance without using the measurement of contact forces and their derivatives. It can be shown that this scheme can be realized by decentralized implementation to reduce the computational burden. Moreover, some efficient adaptive control strategies can be incorporated to reduce the computational complexity.

  13. Development of advanced control schemes for telerobot manipulators

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Zhou, Zhen-Lei

    1991-01-01

    To study space applications of telerobotics, Goddard Space Flight Center (NASA) has recently built a testbed composed mainly of a pair of redundant slave arms having seven degrees of freedom and a master hand controller system. The mathematical developments required for the computerized simulation study and motion control of the slave arms are presented. The slave arm forward kinematic transformation is presented which is derived using the D-H notation and is then reduced to its most simplified form suitable for real-time control applications. The vector cross product method is then applied to obtain the slave arm Jacobian matrix. Using the developed forward kinematic transformation and quaternions representation of the slave arm end-effector orientation, computer simulation is conducted to evaluate the efficiency of the Jacobian in converting joint velocities into Cartesian velocities and to investigate the accuracy of the Jacobian pseudo-inverse for various sampling times. In addition, the equivalence between Cartesian velocities and quaternion is also verified using computer simulation. The motion control of the slave arm is examined. Three control schemes, the joint-space adaptive control scheme, the Cartesian adaptive control scheme, and the hybrid position/force control scheme are proposed for controlling the motion of the slave arm end-effector. Development of the Cartesian adaptive control scheme is presented and some preliminary results of the remaining control schemes are presented and discussed.

  14. Control Scheme of Tether Drag Deorbit System in Orbital Plane

    NASA Astrophysics Data System (ADS)

    Cui, Wei-Dong; Sun, Liang; Zhao, Guo-Wei

    In this paper, based on a dumbbell model of tethered satellite, a tension control scheme and a thrust control scheme of tether drag deorbit system in orbital plane are respectively proposed. In the tension control scheme, the tether tension can be measured by tension sensor and controlled by adjusting the tether length with a certain windlass mechanism, so that the librational angles could track the expected value; meanwhile, the tether could come back to the initial value. Because of the windlass mechanism, the slackness of tether can be avoided. In the thrust control scheme, the tether drag deorbit system is with a short tether in orbital maneuvering and the thrust acceleration imposed on the base satellite can be adjusted to avoid the slackness of tether and damp out the librational angles; besides, it is required that the regulation value of thrust acceleration meets with accuracy trajectory in practical engineering. Afterwards, a reasonable deorbit case of an abandoned GEO satellite is studied, in which the control of base satellite is considered; then, the advantages and disadvantages of two control schemes are analyzed and an improved control strategy is given. Numerical simulation results indicate that the slackness of tether can be eliminated and the librational angles are damped out according to the designed controllers, and the stability of the attitude of abandoned satellite is also guaranteed during flight. The proposed control schemes are feasible, which is useful for the flight safety.

  15. An expert system based intelligent control scheme for space bioreactors

    NASA Technical Reports Server (NTRS)

    San, Ka-Yiu

    1988-01-01

    An expert system based intelligent control scheme is being developed for the effective control and full automation of bioreactor systems in space. The scheme developed will have the capability to capture information from various resources including heuristic information from process researchers and operators. The knowledge base of the expert system should contain enough expertise to perform on-line system identification and thus be able to adapt the controllers accordingly with minimal human supervision.

  16. An optimized quantum information splitting scheme with multiple controllers

    NASA Astrophysics Data System (ADS)

    Jiang, Min

    2016-09-01

    We propose an efficient scheme for splitting multi-qudit information with cooperative control of multiple agents. Each controller is assigned one controlling qudit, and he can monitor the state sharing of all multi-qudit information. Compared with the existing schemes, our scheme requires less resource consumption and approaches higher communication efficiency. In addition, our proposal involves only generalized Bell-state measurement, single-qudit measurement, one-qudit gates and a unitary-reduction operation, which makes it flexible and achievable for physical implementation.

  17. A Hybrid Nonlinear Control Scheme for Active Magnetic Bearings

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  18. LDFT-based watermarking resilient to local desynchronization attacks.

    PubMed

    Tian, Huawei; Zhao, Yao; Ni, Rongrong; Qin, Lunming; Li, Xuelong

    2013-12-01

    Up to now, a watermarking scheme that is robust against desynchronization attacks (DAs) is still a grand challenge. Most image watermarking resynchronization schemes in literature can survive individual global DAs (e.g., rotation, scaling, translation, and other affine transforms), but few are resilient to challenging cropping and local DAs. The main reason is that robust features for watermark synchronization are only globally invariable rather than locally invariable. In this paper, we present a blind image watermarking resynchronization scheme against local transform attacks. First, we propose a new feature transform named local daisy feature transform (LDFT), which is not only globally but also locally invariable. Then, the binary space partitioning (BSP) tree is used to partition the geometrically invariant LDFT space. In the BSP tree, the location of each pixel is fixed under global transform, local transform, and cropping. Lastly, the watermarking sequence is embedded bit by bit into each leaf node of the BSP tree by using the logarithmic quantization index modulation watermarking embedding method. Simulation results show that the proposed watermarking scheme can survive numerous kinds of distortions, including common image-processing attacks, local and global DAs, and noninvertible cropping.

  19. Desynchronization of stochastically synchronized chemical oscillators

    SciTech Connect

    Snari, Razan; Tinsley, Mark R. E-mail: kshowalt@wvu.edu; Faramarzi, Sadegh; Showalter, Kenneth E-mail: kshowalt@wvu.edu; Wilson, Dan; Moehlis, Jeff; Netoff, Theoden Ivan

    2015-12-15

    Experimental and theoretical studies are presented on the design of perturbations that enhance desynchronization in populations of oscillators that are synchronized by periodic entrainment. A phase reduction approach is used to determine optimal perturbation timing based upon experimentally measured phase response curves. The effectiveness of the perturbation waveforms is tested experimentally in populations of periodically and stochastically synchronized chemical oscillators. The relevance of the approach to therapeutic methods for disrupting phase coherence in groups of stochastically synchronized neuronal oscillators is discussed.

  20. Performance improvement of robots using a learning control scheme

    NASA Technical Reports Server (NTRS)

    Krishna, Ramuhalli; Chiang, Pen-Tai; Yang, Jackson C. S.

    1987-01-01

    Many applications of robots require that the same task be repeated a number of times. In such applications, the errors associated with one cycle are also repeated every cycle of the operation. An off-line learning control scheme is used here to modify the command function which would result in smaller errors in the next operation. The learning scheme is based on a knowledge of the errors and error rates associated with each cycle. Necessary conditions for the iterative scheme to converge to zero errors are derived analytically considering a second order servosystem model. Computer simulations show that the errors are reduced at a faster rate if the error rate is included in the iteration scheme. The results also indicate that the scheme may increase the magnitude of errors if the rate information is not included in the iteration scheme. Modification of the command input using a phase and gain adjustment is also proposed to reduce the errors with one attempt. The scheme is then applied to a computer model of a robot system similar to PUMA 560. Improved performance of the robot is shown by considering various cases of trajectory tracing. The scheme can be successfully used to improve the performance of actual robots within the limitations of the repeatability and noise characteristics of the robot.

  1. Reactivity Control Schemes for Fast Spectrum Space Nuclear Reactors

    SciTech Connect

    Craft, Aaron E.; King, Jeffrey C.

    2008-01-21

    Several different reactivity control schemes are considered for future space nuclear reactor power systems. Each of these control schemes uses a combination of boron carbide absorbers and/or beryllium oxide reflectors to achieve sufficient reactivity swing to keep the reactor subcritical during launch and to provide sufficient excess reactivity to operate the reactor over its expected 7-15 year lifetime. The size and shape of the control system directly impacts the size and mass of the space reactor's reflector and shadow shield, leading to a tradeoff between reactivity swing and total system mass. This paper presents a trade study of drum, shutter, and petal control schemes based on reactivity swing and mass effects for a representative fast-spectrum, gas-cooled reactor. For each control scheme, the dimensions and composition of the core are constant, and the reflector is sized to provide $5 of cold-clean excess reactivity with each configuration in its most reactive state. The advantages and disadvantages of each configuration are discussed, along with optimization techniques and novel geometric approaches for each scheme.

  2. Interface control scheme for computer high-speed interface unit

    NASA Technical Reports Server (NTRS)

    Ballard, B. K.

    1975-01-01

    Control scheme is general and performs for multiplexed and dedicated channels as well as for data-bus interfaces. Control comprises two 64-pin, dual in-line packages, each of which holds custom large-scale integrated array built with silicon-on-sapphire complementary metal-oxide semiconductor technology.

  3. Proposal of Wireless Traffic Control Schemes for Wireless LANs

    NASA Astrophysics Data System (ADS)

    Hiraguri, Takefumi; Ichikawa, Takeo; Iizuka, Masataka; Kubota, Shuji

    This paper proposes two traffic control schemes to support the communication quality of multimedia streaming services such as VoIP and audio/video over IEEE 802.11 wireless LAN systems. The main features of the proposed scheme are bandwidth control for each flow of the multimedia streaming service and load balancing between access points (APs) of the wireless LAN by using information of data link, network and transport layers. The proposed schemes are implemented on a Linux machine which is called the wireless traffic controller (WTC). The WTC connects a high capacity backbone network and an access network to which the APs are attached. We evaluated the performance of the proposed WTC and confirmed that the communication quality of the multimedia streaming would be greatly improved by using this technique.

  4. A discrete-time adaptive control scheme for robot manipulators

    NASA Technical Reports Server (NTRS)

    Tarokh, M.

    1990-01-01

    A discrete-time model reference adaptive control scheme is developed for trajectory tracking of robot manipulators. The scheme utilizes feedback, feedforward, and auxiliary signals, obtained from joint angle measurement through simple expressions. Hyperstability theory is utilized to derive the adaptation laws for the controller gain matrices. It is shown that trajectory tracking is achieved despite gross robot parameter variation and uncertainties. The method offers considerable design flexibility and enables the designer to improve the performance of the control system by adjusting free design parameters. The discrete-time adaptation algorithm is extremely simple and is therefore suitable for real-time implementation. Simulations and experimental results are given to demonstrate the performance of the scheme.

  5. Novel coupling scheme to control dynamics of coupled discrete systems

    NASA Astrophysics Data System (ADS)

    Shekatkar, Snehal M.; Ambika, G.

    2015-08-01

    We present a new coupling scheme to control spatio-temporal patterns and chimeras on 1-d and 2-d lattices and random networks of discrete dynamical systems. The scheme involves coupling with an external lattice or network of damped systems. When the system network and external network are set in a feedback loop, the system network can be controlled to a homogeneous steady state or synchronized periodic state with suppression of the chaotic dynamics of the individual units. The control scheme has the advantage that its design does not require any prior information about the system dynamics or its parameters and works effectively for a range of parameters of the control network. We analyze the stability of the controlled steady state or amplitude death state of lattices using the theory of circulant matrices and Routh-Hurwitz criterion for discrete systems and this helps to isolate regions of effective control in the relevant parameter planes. The conditions thus obtained are found to agree well with those obtained from direct numerical simulations in the specific context of lattices with logistic map and Henon map as on-site system dynamics. We show how chimera states developed in an experimentally realizable 2-d lattice can be controlled using this scheme. We propose this mechanism can provide a phenomenological model for the control of spatio-temporal patterns in coupled neurons due to non-synaptic coupling with the extra cellular medium. We extend the control scheme to regulate dynamics on random networks and adapt the master stability function method to analyze the stability of the controlled state for various topologies and coupling strengths.

  6. Effective desynchronization with a stimulation technique based on soft phase resetting

    NASA Astrophysics Data System (ADS)

    Tass, P. A.

    2002-01-01

    A composite stimulation technique is presented here which effectively desynchronizes a cluster of globally coupled phase oscillators in the presence of noise by means of a soft (i.e. slow and mild) reset. A composite stimulus consists of two different stimuli. The first stimulus is a short periodic pulse train, where the entraining frequency is close to the natural frequency of the cluster. In the course of several periods of the collective oscillation, the first stimulus entrains and, hence, resets (restarts) the cluster, independently of its initial dynamic state. With a fixed delay after the first stimulus the second stimulus, a single pulse, is delivered which desynchronizes the cluster by hitting it in a vulnerable state. The desynchronized cluster starts to resynchronize, since the incoherent state is unstable. Resynchronization can, nevertheless, be blocked by repeated administration of the same composite stimulus. Previously designed stimulation techniques use a hard (i.e. abrupt) reset. By contrast, a soft reset makes it possible to effectively desynchronize even if strong, quickly resetting stimuli are not available or not tolerated. Accordingly, this method is particularly mild and can be applied to effectively maintain incoherency in a population of oscillatory neurons which tend to synchronize their firing. The composite stimulation technique can be used i) for an improved, milder and demand-controlled deep brain stimulation for patients with Parkinson's disease or essential tremor and ii) for the manipulation of cerebral information processing by selectively blocking gamma activity.

  7. Effective desynchronization with a resetting pulse train followed by a single pulse

    NASA Astrophysics Data System (ADS)

    Tass, P. A.

    2001-07-01

    A combined pulse train, single-pulse stimulation technique is presented here which makes it possible to effectively desynchronize a cluster of globally coupled phase oscillators in the presence of noise. Such a composite stimulus consists of a resetting short periodic high-frequent pulse train followed by a desynchronizing single pulse. The pulse train entrains and, thus, restarts the collective oscillation independently of its initial dynamic state. With a fixed delay after the pulse train, a single pulse is delivered which desynchronizes the cluster by hitting it in a vulnerable state. After the desynchronization the cluster wants to become synchronized again since the incoherent state is unstable. Nevertheless, repeated administration of the same composite stimulus blocks the resynchronization. Compared to double-pulse phase resetting and with regard to neurological applications, this method is particularly mild and can be applied to effectively maintain incoherency in a population of oscillatory neurons that tend to synchronize their firing. The composite stimulation approach sheds new light on the mechanism of standard deep brain stimulation and suggests an improved, milder and demand-controlled deep brain stimulation technique for patients with Parkinson's disease or essential tremor.

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

    SciTech Connect

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

    2014-04-15

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

  9. An optimal performance control scheme for a 3D crane

    NASA Astrophysics Data System (ADS)

    Maghsoudi, Mohammad Javad; Mohamed, Z.; Husain, A. R.; Tokhi, M. O.

    2016-01-01

    This paper presents an optimal performance control scheme for control of a three dimensional (3D) crane system including a Zero Vibration shaper which considers two control objectives concurrently. The control objectives are fast and accurate positioning of a trolley and minimum sway of a payload. A complete mathematical model of a lab-scaled 3D crane is simulated in Simulink. With a specific cost function the proposed controller is designed to cater both control objectives similar to a skilled operator. Simulation and experimental studies on a 3D crane show that the proposed controller has better performance as compared to a sequentially tuned PID-PID anti swing controller. The controller provides better position response with satisfactory payload sway in both rail and trolley responses. Experiments with different payloads and cable lengths show that the proposed controller is robust to changes in payload with satisfactory responses.

  10. Control Scheme for Quickly Starting X-ray Tube

    NASA Astrophysics Data System (ADS)

    Nakahama, Masayuki; Nakanishi, Toshiki; Ishitobi, Manabu; Ito, Tuyoshi; Hosoda, Kenichi

    A control scheme for quickly starting a portable X-ray generator used in the livestock industry is proposed in this paper. A portable X-ray generator used to take X-ray images of animals such as horses, sheep and dogs should be capable of starting quickly because it is difficult for veterinarians to take X-ray images of animals at their timing. In order to develop a scheme for starting the X-ray tube quickly, it is necessary to analysis the X-ray tube. However, such an analysis has not been discussed until now. First, the states of an X-ray tube are classified into the temperature-limited state and the space-charge-limited state. Furthermore, existence of “mixed state” that comprises both is newly proposed in this paper. From these analyses, a novel scheme for quickly starting an X-ray generator is proposed; this scheme is considered with the characteristics of the X-ray tube. The proposed X-ray system that is capable of starting quickly is evaluated on the basis of experimental results.

  11. Selection against genetic defects in conservation schemes while controlling inbreeding

    PubMed Central

    Sonesson, Anna K; Janss, Luc LG; Meuwissen, Theo HE

    2003-01-01

    We studied different genetic models and evaluation systems to select against a genetic disease with additive, recessive or polygenic inheritance in genetic conservation schemes. When using optimum contribution selection with a restriction on the rate of inbreeding (ΔF) to select against a disease allele, selection directly on DNA-genotypes is, as expected, the most efficient strategy. Selection for BLUP or segregation analysis breeding value estimates both need 1–2 generations more to halve the frequency of the disease allele, while these methods do not require knowledge of the disease mutation at the DNA level. BLUP and segregation analysis methods were equally efficient when selecting against a disease with single gene or complex polygene inheritance, i.e. knowledge about the mode of inheritance of the disease was not needed for efficient selection against the disease. Smaller schemes or schemes with a more stringent restriction on ΔF needed more generations to halve the frequency of the disease alleles or the fraction of diseased animals. Optimum contribution selection maintained ΔF at its predefined level, even when selection of females was at random. It is argued that in the investigated small conservation schemes with selection against a genetic defect, control of ΔF is very important. PMID:12927071

  12. Secure Dynamic access control scheme of PHR in cloud computing.

    PubMed

    Chen, Tzer-Shyong; Liu, Chia-Hui; Chen, Tzer-Long; Chen, Chin-Sheng; Bau, Jian-Guo; Lin, Tzu-Ching

    2012-12-01

    With the development of information technology and medical technology, medical information has been developed from traditional paper records into electronic medical records, which have now been widely applied. The new-style medical information exchange system "personal health records (PHR)" is gradually developed. PHR is a kind of health records maintained and recorded by individuals. An ideal personal health record could integrate personal medical information from different sources and provide complete and correct personal health and medical summary through the Internet or portable media under the requirements of security and privacy. A lot of personal health records are being utilized. The patient-centered PHR information exchange system allows the public autonomously maintain and manage personal health records. Such management is convenient for storing, accessing, and sharing personal medical records. With the emergence of Cloud computing, PHR service has been transferred to storing data into Cloud servers that the resources could be flexibly utilized and the operation cost can be reduced. Nevertheless, patients would face privacy problem when storing PHR data into Cloud. Besides, it requires a secure protection scheme to encrypt the medical records of each patient for storing PHR into Cloud server. In the encryption process, it would be a challenge to achieve accurately accessing to medical records and corresponding to flexibility and efficiency. A new PHR access control scheme under Cloud computing environments is proposed in this study. With Lagrange interpolation polynomial to establish a secure and effective PHR information access scheme, it allows to accurately access to PHR with security and is suitable for enormous multi-users. Moreover, this scheme also dynamically supports multi-users in Cloud computing environments with personal privacy and offers legal authorities to access to PHR. From security and effectiveness analyses, the proposed PHR access

  13. Security Encryption Scheme for Communication of Web Based Control Systems

    NASA Astrophysics Data System (ADS)

    Robles, Rosslin John; Kim, Tai-Hoon

    A control system is a device or set of devices to manage, command, direct or regulate the behavior of other devices or systems. The trend in most systems is that they are connected through the Internet. Traditional Supervisory Control and Data Acquisition Systems (SCADA) is connected only in a limited private network Since the internet Supervisory Control and Data Acquisition Systems (SCADA) facility has brought a lot of advantages in terms of control, data viewing and generation. Along with these advantages, are security issues regarding web SCADA, operators are pushed to connect Control Systems through the internet. Because of this, many issues regarding security surfaced. In this paper, we discuss web SCADA and the issues regarding security. As a countermeasure, a web SCADA security solution using crossed-crypto-scheme is proposed to be used in the communication of SCADA components.

  14. Modeling of power control schemes in induction cooking devices

    NASA Astrophysics Data System (ADS)

    Beato, Alessio; Conti, Massimo; Turchetti, Claudio; Orcioni, Simone

    2005-06-01

    In recent years, with remarkable advancements of power semiconductor devices and electronic control systems, it becomes possible to apply the induction heating technique for domestic use. In order to achieve the supply power required by these devices, high-frequency resonant inverters are used: the force commutated, half-bridge series resonant converter is well suited for induction cooking since it offers an appropriate balance between complexity and performances. Power control is a key issue to attain efficient and reliable products. This paper describes and compares four power control schemes applied to the half-bridge series resonant inverter. The pulse frequency modulation is the most common control scheme: according to this strategy, the output power is regulated by varying the switching frequency of the inverter circuit. Other considered methods, originally developed for induction heating industrial applications, are: pulse amplitude modulation, asymmetrical duty cycle and pulse density modulation which are respectively based on variation of the amplitude of the input supply voltage, on variation of the duty cycle of the switching signals and on variation of the number of switching pulses. Each description is provided with a detailed mathematical analysis; an analytical model, built to simulate the circuit topology, is implemented in the Matlab environment in order to obtain the steady-state values and waveforms of currents and voltages. For purposes of this study, switches and all reactive components are modelled as ideal and the "heating-coil/pan" system is represented by an equivalent circuit made up of a series connected resistance and inductance.

  15. Study on noise prediction model and control schemes for substation.

    PubMed

    Chen, Chuanmin; Gao, Yang; Liu, Songtao

    2014-01-01

    With the government's emphasis on environmental issues of power transmission and transformation project, noise pollution has become a prominent problem now. The noise from the working transformer, reactor, and other electrical equipment in the substation will bring negative effect to the ambient environment. This paper focuses on using acoustic software for the simulation and calculation method to control substation noise. According to the characteristics of the substation noise and the techniques of noise reduction, a substation's acoustic field model was established with the SoundPLAN software to predict the scope of substation noise. On this basis, 4 reasonable noise control schemes were advanced to provide some helpful references for noise control during the new substation's design and construction process. And the feasibility and application effect of these control schemes can be verified by using the method of simulation modeling. The simulation results show that the substation always has the problem of excessive noise at boundary under the conventional measures. The excess noise can be efficiently reduced by taking the corresponding noise reduction methods. PMID:24672356

  16. Study on noise prediction model and control schemes for substation.

    PubMed

    Chen, Chuanmin; Gao, Yang; Liu, Songtao

    2014-01-01

    With the government's emphasis on environmental issues of power transmission and transformation project, noise pollution has become a prominent problem now. The noise from the working transformer, reactor, and other electrical equipment in the substation will bring negative effect to the ambient environment. This paper focuses on using acoustic software for the simulation and calculation method to control substation noise. According to the characteristics of the substation noise and the techniques of noise reduction, a substation's acoustic field model was established with the SoundPLAN software to predict the scope of substation noise. On this basis, 4 reasonable noise control schemes were advanced to provide some helpful references for noise control during the new substation's design and construction process. And the feasibility and application effect of these control schemes can be verified by using the method of simulation modeling. The simulation results show that the substation always has the problem of excessive noise at boundary under the conventional measures. The excess noise can be efficiently reduced by taking the corresponding noise reduction methods.

  17. An adaptive identification and control scheme for large space structures

    NASA Technical Reports Server (NTRS)

    Carroll, J. V.

    1988-01-01

    A unified identification and control scheme capable of achieving space at form performance objectives under nominal or failure conditions is described. Preliminary results are also presented, showing that the methodology offers much promise for effective robust control of large space structures. The control method is a multivariable, adaptive, output predictive controller called Model Predictive Control (MPC). MPC uses a state space model and input reference trajectories of set or tracking points to adaptively generate optimum commands. For a fixed model, MPC processes commands with great efficiency, and is also highly robust. A key feature of MPC is its ability to control either nonminimum phase or open loop unstable systems. As an output controller, MPC does not explicitly require full state feedback, as do most multivariable (e.g., Linear Quadratic) methods. Its features are very useful in LSS operations, as they allow non-collocated actuators and sensors. The identification scheme is based on canonical variate analysis (CVA) of input and output data. The CVA technique is particularly suited for the measurement and identification of structural dynamic processes - that is, unsteady transient or dynamically interacting processes such as between aerodynamics and structural deformation - from short, noisy data. CVA is structured so that the identification can be done in real or near real time, using computationally stable algorithms. Modeling LSS dynamics in 1-g laboratories has always been a major impediment not only to understanding their behavior in orbit, but also to controlling it. In cases where the theoretical model is not confirmed, current methods provide few clues concerning additional dynamical relationships that are not included in the theoretical models. CVA needs no a priori model data, or structure; all statistically significant dynamical states are determined using natural, entropy-based methods. Heretofore, a major limitation in applying adaptive

  18. Mu rhythm desynchronization by tongue thrust observation

    PubMed Central

    Sakihara, Kotoe; Inagaki, Masumi

    2015-01-01

    We aimed to investigate the mu rhythm in the sensorimotor area during tongue thrust observation and to obtain an answer to the question as to how subtle non-verbal orofacial movement observation activates the sensorimotor area. Ten healthy volunteers performed finger tap execution, tongue thrust execution, and tongue thrust observation. The electroencephalogram (EEG) was recorded from 128 electrodes placed on the scalp, and regions of interest were set at sensorimotor areas. The event-related desynchronization (ERD) and event-related synchronization (ERS) for the mu rhythm (8–13 Hz) and beta (13−25 Hz) bands were measured. Tongue thrust observation induced mu rhythm ERD, and the ERD was detected at the left hemisphere regardless whether the observed tongue thrust was toward the left or right. Mu rhythm ERD was also recorded during tongue thrust execution. However, temporal analysis revealed that the ERD associated with tongue thrust observation preceded that associated with execution by approximately 2 s. Tongue thrust observation induces mu rhythm ERD in sensorimotor cortex with left hemispheric dominance. PMID:26441599

  19. Peripheral Attentional Targets under Covert Attention Lead to Paradoxically Enhanced Alpha Desynchronization in Neurofibromatosis Type 1

    PubMed Central

    Silva, Gilberto; Ribeiro, Maria J.; Costa, Gabriel N.; Violante, Inês; Ramos, Fabiana; Saraiva, Jorge; Castelo-Branco, Miguel

    2016-01-01

    The limited capacity of the human brain to process the full extent of visual information reaching the visual cortex requires the recruitment of mechanisms of information selection through attention. Neurofibromatosis type-1 (NF1) is a neurodevelopmental disease often exhibiting attentional deficits and learning disabilities, and is considered to model similar impairments common in other neurodevelopmental disorders such as autism. In a previous study, we found that patients with NF1 are more prone to miss targets under overt attention conditions. This finding was interpreted as a result of increased occipito-parietal alpha oscillations. In the present study, we used electroencephalography (EEG) to study alpha power modulations and the performance of patients with NF1 in a covert attention task. Covert attention was required in order to perceive changes (target offset) of a peripherally presented stimulus. Interestingly, alpha oscillations were found to undergo greater desynchronization under this task in the NF1 group compared with control subjects. A similar pattern of desynchronization was found for beta frequencies while no changes in gamma oscillations could be identified. These results are consistent with the notion that different attentional states and task demands generate different patterns of abnormal modulation of alpha oscillatory processes in NF1. Under covert attention conditions and while target offset was reported with relatively high accuracy (over 90% correct responses), excessive desynchronization was found. These findings suggest an abnormal modulation of oscillatory activity and attentional processes in NF1. Given the known role of alpha in modulating attention, we suggest that alpha patterns can show both abnormal increases and decreases that are task and performance dependent, in a way that enhanced alpha desynchronization may reflect a compensatory mechanism to keep performance at normal levels. These results suggest that dysregulation of

  20. Peripheral Attentional Targets under Covert Attention Lead to Paradoxically Enhanced Alpha Desynchronization in Neurofibromatosis Type 1.

    PubMed

    Silva, Gilberto; Ribeiro, Maria J; Costa, Gabriel N; Violante, Inês; Ramos, Fabiana; Saraiva, Jorge; Castelo-Branco, Miguel

    2016-01-01

    The limited capacity of the human brain to process the full extent of visual information reaching the visual cortex requires the recruitment of mechanisms of information selection through attention. Neurofibromatosis type-1 (NF1) is a neurodevelopmental disease often exhibiting attentional deficits and learning disabilities, and is considered to model similar impairments common in other neurodevelopmental disorders such as autism. In a previous study, we found that patients with NF1 are more prone to miss targets under overt attention conditions. This finding was interpreted as a result of increased occipito-parietal alpha oscillations. In the present study, we used electroencephalography (EEG) to study alpha power modulations and the performance of patients with NF1 in a covert attention task. Covert attention was required in order to perceive changes (target offset) of a peripherally presented stimulus. Interestingly, alpha oscillations were found to undergo greater desynchronization under this task in the NF1 group compared with control subjects. A similar pattern of desynchronization was found for beta frequencies while no changes in gamma oscillations could be identified. These results are consistent with the notion that different attentional states and task demands generate different patterns of abnormal modulation of alpha oscillatory processes in NF1. Under covert attention conditions and while target offset was reported with relatively high accuracy (over 90% correct responses), excessive desynchronization was found. These findings suggest an abnormal modulation of oscillatory activity and attentional processes in NF1. Given the known role of alpha in modulating attention, we suggest that alpha patterns can show both abnormal increases and decreases that are task and performance dependent, in a way that enhanced alpha desynchronization may reflect a compensatory mechanism to keep performance at normal levels. These results suggest that dysregulation of

  1. Event-related desynchronization evoked by auditory stimuli.

    PubMed

    Krause, C M; Lang, H A; Laine, M; Helle, S I; Kuusisto, M J; Pörn, B

    1994-01-01

    Event-Related Desynchronization (ERD) and Synchronization (ERS) of several EEG alpha frequencies was studied in 19 subjects during the presentation of linguistic and/or melodic auditory stimuli. The stimulus length was 1300 msec (+/-100 msec) and the interstimulus interval was 2000 msec. A significant ERD was found during auditory stimulation in the 8-10 Hz and 10-12 Hz alpha frequency bands, and there were also significant differences in the spatiotemporal pattern of the ERD between these frequency bands. Significant ERD was elicited also in the 10-11 and 11-12 Hz frequency bands by auditory stimulation. There were no significant differences between these one-hertz frequency bands. The subjects were assigned to two analysis groups according to their individual alpha peak frequency (10-11 or 11-12 Hz) at rest. The ERD in these groups reached statistical significance and there were significant differences between the groups. The ERD of the two groups differed significantly also when their EEG data was studied in the 10-12 Hz frequency band. The results from this study show that ERD is not modality-specific, i.e., it can be elicited also by auditory stimuli. Moreover, they indicate that it is important to control over interindividual variation in the EEG when studying the ERD phenomenon.

  2. Controllability of Boolean networks via input controls under Harvey's update scheme

    NASA Astrophysics Data System (ADS)

    Luo, Chao; Zhang, Xiaolin; Shao, Rui; Zheng, YuanJie

    2016-02-01

    In this article, the controllability of Boolean networks via input controls under Harvey's update scheme is investigated. First, the model of Boolean control networks under Harvey's stochastic update is proposed, by means of semi-tensor product approach, which is converted into discrete-time linear representation. And, a general formula of control-depending network transition matrix is provided. Second, based on discrete-time dynamics, controllability of the proposed model is analytically discussed by revealing the necessary and sufficient conditions of the reachable sets, respectively, for three kinds of controls, i.e., free Boolean control sequence, input control networks, and close-loop control. Examples are showed to demonstrate the effectiveness and feasibility of the proposed scheme.

  3. Controllability of Boolean networks via input controls under Harvey's update scheme.

    PubMed

    Luo, Chao; Zhang, Xiaolin; Shao, Rui; Zheng, YuanJie

    2016-02-01

    In this article, the controllability of Boolean networks via input controls under Harvey's update scheme is investigated. First, the model of Boolean control networks under Harvey's stochastic update is proposed, by means of semi-tensor product approach, which is converted into discrete-time linear representation. And, a general formula of control-depending network transition matrix is provided. Second, based on discrete-time dynamics, controllability of the proposed model is analytically discussed by revealing the necessary and sufficient conditions of the reachable sets, respectively, for three kinds of controls, i.e., free Boolean control sequence, input control networks, and close-loop control. Examples are showed to demonstrate the effectiveness and feasibility of the proposed scheme.

  4. Degree-based attacks are not optimal for desynchronization in general networks

    NASA Astrophysics Data System (ADS)

    Li, Ping; Sun, Xian; Zhang, Kai; Zhang, Jie; Small, Michael

    2013-08-01

    Suppressing harmful synchronization in complex networked systems is receiving increasing interest in various contexts including epileptic seizure and the Internet and traffic congestion. It is traditionally believed that by disrupting the most important nodes (i.e., those nodes of high degrees) synchronization can be effectively mitigated. However, this approach can perform poorly in more general situations such as homogeneous (random) or small world networks. In this article, we investigate how topological properties, such as the heterogeneity of the network can have an impact on its desynchronization. In particular, we propose a topology-aware scheme that chooses topologically sufficiently diversified contrarian nodes by taking into account the patterns of connectivity among them. Hence, a maximal number of nodes in the network can be influenced, leading to a more global impact and greater disruption to synchronization. Our scheme demonstrates significantly improved performance on various networked systems including homogeneous networks, small world, and even scale-free networks.

  5. Degree-based attacks are not optimal for desynchronization in general networks.

    PubMed

    Li, Ping; Sun, Xian; Zhang, Kai; Zhang, Jie; Small, Michael

    2013-08-01

    Suppressing harmful synchronization in complex networked systems is receiving increasing interest in various contexts including epileptic seizure and the Internet and traffic congestion. It is traditionally believed that by disrupting the most important nodes (i.e., those nodes of high degrees) synchronization can be effectively mitigated. However, this approach can perform poorly in more general situations such as homogeneous (random) or small world networks. In this article, we investigate how topological properties, such as the heterogeneity of the network can have an impact on its desynchronization. In particular, we propose a topology-aware scheme that chooses topologically sufficiently diversified contrarian nodes by taking into account the patterns of connectivity among them. Hence, a maximal number of nodes in the network can be influenced, leading to a more global impact and greater disruption to synchronization. Our scheme demonstrates significantly improved performance on various networked systems including homogeneous networks, small world, and even scale-free networks.

  6. Active sway control of a gantry crane using hybrid input shaping and PID control schemes

    NASA Astrophysics Data System (ADS)

    Mohd Tumari, M. Z.; Shabudin, L.; Zawawi, M. A.; Shah, L. H. Ahmad

    2013-12-01

    This project presents investigations into the development of hybrid input-shaping and PID control schemes for active sway control of a gantry crane system. The application of positive input shaping involves a technique that can reduce the sway by creating a common signal that cancels its own vibration and used as a feed-forward control which is for controlling the sway angle of the pendulum, while the proportional integral derivative (PID) controller is used as a feedback control which is for controlling the crane position. The PID controller was tuned using Ziegler-Nichols method to get the best performance of the system. The hybrid input-shaping and PID control schemes guarantee a fast input tracking capability, precise payload positioning and very minimal sway motion. The modeling of gantry crane is used to simulate the system using MATLAB/SIMULINK software. The results of the response with the controllers are presented in time domains and frequency domains. The performances of control schemes are examined in terms of level of input tracking capability, sway angle reduction and time response specification.

  7. Relative alpha desynchronization and synchronization during speech perception.

    PubMed

    Krause, C M; Pörn, B; Lang, A H; Laine, M

    1997-06-01

    Brain processes elicited by speech were studied in 10 right-handed subjects by means of examining the desynchronization and synchronization of the 8-10 Hz and 10-12 Hz EEG alpha frequency bands. The subjects listened to an auditorily presented 5 min text passage. The text was presented both forward and backward. Listening to the text forward elicited alpha desynchronization in both of the frequency bands studied, whereas listening to the same text presented backward elicited synchronization in the 10-12 Hz frequency band only. Listening to the text forward elicited greater desynchronization than listening to the text backward. In the 10-12 Hz frequency band, listening to the text forward elicited desynchronization whereas listening to the same text backward elicited synchronization. This dissociation was not observed in the 8-10 Hz frequency band. The results suggest that the lower and upper alpha bands differ such that the 10-12 Hz frequency band exhibits reactivity to the presence of linguistic content while the 8-10 Hz band shows an unspecific response.

  8. Several CASE Lessons Can Improve Students' Control of Variables Reasoning Scheme Ability

    ERIC Educational Resources Information Center

    Babai, Reuven; Levit-Dori, Tamar

    2009-01-01

    This study addressed one aspect of scientific reasoning, the control of variables reasoning scheme. We explored whether a short intervention aimed at accelerating this reasoning scheme by CASE lessons would improve students' ability to apply this scheme in problems related to the biology curriculum. About 120 students from grade nine were assessed…

  9. Third-order 2N-storage Runge-Kutta schemes with error control

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Kennedy, Christopher A.

    1994-01-01

    A family of four-stage third-order explicit Runge-Kutta schemes is derived that requires only two storage locations and has desirable stability characteristics. Error control is achieved by embedding a second-order scheme within the four-stage procedure. Certain schemes are identified that are as efficient and accurate as conventional embedded schemes of comparable order and require fewer storage locations.

  10. A Rate Feedback Predictive Control Scheme Based on Neural Network and Control Theory for Autonomic Communication

    NASA Astrophysics Data System (ADS)

    Xiong, Naixue; Vasilakos, Athanasios V.; Yang, Laurence T.; Long, Fei; Shu, Lei; Li, Yingshu

    The main difficulty arising in designing an efficient congestion control scheme lies in the large propagation delay in data transfer which usually leads to a mismatch between the network resources and the amount of admitted traffic. To attack this problem, this chapter describes a novel congestion control scheme that is based on a Back Propagation (BP) neural network technique.We consider a general computer communication model with multiple sources and one destination node. The dynamic buffer occupancy of the bottleneck node is predicted and controlled by using a BP neural network. The controlled best-effort traffic of the sources uses the bandwidth, which is left over by the guaranteed traffic. This control mechanism is shown to be able to avoid network congestion efficiently and to optimize the transfer performance both by the theoretic analyzing procedures and by the simulation studies.

  11. RCRA ground-water monitoring decision procedures viewed as quality control schemes.

    PubMed

    Starks, T H; Flatman, G T

    1991-01-01

    The problems of developing and comparing statistical procedures appropriate to the monitoring of ground water at hazardous waste sites are discussed. It is suggested that these decision procedures should be viewed as quality control schemes and compared in the same way that industrial quality control schemes are compared. The results of a Monte Carlo simulation study of run-length distribution of a combined Shewhart-CUSUM quality control scheme are reported.

  12. Design principle of multi-cluster and desynchronized states in oscillatory media via nonlinear global feedback

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yasuaki; Kori, Hiroshi

    2009-03-01

    A theoretical framework is developed for the precise control of spatial patterns in oscillatory media using nonlinear global feedback, where a proper form of the feedback function corresponding to a specific pattern is predicted through the analysis of a phase diffusion equation with global coupling. In particular, feedback functions that generate the following spatial patterns are analytically given: (i) 2-cluster states with an arbitrary population ratio, (ii) equally populated multi-cluster states and (iii) a desynchronized state. Our method is demonstrated numerically by using the Brusselator model in the oscillatory regime. Experimental realization is also discussed.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  14. Internal desynchronization in a model of night-work by forced activity in rats.

    PubMed

    Salgado-Delgado, R; Angeles-Castellanos, M; Buijs, M R; Escobar, C

    2008-06-26

    Individuals engaged in shift- or night-work show disturbed diurnal rhythms, out of phase with temporal signals associated to the light/dark (LD) cycle, resulting in internal desynchronization. The mechanisms underlying internal desynchrony have been mainly investigated in experimental animals with protocols that induce phase shifts of the LD cycle and thus modify the activity of the suprachiasmatic nucleus (SCN). In this study we developed an animal model of night-work in which the light-day cycle remained stable and rats were required to be active in a rotating wheel for 8 h daily during their sleeping phase (W-SP). This group was compared with rats that were working in the wheel during their activity phase (W-AP) and with undisturbed rats (C). We provide evidence that forced activity during the sleeping phase (W-SP group) alters not only activity, but also the temporal pattern of food intake. In consequence W-SP rats showed a loss of glucose rhythmicity and a reversed rhythm of triacylglycerols. In contrast W-AP rats did not show such changes and exhibited metabolic rhythms similar to those of the controls. The three groups exhibited the nocturnal corticosterone increase, in addition the W-SP and W-AP groups showed increase of plasma corticosterone associated with the start of the working session. Forced activity during the sleep phase did not modify SCN activity characterized by the temporal patterns of PER1 and PER2 proteins, which remained in phase with the LD cycle. These observations indicate that a working regimen during the sleeping period elicits internal desynchronization in which activity combined with feeding uncouples metabolic functions from the biological clock which remains fixed to the LD cycle. The present data suggest that in the night worker the combination of work and eating during working hours may be the cause of internal desynchronization.

  15. Dissociation of circadian and light inhibition of melatonin release through forced desynchronization in the rat.

    PubMed

    Schwartz, Michael D; Wotus, Cheryl; Liu, Tiecheng; Friesen, W Otto; Borjigin, Jimo; Oda, Gisele A; de la Iglesia, Horacio O

    2009-10-13

    Pineal melatonin release exhibits a circadian rhythm with a tight nocturnal pattern. Melatonin synthesis is regulated by the master circadian clock within the hypothalamic suprachiasmatic nucleus (SCN) and is also directly inhibited by light. The SCN is necessary for both circadian regulation and light inhibition of melatonin synthesis and thus it has been difficult to isolate these two regulatory limbs to define the output pathways by which the SCN conveys circadian and light phase information to the pineal. A 22-h light-dark (LD) cycle forced desynchrony protocol leads to the stable dissociation of rhythmic clock gene expression within the ventrolateral SCN (vlSCN) and the dorsomedial SCN (dmSCN). In the present study, we have used this protocol to assess the pattern of melatonin release under forced desynchronization of these SCN subregions. In light of our reported patterns of clock gene expression in the forced desynchronized rat, we propose that the vlSCN oscillator entrains to the 22-h LD cycle whereas the dmSCN shows relative coordination to the light-entrained vlSCN, and that this dual-oscillator configuration accounts for the pattern of melatonin release. We present a simple mathematical model in which the relative coordination of a single oscillator within the dmSCN to a single light-entrained oscillator within the vlSCN faithfully portrays the circadian phase, duration and amplitude of melatonin release under forced desynchronization. Our results underscore the importance of the SCN's subregional organization to both photic input processing and rhythmic output control.

  16. Inter-hemispheric desynchronization of the human MT+ during visually induced motion sickness.

    PubMed

    Miyazaki, Jungo; Yamamoto, Hiroki; Ichimura, Yoshikatsu; Yamashiro, Hiroyuki; Murase, Tomokazu; Yamamoto, Tetsuya; Umeda, Masahiro; Higuchi, Toshihiro

    2015-08-01

    Visually induced motion sickness (VIMS) is triggered in susceptible individuals by stationary viewing of moving visual scenes. VIMS is often preceded by an illusion of self-motion (vection) and/or by inappropriate optokinetic nystagmus (OKN) responses associated with increased activity in the human motion-sensitive middle temporal area (MT+). Neuroimaging studies have reported predominant right hemispheric activation in MT+ during both vection and OKN, suggesting that VIMS may result from desynchronization of activity between left and right MT+ cortices. However, this possibility has not been directly tested. To this end, we presented VIMS-free and VIMS-inducing movies in that order while measuring the temporal correlations between corresponding left and right visual cortices (including MT+) using functional magnetic resonance imaging. The inter-hemispheric correlation was reduced significantly during the viewing of the VIMS-inducing movie compared to the control VIMS-free movie in the MT+ of subjects reporting VIMS, but not in insusceptible subjects. In contrast, there were no significant inter-hemispheric differences within VIMS-free or VIMS-inducing movie exposure for visual area V1, V2, V3, V3A or V7. Our findings provide the first evidence for an association between asynchronous bilateral MT+ activation and VIMS. Desynchronization of left and right MT+ regions may reflect hemispheric asymmetry in the activities of functional networks involved in eye movement control, vection perception and/or postural control. PMID:26014459

  17. Clustered Desynchronization from High-Frequency Deep Brain Stimulation.

    PubMed

    Wilson, Dan; Moehlis, Jeff

    2015-12-01

    While high-frequency deep brain stimulation is a well established treatment for Parkinson's disease, its underlying mechanisms remain elusive. Here, we show that two competing hypotheses, desynchronization and entrainment in a population of model neurons, may not be mutually exclusive. We find that in a noisy group of phase oscillators, high frequency perturbations can separate the population into multiple clusters, each with a nearly identical proportion of the overall population. This phenomenon can be understood by studying maps of the underlying deterministic system and is guaranteed to be observed for small noise strengths. When we apply this framework to populations of Type I and Type II neurons, we observe clustered desynchronization at many pulsing frequencies. PMID:26713619

  18. Symmetries, Cluster Synchronization, and Isolated Desynchronization in Complex Networks

    NASA Astrophysics Data System (ADS)

    Pecora, Louis

    2015-03-01

    Many networks are observed to produce patterns of synchronized clusters, but it has been difficult to predict these clusters in general or understand the conditions for their formation. We show the intimate connection between network symmetry and cluster synchronization. We apply computational group theory to reveal the clusters and determine their stability. In complex networks the symmetries can number in the millions, billions, and more. The connection between symmetry and cluster synchronization is experimentally explored using an electro-optic network. We observe and explain a surprising and common phenomenon (isolated desynchronization) in which some clusters lose synchrony while leaving others connected to them synchronized. We show the isolated desynchronization is intimately related to the decomposition of the group of symmetries into subgroups. The results could guide the design of new power grid systems or lead to new understanding of the dynamical behavior of networks ranging from neural to social.

  19. Clustered Desynchronization from High-Frequency Deep Brain Stimulation

    PubMed Central

    Wilson, Dan; Moehlis, Jeff

    2015-01-01

    While high-frequency deep brain stimulation is a well established treatment for Parkinson’s disease, its underlying mechanisms remain elusive. Here, we show that two competing hypotheses, desynchronization and entrainment in a population of model neurons, may not be mutually exclusive. We find that in a noisy group of phase oscillators, high frequency perturbations can separate the population into multiple clusters, each with a nearly identical proportion of the overall population. This phenomenon can be understood by studying maps of the underlying deterministic system and is guaranteed to be observed for small noise strengths. When we apply this framework to populations of Type I and Type II neurons, we observe clustered desynchronization at many pulsing frequencies. PMID:26713619

  20. Novel neural networks-based fault tolerant control scheme with fault alarm.

    PubMed

    Shen, Qikun; Jiang, Bin; Shi, Peng; Lim, Cheng-Chew

    2014-11-01

    In this paper, the problem of adaptive active fault-tolerant control for a class of nonlinear systems with unknown actuator fault is investigated. The actuator fault is assumed to have no traditional affine appearance of the system state variables and control input. The useful property of the basis function of the radial basis function neural network (NN), which will be used in the design of the fault tolerant controller, is explored. Based on the analysis of the design of normal and passive fault tolerant controllers, by using the implicit function theorem, a novel NN-based active fault-tolerant control scheme with fault alarm is proposed. Comparing with results in the literature, the fault-tolerant control scheme can minimize the time delay between fault occurrence and accommodation that is called the time delay due to fault diagnosis, and reduce the adverse effect on system performance. In addition, the FTC scheme has the advantages of a passive fault-tolerant control scheme as well as the traditional active fault-tolerant control scheme's properties. Furthermore, the fault-tolerant control scheme requires no additional fault detection and isolation model which is necessary in the traditional active fault-tolerant control scheme. Finally, simulation results are presented to demonstrate the efficiency of the developed techniques.

  1. A Quantum Proxy Weak Blind Signature Scheme Based on Controlled Quantum Teleportation

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Jing; Yu, Yao-Feng; Song, Qin; Gao, Lan-Xiang

    2014-09-01

    Proxy blind signature is applied to the electronic paying system, electronic voting system, mobile agent system, security of internet, etc. A quantum proxy weak blind signature scheme is proposed in this paper. It is based on controlled quantum teleportation. Five-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to implement message blinding, so it could guarantee not only the unconditional security of the scheme but also the anonymity of the messages owner.

  2. A Quantum Proxy Weak Blind Signature Scheme Based on Controlled Quantum Teleportation

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Jing; Yu, Yao-Feng; Song, Qin; Gao, Lan-Xiang

    2015-04-01

    Proxy blind signature is applied to the electronic paying system, electronic voting system, mobile agent system, security of internet, etc. A quantum proxy weak blind signature scheme is proposed in this paper. It is based on controlled quantum teleportation. Five-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to implement message blinding, so it could guarantee not only the unconditional security of the scheme but also the anonymity of the messages owner.

  3. Evaluation of ABR traffic control schemes for ATM LAN and WAN: effects of congestion indication schemes and ER switch algorithms

    NASA Astrophysics Data System (ADS)

    Moh, W. Melody; Shenoy, Sandeep

    1997-10-01

    The ATM Forum has adopted rate-based congestion control for ABR (available bit rate) traffic. Much of the existing work evaluating ABR congestion control schemes has used some threshold value on buffer queue length to indicate congestion. On the other hand, many ER (explicit rate) algorithms calculate their 'fair-share' values based on utilization level, with the assumption that ER switches are able to measure the current utilization level of ABR traffic. If one would use the same mechanism -- measuring utilization level -- to indicate congestion, then the same switch could easily implement both binary and ER ABR control algorithms. Based on the above observations, in this paper we study the effect of using two different congestion indication methods: (1) buffer queue length (the most commonly used method); and (2) utilization level (the new method). We evaluate two binary ABR control schemes: EFCI (explicit forward congestion indication) and CI (congestion indication) using backward notification, using the two different congestion methods. We also evaluate and compare two ER algorithms: the ERICA (explicit rate indication for congestion avoidance) algorithm proposed by Jain and the CAPC-2 (congestion avoidance with proportional control - 2) algorithm proposed by Barnhart. Performance evaluation are carried out by computer simulation. We simulate two ABR switches connected by an OC-3 link, with each switch connecting five end-systems. The distance between the two switches are 20 km for LAN and 1,000 km for WAN, based on ATM forum specification. For each simulation run, we measure average queuing delay, maximum queue length, and network utilization. Traces of ACR (allowed cell rate) and buffer queue length are also examined. We found that using the new congestion method indication dramatically reduces the maximum queue length and average queuing delay, with a slight decrease in utilization. Both ER schemes show smooth buffer occupancy and attain high utilization.

  4. Active control for drag reduction in turbulent channel flow: the opposition control schemes revisited

    NASA Astrophysics Data System (ADS)

    Wang, Yin-Shan; Huang, Wei-Xi; Xu, Chun-Xiao

    2016-10-01

    The opposition control schemes first proposed by Choi et al (1994 J. Fluid Mech. 262 75) employing wall-normal (v) and spanwise (w) velocity are revisited in the present study by performing direct numerical simulation to turbulent channel flow at R{e}τ = 180. Special attention is paid to the combined control, in which the wall-normal and spanwise velocities are imposed at the wall just instantaneously opposite to those at a small distance to the wall. In comparison to the v- and w-controls, combined-control could achieve the best drag reduction rate and control efficiency, with the greatest suppression of turbulence intensities. The influence of control on the statistical properties of vortices is scrutinized. By control, the numbers of vortices with every circulation and radius apparently decrease at the same normal location near the wall, while the vortex radius scaled by the actual wall-friction velocity almost remains the same. The streamwise vortices and the induced Reynolds shear stress undergo the greatest suppression by combined control. It is shown that combined control achieves a better efficacy, attributed to the co-work of the mechanisms of the v- and w-controls. At a higher Reynolds number R{e}τ = 1000, combined control is also more effective than v- and w-controls. The better suppression effect on the outer large scales is the primary reason for the larger drag reduction rate in combined control.

  5. Trajectory-probed instability and statistics of desynchronization events in coupled chaotic systems

    NASA Astrophysics Data System (ADS)

    de Oliveira, Gilson F.; Chevrollier, Martine; Passerat de Silans, Thierry; Oriá, Marcos; de Souza Cavalcante, Hugo L. D.

    2015-11-01

    Complex systems, such as financial markets, earthquakes, and neurological networks, exhibit extreme events whose mechanisms of formation are not still completely understood. These mechanisms may be identified and better studied in simpler systems with dynamical features similar to the ones encountered in the complex system of interest. For instance, sudden and brief departures from the synchronized state observed in coupled chaotic systems were shown to display non-normal statistical distributions similar to events observed in the complex systems cited above. The current hypothesis accepted is that these desynchronization events are influenced by the presence of unstable object(s) in the phase space of the system. Here, we present further evidence that the occurrence of large events is triggered by the visitation of the system's phase-space trajectory to the vicinity of these unstable objects. In the system studied here, this visitation is controlled by a single parameter, and we exploit this feature to observe the effect of the visitation rate in the overall instability of the synchronized state. We find that the probability of escapes from the synchronized state and the size of those desynchronization events are enhanced in attractors whose shapes permit the chaotic trajectories to approach the region of strong instability. This result shows that the occurrence of large events requires not only a large local instability to amplify noise, or to amplify the effect of parameter mismatch between the coupled subsystems, but also that the trajectories of the system wander close to this local instability.

  6. Trajectory-probed instability and statistics of desynchronization events in coupled chaotic systems

    SciTech Connect

    Oliveira, Gilson F. de Chevrollier, Martine; Oriá, Marcos; Passerat de Silans, Thierry; Souza Cavalcante, Hugo L. D. de

    2015-11-15

    Complex systems, such as financial markets, earthquakes, and neurological networks, exhibit extreme events whose mechanisms of formation are not still completely understood. These mechanisms may be identified and better studied in simpler systems with dynamical features similar to the ones encountered in the complex system of interest. For instance, sudden and brief departures from the synchronized state observed in coupled chaotic systems were shown to display non-normal statistical distributions similar to events observed in the complex systems cited above. The current hypothesis accepted is that these desynchronization events are influenced by the presence of unstable object(s) in the phase space of the system. Here, we present further evidence that the occurrence of large events is triggered by the visitation of the system's phase-space trajectory to the vicinity of these unstable objects. In the system studied here, this visitation is controlled by a single parameter, and we exploit this feature to observe the effect of the visitation rate in the overall instability of the synchronized state. We find that the probability of escapes from the synchronized state and the size of those desynchronization events are enhanced in attractors whose shapes permit the chaotic trajectories to approach the region of strong instability. This result shows that the occurrence of large events requires not only a large local instability to amplify noise, or to amplify the effect of parameter mismatch between the coupled subsystems, but also that the trajectories of the system wander close to this local instability.

  7. Relations between infants' emerging reach-grasp competence and event-related desynchronization in EEG.

    PubMed

    Cannon, Erin N; Simpson, Elizabeth A; Fox, Nathan A; Vanderwert, Ross E; Woodward, Amanda L; Ferrari, Pier F

    2016-01-01

    Recent reports of similar patterns of brain electrical activity (electroencephalogram: EEG) during action execution and observation, recorded from scalp locations over motor-related regions in infants and adults, have raised the possibility that two foundational abilities--controlling one's own intentional actions and perceiving others' actions--may be integrally related during ontogeny. However, to our knowledge, there are no published reports of the relations between developments in motor skill (i.e. recording actual motor skill performance) and EEG during both action execution and action observation. In the present study we collected EEG from 21 9-month-olds who were given opportunities to reach for toys and who also observed an experimenter reach for toys. Event-related desynchronization (ERD) was computed from the EEG during the reaching events. We assessed infants' reaching-grasping competence, including reach latency, errors, preshaping of the hand, and bimanual reaches, and found that desynchronization recorded in scalp electrodes over motor-related regions during action observation was associated with action competence during execution. Infants who were more competent reachers, compared to less competent reachers, exhibited greater ERD while observing reaching-grasping. These results provide initial evidence for an early emerging neural system integrating one's own actions with the perception of others' actions. PMID:25754667

  8. Regulation control and energy management scheme for wireless power transfer

    SciTech Connect

    Miller, John M.

    2015-12-29

    Power transfer rate at a charging facility can be maximized by employing a feedback scheme. The state of charge (SOC) and temperature of the regenerative energy storage system (RESS) pack of a vehicle is monitored to determine the load due to the RESS pack. An optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f.sub.0 of the grid converter output based on the resonance frequency of a magnetically coupled circuit. The optimal frequency can maximize the efficiency of the power transfer. Further, an optimal grid converter duty ratio d* can be derived from the charge rate of the RESS pack. The grid converter duty ratio d* regulates wireless power transfer (WPT) power level.

  9. Adaptive Numerical Dissipative Control in High Order Schemes for Multi-D Non-Ideal MHD

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Sjoegreen, B.

    2004-01-01

    The goal is to extend our adaptive numerical dissipation control in high order filter schemes and our new divergence-free methods for ideal MHD to non-ideal MHD that include viscosity and resistivity. The key idea consists of automatic detection of different flow features as distinct sensors to signal the appropriate type and amount of numerical dissipation/filter where needed and leave the rest of the region free of numerical dissipation contamination. These scheme-independent detectors are capable of distinguishing shocks/shears, flame sheets, turbulent fluctuations and spurious high-frequency oscillations. The detection algorithm is based on an artificial compression method (ACM) (for shocks/shears), and redundant multi-resolution wavelets (WAV) (for the above types of flow feature). These filter approaches also provide a natural and efficient way for the minimization of Div(B) numerical error. The filter scheme consists of spatially sixth order or higher non-dissipative spatial difference operators as the base scheme for the inviscid flux derivatives. If necessary, a small amount of high order linear dissipation is used to remove spurious high frequency oscillations. For example, an eighth-order centered linear dissipation (AD8) might be included in conjunction with a spatially sixth-order base scheme. The inviscid difference operator is applied twice for the viscous flux derivatives. After the completion of a full time step of the base scheme step, the solution is adaptively filtered by the product of a 'flow detector' and the 'nonlinear dissipative portion' of a high-resolution shock-capturing scheme. In addition, the scheme independent wavelet flow detector can be used in conjunction with spatially compact, spectral or spectral element type of base schemes. The ACM and wavelet filter schemes using the dissipative portion of a second-order shock-capturing scheme with sixth-order spatial central base scheme for both the inviscid and viscous MHD flux

  10. A contention-based bus-control scheme for multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Juang, Jie-Yong; Wah, Benjamin W.

    1991-01-01

    The authors study contention-based bus-control schemes for scheduling processors in using a bit-parallel shared bus. The protocol is designed under the requirements that each processor exhibit a random access behavior, that there be no centralized bus control in the system, and that access be granted in real time. The proposed scheme is based on splitting algorithms used in conventional contention-resolution schemes, and utilizes two-state information obtained from collision detection. Two versions of the bus-control scheme are studied. The static one resolves contentions of N requesting processors in an average of O(logW/2N) iterations, where W is the number of bits in the bit-parallel bus. An adaptive version resolves contentions in an average time that is independent of N.

  11. State of the art of control schemes for smart systems featuring magneto-rheological materials

    NASA Astrophysics Data System (ADS)

    Choi, Seung-Bok; Li, Weihua; Yu, Miao; Du, Haiping; Fu, Jie; Do, Phu Xuan

    2016-04-01

    This review presents various control strategies for application systems utilizing smart magneto-rheological fluid (MRF) and magneto-rheological elastomers (MRE). It is well known that both MRF and MRE are actively studied and applied to many practical systems such as vehicle dampers. The mandatory requirements for successful applications of MRF and MRE include several factors: advanced material properties, optimal mechanisms, suitable modeling, and appropriate control schemes. Among these requirements, the use of an appropriate control scheme is a crucial factor since it is the final action stage of the application systems to achieve the desired output responses. There are numerous different control strategies which have been applied to many different application systems of MRF and MRE, summarized in this review. In the literature review, advantages and disadvantages of each control scheme are discussed so that potential researchers can develop more effective strategies to achieve higher control performance of many application systems utilizing magneto-rheological materials.

  12. Broadband cortical desynchronization underlies the human psychedelic state.

    PubMed

    Muthukumaraswamy, Suresh D; Carhart-Harris, Robin L; Moran, Rosalyn J; Brookes, Matthew J; Williams, Tim M; Errtizoe, David; Sessa, Ben; Papadopoulos, Andreas; Bolstridge, Mark; Singh, Krish D; Feilding, Amanda; Friston, Karl J; Nutt, David J

    2013-09-18

    Psychedelic drugs produce profound changes in consciousness, but the underlying neurobiological mechanisms for this remain unclear. Spontaneous and induced oscillatory activity was recorded in healthy human participants with magnetoencephalography after intravenous infusion of psilocybin--prodrug of the nonselective serotonin 2A receptor agonist and classic psychedelic psilocin. Psilocybin reduced spontaneous cortical oscillatory power from 1 to 50 Hz in posterior association cortices, and from 8 to 100 Hz in frontal association cortices. Large decreases in oscillatory power were seen in areas of the default-mode network. Independent component analysis was used to identify a number of resting-state networks, and activity in these was similarly decreased after psilocybin. Psilocybin had no effect on low-level visually induced and motor-induced gamma-band oscillations, suggesting that some basic elements of oscillatory brain activity are relatively preserved during the psychedelic experience. Dynamic causal modeling revealed that posterior cingulate cortex desynchronization can be explained by increased excitability of deep-layer pyramidal neurons, which are known to be rich in 5-HT2A receptors. These findings suggest that the subjective effects of psychedelics result from a desynchronization of ongoing oscillatory rhythms in the cortex, likely triggered by 5-HT2A receptor-mediated excitation of deep pyramidal cells. PMID:24048847

  13. Broadband cortical desynchronization underlies the human psychedelic state.

    PubMed

    Muthukumaraswamy, Suresh D; Carhart-Harris, Robin L; Moran, Rosalyn J; Brookes, Matthew J; Williams, Tim M; Errtizoe, David; Sessa, Ben; Papadopoulos, Andreas; Bolstridge, Mark; Singh, Krish D; Feilding, Amanda; Friston, Karl J; Nutt, David J

    2013-09-18

    Psychedelic drugs produce profound changes in consciousness, but the underlying neurobiological mechanisms for this remain unclear. Spontaneous and induced oscillatory activity was recorded in healthy human participants with magnetoencephalography after intravenous infusion of psilocybin--prodrug of the nonselective serotonin 2A receptor agonist and classic psychedelic psilocin. Psilocybin reduced spontaneous cortical oscillatory power from 1 to 50 Hz in posterior association cortices, and from 8 to 100 Hz in frontal association cortices. Large decreases in oscillatory power were seen in areas of the default-mode network. Independent component analysis was used to identify a number of resting-state networks, and activity in these was similarly decreased after psilocybin. Psilocybin had no effect on low-level visually induced and motor-induced gamma-band oscillations, suggesting that some basic elements of oscillatory brain activity are relatively preserved during the psychedelic experience. Dynamic causal modeling revealed that posterior cingulate cortex desynchronization can be explained by increased excitability of deep-layer pyramidal neurons, which are known to be rich in 5-HT2A receptors. These findings suggest that the subjective effects of psychedelics result from a desynchronization of ongoing oscillatory rhythms in the cortex, likely triggered by 5-HT2A receptor-mediated excitation of deep pyramidal cells.

  14. Optimum management scheme to control nonpoint pollution in Korea.

    PubMed

    Hwang, D-H; Choi, J-Y

    2007-01-01

    Comprehensive measures to control nonpoint source were developed by the Office of the Prime Minister, Korea in March 2004. These management measures present the government's policies and directions relating to nonpoint source management by 2020. However, the government has encountered difficulties since the government implemented such policies without preparing legal and institutional arrangements associated with nonpoint source management practices. Particularly, there was no legal system to manage the workplaces and construction sites that discharge the polluted runoff. To provide legal arrangements to achieve efficient implementation of the government's nonpoint source management policies, amendments to the "Water Quality Preservation Act" were proposed in the congress in March 2005 and took effect from April 2006. Subsequently, the nationally mandated nonpoint source control system was to be applied to such industries and construction sites. This paper attempts to propose the scope of the nonpoint source control system and effective strategies applied to the construction sites and industrial workplaces in Korea.

  15. Adaptive fuzzy sliding mode control scheme for uncertain systems

    NASA Astrophysics Data System (ADS)

    Noroozi, Navid; Roopaei, Mehdi; Jahromi, M. Zolghadri

    2009-11-01

    Most physical systems inherently contain nonlinearities which are commonly unknown to the system designer. Therefore, in modeling and analysis of such dynamic systems, one needs to handle unknown nonlinearities and/or uncertain parameters. This paper proposes a new adaptive tracking fuzzy sliding mode controller for a class of nonlinear systems in the presence of uncertainties and external disturbances. The main contribution of the proposed method is that the structure of the controlled system is partially unknown and does not require the bounds of uncertainty and disturbance of the system to be known; meanwhile, the chattering phenomenon that frequently appears in the conventional variable structure systems is also eliminated without deteriorating the system robustness. The performance of the proposed approach is evaluated for two well-known benchmark problems. The simulation results illustrate the effectiveness of our proposed controller.

  16. Physical control oriented model of large scale refrigerators to synthesize advanced control schemes. Design, validation, and first control results

    SciTech Connect

    Bonne, François; Bonnay, Patrick

    2014-01-29

    In this paper, a physical method to obtain control-oriented dynamical models of large scale cryogenic refrigerators is proposed, in order to synthesize model-based advanced control schemes. These schemes aim to replace classical user experience designed approaches usually based on many independent PI controllers. This is particularly useful in the case where cryoplants are submitted to large pulsed thermal loads, expected to take place in the cryogenic cooling systems of future fusion reactors such as the International Thermonuclear Experimental Reactor (ITER) or the Japan Torus-60 Super Advanced Fusion Experiment (JT-60SA). Advanced control schemes lead to a better perturbation immunity and rejection, to offer a safer utilization of cryoplants. The paper gives details on how basic components used in the field of large scale helium refrigeration (especially those present on the 400W @1.8K helium test facility at CEA-Grenoble) are modeled and assembled to obtain the complete dynamic description of controllable subsystems of the refrigerator (controllable subsystems are namely the Joule-Thompson Cycle, the Brayton Cycle, the Liquid Nitrogen Precooling Unit and the Warm Compression Station). The complete 400W @1.8K (in the 400W @4.4K configuration) helium test facility model is then validated against experimental data and the optimal control of both the Joule-Thompson valve and the turbine valve is proposed, to stabilize the plant under highly variable thermals loads. This work is partially supported through the European Fusion Development Agreement (EFDA) Goal Oriented Training Program, task agreement WP10-GOT-GIRO.

  17. Physical control oriented model of large scale refrigerators to synthesize advanced control schemes. Design, validation, and first control results

    NASA Astrophysics Data System (ADS)

    Bonne, François; Alamir, Mazen; Bonnay, Patrick

    2014-01-01

    In this paper, a physical method to obtain control-oriented dynamical models of large scale cryogenic refrigerators is proposed, in order to synthesize model-based advanced control schemes. These schemes aim to replace classical user experience designed approaches usually based on many independent PI controllers. This is particularly useful in the case where cryoplants are submitted to large pulsed thermal loads, expected to take place in the cryogenic cooling systems of future fusion reactors such as the International Thermonuclear Experimental Reactor (ITER) or the Japan Torus-60 Super Advanced Fusion Experiment (JT-60SA). Advanced control schemes lead to a better perturbation immunity and rejection, to offer a safer utilization of cryoplants. The paper gives details on how basic components used in the field of large scale helium refrigeration (especially those present on the 400W @1.8K helium test facility at CEA-Grenoble) are modeled and assembled to obtain the complete dynamic description of controllable subsystems of the refrigerator (controllable subsystems are namely the Joule-Thompson Cycle, the Brayton Cycle, the Liquid Nitrogen Precooling Unit and the Warm Compression Station). The complete 400W @1.8K (in the 400W @4.4K configuration) helium test facility model is then validated against experimental data and the optimal control of both the Joule-Thompson valve and the turbine valve is proposed, to stabilize the plant under highly variable thermals loads. This work is partially supported through the European Fusion Development Agreement (EFDA) Goal Oriented Training Program, task agreement WP10-GOT-GIRO.

  18. Linear and Nonlinear Schemes Applied to Pitch Control of Wind Turbines

    PubMed Central

    Yang, Geng

    2014-01-01

    Linear controllers have been employed in industrial applications for many years, but sometimes they are noneffective on the system with nonlinear characteristics. This paper discusses the structure, performance, implementation cost, advantages, and disadvantages of different linear and nonlinear schemes applied to the pitch control of the wind energy conversion systems (WECSs). The linear controller has the simplest structure and is easily understood by the engineers and thus is widely accepted by the industry. In contrast, nonlinear schemes are more complicated, but they can provide better performance. Although nonlinear algorithms can be implemented in a powerful digital processor nowadays, they need time to be accepted by the industry and their reliability needs to be verified in the commercial products. More information about the system nonlinear feature is helpful to simplify the controller design. However, nonlinear schemes independent of the system model are more robust to the uncertainties or deviations of the system parameters. PMID:25295299

  19. Linear and nonlinear schemes applied to pitch control of wind turbines.

    PubMed

    Geng, Hua; Yang, Geng

    2014-01-01

    Linear controllers have been employed in industrial applications for many years, but sometimes they are noneffective on the system with nonlinear characteristics. This paper discusses the structure, performance, implementation cost, advantages, and disadvantages of different linear and nonlinear schemes applied to the pitch control of the wind energy conversion systems (WECSs). The linear controller has the simplest structure and is easily understood by the engineers and thus is widely accepted by the industry. In contrast, nonlinear schemes are more complicated, but they can provide better performance. Although nonlinear algorithms can be implemented in a powerful digital processor nowadays, they need time to be accepted by the industry and their reliability needs to be verified in the commercial products. More information about the system nonlinear feature is helpful to simplify the controller design. However, nonlinear schemes independent of the system model are more robust to the uncertainties or deviations of the system parameters. PMID:25295299

  20. Linear and nonlinear schemes applied to pitch control of wind turbines.

    PubMed

    Geng, Hua; Yang, Geng

    2014-01-01

    Linear controllers have been employed in industrial applications for many years, but sometimes they are noneffective on the system with nonlinear characteristics. This paper discusses the structure, performance, implementation cost, advantages, and disadvantages of different linear and nonlinear schemes applied to the pitch control of the wind energy conversion systems (WECSs). The linear controller has the simplest structure and is easily understood by the engineers and thus is widely accepted by the industry. In contrast, nonlinear schemes are more complicated, but they can provide better performance. Although nonlinear algorithms can be implemented in a powerful digital processor nowadays, they need time to be accepted by the industry and their reliability needs to be verified in the commercial products. More information about the system nonlinear feature is helpful to simplify the controller design. However, nonlinear schemes independent of the system model are more robust to the uncertainties or deviations of the system parameters.

  1. SLAC P2 Marx Control System and Regulation Scheme

    SciTech Connect

    MacNair, David; Kemp, Mark A.; Macken, Koen; Nguyen, Minh N.; Olsen, Jeff; /SLAC

    2011-05-20

    The SLAC P2 MARX Modulator consists of 32 cells charged in parallel by a -4 kV supply and discharged in series to provide a -120 kV 140 amp 1.7 millisecond pulse. Each cell has a 350 uF main storage capacitor. The voltage on the capacitor will droop approximately 640 volts during each pulse. Each cell will have a boost supply that can add up to 700 V to the cell output. This allows the output voltage of the cell to remain constant within 0.1% during the pulse. The modulator output voltage control is determined by the -4 kV charging voltage. A voltage divider will measure the modulator voltage on each pulse. The charging voltage will be adjusted by the data from previous pulses to provide the desired output. The boost supply in each cell consists of a 700 V buck regulator in series with the main capacitor. The supply uses a lookup table for PWM control. The lookup table is calculated from previous pulse data to provide a constant cell output. The paper will describe the modulator and cell regulation used by the MARX modulator. Measured data from a single cell and three cell string will be included.

  2. A study of multiple access schemes in satellite control network

    NASA Astrophysics Data System (ADS)

    Mo, Zijian; Wang, Zhonghai; Xiang, Xingyu; Wang, Gang; Chen, Genshe; Nguyen, Tien; Pham, Khanh; Blasch, Erik

    2016-05-01

    Satellite Control Networks (SCN) have provided launch control for space lift vehicles; tracking, telemetry and commanding (TTC) for on-orbit satellites; and, test support for space experiments since the 1960s. Currently, SCNs encounter a new challenge: how to maintain the high reliability of services when sharing the spectrum with emerging commercial services. To achieve this goal, the capability of multiple satellites reception is deserved as an update/modernization of SCN in the future. In this paper, we conducts an investigation of multiple access techniques in SCN scenario, e.g., frequency division multiple access (FDMA) and coded division multiple access (CDMA). First, we introduce two upgrade options of SCN based on FDMA and CDMA techniques. Correspondingly, we also provide their performance analysis, especially the system improvement in spectrum efficiency and interference mitigation. Finally, to determine the optimum upgrade option, this work uses CRISP, i.e., Cost, Risk, Installation, Supportability and Performance, as the baseline approach for a comprehensive trade study of these two options. Extensive numerical and simulation results are presented to illustrate the theoretical development.

  3. Adaptive control schemes for improving dynamic performance of efficiency-optimized induction motor drives.

    PubMed

    Kumar, Navneet; Raj Chelliah, Thanga; Srivastava, S P

    2015-07-01

    Model Based Control (MBC) is one of the energy optimal controllers used in vector-controlled Induction Motor (IM) for controlling the excitation of motor in accordance with torque and speed. MBC offers energy conservation especially at part-load operation, but it creates ripples in torque and speed during load transition, leading to poor dynamic performance of the drive. This study investigates the opportunity for improving dynamic performance of a three-phase IM operating with MBC and proposes three control schemes: (i) MBC with a low pass filter (ii) torque producing current (iqs) injection in the output of speed controller (iii) Variable Structure Speed Controller (VSSC). The pre and post operation of MBC during load transition is also analyzed. The dynamic performance of a 1-hp, three-phase squirrel-cage IM with mine-hoist load diagram is tested. Test results are provided for the conventional field-oriented (constant flux) control and MBC (adjustable excitation) with proposed schemes. The effectiveness of proposed schemes is also illustrated for parametric variations. The test results and subsequent analysis confer that the motor dynamics improves significantly with all three proposed schemes in terms of overshoot/undershoot peak amplitude of torque and DC link power in addition to energy saving during load transitions. PMID:25820090

  4. New scheme of variable optical buffer for IP packets used in access control of HORNET

    NASA Astrophysics Data System (ADS)

    Fang, Nian; Wang, Lutang; Huang, Zhaoming

    2002-09-01

    A new scheme of variable optical buffer for IP packets is reported. It may be used in access control of HORNET (Hybrid Optoelectronic Ring NETwork), to avoid collision of added packet and the packet already on the ring and improve the loss ratio of the packets. In this scheme, a new multi-wavelength fiber loop memory technique is employed. This architecture uses the wavelength converter (WC) to specify the packets delay and wavelength conversion is accomplished by the technique of four-wave-mixing (FWM) with a semiconductor optical amplifier (SOA). The range of delay is 10 to 9990 bytes periods. First, architecture, operation principle, characteristics and applications of this scheme of variable optical buffer are introduced. Next, a new unslotted CSMA/CA MAC scheme based on the variable optical buffer is briefly introduced too. Finally, the simulation results are presented.

  5. Remote automatic control scheme for plasma arc cutting of contaminated waste

    SciTech Connect

    Dudar, A.M.; Ward, C.R.; Kriikku, E.M.

    1993-10-01

    The Robotics Development Group at the Savannah River Technology Center has developed and implemented a scheme to perform automatic cutting of metallic contaminated waste. The scheme employs a plasma arc cutter in conjunction with a laser ranging sensor attached to a robotic manipulator called the Telerobot. A software algorithm using proportional control is then used to perturb the robot`s trajectory in such a way as to regulate the plasma arc standoff and the robot`s speed in order to achieve automatic plasma arc cuts. The scheme has been successfully tested on simulated waste materials and the results have been very favorable. This report details the development and testing of the scheme.

  6. A self-adjusting compliant bilateral control scheme for time-delay teleoperation in constrained environment

    NASA Astrophysics Data System (ADS)

    Chen, Zhang; Liang, Bin; Zhang, Tao

    2016-05-01

    When teleoperations are implemented in the constrained environment, the lack of environment information would lead to contacts and undesired excessive contact forces, which are more evident with the existence of time delays. In this paper, a hybrid compliant bilateral controller is proposed to deal with this problem. The controller adopts a self-adjusting selecting scheme to divide the subspaces online. The master and slave manipulators are synchronized in the position subspace through an adaptive bilateral control scheme. At the same time, the slave manipulator is controlled by a local sliding mode impedance controller in order to achieve the desired compliant motion when contacting with the environment. Theoretical analysis proves the stability of the hybrid bilateral controller and concludes the transient performance of the teleoperators. Simulations are carried out to verify the effectiveness of the proposed approach. The results show that the control goals are all achieved.

  7. Effects of chronic forced circadian desynchronization on body weight and metabolism in male mice.

    PubMed

    Casiraghi, Leandro P; Alzamendi, Ana; Giovambattista, Andrés; Chiesa, Juan J; Golombek, Diego A

    2016-04-01

    Metabolic functions are synchronized by the circadian clock setting daily patterns of food intake, nutrient delivery, and behavioral activity. Here, we study the impact of chronic jet-lag (CJL) on metabolism, and test manipulations aimed to overcome potential alterations. We recorded weight gain in C57Bl/6 mice under chronic 6 h advances or delays of the light-dark cycle every 2 days (ChrA and ChrD, respectively). We have previously reported ChrA, but not ChrD, to induce forced desynchronization of locomotor activity rhythms in mice (Casiraghi et al. 2012). Body weight was rapidly increased under ChrA, with animals tripling the mean weight gain observed in controls by day 10, and doubling it by day 30 (6% vs. 2%, and 15% vs. 7%, respectively). Significant increases in retroperitoneal and epidydimal adipose tissue masses (172% and 61%, respectively), adipocytes size (28%), and circulating triglycerides (39%) were also detected. Daily patterns of food and water intake were abolished under ChrA In contrast, ChrD had no effect on body weight. Wheel-running, housing of animals in groups, and restriction of food availability to hours of darkness prevented abnormal increase in body weight under ChrA Our findings suggest that the observed alterations under ChrA may arise either from a direct effect of circadian disruption on metabolism, from desynchronization between feeding and metabolic rhythms, or both. Direction of shifts, timing of feeding episodes, and other reinforcing signals deeply affect the outcome of metabolic function under CJL Such features should be taken into account in further studies of shift working schedules in humans. PMID:27125665

  8. Event-related desynchronization of frontal-midline theta rhythm during preconscious auditory oddball processing.

    PubMed

    Kawamata, Masaru; Kirino, Eiji; Inoue, Reiichi; Arai, Heii

    2007-10-01

    The goal of this study was to explore the frontal-midline theta rhythm (Fm theta) generation mechanism employing event-related desynchronization/synchronization (ERD/ERS) analysis in relation to task-irrelevant external stimuli. A dual paradigm was employed: a videogame and the simultaneous presentation of passive auditory oddball stimuli. We analyzed the data concerning ERD/ERS using both Fast Fourier Transformation (FFT) and wavelet transform (WT). In the FFT data, during the periods with appearance of Fm theta, apparent ERD of the theta band was observed at Fz and Cz. ERD when Fm theta was present was much more prominent than when Fm theta was absent. In the WT data, as in the FFT data, ERD was seen again, but in this case the ERD was preceded by ERS during both the periods with and without Fm theta. Furthermore, the WT analysis indicated that ERD was followed by ERS during the periods without Fm theta. However, during Fm theta, no apparent ERS following ERD was seen. In our study, Fm theta was desynchronized by the auditory stimuli that were independent of the video game task used to evoke the Fm theta. The ERD of Fm theta might be reflecting the mechanism of "positive suppression" to process external auditory stimuli automatically and preventing attentional resources from being unnecessarily allocated to those stimuli. Another possibility is that Fm theta induced by our dual paradigm may reflect information processing modeled by multi-item working memory requirements for playing the videogame and the simultaneous auditory processing using a memory trace. ERS in the WT data without Fm theta might indicate further processing of the auditory information free from "positive suppression" control reflected by Fm theta. PMID:17993201

  9. Taming desynchronized bursting with delays in the Macaque cortical network

    NASA Astrophysics Data System (ADS)

    Wang, Qing-Yun; Murks, Aleksandra; Perc, Matjaž; Lu, Qi-Shao

    2011-04-01

    Inhibitory coupled bursting Hindmarsh—Rose neurons are considered as constitutive units of the Macaque cortical network. In the absence of information transmission delay the bursting activity is desynchronized, giving rise to spatiotemporally disordered dynamics. This paper shows that the introduction of finite delays can lead to the synchronization of bursting and thus to the emergence of coherent propagating fronts of excitation in the space-time domain. Moreover, it shows that the type of synchronous bursting is uniquely determined by the delay length, with the transitions from one type to the other occurring in a step-like manner depending on the delay. Interestingly, as the delay is tuned close to the transition points, the synchronization deteriorates, which implies the coexistence of different bursting attractors. These phenomena can be observed by different but fixed coupling strengths, thus indicating a new role for information transmission delays in realistic neuronal networks.

  10. A Simulink Library of cryogenic components to automatically generate control schemes for large Cryorefrigerators

    NASA Astrophysics Data System (ADS)

    Bonne, François; Alamir, Mazen; Hoa, Christine; Bonnay, Patrick; Bon-Mardion, Michel; Monteiro, Lionel

    2015-12-01

    In this article, we present a new Simulink library of cryogenics components (such as valve, phase separator, mixer, heat exchanger...) to assemble to generate model-based control schemes. Every component is described by its algebraic or differential equation and can be assembled with others to build the dynamical model of a complete refrigerator or the model of a subpart of it. The obtained model can be used to automatically design advanced model based control scheme. It also can be used to design a model based PI controller. Advanced control schemes aim to replace classical user experience designed approaches usually based on many independent PI controllers. This is particularly useful in the case where cryoplants are submitted to large pulsed thermal loads, expected to take place in future fusion reactors such as those expected in the cryogenic cooling systems of the International Thermonuclear Experimental Reactor (ITER) or the Japan Torus-60 Super Advanced Fusion Experiment (JT- 60SA). The paper gives the example of the generation of the dynamical model of the 400W@1.8K refrigerator and shows how to build a Constrained Model Predictive Control for it. Based on the scheme, experimental results will be given. This work is being supported by the French national research agency (ANR) through the ANR-13-SEED-0005 CRYOGREEN program.

  11. Single Input Fuzzy Controller with Command Shaping Schemes for Double-Pendulum Overhead Crane

    NASA Astrophysics Data System (ADS)

    Ahmad, M. A.; Saealal, M. S.; Ismail, R. M. T. Raja; Zawawi, M. A.; Nasir, A. N. K.; Ramli, M. S.

    2011-06-01

    This paper presents investigations into the development of composite control schemes for trajectory tracking and anti-sway control of a double-pendulum-type overhead crane (DPTOC) system. A nonlinear DPTOC system is considered and the dynamic model of the system is derived using the Euler-Lagrange formulation. The proposed method, known as the Single Input Fuzzy Logic Controller (SIFLC), reduces the conventional two-input FLC (CFLC) to a single input single output (SISO) controller. The SIFLC is developed for position control of cart movement. This is then extended to incorporate input shaping schemes for anti-swaying control of the system. The input shapers with different mode selection are designed based on the properties of the system. The results of the response with the controllers are presented in time and frequency domains. The performances of control schemes are examined in terms of level of input tracking capability, sway angle reduction and time response specifications in comparison to SIFLC controller. Finally, a comparative assessment of the control techniques is discussed and presented.

  12. Study on protection scheme using SFCL for transmission system with Thyristor Controlled Series Capacitor

    NASA Astrophysics Data System (ADS)

    Huh, Jae-Sun; Moon, Won-Sik; Kim, Jae-Chul

    2015-11-01

    In this paper, we propose a protection scheme using a superconducting fault current limiter (SFCL) for the power transmission system with Thyristor Controlled Series Capacitor (TCSC). TCSC can lead effectiveness such as power flow control, increase in transmission capacity, and improvement for system transient phenomena. But, because this has same effect to the reducing series impedances in transmission system, there are serious problem such as increase in fault current, transient stability deterioration and series voltage stress of TCSC in the transmission line. The proposed protection scheme using the SFCL into TCSC configuration can mitigate these problems. In addition, SFCL can be expected to protect the TCSC from a large transient current generated by lightning or switching surge in power transmission system. To verify the effect of the proposed protection scheme, PSCAD/EMTDC is used. From simulation result, we had good results for fault current limitation and insulating protection of TCSC.

  13. Actuator fault tolerant multi-controller scheme using set separation based diagnosis

    NASA Astrophysics Data System (ADS)

    Seron, María M.; De Doná, José A.

    2010-11-01

    We present a fault tolerant control strategy based on a new principle for actuator fault diagnosis. The scheme employs a standard bank of observers which match the different fault situations that can occur in the plant. Each of these observers has an associated estimation error with distinctive dynamics when an estimator matches the current fault situation of the plant. Based on the information from each observer, a fault detection and isolation (FDI) module is able to reconfigure the control loop by selecting the appropriate control law from a bank of controllers, each of them designed to stabilise and achieve reference tracking for one of the given fault models. The main contribution of this article is to propose a new FDI principle which exploits the separation of sets that characterise healthy system operation from sets that characterise transitions from healthy to faulty behaviour. The new principle allows to provide pre-checkable conditions for guaranteed fault tolerance of the overall multi-controller scheme.

  14. An effective and secure key-management scheme for hierarchical access control in E-medicine system.

    PubMed

    Odelu, Vanga; Das, Ashok Kumar; Goswami, Adrijit

    2013-04-01

    Recently several hierarchical access control schemes are proposed in the literature to provide security of e-medicine systems. However, most of them are either insecure against 'man-in-the-middle attack' or they require high storage and computational overheads. Wu and Chen proposed a key management method to solve dynamic access control problems in a user hierarchy based on hybrid cryptosystem. Though their scheme improves computational efficiency over Nikooghadam et al.'s approach, it suffers from large storage space for public parameters in public domain and computational inefficiency due to costly elliptic curve point multiplication. Recently, Nikooghadam and Zakerolhosseini showed that Wu-Chen's scheme is vulnerable to man-in-the-middle attack. In order to remedy this security weakness in Wu-Chen's scheme, they proposed a secure scheme which is again based on ECC (elliptic curve cryptography) and efficient one-way hash function. However, their scheme incurs huge computational cost for providing verification of public information in the public domain as their scheme uses ECC digital signature which is costly when compared to symmetric-key cryptosystem. In this paper, we propose an effective access control scheme in user hierarchy which is only based on symmetric-key cryptosystem and efficient one-way hash function. We show that our scheme reduces significantly the storage space for both public and private domains, and computational complexity when compared to Wu-Chen's scheme, Nikooghadam-Zakerolhosseini's scheme, and other related schemes. Through the informal and formal security analysis, we further show that our scheme is secure against different attacks and also man-in-the-middle attack. Moreover, dynamic access control problems in our scheme are also solved efficiently compared to other related schemes, making our scheme is much suitable for practical applications of e-medicine systems.

  15. An effective and secure key-management scheme for hierarchical access control in E-medicine system.

    PubMed

    Odelu, Vanga; Das, Ashok Kumar; Goswami, Adrijit

    2013-04-01

    Recently several hierarchical access control schemes are proposed in the literature to provide security of e-medicine systems. However, most of them are either insecure against 'man-in-the-middle attack' or they require high storage and computational overheads. Wu and Chen proposed a key management method to solve dynamic access control problems in a user hierarchy based on hybrid cryptosystem. Though their scheme improves computational efficiency over Nikooghadam et al.'s approach, it suffers from large storage space for public parameters in public domain and computational inefficiency due to costly elliptic curve point multiplication. Recently, Nikooghadam and Zakerolhosseini showed that Wu-Chen's scheme is vulnerable to man-in-the-middle attack. In order to remedy this security weakness in Wu-Chen's scheme, they proposed a secure scheme which is again based on ECC (elliptic curve cryptography) and efficient one-way hash function. However, their scheme incurs huge computational cost for providing verification of public information in the public domain as their scheme uses ECC digital signature which is costly when compared to symmetric-key cryptosystem. In this paper, we propose an effective access control scheme in user hierarchy which is only based on symmetric-key cryptosystem and efficient one-way hash function. We show that our scheme reduces significantly the storage space for both public and private domains, and computational complexity when compared to Wu-Chen's scheme, Nikooghadam-Zakerolhosseini's scheme, and other related schemes. Through the informal and formal security analysis, we further show that our scheme is secure against different attacks and also man-in-the-middle attack. Moreover, dynamic access control problems in our scheme are also solved efficiently compared to other related schemes, making our scheme is much suitable for practical applications of e-medicine systems. PMID:23392626

  16. Neural Computation Scheme of Compound Control: Tacit Learning for Bipedal Locomotion

    NASA Astrophysics Data System (ADS)

    Shimoda, Shingo; Kimura, Hidenori

    The growing need for controlling complex behaviors of versatile robots working in unpredictable environment has revealed the fundamental limitation of model-based control strategy that requires precise models of robots and environments before their operations. This difficulty is fundamental and has the same root with the well-known frame problem in artificial intelligence. It has been a central long standing issue in advanced robotics, as well as machine intelligence, to find a prospective clue to attack this fundamental difficulty. The general consensus shared by many leading researchers in the related field is that the body plays an important role in acquiring intelligence that can conquer unknowns. In particular, purposeful behaviors emerge during body-environment interactions with the help of an appropriately organized neural computational scheme that can exploit what the environment can afford. Along this line, we propose a new scheme of neural computation based on compound control which represents a typical feature of biological controls. This scheme is based on classical neuron models with local rules that can create macroscopic purposeful behaviors. This scheme is applied to a bipedal robot and generates the rhythm of walking without any model of robot dynamics and environments.

  17. Upper alpha neurofeedback training over the motor cortex increases SMR desynchronization in motor tasks.

    PubMed

    López-Larraz, Eduardo; Escolano, Carlos; Minguez, Javier

    2012-01-01

    Desynchronization of sensorimotor rhythms (SMR) is a distinctive feature that provides a discriminative pattern for BCI operation. However, individuals such as BCI illiterates can not produce these discriminable patterns with sufficient reliability. Additionally, SMR desynchronization can become deteriorated or extinct in patients with spinal cord injury or a cerebrovascular accident. In all these situations BCI usage is compromised. This paper proposes an intervention based on neurofeedback training of the upper alpha band to improve SMR desynchronization. The feasibility of this intervention is demonstrated in a preliminary study in which five healthy subjects were trained to increase their upper alpha band power. Such increases produced higher SMR desynchronization and better discrimination between rest and execution states of a motor task.

  18. Two degree of freedom control scheme for unstable processes with small time delay.

    PubMed

    Ajmeri, Moina; Ali, Ahmad

    2015-05-01

    In this work, a recently reported two degree of freedom control structure namely the Parallel Control Structure (PCS) is modified to achieve improved control performance for unstable processes. New tuning rules are proposed using a direct synthesis approach for unstable first order plus time delay (UFOPTD), unstable second order plus time delay (USOPTD) and integrating and unstable plus time delay (IUPTD) process models. The proposed method has two tuning parameters whose suitable values are recommended after studying their effect on the system performance and robustness. This is an advantage of the present work over the other reported control schemes where the authors provide suitable ranges of the tuning parameters values. Simulation examples show that the present scheme results in improved nominal and perturbed responses as compared to the recently reported methods. Also it is observed that satisfactory performance is achieved when the proposed tuning rules are applied on an isothermal chemical reactor which exhibits multiple steady state solutions. PMID:25617941

  19. Simultaneous EEG-fMRI in patients with Unverricht-Lundborg disease: event-related desynchronization/synchronization and hemodynamic response analysis.

    PubMed

    Visani, Elisa; Minati, Ludovico; Canafoglia, Laura; Gilioli, Isabella; Salvatoni, Lucia; Varotto, Giulia; Fazio, Patrik; Aquino, Domenico; Bruzzone, Maria Grazia; Franceschetti, Silvana; Panzica, Ferruccio

    2010-01-01

    We performed simultaneous acquisition of EEG-fMRI in seven patients with Unverricht-Lundborg disease (ULD) and in six healthy controls using self-paced finger extension as a motor task. The event-related desynchronization/synchronization (ERD/ERS) analysis showed a greater and more diffuse alpha desynchronization in central regions and a strongly reduced post-movement beta-ERS in patients compared with controls, suggesting a significant dysfunction of the mechanisms regulating active movement and movement end. The event-related hemodynamic response obtained from fMRI showed delayed BOLD peak latency in the contralateral primary motor area suggesting a less efficient activity of the neuronal populations driving fine movements, which are specifically impaired in ULD. PMID:20111730

  20. Hierarchical Control Scheme for Improving Transient Voltage Recovery of a DFIG-Based WPP

    SciTech Connect

    Kim, Jinho; Muljadi, Eduard; Kang, Yong Cheol

    2015-06-05

    Modern grid codes require that wind power plants (WPPs) inject reactive power according to the voltage dip at a point of interconnection (POI). This requirement helps to support a POI voltage during a fault. However, if a fault is cleared, the POI and wind turbine generator (WTG) voltages are likely to exceed acceptable levels unless the WPP reduces the injected reactive power quickly. This might deteriorate the stability of a grid by allowing the disconnection of WTGs to avoid any damage. This paper proposes a hierarchical control scheme of a doubly-fed induction generator (DFIG)-based WPP. The proposed scheme aims to improve the reactive power injecting capability during the fault and suppress the overvoltage after the fault clearance. To achieve the former, an adaptive reactive power-to-voltage scheme is implemented in each DFIG controller so that a DFIG with a larger reactive power capability will inject more reactive power. To achieve the latter, a washout filter is used to capture a high frequency component contained in the WPP voltage, which is used to remove the accumulated values in the proportional-integral controllers. Test results indicate that the scheme successfully supports the grid voltage during the fault, and recovers WPP voltages without exceeding the limit after the fault clearance.

  1. Microscale position control of an electroactive polymer using an anti-windup scheme

    NASA Astrophysics Data System (ADS)

    Yun, Kwansoo; Kim, Won-jong

    2006-08-01

    Smart materials have been widely used for control actuation. In this paper, we present a microscale position control system using a novel electroactive polymer (EAP). We built a third-order model based on the system identification of the EAP actuator with an autoregressive moving average with exogenous input (ARMAX) method using a chirp signal input from 0.01 Hz to 1 Hz with the magnitude limited to ± 7 V. With the derived plant model, we designed a digital PID (proportional-integral-derivative) controller with an integrator anti-windup scheme. We provide test results on macro (0.8 mm) and micro (50 µm) step responses of the EAP actuator, and its position tracking capability is demonstrated. The overshoot decreased from 79.7% to 37.1% and the control effort decreased by 16.3%. The settling time decreased from 1.79 s to 1.61 s. The controller with the anti-windup scheme effectively reduced the degradation in the system performance due to actuator saturation. EAP microgrippers based on the control scheme presented in this paper will have significant applications including picking-and-placing micro-sized objects or as medical instruments.

  2. Baseline scheme for polarization preservation and control in the MEIC ion complex

    SciTech Connect

    Derbenev, Yaroslav S.; Lin, Fanglei; Morozov, Vasiliy; Zhang, Yuhong; Kondratenko, Anatoliy; Kondratenko, M. A.; Filatov, Yury

    2015-09-01

    The scheme for preservation and control of the ion polarization in the Medium-energy Electron-Ion Collider (MEIC) has been under active development in recent years. The figure-8 configuration of the ion rings provides a unique capability to control the polarization of any ion species including deuterons by means of "weak" solenoids rotating the particle spins by small angles. Insertion of "weak" solenoids into the magnetic lattices of the booster and collider rings solves the problem of polarization preservation during acceleration of the ion beam. Universal 3D spin rotators designed on the basis of "weak" solenoids allow one to obtain any polarization orientation at an interaction point of MEIC. This paper presents the baseline scheme for polarization preservation and control in the MEIC ion complex.

  3. Is event-related desynchronization a biomarker representing corticospinal excitability?

    PubMed

    Takemi, Mitsuaki; Masakado, Yoshihisa; Liu, Meigen; Ushiba, Junichi

    2013-01-01

    Brain computer interfaces (BCIs) using event-related desynchronization (ERD) of the electroencephalogram (EEG), which is believed to represent increased activation of the sensorimotor cortex, have attracted attention as tools for rehabilitation of upper limb motor functions in hemiplegic stroke patients. However, it remains unclear whether the corticospinal excitability is actually correlated with ERD. The purpose of this study was to assess the association between the ERD magnitude and the excitability of primary motor cortex (M1) and spinal motoneurons. M1 excitability was tested by motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) using transcranial magnetic stimulation, and spinal motoneuronal excitability was tested by F-waves using peripheral nerve stimulation. Results showed that large ERD during motor imagery was associated with significantly increased F-wave persistence and reduced SICI, but no significant changes in ICF and the response average of F-wave amplitudes. Our findings suggest that ERD magnitude during motor imagery represents the instantaneous excitability of both M1 and spinal motoneurons. This study provides electrophysiological evidence that ERD-based BCI with motor imagery task increases corticospinal excitability as changes accompanying actual movements.

  4. Synchronization and desynchronization in epilepsy: controversies and hypotheses

    PubMed Central

    Jiruska, Premysl; de Curtis, Marco; Jefferys, John G R; Schevon, Catherine A; Schiff, Steven J; Schindler, Kaspar

    2013-01-01

    Epilepsy has been historically seen as a functional brain disorder associated with excessive synchronization of large neuronal populations leading to a hypersynchronous state. Recent evidence showed that epileptiform phenomena, particularly seizures, result from complex interactions between neuronal networks characterized by heterogeneity of neuronal firing and dynamical evolution of synchronization. Desynchronization is often observed preceding seizures or during their early stages; in contrast, high levels of synchronization observed towards the end of seizures may facilitate termination. In this review we discuss cellular and network mechanisms responsible for such complex changes in synchronization. Recent work has identified cell-type-specific inhibitory and excitatory interactions, the dichotomy between neuronal firing and the non-local measurement of local field potentials distant to that firing, and the reflection of the neuronal dark matter problem in non-firing neurons active in seizures. These recent advances have challenged long-established views and are leading to a more rigorous and realistic understanding of the pathophysiology of epilepsy. PMID:23184516

  5. Movement-related event-related desynchronization in neuropsychiatric disorders.

    PubMed

    Leocani, Letizia; Comi, Giancarlo

    2006-01-01

    The analysis of event-related desynchronization (ERD) and event-related synchronization (ERS) provides information on the dynamics of cortical activation during cognitive and motor tasks and has been applied in a variety of neurological and psychiatric disorders. In this chapter, we focus on studies concerning movement-related activity, which showed changes in amount, topography, or time course in relation to not only involvement of the motor system--such as Parkinson's disease (PD), dystonia, and stroke affecting the sensorimotor (SM) pathways--but also physiological aging, degenerative dementia, obsessive-compulsive disorder (OCD), and fatigue associated with multiple sclerosis (MS). In these disorders, the extent of abnormality in the pattern of ERD/ERS is related to the severity of the underlying pathology. Moreover in MS, a correlation with the severity of brain tissue has been found. While there is consistency in changes related to ipokinetic disorders, mainly consisting of delayed appearance of ERD to movement preparation, changes occurring in other brain disorders need to be replicated or raise doubts on the specificity of changes across different diseases. Further studies are needed in order to validate the usefulness of this methodology in the assessment of the single patient for diagnosis and monitoring of the natural course of the disease and of treatment efficacy. PMID:17071242

  6. Using a Novel Wireless-Networked Decentralized Control Scheme under Unpredictable Environmental Conditions.

    PubMed

    Chang, Chung-Liang; Huang, Yi-Ming; Hong, Guo-Fong

    2015-01-01

    The direction of sunshine or the installation sites of environmental control facilities in the greenhouse result in different temperature and humidity levels in the various zones of the greenhouse, and thus, the production quality of crop is inconsistent. This study proposed a wireless-networked decentralized fuzzy control scheme to regulate the environmental parameters of various culture zones within a greenhouse. The proposed scheme can create different environmental conditions for cultivating different crops in various zones and achieve diversification or standardization of crop production. A star-type wireless sensor network is utilized to communicate with each sensing node, actuator node, and control node in various zones within the greenhouse. The fuzzy rule-based inference system is used to regulate the environmental parameters for temperature and humidity based on real-time data of plant growth response provided by a growth stage selector. The growth stage selector defines the control ranges of temperature and humidity of the various culture zones according to the leaf area of the plant, the number of leaves, and the cumulative amount of light. The experimental results show that the proposed scheme is stable and robust and provides basis for future greenhouse applications. PMID:26569264

  7. Using a Novel Wireless-Networked Decentralized Control Scheme under Unpredictable Environmental Conditions

    PubMed Central

    Chang, Chung-Liang; Huang, Yi-Ming; Hong, Guo-Fong

    2015-01-01

    The direction of sunshine or the installation sites of environmental control facilities in the greenhouse result in different temperature and humidity levels in the various zones of the greenhouse, and thus, the production quality of crop is inconsistent. This study proposed a wireless-networked decentralized fuzzy control scheme to regulate the environmental parameters of various culture zones within a greenhouse. The proposed scheme can create different environmental conditions for cultivating different crops in various zones and achieve diversification or standardization of crop production. A star-type wireless sensor network is utilized to communicate with each sensing node, actuator node, and control node in various zones within the greenhouse. The fuzzy rule-based inference system is used to regulate the environmental parameters for temperature and humidity based on real-time data of plant growth response provided by a growth stage selector. The growth stage selector defines the control ranges of temperature and humidity of the various culture zones according to the leaf area of the plant, the number of leaves, and the cumulative amount of light. The experimental results show that the proposed scheme is stable and robust and provides basis for future greenhouse applications. PMID:26569264

  8. A self-learning call admission control scheme for CDMA cellular networks.

    PubMed

    Liu, Derong; Zhang, Yi; Zhang, Huaguang

    2005-09-01

    In the present paper, a call admission control scheme that can learn from the network environment and user behavior is developed for code division multiple access (CDMA) cellular networks that handle both voice and data services. The idea is built upon a novel learning control architecture with only a single module instead of two or three modules in adaptive critic designs (ACDs). The use of adaptive critic approach for call admission control in wireless cellular networks is new. The call admission controller can perform learning in real-time as well as in offline environments and the controller improves its performance as it gains more experience. Another important contribution in the present work is the choice of utility function for the present self-learning control approach which makes the present learning process much more efficient than existing learning control methods. The performance of our algorithm will be shown through computer simulation and compared with existing algorithms. PMID:16252828

  9. An adaptive critic-based scheme for consensus control of nonlinear multi-agent systems

    NASA Astrophysics Data System (ADS)

    Heydari, Ali; Balakrishnan, S. N.

    2014-12-01

    The problem of decentralised consensus control of a network of heterogeneous nonlinear systems is formulated as an optimal tracking problem and a solution is proposed using an approximate dynamic programming based neurocontroller. The neurocontroller training comprises an initial offline training phase and an online re-optimisation phase to account for the fact that the reference signal subject to tracking is not fully known and available ahead of time, i.e., during the offline training phase. As long as the dynamics of the agents are controllable, and the communication graph has a directed spanning tree, this scheme guarantees the synchronisation/consensus even under switching communication topology and directed communication graph. Finally, an aerospace application is selected for the evaluation of the performance of the method. Simulation results demonstrate the potential of the scheme.

  10. Control scheme for power modulation of a free piston Stirling engine

    DOEpatents

    Dhar, Manmohan

    1989-01-01

    The present invention relates to a control scheme for power modulation of a free-piston Stirling engine-linear alternator power generator system. The present invention includes connecting an autotransformer in series with a tuning capacitance between a linear alternator and a utility grid to maintain a constant displacement to piston stroke ratio and their relative phase angle over a wide range of operating conditions.

  11. Numerical dissipation control in high order shock-capturing schemes for LES of low speed flows

    NASA Astrophysics Data System (ADS)

    Kotov, D. V.; Yee, H. C.; Wray, A. A.; Sjögreen, B.; Kritsuk, A. G.

    2016-02-01

    The Yee & Sjögreen adaptive numerical dissipation control in high order scheme (High Order Filter Methods for Wide Range of Compressible Flow Speeds, ICOSAHOM 09, 2009) is further improved for DNS and LES of shock-free turbulence and low speed turbulence with shocklets. There are vastly different requirements in the minimization of numerical dissipation for accurate turbulence simulations of different compressible flow types and flow speeds. Traditionally, the method of choice for shock-free turbulence and low speed turbulence are by spectral, high order central or high order compact schemes with high order linear filters. With a proper control of a local flow sensor, appropriate amount of numerical dissipation in high order shock-capturing schemes can have spectral-like accuracy for compressible low speed turbulent flows. The development of the method includes an adaptive flow sensor with automatic selection on the amount of numerical dissipation needed at each flow location for more accurate DNS and LES simulations with less tuning of parameters for flows with a wide range of flow speed regime during the time-accurate evolution, e.g., time varying random forcing. An automatic selection of the different flow sensors catered to the different flow types is constructed. A Mach curve and high-frequency oscillation indicators are used to reduce the tuning of parameters in controlling the amount of shock-capturing numerical dissipation to be employed for shock-free turbulence, low speed turbulence and turbulence with strong shocks. In Kotov et al. (High Order Numerical Methods for LES of Turbulent Flows with Shocks, ICCFD8, Chengdu, Sichuan, China, July 14-18, 2014) the LES of a turbulent flow with a strong shock by the Yee & Sjögreen scheme indicated a good agreement with the filtered DNS data. A work in progress for the application of the adaptive flow sensor for compressible turbulence with time-varying random forcing is forthcoming. The present study examines the

  12. Cortical Thinning in Healthy Aging Correlates with Larger Motor-Evoked EEG Desynchronization

    PubMed Central

    Provencher, David; Hennebelle, Marie; Cunnane, Stephen C.; Bérubé-Lauzière, Yves; Whittingstall, Kevin

    2016-01-01

    Although electroencephalography (EEG) is a valuable tool to investigate neural activity in patients and controls, exactly how local anatomy impacts the measured signal remains unclear. Better characterizing this relationship is important to improve the understanding of how inter-subject differences in the EEG signal are related to neural activity. We hypothesized that cortical structure might affect event-related desynchronization (ERD) in EEG. Since aging is a well-documented cause of cortical thinning, we investigated the effects of cortical thickness (CT) and cortical depth (CD – the skull-to-cortex distance) on ERD using anatomical MRI and motor-evoked EEG in 17 healthy young adults and 20 healthy older persons. Results showed a significant negative correlation between ERD and CT, but no consistent relationship between ERD and CD. A thinner cortex was associated with a larger ERD in the α/β band and correcting for CT removed most of the inter-group difference in ERD. This indicates that differences in neural activity might not be the primary cause for the observed aging-related differences in ERD, at least in the motor cortex. Further, it emphasizes the importance of considering conditions affecting the EEG signal, such as cortical anatomical changes due to aging, when interpreting differences between healthy controls and/or patients. PMID:27064767

  13. Farmer Attitudes and Livestock Disease: Exploring Citizenship Behaviour and Peer Monitoring across Two BVD Control Schemes in the UK.

    PubMed

    Heffernan, Claire; Azbel-Jackson, Lena; Brownlie, Joe; Gunn, George

    2016-01-01

    The eradication of BVD in the UK is technically possible but appears to be socially untenable. The following study explored farmer attitudes to BVD control schemes in relation to advice networks and information sharing, shared aims and goals, motivation and benefits of membership, notions of BVD as a priority disease and attitudes toward regulation. Two concepts from the organisational management literature framed the study: citizenship behaviour where actions of individuals support the collective good (but are not explicitly recognised as such) and peer to peer monitoring (where individuals evaluate other's behaviour). Farmers from two BVD control schemes in the UK participated in the study: Orkney Livestock Association BVD Eradication Scheme and Norfolk and Suffolk Cattle Breeders Association BVD Eradication Scheme. In total 162 farmers participated in the research (109 in-scheme and 53 out of scheme). The findings revealed that group helping and information sharing among scheme members was low with a positive BVD status subject to social censure. Peer monitoring in the form of gossip with regard to the animal health status of other farms was high. Interestingly, farmers across both schemes supported greater regulation with regard to animal health, largely due to the mistrust of fellow farmers following voluntary disease control measures. While group cohesiveness varied across the two schemes, without continued financial inducements, longer-term sustainability is questionable.

  14. Farmer Attitudes and Livestock Disease: Exploring Citizenship Behaviour and Peer Monitoring across Two BVD Control Schemes in the UK.

    PubMed

    Heffernan, Claire; Azbel-Jackson, Lena; Brownlie, Joe; Gunn, George

    2016-01-01

    The eradication of BVD in the UK is technically possible but appears to be socially untenable. The following study explored farmer attitudes to BVD control schemes in relation to advice networks and information sharing, shared aims and goals, motivation and benefits of membership, notions of BVD as a priority disease and attitudes toward regulation. Two concepts from the organisational management literature framed the study: citizenship behaviour where actions of individuals support the collective good (but are not explicitly recognised as such) and peer to peer monitoring (where individuals evaluate other's behaviour). Farmers from two BVD control schemes in the UK participated in the study: Orkney Livestock Association BVD Eradication Scheme and Norfolk and Suffolk Cattle Breeders Association BVD Eradication Scheme. In total 162 farmers participated in the research (109 in-scheme and 53 out of scheme). The findings revealed that group helping and information sharing among scheme members was low with a positive BVD status subject to social censure. Peer monitoring in the form of gossip with regard to the animal health status of other farms was high. Interestingly, farmers across both schemes supported greater regulation with regard to animal health, largely due to the mistrust of fellow farmers following voluntary disease control measures. While group cohesiveness varied across the two schemes, without continued financial inducements, longer-term sustainability is questionable. PMID:27023269

  15. Farmer Attitudes and Livestock Disease: Exploring Citizenship Behaviour and Peer Monitoring across Two BVD Control Schemes in the UK

    PubMed Central

    Heffernan, Claire; Azbel-Jackson, Lena; Brownlie, Joe; Gunn, George

    2016-01-01

    The eradication of BVD in the UK is technically possible but appears to be socially untenable. The following study explored farmer attitudes to BVD control schemes in relation to advice networks and information sharing, shared aims and goals, motivation and benefits of membership, notions of BVD as a priority disease and attitudes toward regulation. Two concepts from the organisational management literature framed the study: citizenship behaviour where actions of individuals support the collective good (but are not explicitly recognised as such) and peer to peer monitoring (where individuals evaluate other’s behaviour). Farmers from two BVD control schemes in the UK participated in the study: Orkney Livestock Association BVD Eradication Scheme and Norfolk and Suffolk Cattle Breeders Association BVD Eradication Scheme. In total 162 farmers participated in the research (109 in-scheme and 53 out of scheme). The findings revealed that group helping and information sharing among scheme members was low with a positive BVD status subject to social censure. Peer monitoring in the form of gossip with regard to the animal health status of other farms was high. Interestingly, farmers across both schemes supported greater regulation with regard to animal health, largely due to the mistrust of fellow farmers following voluntary disease control measures. While group cohesiveness varied across the two schemes, without continued financial inducements, longer-term sustainability is questionable. PMID:27023269

  16. Effect of acute exercise and cardiovascular fitness on cognitive function: an event-related cortical desynchronization study.

    PubMed

    Chang, Yu-Kai; Chu, Chien-Heng; Wang, Chun-Chih; Song, Tai-Fen; Wei, Gao-Xia

    2015-03-01

    This study aimed to clarify the effects of acute exercise and cardiovascular fitness on cognitive function using the Stroop test and event-related desynchronization (ERD) in an aged population. Old adults (63.10 ± 2.89 years) were first assigned to either a high-fitness or a low-fitness group, and they were then subjected to an acute exercise treatment and a reading control treatment in a counterbalanced order. Alpha ERD was recorded during the Stroop test, which was administered after both treatments. Acute exercise improved cognitive performance regardless of the level of cognition, and old adults with higher fitness levels received greater benefits from acute exercise. Additionally, acute exercise, rather than overall fitness, elicited greater lower and upper alpha ERDs relative to the control condition. These findings indirectly suggest that the beneficial effects of acute exercise on cognitive performance may result from exercise-induced attentional control observed during frontal neural excitation. PMID:25308605

  17. Effects of 6-Days Dry Immersion on Event-Related EEG Rhythm Desynchronization in the Antisaccadic Task

    NASA Astrophysics Data System (ADS)

    Kirenskaya, A.; Tomilovskaya, E.; Novototsky-Vlasov, V.; Kozlovskaya, I.

    2008-06-01

    The study was carried out in 12 volunteers with the right (RE group) and left (LE group) eye dominance. Participants performed antisaccades before and on 6th day of dry immersion (DI). The analysis of saccade characteristics and event-related desynchronization (ERD) was performed within theta, alpha, and beta bands. Certain increase of errors percent and saccade latencies was observed in DI in LE group but not in RE one. In control conditions two ERD foci were observed - in occipital and frontal areas, with maximal values in occipital areas in alpha range. ERD magnitude sharply decreased in both groups in DI. ERD amplitude was lower in LE group as compared to RE one under control and microgravity conditions, especially in right anterior regions in DI. The ERD magnitude decline may be interpreted as decrease of cortical activation level. Thus, cortical processes associated with saccadic control were greatly disturbed in microgravity in subjects with left eye dominance.

  18. PSO-tuned PID controller for coupled tank system via priority-based fitness scheme

    NASA Astrophysics Data System (ADS)

    Jaafar, Hazriq Izzuan; Hussien, Sharifah Yuslinda Syed; Selamat, Nur Asmiza; Abidin, Amar Faiz Zainal; Aras, Mohd Shahrieel Mohd; Nasir, Mohamad Na'im Mohd; Bohari, Zul Hasrizal

    2015-05-01

    The industrial applications of Coupled Tank System (CTS) are widely used especially in chemical process industries. The overall process is require liquids to be pumped, stored in the tank and pumped again to another tank. Nevertheless, the level of liquid in tank need to be controlled and flow between two tanks must be regulated. This paper presents development of an optimal PID controller for controlling the desired liquid level of the CTS. Two method of Particle Swarm Optimization (PSO) algorithm will be tested in optimizing the PID controller parameters. These two methods of PSO are standard Particle Swarm Optimization (PSO) and Priority-based Fitness Scheme in Particle Swarm Optimization (PFPSO). Simulation is conducted within Matlab environment to verify the performance of the system in terms of settling time (Ts), steady state error (SSE) and overshoot (OS). It has been demonstrated that implementation of PSO via Priority-based Fitness Scheme (PFPSO) for this system is potential technique to control the desired liquid level and improve the system performances compared with standard PSO.

  19. A closed-loop control scheme for steering steady states of glycolysis and glycogenolysis pathway.

    PubMed

    Panja, Surajit; Patra, Sourav; Mukherjee, Anirban; Basu, Madhumita; Sengupta, Sanghamitra; Dutta, Pranab K

    2013-01-01

    Biochemical networks normally operate in the neighborhood of one of its multiple steady states. It may reach from one steady state to other within a finite time span. In this paper, a closed-loop control scheme is proposed to steer states of the glycolysis and glycogenolysis (GG) pathway from one of its steady states to other. The GG pathway is modeled in the synergism and saturation system formalism, known as S-system. This S-system model is linearized into the controllable Brunovsky canonical form using a feedback linearization technique. For closed-loop control, the linear-quadratic regulator (LQR) and the linear-quadratic gaussian (LQG) regulator are invoked to design a controller for tracking prespecified steady states. In the feedback linearization technique, a global diffeomorphism function is proposed that facilitates in achieving the regulation requirement. The robustness of the regulated GG pathway is studied considering input perturbation and with measurement noise.

  20. Wavelet-based ECG data compression system with linear quality control scheme.

    PubMed

    Ku, Cheng-Tung; Hung, King-Chu; Wu, Tsung-Ching; Wang, Huan-Sheng

    2010-06-01

    Maintaining reconstructed signals at a desired level of quality is crucial for lossy ECG data compression. Wavelet-based approaches using a recursive decomposition process are unsuitable for real-time ECG signal recoding and commonly obtain a nonlinear compression performance with distortion sensitive to quantization error. The sensitive response is caused without compromising the influences of word-length-growth (WLG) effect and unfavorable for the reconstruction quality control of ECG data compression. In this paper, the 1-D reversible round-off nonrecursive discrete periodic wavelet transform is applied to overcome the WLG magnification effect in terms of the mechanisms of error propagation resistance and significant normalization of octave coefficients. The two mechanisms enable the design of a multivariable quantization scheme that can obtain a compression performance with the approximate characteristics of linear distortion. The quantization scheme can be controlled with a single control variable. Based on the linear compression performance, a linear quantization scale prediction model is presented for guaranteeing reconstruction quality. Following the use of the MIT-BIH arrhythmia database, the experimental results show that the proposed system, with lower computational complexity, can obtain much better reconstruction quality control than other wavelet-based methods.

  1. Rate control scheme for consistent video quality in scalable video codec.

    PubMed

    Seo, Chan-Won; Han, Jong-Ki; Nguyen, Truong Q

    2011-08-01

    Multimedia data delivered to mobile devices over wireless channels or the Internet are complicated by bandwidth fluctuation and the variety of mobile devices. Scalable video coding has been developed as an extension of H.264/AVC to solve this problem. Since scalable video codec provides various scalabilities to adapt the bitstream for the channel conditions and terminal types, scalable codec is one of the useful codecs for wired or wireless multimedia communication systems, such as IPTV and streaming services. In such scalable multimedia communication systems, video quality fluctuation degrades the visual perception significantly. It is important to efficiently use the target bits in order to maintain a consistent video quality or achieve a small distortion variation throughout the whole video sequence. The scheme proposed in this paper provides a useful function to control video quality in applications supporting scalability, whereas conventional schemes have been proposed to control video quality in the H.264 and MPEG-4 systems. The proposed algorithm decides the quantization parameter of the enhancement layer to maintain a consistent video quality throughout the entire sequence. The video quality of the enhancement layer is controlled based on a closed-form formula which utilizes the residual data and quantization error of the base layer. The simulation results show that the proposed algorithm controls the frame quality of the enhancement layer in a simple operation, where the parameter decision algorithm is applied to each frame.

  2. Robust fuzzy neural network sliding mode control scheme for IPMSM drives

    NASA Astrophysics Data System (ADS)

    Leu, V. Q.; Mwasilu, F.; Choi, H. H.; Lee, J.; Jung, J. W.

    2014-07-01

    This article proposes a robust fuzzy neural network sliding mode control (FNNSMC) law for interior permanent magnet synchronous motor (IPMSM) drives. The proposed control strategy not only guarantees accurate and fast command speed tracking but also it ensures the robustness to system uncertainties and sudden speed and load changes. The proposed speed controller encompasses three control terms: a decoupling control term which compensates for nonlinear coupling factors using nominal parameters, a fuzzy neural network (FNN) control term which approximates the ideal control components and a sliding mode control (SMC) term which is proposed to compensate for the errors of that approximation. Next, an online FNN training methodology, which is developed using the Lyapunov stability theorem and the gradient descent method, is proposed to enhance the learning capability of the FNN. Moreover, the maximum torque per ampere (MTPA) control is incorporated to maximise the torque generation in the constant torque region and increase the efficiency of the IPMSM drives. To verify the effectiveness of the proposed robust FNNSMC, simulations and experiments are performed by using MATLAB/Simulink platform and a TI TMS320F28335 DSP on a prototype IPMSM drive setup, respectively. Finally, the simulated and experimental results indicate that the proposed design scheme can achieve much better control performances (e.g. more rapid transient response and smaller steady-state error) when compared to the conventional SMC method, especially in the case that there exist system uncertainties.

  3. Quantifying Motor Experience in the Infant Brain: EEG Power, Coherence, and Mu Desynchronization

    PubMed Central

    Gonzalez, Sandy L.; Reeb-Sutherland, Bethany C.; Nelson, Eliza L.

    2016-01-01

    The emergence of new motor skills, such as reaching and walking, dramatically changes how infants engage with the world socially and cognitively. Several examples of how motor experience can cascade into cognitive and social development have been documented, yet a significant knowledge gap remains in our understanding of whether these observed behavioral changes are accompanied by underlying neural changes. We propose that electroencephalography (EEG) measures such as power, coherence, and mu desynchronization are optimal tools to quantify motor experience in the infant brain. In this mini-review, we will summarize existing infant research that has separately assessed the relation between motor, cognitive, or social development with coherence, power, or mu desynchronization. We will discuss how the reviewed neural changes seen in seemingly separate developmental domains may be linked based on existing behavioral evidence. We will further propose that power, coherence, and mu desynchronization be used in research exploring the links between motor experience and cognitive and social development. PMID:26925022

  4. Stream nitrogen sources apportionment and pollution control scheme development in an agricultural watershed in eastern China.

    PubMed

    Chen, Dingjiang; Lu, Jun; Huang, Hong; Liu, Mei; Gong, Dongqin; Chen, Jiabo

    2013-08-01

    A modeling system that couples a land-usebased export coefficient model, a stream nutrient transport equation, and Bayesian statistics was developed for stream nitrogen source apportionment. It divides a watershed into several sub-catchments, and then considers the major landuse categories as stream nitrogen sources in each subcatchment. The runoff depth and stream water depth are considered as the major factors influencing delivery of nitrogen from land to downstream stream node within each sub-catchment. The nitrogen sources and delivery processes are lumped into several constant parameters that were calibrated using Bayesian statistics from commonly available stream monitoring and land-use datasets. This modeling system was successfully applied to total nitrogen (TN) pollution control scheme development for the ChangLe River watershed containing six sub-catchments and four land-use categories. The temporal (across months and years) and spatial (across sub-catchments and land-use categories) variability of nonpoint source (NPS) TN export to stream channels and delivery to the watershed outlet were assessed. After adjustment for in-stream TNretention, the time periods and watershed areas with disproportionately high-TN contributions to the stream were identified. Aimed at a target stream TN level of 2 mg L-1, a quantitative TN pollution control scheme was further developed to determine which sub-catchments, which land-use categories in a sub-catchment, which time periods, and how large of NPS TN export reduction were required. This modeling system provides a powerful tool for stream nitrogen source apportionment and pollution control scheme development at the watershed scale and has only limited data requirements.

  5. Fountain code-based error control scheme for dimmable visible light communication systems

    NASA Astrophysics Data System (ADS)

    Feng, Lifang; Hu, Rose Qingyang; Wang, Jianping; Xu, Peng

    2015-07-01

    In this paper, a novel error control scheme using Fountain codes is proposed in on-off keying (OOK) based visible light communications (VLC) systems. By using Fountain codes, feedback information is needed to be sent back to the transmitter only when transmitted messages are successfully recovered. Therefore improved transmission efficiency, reduced protocol complexity and relative little wireless link-layer delay are gained. By employing scrambling techniques and complementing symbols, the least complemented symbols are needed to support arbitrary dimming target values, and the value of entropy of encoded message are increased.

  6. CCS_WHMS: A Congestion Control Scheme for Wearable Health Management System.

    PubMed

    Kafi, Mohamed Amine; Ben Othman, Jalel; Bagaa, Miloud; Badache, Nadjib

    2015-12-01

    Wearable computing is becoming a more and more attracting field in the last years thanks to the miniaturisation of electronic devices. Wearable healthcare monitoring systems (WHMS) as an important client of wearable computing technology has gained a lot. Indeed, the wearable sensors and their surrounding healthcare applications bring a lot of benefits to patients, elderly people and medical staff, so facilitating their daily life quality. But from a research point of view, there is still work to accomplish in order to overcome the gap between hardware and software parts. In this paper, we target the problem of congestion control when all these healthcare sensed data have to reach the destination in a reliable manner that avoids repetitive transmission which wastes precious energy or leads to loss of important information in emergency cases, too. We propose a congestion control scheme CCS_WHMS that ensures efficient and fair data delivery while used in the body wearable system part or in the multi-hop inter bodies wearable ones to get the destination. As the congestion detection paradigm is very important in the control process, we do experimental tests to compare between state of the art congestion detection methods, using MICAz motes, in order to choose the appropriate one for our scheme.

  7. Sliding mode based fault detection, reconstruction and fault tolerant control scheme for motor systems.

    PubMed

    Mekki, Hemza; Benzineb, Omar; Boukhetala, Djamel; Tadjine, Mohamed; Benbouzid, Mohamed

    2015-07-01

    The fault-tolerant control problem belongs to the domain of complex control systems in which inter-control-disciplinary information and expertise are required. This paper proposes an improved faults detection, reconstruction and fault-tolerant control (FTC) scheme for motor systems (MS) with typical faults. For this purpose, a sliding mode controller (SMC) with an integral sliding surface is adopted. This controller can make the output of system to track the desired position reference signal in finite-time and obtain a better dynamic response and anti-disturbance performance. But this controller cannot deal directly with total system failures. However an appropriate combination of the adopted SMC and sliding mode observer (SMO), later it is designed to on-line detect and reconstruct the faults and also to give a sensorless control strategy which can achieve tolerance to a wide class of total additive failures. The closed-loop stability is proved, using the Lyapunov stability theory. Simulation results in healthy and faulty conditions confirm the reliability of the suggested framework.

  8. Adaptive Numerical Dissipation Control in High Order Schemes for Multi-D Non-Ideal MHD

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Sjoegreen, B.

    2005-01-01

    The required type and amount of numerical dissipation/filter to accurately resolve all relevant multiscales of complex MHD unsteady high-speed shock/shear/turbulence/combustion problems are not only physical problem dependent, but also vary from one flow region to another. In addition, proper and efficient control of the divergence of the magnetic field (Div(B)) numerical error for high order shock-capturing methods poses extra requirements for the considered type of CPU intensive computations. The goal is to extend our adaptive numerical dissipation control in high order filter schemes and our new divergence-free methods for ideal MHD to non-ideal MHD that include viscosity and resistivity. The key idea consists of automatic detection of different flow features as distinct sensors to signal the appropriate type and amount of numerical dissipation/filter where needed and leave the rest of the region free from numerical dissipation contamination. These scheme-independent detectors are capable of distinguishing shocks/shears, flame sheets, turbulent fluctuations and spurious high-frequency oscillations. The detection algorithm is based on an artificial compression method (ACM) (for shocks/shears), and redundant multiresolution wavelets (WAV) (for the above types of flow feature). These filters also provide a natural and efficient way for the minimization of Div(B) numerical error.

  9. On the relationship between the local tracking procedures and monotonic schemes in quantum optimal control.

    PubMed

    Salomon, Julien; Turinici, Gabriel

    2006-02-21

    Numerical simulations of (bilinear) quantum control often rely on either monotonically convergent algorithms or tracking schemes. However, despite their mathematical simplicity, very limited intuitive understanding exists at this time to explain the former type of algorithms. Departing from the usual mathematical formalization, we present in this paper an interpretation of the monotonic algorithms as finite horizon, local in time, tracking schemes. Our purpose is not to present a new class of procedures but rather to introduce the necessary rigorous framework that supports this interpretation. As a by-product we show that at each instant, estimates of the future quality of the current control field are available and used in the optimization. When the target is expressed as reaching a prescribed final state, we also present an intuitive geometrical interpretation as the minimization of the distance between two correlated trajectories: one starting from the given initial state and the other backward in time from the target state. As an illustration, a stochastic monotonic algorithm is introduced. Numerical discretizations of the two procedures are also presented. PMID:16497025

  10. On the relationship between the local tracking procedures and monotonic schemes in quantum optimal control

    NASA Astrophysics Data System (ADS)

    Salomon, Julien; Turinici, Gabriel

    2006-02-01

    Numerical simulations of (bilinear) quantum control often rely on either monotonically convergent algorithms or tracking schemes. However, despite their mathematical simplicity, very limited intuitive understanding exists at this time to explain the former type of algorithms. Departing from the usual mathematical formalization, we present in this paper an interpretation of the monotonic algorithms as finite horizon, local in time, tracking schemes. Our purpose is not to present a new class of procedures but rather to introduce the necessary rigorous framework that supports this interpretation. As a by-product we show that at each instant, estimates of the future quality of the current control field are available and used in the optimization. When the target is expressed as reaching a prescribed final state, we also present an intuitive geometrical interpretation as the minimization of the distance between two correlated trajectories: one starting from the given initial state and the other backward in time from the target state. As an illustration, a stochastic monotonic algorithm is introduced. Numerical discretizations of the two procedures are also presented.

  11. Virtual Reality-based Telesurgery via Teleprogramming Scheme Combined with Semi-autonomous Control.

    PubMed

    Zhijiang, Du; Zhiheng, Jia; Minxiu, Kong

    2005-01-01

    Telesurgery systems have long been suffering variable and unpredictable Internet commutation time delay, operation fatigue, and other drawbacks. Based on virtual reality technology, a teleprogramming scheme combined with semi-autonomous control is introduced to guarantee the robustness and efficiency of teleoperation of HIT-RAOS, a robot-assisted orthopedic surgery system. In this system, without considering time delay, the operator can just interact with virtual environment which provides real-time 3D vision, stereophonic sound, and tactile and force feedback imitated by a parallel master manipulator. And several tasks can be managed simultaneously via semi-autonomous control. Finally, the method is experimentally demonstrated on an experiment of locking of intramedullary nails, and is shown to effectively provide stability and performances. PMID:17282656

  12. Virtual Reality-based Telesurgery via Teleprogramming Scheme Combined with Semi-autonomous Control.

    PubMed

    Zhijiang, Du; Zhiheng, Jia; Minxiu, Kong

    2005-01-01

    Telesurgery systems have long been suffering variable and unpredictable Internet commutation time delay, operation fatigue, and other drawbacks. Based on virtual reality technology, a teleprogramming scheme combined with semi-autonomous control is introduced to guarantee the robustness and efficiency of teleoperation of HIT-RAOS, a robot-assisted orthopedic surgery system. In this system, without considering time delay, the operator can just interact with virtual environment which provides real-time 3D vision, stereophonic sound, and tactile and force feedback imitated by a parallel master manipulator. And several tasks can be managed simultaneously via semi-autonomous control. Finally, the method is experimentally demonstrated on an experiment of locking of intramedullary nails, and is shown to effectively provide stability and performances.

  13. A novel walking speed estimation scheme and its application to treadmill control for gait rehabilitation

    PubMed Central

    2012-01-01

    Background Virtual reality (VR) technology along with treadmill training (TT) can effectively provide goal-oriented practice and promote improved motor learning in patients with neurological disorders. Moreover, the VR + TT scheme may enhance cognitive engagement for more effective gait rehabilitation and greater transfer to over ground walking. For this purpose, we developed an individualized treadmill controller with a novel speed estimation scheme using swing foot velocity, which can enable user-driven treadmill walking (UDW) to more closely simulate over ground walking (OGW) during treadmill training. OGW involves a cyclic acceleration-deceleration profile of pelvic velocity that contrasts with typical treadmill-driven walking (TDW), which constrains a person to walk at a preset constant speed. In this study, we investigated the effects of the proposed speed adaptation controller by analyzing the gait kinematics of UDW and TDW, which were compared to those of OGW at three pre-determined velocities. Methods Ten healthy subjects were asked to walk in each mode (TDW, UDW, and OGW) at three pre-determined speeds (0.5 m/s, 1.0 m/s, and 1.5 m/s) with real time feedback provided through visual displays. Temporal-spatial gait data and 3D pelvic kinematics were analyzed and comparisons were made between UDW on a treadmill, TDW, and OGW. Results The observed step length, cadence, and walk ratio defined as the ratio of stride length to cadence were not significantly different between UDW and TDW. Additionally, the average magnitude of pelvic acceleration peak values along the anterior-posterior direction for each step and the associated standard deviations (variability) were not significantly different between the two modalities. The differences between OGW and UDW and TDW were mainly in swing time and cadence, as have been reported previously. Also, step lengths between OGW and TDW were different for 0.5 m/s and 1.5 m/s gait velocities, and walk ratio

  14. Model assessment of atmospheric pollution control schemes for critical emission regions

    NASA Astrophysics Data System (ADS)

    Zhai, Shixian; An, Xingqin; Liu, Zhao; Sun, Zhaobin; Hou, Qing

    2016-01-01

    In recent years, the atmospheric environment in portions of China has become significantly degraded and the need for emission controls has become urgent. Because more international events are being planned, it is important to implement air quality assurance targeted at significant events held over specific periods of time. This study sets Yanqihu (YQH), Beijing, the location of the 2014 Beijing APEC (Asia-Pacific Economic Cooperation) summit, as the target region. By using the atmospheric inversion model FLEXPART, we determined the sensitive source zones that had the greatest impact on the air quality of the YQH region in November 2012. We then used the air-quality model Models-3/CMAQ and a high-resolution emissions inventory of the Beijing-Tianjian-Hebei region to establish emission reduction tests for the entire source area and for specific sensitive source zones. This was achieved by initiating emission reduction schemes at different ratios and different times. The results showed that initiating a moderate reduction of emissions days prior to a potential event is more beneficial to the air quality of Beijing than initiating a high-strength reduction campaign on the day of the event. The sensitive source zone of Beijing (BJ-Sens) accounts for 54.2% of the total source area of Beijing (BJ), but its reduction effect reaches 89%-100% of the total area, with a reduction efficiency 1.6-1.9 times greater than that of the entire area. The sensitive source zone of Huabei (HuaB-Sens.) only represents 17.6% of the total area of Huabei (HuaB), but its emission reduction effect reaches 59%-97% of the entire area, with a reduction efficiency 4.2-5.5 times greater than that of the total area. The earlier that emission reduction measures are implemented, the greater the effect they have on preventing the transmission of pollutants. In addition, expanding the controlling areas to sensitive provinces and cities around Beijing (HuaB-sens) can significantly accelerate the reduction

  15. Effect of synchronized or desynchronized music listening during osteopathic treatment: an EEG study.

    PubMed

    Mercadié, Lolita; Caballe, Julie; Aucouturier, Jean-Julien; Bigand, Emmanuel

    2014-01-01

    While background music is often used during osteopathic treatment, it remains unclear whether it facilitates treatment, and, if it does, whether it is listening to music or jointly listening to a common stimulus that is most important. We created three experimental situations for a standard osteopathic procedure in which patients and practitioner listened either to silence, to the same music in synchrony, or (unknowingly) to different desynchronized montages of the same material. Music had no effect on heart rate and arterial pressure pre- and posttreatment compared to silence, but EEG measures revealed a clear effect of synchronized versus desynchronized listening: listening to desynchronized music was associated with larger amounts of mu-rhythm event-related desynchronization (ERD), indicating decreased sensorimotor fluency compared to what was gained in the synchronized music listening condition. This result suggests that, if any effect can be attributed to music for osteopathy, it is related to its capacity to modulate empathy between patient and therapist and, further, that music does not systematically create better conditions for empathy than silence.

  16. Desynchronization of epileptiform activity by extracellular current pulses in rat hippocampal slices.

    PubMed Central

    Durand, D M; Warman, E N

    1994-01-01

    1. A single cathodic current pulse applied in the somatic CA1 region of the hippocampus was found to induce a large decrease in the amplitude of the population spike. 2. Intracellular recordings showed intense cellular firing suggesting the amplitude decrease could not be attributed to a decrease in neuronal firing. 3. Simultaneous intracellular and extracellular potentials were recorded to analyse the synchronization of neuronal firing in the CA1 region. Action potentials were synchronized with the first population spike but this synchronization decreased with subsequent spikes. Histograms of the phase of the action potentials displayed a normal distribution. 4. Histograms of the phases of the action potentials following the application of the 'singular stimulus' (one producing a singular response) revealed a uniform distribution of the phases suggesting that the neuronal population was desynchronized. 5. This desynchronization effect of the singular stimulus was verified by double intracellular recordings. The simultaneous firing of two neurons could be desynchronized by the application of the singular stimulus. 6. These findings indicate that it is possible to desynchronize a neuronal pool with the application of a single current pulse. In addition, the results show that it is possible for a neuronal population to fire a large number of action potentials with no resulting evoked potentials in the extracellular space. Images Figure 2 Figure 4 Figure 7 Figure 8 PMID:7869266

  17. Motion control of nonlinear gantry crane system via priority-based fitness scheme in firefly algorithm

    NASA Astrophysics Data System (ADS)

    Jaafar, Hazriq Izzuan; Latif, Norfaneysa Abd; Kassim, Anuar Mohamed; Abidin, Amar Faiz Zainal; Hussien, Sharifah Yuslinda Syed; Aras, Mohd Shahrieel Mohd

    2015-05-01

    Advanced manufacturing technology made Gantry Crane System (GCS) is one of the suitable heavy machinery transporters and frequently employed in handling with huge materials. The interconnection of trolley movement and payload oscillation has a technical impact which needs to be considered. Once the trolley moves to the desired position with high speed, this will induce undesirable's payload oscillation. This frequent unavoidable load swing causes an efficiency drop, load damages and even accidents. In this paper, a new control strategy of Firefly Algorithm (FA) will be developed to obtain five optimal controller parameters (PID and PD) via Priority-based Fitness Scheme (PFS). Combinations of these five parameters are utilized for controlling trolley movement and minimizing the angle of payload oscillation. This PFS is prioritized based on steady-state error (SSE), overshoot (OS) and settling time (Ts) according to the needs and circumstances. Lagrange equation will be chosen for modeling and simulation will be conducted by using related software. Simulation results show that the proposed control strategy is efficient to control the trolley movement to the desired position and minimize the angle of payload oscillation.

  18. Definition of a Robust Supervisory Control Scheme for Sodium-Cooled Fast Reactors

    SciTech Connect

    Ponciroli, Roberto; Passerini, Stefano; Vilim, Richard B.

    2016-01-01

    In this work, an innovative control approach for metal-fueled Sodium-cooled Fast Reactors is proposed. With respect to the classical approach adopted for base-load Nuclear Power Plants, an alternative control strategy for operating the reactor at different power levels by respecting the system physical constraints is presented. In order to achieve a higher operational flexibility along with ensuring that the implemented control loops do not influence the system inherent passive safety features, a dedicated supervisory control scheme for the dynamic definition of the corresponding set-points to be supplied to the PID controllers is designed. In particular, the traditional approach based on the adoption of tabulated lookup tables for the set-point definition is found not to be robust enough when failures of the implemented SISO (Single Input Single Output) actuators occur. Therefore, a feedback algorithm based on the Reference Governor approach, which allows for the optimization of reference signals according to the system operating conditions, is proposed.

  19. An Improved Call Admission Control Mechanism with Prioritized Handoff Queuing Scheme for BWA Networks

    NASA Astrophysics Data System (ADS)

    Chowdhury, Prasun; Saha Misra, Iti

    2014-10-01

    Nowadays, due to increased demand for using the Broadband Wireless Access (BWA) networks in a satisfactory manner a promised Quality of Service (QoS) is required to manage the seamless transmission of the heterogeneous handoff calls. To this end, this paper proposes an improved Call Admission Control (CAC) mechanism with prioritized handoff queuing scheme that aims to reduce dropping probability of handoff calls. Handoff calls are queued when no bandwidth is available even after the allowable bandwidth degradation of the ongoing calls and get admitted into the network when an ongoing call is terminated with a higher priority than the newly originated call. An analytical Markov model for the proposed CAC mechanism is developed to analyze various performance parameters. Analytical results show that our proposed CAC with handoff queuing scheme prioritizes the handoff calls effectively and reduces dropping probability of the system by 78.57% for real-time traffic without degrading the number of failed new call attempts. This results in the increased bandwidth utilization of the network.

  20. New synchronization criteria for memristor-based networks: adaptive control and feedback control schemes.

    PubMed

    Li, Ning; Cao, Jinde

    2015-01-01

    In this paper, we investigate synchronization for memristor-based neural networks with time-varying delay via an adaptive and feedback controller. Under the framework of Filippov's solution and differential inclusion theory, and by using the adaptive control technique and structuring a novel Lyapunov functional, an adaptive updated law was designed, and two synchronization criteria were derived for memristor-based neural networks with time-varying delay. By removing some of the basic literature assumptions, the derived synchronization criteria were found to be more general than those in existing literature. Finally, two simulation examples are provided to illustrate the effectiveness of the theoretical results.

  1. New synchronization criteria for memristor-based networks: adaptive control and feedback control schemes.

    PubMed

    Li, Ning; Cao, Jinde

    2015-01-01

    In this paper, we investigate synchronization for memristor-based neural networks with time-varying delay via an adaptive and feedback controller. Under the framework of Filippov's solution and differential inclusion theory, and by using the adaptive control technique and structuring a novel Lyapunov functional, an adaptive updated law was designed, and two synchronization criteria were derived for memristor-based neural networks with time-varying delay. By removing some of the basic literature assumptions, the derived synchronization criteria were found to be more general than those in existing literature. Finally, two simulation examples are provided to illustrate the effectiveness of the theoretical results. PMID:25299765

  2. Design and implementation of adaptive PI control schemes for web tension control in roll-to-roll (R2R) manufacturing.

    PubMed

    Raul, Pramod R; Pagilla, Prabhakar R

    2015-05-01

    In this paper, two adaptive Proportional-Integral (PI) control schemes are designed and discussed for control of web tension in Roll-to-Roll (R2R) manufacturing systems. R2R systems are used to transport continuous materials (called webs) on rollers from the unwind roll to the rewind roll. Maintaining web tension at the desired value is critical to many R2R processes such as printing, coating, lamination, etc. Existing fixed gain PI tension control schemes currently used in industrial practice require extensive tuning and do not provide the desired performance for changing operating conditions and material properties. The first adaptive PI scheme utilizes the model reference approach where the controller gains are estimated based on matching of the actual closed-loop tension control systems with an appropriately chosen reference model. The second adaptive PI scheme utilizes the indirect adaptive control approach together with relay feedback technique to automatically initialize the adaptive PI gains. These adaptive tension control schemes can be implemented on any R2R manufacturing system. The key features of the two adaptive schemes is that their designs are simple for practicing engineers, easy to implement in real-time, and automate the tuning process. Extensive experiments are conducted on a large experimental R2R machine which mimics many features of an industrial R2R machine. These experiments include trials with two different polymer webs and a variety of operating conditions. Implementation guidelines are provided for both adaptive schemes. Experimental results comparing the two adaptive schemes and a fixed gain PI tension control scheme used in industrial practice are provided and discussed.

  3. Intermittent spatio-temporal desynchronization and sequenced synchrony in ECoG signals

    NASA Astrophysics Data System (ADS)

    Kozma, Robert; Freeman, Walter J.

    2008-09-01

    Electrocorticographic (ECoG) signals from the brain surface typically exhibit high synchrony across large cortical areas, interrupted by brief periods of desynchronization exhibiting propagating phase discontinuities, across which spatial patterns of phase emerge in selected frequency bands. Experiments with rabbits trained using classical conditioning paradigms indicated that such desynchronization periods demarcate cognitive processing in the subjects; the ECoG in the frames between such periods revealed spatial patterns of amplitude modulation that were classified with respect to sensory stimuli that the rabbits had been trained to recognize. The present work describes intermittent synchrony and desynchronization of ECoG signals measured over the visual cortex. We analyze the analytic amplitude (AA) and analytic phase (AP) of the signals bandpassed over the beta band (12.5-25Hz) and theta band (3-7Hz) using the Hilbert transform. The AP of analytic signals evaluated using a Shannon-based synchronization index in theta band exhibits phase synchronization for varying time periods averaging about 1s, interrupted by desynchronization periods of duration about 0.1s. Synchronization periods in the beta-band last <100ms, with interruptions by desynchronization lasting one-tenth that, in which the analytic amplitude drops drastically. During these "null spikes," the analytic phase is undefined, and the spatial and temporal phase differences show high dispersion. Detailed examination of the bandpass filtered ECoG confirms the presence of a shared mean frequency in a frame of synchronized oscillation, at which frequency the spatial pattern of the AP has the form of a cone. Between frames the AA approaches zero. The form of the null spike resembles a tornado (a vortex), as shown in sequential frames by a rotating spatial pattern of amplitude in the filtered ECoG.

  4. New MHD feedback control schemes using the MARTe framework in RFX-mod

    NASA Astrophysics Data System (ADS)

    Piron, Chiara; Manduchi, Gabriele; Marrelli, Lionello; Piovesan, Paolo; Zanca, Paolo

    2013-10-01

    Real-time feedback control of MHD instabilities is a topic of major interest in magnetic thermonuclear fusion, since it allows to optimize a device performance even beyond its stability bounds. The stability properties of different magnetic configurations are important test benches for real-time control systems. RFX-mod, a Reversed Field Pinch experiment that can also operate as a tokamak, is a well suited device to investigate this topic. It is equipped with a sophisticated magnetic feedback system that controls MHD instabilities and error fields by means of 192 active coils and a corresponding grid of sensors. In addition, the RFX-mod control system has recently gained new potentialities thanks to the introduction of the MARTe framework and of a new CPU architecture. These capabilities allow to study new feedback algorithms relevant to both RFP and tokamak operation and to contribute to the debate on the optimal feedback strategy. This work focuses on the design of new feedback schemes. For this purpose new magnetic sensors have been explored, together with new algorithms that refine the de-aliasing computation of the radial sideband harmonics. The comparison of different sensor and feedback strategy performance is described in both RFP and tokamak experiments.

  5. A Novel Current Angle Control Scheme in a Current Source Inverter Fed Permanent Magnet Synchronous Motor Drive for Automotive Applications

    SciTech Connect

    Tang, Lixin; Su, Gui-Jia

    2011-01-01

    This paper describes a novel speed control scheme to operate a current source inverter (CSI) driven surface-mounted permanent magnet synchronous machine (SPMSM) for hybrid electric vehicles (HEVs) applications. The idea is to use the angle of the current vector to regulate the rotor speed while keeping the two dc-dc converter power switches on all the time to boost system efficiency. The effectiveness of the proposed scheme was verified with a 3 kW CSI-SPMSM drive prototype.

  6. Exploring efficiencies of SISO, multi-SISO, and MIMO AVC schemes for floor vibration control

    NASA Astrophysics Data System (ADS)

    Nyawako, Donald S.; Reynolds, Paul; Hudson, Malcolm J.

    2012-04-01

    Continued advancements in steel and concrete materials as well as improved computer-optimized designs are resulting in more efficient floor structures, which have longer spans and are more lightweight. In addition, there is a tendency for offices to be more open-plan with fewer internal partitions. These structures possess low and closely spaced natural frequencies, sometimes falling within the range of frequencies produced by human activities, as well as low damping levels. Vibration serviceability problems are thus arising more frequently than before. The tendency for developers to require floor structures suitable for a variety of types of occupation so as to increase their economic viability also has clear ramifications for their vibration serviceability. Active vibration control (AVC) is emerging as a viable technology for mitigation of human-induced vibrations in problem floors. Past AVC research work, as demonstrated in analytical studies and successfully implemented in field trials, have focused predominantly on collocated sensor and actuator pairs in SISO or multi-SISO direct-output feedback schemes, for example, direct velocity feedback (DVF). This paper demonstrates the potential benefits that may be derived from using model-based control approaches, for example, in isolating and controlling specific problematic frequencies only. The approaches investigated here comprise of independent modal space control (IMSC) and pole-placement controllers that are implemented in SISO, SIMO, and MIMO control structures. Both the analytical and experimental studies presented are based on a laboratory structure. Attenuations in target modes of vibration ranged between 15.0-27.0 dB in the analytical studies and experimental implementation for all the controllers studied. Further, both analytical studies and experimental implementation yielded a 70-89 % reduction in acceleration responses from two different walking frequencies.

  7. Event-related desynchronization/synchronization during discrimination task conditions in patients with Parkinson's disease.

    PubMed

    Dushanova, Juliana; Philipova, Dolja; Nikolova, Gloria

    2009-09-01

    Parkinson's disease is a neurodegenerative disorder with symptoms, which include movement disturbances and changes of cognitive information processing. The aim of the present study was to investigate the functional relationships between oscillatory electroencephalographic (EEG) dominant components with event-related desynchronization/synchronization (ERD/ERS) method for idiopathic non-demented Parkinson's patients (PP) and control subjects (CS) during auditory discrimination tasks within two post-stimulus intervals of 0-250 and 250-600 ms. When comparing the CS and PP during the first post-stimulus period, we found delta- and theta-ERS significantly pronounced in CS for both tone types (low--800, high--1,000 Hz) with the following exceptions: at Fz, PP displayed higher delta-ERS, while at C3' theta-ERD in response to a high tone. Alpha-ERS was found in PP in response to either tone at all electrodes and mainly alpha-ERD in CS. In the second post-stimulus interval, the significant differences between the groups were: (i) delta-ERS in CS and delta-ERD in PP in response to the low tone and (ii) delta-ERS for both groups in answer to the high tone, more prominent in CS at Cz and Pz, except for delta-ERD in PP at C3'. For both groups, we detected predominantly theta-ERD and alpha-ERD following both tone types within this second interval. PP showed more expressed theta-ERD at Fz and parietal theta-ERS. Alpha-ERD was significantly higher in CS, while frontal alpha-ERD was more prominent in the PP in response to both tones. The data obtained showed specific functional differences of event-related oscillatory activity in cognitive and sensory-motor information processing between the PP and CS. PMID:19291392

  8. EFPC: An Environmentally Friendly Power Control Scheme for Underwater Sensor Networks.

    PubMed

    Yang, Qiuling; Su, Yishan; Jin, Zhigang; Yao, Guidan

    2015-01-01

    In oceans, the limited acoustic spectrum resource is heavily shared by marine mammals and manmade systems including underwater sensor networks. In order to limit the negative impact of acoustic signal on marine mammals, we propose an environmentally friendly power control (EFPC) scheme for underwater sensor networks. EFPC allocates transmission power of sensor nodes with a consideration of the existence of marine mammals. By applying a Nash Equilibrium based utility function with a set of limitations to optimize transmission power, the proposed power control algorithm can conduct parallel transmissions to improve the network's goodput, while avoiding interference with marine mammals. Additionally, to localize marine mammals, which is a prerequisite of EFPC, we propose a novel passive hyperboloid localization algorithm (PHLA). PHLA passively localize marine mammals with the help of the acoustic characteristic of these targets. Simulation results show that PHLA can localize most of the target with a relatively small localization error and EFPC can achieve a close goodput performance compared with an existing power control algorithm while avoiding interfering with marine mammals.

  9. An operational rate control scheme for H.264 with two-stage encoding

    NASA Astrophysics Data System (ADS)

    Kwon, Do-Kyoung; Shen, Mei-Yin; Kuo, C.-C. Jay

    2005-08-01

    An operational rate control (RC) scheme based on two-stage encoding is studied in this research, where frame-layer rate control with a constant bit rate to achieve constant video quality is examined. In the first encoding stage, the R-D optimized mode decision and its associated motion estimation (RDO) as well as DCT/Q, IQ/IDCT and entropy coding are performed for all macroblocks (MBs) for a target frame using an initial quantization parameter (QP), which is the QP of its previous frame. In the second encoding stage, the residual signal from the first stage is encoded using several QP values around the initial QP. Given the target bits and distortion for the current frame, the residual signal is finally encoded using the QP determined by comparing target bits and distortion with actual bits and distortion. To reduce the additional coding complexity of the two-stage encoding, upper and lower bounds around target bits and distortion are employed to reduce the number of encoding required in the second stage. Experimental results are given to show the superior performance of two proposed rate control algorithms, where one targets at the constant bit rate while the other at constant quality.

  10. EFPC: An Environmentally Friendly Power Control Scheme for Underwater Sensor Networks

    PubMed Central

    Yang, Qiuling; Su, Yishan; Jin, Zhigang; Yao, Guidan

    2015-01-01

    In oceans, the limited acoustic spectrum resource is heavily shared by marine mammals and manmade systems including underwater sensor networks. In order to limit the negative impact of acoustic signal on marine mammals, we propose an environmentally friendly power control (EFPC) scheme for underwater sensor networks. EFPC allocates transmission power of sensor nodes with a consideration of the existence of marine mammals. By applying a Nash Equilibrium based utility function with a set of limitations to optimize transmission power, the proposed power control algorithm can conduct parallel transmissions to improve the network’s goodput, while avoiding interference with marine mammals. Additionally, to localize marine mammals, which is a prerequisite of EFPC, we propose a novel passive hyperboloid localization algorithm (PHLA). PHLA passively localize marine mammals with the help of the acoustic characteristic of these targets. Simulation results show that PHLA can localize most of the target with a relatively small localization error and EFPC can achieve a close goodput performance compared with an existing power control algorithm while avoiding interfering with marine mammals. PMID:26593922

  11. An Indirect Adaptive Control Scheme in the Presence of Actuator and Sensor Failures

    NASA Technical Reports Server (NTRS)

    Sun, Joy Z.; Josh, Suresh M.

    2009-01-01

    The problem of controlling a system in the presence of unknown actuator and sensor faults is addressed. The system is assumed to have groups of actuators, and groups of sensors, with each group consisting of multiple redundant similar actuators or sensors. The types of actuator faults considered consist of unknown actuators stuck in unknown positions, as well as reduced actuator effectiveness. The sensor faults considered include unknown biases and outages. The approach employed for fault detection and estimation consists of a bank of Kalman filters based on multiple models, and subsequent control reconfiguration to mitigate the effect of biases caused by failed components as well as to obtain stability and satisfactory performance using the remaining actuators and sensors. Conditions for fault identifiability are presented, and the adaptive scheme is applied to an aircraft flight control example in the presence of actuator failures. Simulation results demonstrate that the method can rapidly and accurately detect faults and estimate the fault values, thus enabling safe operation and acceptable performance in spite of failures.

  12. Artificial Sun synchronous frozen orbit control scheme design based on J 2 perturbation

    NASA Astrophysics Data System (ADS)

    Wang, Gong-Bo; Meng, Yun-He; Zheng, Wei; Tang, Guo-Jian

    2011-10-01

    Sun synchronous orbit and frozen orbit formed due to J 2 perturbation have very strict constraints on orbital parameters, which have restricted the application a lot. In this paper, several control strategies were illustrated to realize Sun synchronous frozen orbit with arbitrary orbital elements using continuous low-thrust. Firstly, according to mean element method, the averaged rate of change of the orbital elements, originating from disturbing constant accelerations over one orbital period, was derived from Gauss' variation of parameters equations. Then, we proposed that binormal acceleration could be used to realize Sun synchronous orbit, and radial or transverse acceleration could be adopted to eliminate the rotation of the argument of the perigee. Finally, amending methods on the control strategies mentioned above were presented to eliminate the residual secular growth. Simulation results showed that the control strategies illustrated in this paper could realize Sun synchronous frozen orbit with arbitrary orbital elements, and can save much more energy than the schemes presented in previous studies, and have no side effect on other orbital parameters' secular motion.

  13. Vector Field Driven Design for Lightweight Signal Processing and Control Schemes for Autonomous Robotic Navigation

    NASA Astrophysics Data System (ADS)

    Mathai, Nebu John; Zourntos, Takis; Kundur, Deepa

    2009-12-01

    We address the problem of realizing lightweight signal processing and control architectures for agents in multirobot systems. Motivated by the promising results of neuromorphic engineering which suggest the efficacy of analog as an implementation substrate for computation, we present the design of an analog-amenable signal processing scheme. We use control and dynamical systems theory both as a description language and as a synthesis toolset to rigorously develop our computational machinery; these mechanisms are mated with structural insights from behavior-based robotics to compose overall algorithmic architectures. Our perspective is that robotic behaviors consist of actions taken by an agent to cause its sensory perception of the environment to evolve in a desired manner. To provide an intuitive aid for designing these behavioral primitives we present a novel visual tool, inspired vector field design, that helps the designer to exploit the dynamics of the environment. We present simulation results and animation videos to demonstrate the signal processing and control architecture in action.

  14. Schemes for Oestrus Synchronization Protocols and Controlled Breeding Programs in Cattle

    NASA Astrophysics Data System (ADS)

    Sabo, Y. G.; Sandabe, U. K.; Maina, V. A.; Balla, H. G.

    Today prostaglandin and progesterone has been found widely used in several schemes of oestrus synchronization and controlled breeding program. Several controlled breeding program, have been developed for synchronizing groups of all open or lactating cows within a breeding group with or without ovarian palpation. Such programs are reviewed in this article which involves extending the luteal phase by treatment with exogenous progesterone such as: progesterone treatment regimes using syncro-mate-B, progesterone releasing intravaginal device, melengesterol acetate-select and melegestrol acetate plus prostaglandin. Also reviewed in the program is the termination of the luteal phase by treatment with prostaglandin or its analogues. These includes, controlled breeding without ovarian palpation such as, the 7-days program; 11-days program, target breeding, ovsynch program, Heat synch, Cosynch and pre synch-ovsynch program. In our opinion full potential of progesterone and prostaglandin for the detection of oestrus and timed artificial insemination should be utilized. This reduces the much labour input employed in previous years. The practitioner of the livestock herd health must-develop strategies for the delivery of this technology to livestock farmers, its use and limitations.

  15. The design schemes of graphic user interface database and intelligent local controller in the SRRC control system

    NASA Astrophysics Data System (ADS)

    Wang, C. J.; Chen, Jenny; Chen, J. S.; Jan, G. J.

    1994-12-01

    The control system of the SRRC has been utilized to facilitate commisioning since the beginning, and it provides operators an easy to use environment. Hence, we would like to discuss the design schemes and relationships between the user's interface, the database and the ILC (Intelligent Local Controller) levels. The whole control system in SRRC is a two-level design connected by Ethernet. From operator's view, the upper level is the CONSOLE level and the lower one is the ILC level. Those signals from, or to, equipment are connected to ILCs through analog/digital interfaces, GPIB buses, RS232 serial links, etc.; the ILC is an IEEE 1014 bus (VMEbus) based system running PSOS + real-time multi-tasking kernel and PNA + (TCP/IP protocols) communication software. The control software of CONSOLE level is developed in the VMS operating system on DEC workstations, and The Graphic User Interfaces are built on the X-Window/Motif environment. The control system has fulfilled the expectations of the facility commissioning group. It has also proved to be a simple, stable, accurate, easily maintained system.

  16. Optimal control, investment and utilization schemes for energy storage under uncertainty

    NASA Astrophysics Data System (ADS)

    Mirhosseini, Niloufar Sadat

    Energy storage has the potential to offer new means for added flexibility on the electricity systems. This flexibility can be used in a number of ways, including adding value towards asset management, power quality and reliability, integration of renewable resources and energy bill savings for the end users. However, uncertainty about system states and volatility in system dynamics can complicate the question of when to invest in energy storage and how best to manage and utilize it. This work proposes models to address different problems associated with energy storage within a microgrid, including optimal control, investment, and utilization. Electric load, renewable resources output, storage technology cost and electricity day-ahead and spot prices are the factors that bring uncertainty to the problem. A number of analytical methodologies have been adopted to develop the aforementioned models. Model Predictive Control and discretized dynamic programming, along with a new decomposition algorithm are used to develop optimal control schemes for energy storage for two different levels of renewable penetration. Real option theory and Monte Carlo simulation, coupled with an optimal control approach, are used to obtain optimal incremental investment decisions, considering multiple sources of uncertainty. Two stage stochastic programming is used to develop a novel and holistic methodology, including utilization of energy storage within a microgrid, in order to optimally interact with energy market. Energy storage can contribute in terms of value generation and risk reduction for the microgrid. The integration of the models developed here are the basis for a framework which extends from long term investments in storage capacity to short term operational control (charge/discharge) of storage within a microgrid. In particular, the following practical goals are achieved: (i) optimal investment on storage capacity over time to maximize savings during normal and emergency

  17. Kinematics and force analysis of a robot hand based on an artificial biological control scheme

    NASA Astrophysics Data System (ADS)

    Kim, Man Guen

    An artificial biological control scheme (ABCS) is used to study the kinematics and statics of a multifingered hand with a view to developing an efficient control scheme for grasping. The ABCS is based on observation of human grasping, intuitively taking it as the optimum model for robotic grasping. A final chapter proposes several grasping measures to be applied to the design and control of a robot hand. The ABCS leads to the definition of two modes of the grasping action: natural grasping (NG), which is the human motion to grasp the object without any special task command, and forced grasping (FG), which is the motion with a specific task. The grasping direction line (GDL) is defined to determine the position and orientation of the object in the hand. The kinematic model of a redundant robot arm and hand is developed by reconstructing the human upper extremity and using anthropometric measurement data. The inverse kinematic analyses of various types of precision and power grasping are studied by replacing the three-link with one virtual link and using the GDL. The static force analysis for grasping with fingertips is studied by applying the ABCS. A measure of grasping stability, that maintains the positions of contacts as well as the configurations of the redundant fingers, is derived. The grasping stability measure (GSM), a measure of how well the hand maintains grasping under the existence of external disturbance, is derived by the torque vector of the hand calculated from the external force applied to the object. The grasping manipulability measure (GMM), a measure of how well the hand manipulates the object for the task, is derived by the joint velocity vector of the hand calculated from the object velocity. The grasping performance measure (GPM) is defined by the sum of the directional components of the GSM and the GMM. Finally, a planar redundant hand with two fingers is examined in order to study the various postures of the hand performing pinch grasping by

  18. An optimal output feedback gain variation scheme for the control of plants exhibiting gross parameter changes

    NASA Technical Reports Server (NTRS)

    Moerder, Daniel D.

    1987-01-01

    A concept for optimally designing output feedback controllers for plants whose dynamics exhibit gross changes over their operating regimes was developed. This was to formulate the design problem in such a way that the implemented feedback gains vary as the output of a dynamical system whose independent variable is a scalar parameterization of the plant operating point. The results of this effort include derivation of necessary conditions for optimality for the general problem formulation, and for several simplified cases. The question of existence of a solution to the design problem was also examined, and it was shown that the class of gain variation schemes developed are capable of achieving gain variation histories which are arbitrarily close to the unconstrained gain solution for each point in the plant operating range. The theory was implemented in a feedback design algorithm, which was exercised in a numerical example. The results are applicable to the design of practical high-performance feedback controllers for plants whose dynamics vary significanly during operation. Many aerospace systems fall into this category.

  19. Optimal tracking performance of MIMO control systems with communication constraints and a code scheme

    NASA Astrophysics Data System (ADS)

    Zhan, Xi-Sheng; Guan, Zhi-Hong; Zhang, Xian-He; Yuan, Fu-Shun

    2015-02-01

    This paper investigates the issue of the optimal tracking performance for multiple-input multiple-output linear time-invariant continuous-time systems with power constrained. An H2 criterion of the error signal and the signal of the input channel are used as a measure for the tracking performance. A code scheme is introduced as a means of integrating controller and channel design to obtain the optimal tracking performance. It is shown that the optimal tracking performance index consists of two parts, one depends on the non-minimum phase zeros and zero direction of the given plant, as well as the reference input signal, while the other depends on the unstable poles and pole direction of the given plant, as well as on the bandwidth and additive white noise of a communication channel. It is also shown that when the communication does not exist, the optimal tracking performance reduces to the existing normal tracking performance of the control system. The results show how the optimal tracking performance is limited by the bandwidth and additive white noise of the communication channel. A typical example is given to illustrate the theoretical results.

  20. Modular Patterns of Phase Desynchronization Networks During a Simple Visuomotor Task.

    PubMed

    Mylonas, D S; Siettos, C I; Evdokimidis, I; Papanicolaou, A C; Smyrnis, N

    2016-01-01

    By performing sensor-level analysis on magnetoencephalography (MEG) data we identified the dynamic evolution of the functional connectivity networks during a simple visuomotor task. The functional connectivity networks were constructed using the concept of phase-locking value (PLV). We illustrate that the task-related activity is mediated by distinct complex networks related to the PLV desynchronization that configure their architecture dynamically during the task. These networks are prominent at β and α band, and are characterized by coherent modular organization. Moreover the time for the development of the desynchronization networks at α band predicts the intra-subject variability of reaction time. Thus, the spatio-temporal dynamics and the structural properties of the emerged functional networks share common characteristics with the mechanism of coactivation and resting state networks.

  1. Noise-induced synchronization, desynchronization, and clustering in globally coupled nonidentical oscillators.

    PubMed

    Lai, Yi Ming; Porter, Mason A

    2013-07-01

    We study ensembles of globally coupled, nonidentical phase oscillators subject to correlated noise, and we identify several important factors that cause noise and coupling to synchronize or desynchronize a system. By introducing noise in various ways, we find an estimate for the onset of synchrony of a system in terms of the coupling strength, noise strength, and width of the frequency distribution of its natural oscillations. We also demonstrate that noise alone can be sufficient to synchronize nonidentical oscillators. However, this synchrony depends on the first Fourier mode of a phase-sensitivity function, through which we introduce common noise into the system. We show that higher Fourier modes can cause desynchronization due to clustering effects, and that this can reinforce clustering caused by different forms of coupling. Finally, we discuss the effects of noise on an ensemble in which antiferromagnetic coupling causes oscillators to form two clusters in the absence of noise.

  2. Long-lasting desynchronization in rat hippocampal slice induced by coordinated reset stimulation

    SciTech Connect

    Tass, P. A.; Barnikol, U. B.; Silchenko, A. N.; Hauptmann, C.; Speckmann, E.-J.

    2009-07-15

    In computational models it has been shown that appropriate stimulation protocols may reshape the connectivity pattern of neural or oscillator networks with synaptic plasticity in a way that the network learns or unlearns strong synchronization. The underlying mechanism is that a network is shifted from one attractor to another, so that long-lasting stimulation effects are caused which persist after the cessation of stimulation. Here we study long-lasting effects of multisite electrical stimulation in a rat hippocampal slice rendered epileptic by magnesium withdrawal. We show that desynchronizing coordinated reset stimulation causes a long-lasting desynchronization between hippocampal neuronal populations together with a widespread decrease in the amplitude of the epileptiform activity. In contrast, periodic stimulation induces a long-lasting increase in both synchronization and amplitude.

  3. Rapidly optimizing an aptamer based BoNT sensor by feedback system control (FSC) scheme.

    PubMed

    Wei, Fang; Bai, Bin; Ho, Chih-Ming

    2011-12-15

    The sensitivity and detection time of an aptamer based biosensor for detecting botulinum neurotoxin (BoNT) depend upon the formation of proper tertiary architecture of aptamer, which closely correlates with the combinatorial effects of multiple types of ions and their concentrations presented in the buffer. Finding the optimal conditions for four different ions at 12 different concentrations, 20,736 possible combinations, by brute force is an extremely laborious and time-consuming task. Here, we introduce a feedback system control (FSC) scheme that can rapidly identify the best combination of components to form the optimal aptamer structure binding to a target molecule. In this study, rapid identification of optimized ionic combinations for electrochemical aptasensor of BoNT type A (BoNT/A) detection has been achieved. Only about 10 iterations with about 50 tests in each iteration are needed to identify the optimal ionic concentration out of the 20,736 possibilities. The most exciting finding was that a very short detection time and high sensitivity could be achieved with the optimized combinational ion buffer. Only a 5-min detection time, compared with hours or even days, was needed for aptamer-based BoNT/A detection with a limit of detection of 40 pg/ml. The methodologies described here can be applied to other multi-parameter chemical systems, which should significantly improve the rate of parameter optimization.

  4. A Reconfiguration Scheme for Accommodating Actuator Failures in Multi-Input, Multi-Output Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Siwakosit, W.; Hess, R. A.; Bacon, Bart (Technical Monitor); Burken, John (Technical Monitor)

    2000-01-01

    A multi-input, multi-output reconfigurable flight control system design utilizing a robust controller and an adaptive filter is presented. The robust control design consists of a reduced-order, linear dynamic inversion controller with an outer-loop compensation matrix derived from Quantitative Feedback Theory (QFT). A principle feature of the scheme is placement of the adaptive filter in series with the QFT compensator thus exploiting the inherent robustness of the nominal flight control system in the presence of plant uncertainties. An example of the scheme is presented in a pilot-in-the-loop computer simulation using a simplified model of the lateral-directional dynamics of the NASA F18 High Angle of Attack Research Vehicle (HARV) that included nonlinear anti-wind up logic and actuator limitations. Prediction of handling qualities and pilot-induced oscillation tendencies in the presence of these nonlinearities is included in the example.

  5. Non-iterative adaptive time-stepping scheme with temporal truncation error control for simulating variable-density flow

    NASA Astrophysics Data System (ADS)

    Hirthe, Eugenia M.; Graf, Thomas

    2012-12-01

    The automatic non-iterative second-order time-stepping scheme based on the temporal truncation error proposed by Kavetski et al. [Kavetski D, Binning P, Sloan SW. Non-iterative time-stepping schemes with adaptive truncation error control for the solution of Richards equation. Water Resour Res 2002;38(10):1211, http://dx.doi.org/10.1029/2001WR000720.] is implemented into the code of the HydroGeoSphere model. This time-stepping scheme is applied for the first time to the low-Rayleigh-number thermal Elder problem of free convection in porous media [van Reeuwijk M, Mathias SA, Simmons CT, Ward JD. Insights from a pseudospectral approach to the Elder problem. Water Resour Res 2009;45:W04416, http://dx.doi.org/10.1029/2008WR007421.], and to the solutal [Shikaze SG, Sudicky EA, Schwartz FW. Density-dependent solute transport in discretely-fractured geological media: is prediction possible? J Contam Hydrol 1998;34:273-91] problem of free convection in fractured-porous media. Numerical simulations demonstrate that the proposed scheme efficiently limits the temporal truncation error to a user-defined tolerance by controlling the time-step size. The non-iterative second-order time-stepping scheme can be applied to (i) thermal and solutal variable-density flow problems, (ii) linear and non-linear density functions, and (iii) problems including porous and fractured-porous media.

  6. Influences of different land use spatial control schemes on farmland conversion and urban development.

    PubMed

    Zhou, Min; Tan, Shukui; Zhang, Lu

    2015-01-01

    Land use planning is always officially implemented as an effective tool to control urban development and protect farmland. However, its impact on land use change remains untested in China. Using a case study of Hang-Jia-Hu region, the main objective of this paper was to investigate the influence of different land use spatial control schemes on farmland conversion and urban development. Comparisons of farmland conversion and urban development patterns between the urban planning area and the non-urban planning area were characterized by using remote sensing, geographical information systems, and landscape metrics. Results indicated that farmland conversion in the non-urban planning area was more intensive than that in the urban planning area, and that farmland patterns was more fragmented in the non-urban planning area. Built-up land patterns in the non-urban planning area showed a trend of aggregation, while those in the urban planning area had a dual trend of fragmentation and aggregation. Existing built-up areas had less influence on built-up land sprawl in the non-urban planning area than that in the urban planning area. Built-up land sprawl in the form of continuous development in the urban planning area led to farmland conversion; and in the non-urban planning area, built-up land sprawl in the form of leapfrogging development resulted in farmland areal declines and fragmentation. We argued that it is a basic requirement to integrate land use plans in urban and non-urban planning areas for land use planning and management. PMID:25915897

  7. Influences of different land use spatial control schemes on farmland conversion and urban development.

    PubMed

    Zhou, Min; Tan, Shukui; Zhang, Lu

    2015-01-01

    Land use planning is always officially implemented as an effective tool to control urban development and protect farmland. However, its impact on land use change remains untested in China. Using a case study of Hang-Jia-Hu region, the main objective of this paper was to investigate the influence of different land use spatial control schemes on farmland conversion and urban development. Comparisons of farmland conversion and urban development patterns between the urban planning area and the non-urban planning area were characterized by using remote sensing, geographical information systems, and landscape metrics. Results indicated that farmland conversion in the non-urban planning area was more intensive than that in the urban planning area, and that farmland patterns was more fragmented in the non-urban planning area. Built-up land patterns in the non-urban planning area showed a trend of aggregation, while those in the urban planning area had a dual trend of fragmentation and aggregation. Existing built-up areas had less influence on built-up land sprawl in the non-urban planning area than that in the urban planning area. Built-up land sprawl in the form of continuous development in the urban planning area led to farmland conversion; and in the non-urban planning area, built-up land sprawl in the form of leapfrogging development resulted in farmland areal declines and fragmentation. We argued that it is a basic requirement to integrate land use plans in urban and non-urban planning areas for land use planning and management.

  8. Dynamic Key Management Schemes for Secure Group Access Control Using Hierarchical Clustering in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Tsaur, Woei-Jiunn; Pai, Haw-Tyng

    2008-11-01

    The applications of group computing and communication motivate the requirement to provide group access control in mobile ad hoc networks (MANETs). The operation in MANETs' groups performs a decentralized manner and accommodated membership dynamically. Moreover, due to lack of centralized control, MANETs' groups are inherently insecure and vulnerable to attacks from both within and outside the groups. Such features make access control more challenging in MANETs. Recently, several researchers have proposed group access control mechanisms in MANETs based on a variety of threshold signatures. However, these mechanisms cannot actually satisfy MANETs' dynamic environments. This is because the threshold-based mechanisms cannot be achieved when the number of members is not up to the threshold value. Hence, by combining the efficient elliptic curve cryptosystem, self-certified public key cryptosystem and secure filter technique, we construct dynamic key management schemes based on hierarchical clustering for securing group access control in MANETs. Specifically, the proposed schemes can constantly accomplish secure group access control only by renewing the secure filters of few cluster heads, when a cluster head joins or leaves a cross-cluster. In such a new way, we can find that the proposed group access control scheme can be very effective for securing practical applications in MANETs.

  9. Euchronism, allochronism, and dyschronism: is internal desynchronization of human circadian rhythms a sign of illness?

    PubMed

    Reinberg, Alain E; Ashkenazi, Israel; Smolensky, Michael H

    2007-01-01

    The authors define a subject as euchronic when the circadian parameters--tau (tau=period), Ø (acrophse or peak time), A (amplitude), and M (MESOR=24 h rhythm-adjusted mean)--of a set of circadian variables are within the confidence limits of appropriate reference values of healthy subjects (HS). We define internal desynchronization as a state in which the circadian tau of a set of rhythms differs from 24 h and when the tau of a given variable differs from that of other variables. Such a state was first observed in singly isolated HS without access to time cues and clues. Herein, data and analyses are presented demonstrating that internal desynchronization appears to be a rather common phenomenon in HS dwelling in their natural environment (i.e., in the presence of usual zeitgebers). This has been documented by longitudinal studies (n approximately=15 days) of the circadian rhythm in sleep-wakefulness, body temperature, right- and left-hand-grip strength, and reaction time involving a total of 246 HS and 134 shift workers (SW), with 45.5% showing good and 54.5% poor SW tolerance. The presence of internal desynchronization observed in SW was associated SW intolerance, with symptoms being sleep alteration/disturbances, sleeping-pill dependence, persisting fatigue (asthenia), mood alteration, and digestive complaints. Internal desynchronization was also documented in groups of HS and tolerant SW, though it was almost the rule among the intolerant SW. The authors introduce two new terms: allochronism to describe the time organization of those SW who evidence internal desynchronization without detectable clinical symptoms, and dyschronism to describe the time organization of those SW who exhibit internal desynchrobization plus the symptoms of SW intolerance or medical illness. The condition of allochronism is not restricted only to SW tolerance, as it was detected in 112 HS without medical complains when exposed to various experimental conditions, including medications

  10. Euchronism, allochronism, and dyschronism: is internal desynchronization of human circadian rhythms a sign of illness?

    PubMed

    Reinberg, Alain E; Ashkenazi, Israel; Smolensky, Michael H

    2007-01-01

    The authors define a subject as euchronic when the circadian parameters--tau (tau=period), Ø (acrophse or peak time), A (amplitude), and M (MESOR=24 h rhythm-adjusted mean)--of a set of circadian variables are within the confidence limits of appropriate reference values of healthy subjects (HS). We define internal desynchronization as a state in which the circadian tau of a set of rhythms differs from 24 h and when the tau of a given variable differs from that of other variables. Such a state was first observed in singly isolated HS without access to time cues and clues. Herein, data and analyses are presented demonstrating that internal desynchronization appears to be a rather common phenomenon in HS dwelling in their natural environment (i.e., in the presence of usual zeitgebers). This has been documented by longitudinal studies (n approximately=15 days) of the circadian rhythm in sleep-wakefulness, body temperature, right- and left-hand-grip strength, and reaction time involving a total of 246 HS and 134 shift workers (SW), with 45.5% showing good and 54.5% poor SW tolerance. The presence of internal desynchronization observed in SW was associated SW intolerance, with symptoms being sleep alteration/disturbances, sleeping-pill dependence, persisting fatigue (asthenia), mood alteration, and digestive complaints. Internal desynchronization was also documented in groups of HS and tolerant SW, though it was almost the rule among the intolerant SW. The authors introduce two new terms: allochronism to describe the time organization of those SW who evidence internal desynchronization without detectable clinical symptoms, and dyschronism to describe the time organization of those SW who exhibit internal desynchrobization plus the symptoms of SW intolerance or medical illness. The condition of allochronism is not restricted only to SW tolerance, as it was detected in 112 HS without medical complains when exposed to various experimental conditions, including medications

  11. Changes in Event-Related Desynchronization and Synchronization during the Auditory Oddball Task in Schizophrenia Patients

    PubMed Central

    Fujimoto, Toshiro; Okumura, Eiichi; Takeuchi, Kouzou; Kodabashi, Atsushi; Tanaka, Hiroaki; Otsubo, Toshiaki; Nakamura, Katsumi; Sekine, Masaki; Kamiya, Shinichiro; Higashi, Yuji; Tsuji, Miwa; Shimooki, Susumu; Tamura, Toshiyo

    2012-01-01

    Objective: We studied differences in the spatiotemporal dynamics of cortical oscillation across brain regions of patients with schizophrenia and normal subjects during the auditory oddball task using magnetoencephalography (MEG) and electroencephalography (EEG). Methods: Ten right-handed male schizophrenia patients were studied. We used a newly developed adaptive spatial filtering algorithm optimized for robust source time-frequency reconstruction of MEG and EEG data, and obtained consecutive images in functional maps of event-related desynchronization (ERD) and synchronization (ERS) in theta, lower alpha (8–10 Hz), upper alpha (10–13 Hz), and beta bands. Results: Beta ERD power at 750–1000 ms in patients was significantly increased in large right upper temporal and parietal regions and small upper portions of bilateral dorsal frontal and dorsal-medial parietal regions. Theta ERS power in schizophrenic patients during the oddball task was significantly increased in the left temporal pole at 250–500 ms, and was significantly increased in dorsal, medial frontal, and anterior portions of the anterior cingulate cortex in both hemispheres, and the left portion of lateral temporal regions at 500–750 ms, compared to the control group (family-wise error correction p<0.05). Lower alpha ERS power was significantly decreased in the right occipital region at 500–750 ms and in the right midline parietal and bilateral occipital regions at 750–1000 ms. Upper alpha ERS power was significantly decreased in right midline parietal and left occipital regions at 750–1000 ms. Conclusions: ERD/ERS changes were noted in the left temporal pole and midline frontal and anterior cingulate cortex in theta ERS, occipital lobe in alpha ERS, and right temporal-frontal-parietal, midline frontal, and anterior cingulate cortex in beta ERD. These findings may reflect disturbances in interaction among active large neuronal groups and their communication with each other that may be

  12. Continuous quality control of the blood sampling procedure using a structured observation scheme

    PubMed Central

    Seemann, Tine Lindberg; Nybo, Mads

    2016-01-01

    Introduction An observational study was conducted using a structured observation scheme to assess compliance with the local phlebotomy guideline, to identify necessary focus items, and to investigate whether adherence to the phlebotomy guideline improved. Materials and methods The questionnaire from the EFLM Working Group for the Preanalytical Phase was adapted to local procedures. A pilot study of three months duration was conducted. Based on this, corrective actions were implemented and a follow-up study was conducted. All phlebotomists at the Department of Clinical Biochemistry and Pharmacology were observed. Three blood collections by each phlebotomist were observed at each session conducted at the phlebotomy ward and the hospital wards, respectively. Error frequencies were calculated for the phlebotomy ward and the hospital wards and for the two study phases. Results A total of 126 blood drawings by 39 phlebotomists were observed in the pilot study, while 84 blood drawings by 34 phlebotomists were observed in the follow-up study. In the pilot study, the three major error items were hand hygiene (42% error), mixing of samples (22%), and order of draw (21%). Minor significant differences were found between the two settings. After focus on the major aspects, the follow-up study showed significant improvement for all three items at both settings (P < 0.01, P < 0.01, and P = 0.01, respectively). Conclusion Continuous quality control of the phlebotomy procedure revealed a number of items not conducted in compliance with the local phlebotomy guideline. It supported significant improvements in the adherence to the recommended phlebotomy procedures and facilitated documentation of the phlebotomy quality. PMID:27812302

  13. Impact of various emission control schemes on air quality using WRF-Chem during APEC China 2014

    NASA Astrophysics Data System (ADS)

    Guo, Jianping; He, Jing; Liu, Hongli; Miao, Yucong; Liu, Huan; Zhai, Panmao

    2016-09-01

    Emission control measures have been implemented to make air quality good enough for Asia-Pacific Economic Cooperation (APEC) China 2014, which provides us with an ideal test-bed to determine how these measures affect air quality in Beijing and surrounding areas. Based on hourly observations at eight monitoring sites of Beijing, the concentrations of other primary atmospheric pollutants during APEC were found to have significantly lower magnitudes than those before APEC, with the exception of a higher O3 concentration. Overall, WRF/Chem reproduced the observed time series of PM2.5, PM10, NO2, CO, and O3 notably well. To investigate the impact of emission control measures on air quality on both local and regional scales, four emission control schemes were developed according to the locations where emission reduction had taken place; the corresponding simulations were subsequently run separately. Scheme S2 (emission control implemented in Beijing) resulted in reductions of 22%, 24%, 10% and 22% for the concentrations of PM2.5, PM10, NO2 and CO, respectively, compared with 14%, 14%, 8%, and 13% for scheme S3 (emission controls implemented from outside of Beijing). This finding indicates that the local emission reduction in Beijing contributes more to the improved air quality in Beijing during APEC China 2014 than does the emission reduction from outside of Beijing. In terms of the impact on the regional scale, the real emission control scheme led to significant reduction of PM2.5 throughout the whole domain. Although the regional impact cannot be completely ignored, both emission reduction measures implemented in Beijing and those implemented outside of Beijing favor greater reduction in PM2.5 in the domains where measurements are presumably taken, as compared with other domains. Therefore, to improve the air quality in Beijing, more coordinated efforts should be made, particularly in the aspect of more stringent reduction and control strategies on pollutant emission

  14. Drive Control Scheme of Electric Power Assisted Wheelchair Based on Neural Network Learning of Human Wheelchair Operation Characteristics

    NASA Astrophysics Data System (ADS)

    Tanohata, Naoki; Seki, Hirokazu

    This paper describes a novel drive control scheme of electric power assisted wheelchairs based on neural network learning of human wheelchair operation characteristics. “Electric power assisted wheelchair” which enhances the drive force of the operator by employing electric motors is expected to be widely used as a mobility support system for elderly and disabled people. However, some handicapped people with paralysis of the muscles of one side of the body cannot maneuver the wheelchair as desired because of the difference in the right and left input force. Therefore, this study proposes a neural network learning system of such human wheelchair operation characteristics and a drive control scheme with variable distribution and assistance ratios. Some driving experiments will be performed to confirm the effectiveness of the proposed control system.

  15. Design and Experimental Evaluation of a Robust Position Controller for an Electrohydrostatic Actuator Using Adaptive Antiwindup Sliding Mode Scheme

    PubMed Central

    Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik

    2013-01-01

    A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. PMID:23983640

  16. Design and experimental evaluation of a robust position controller for an electrohydrostatic actuator using adaptive antiwindup sliding mode scheme.

    PubMed

    Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik

    2013-01-01

    A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities.

  17. An efficient key-management scheme for hierarchical access control in e-medicine system.

    PubMed

    Wu, Shuhua; Chen, Kefei

    2012-08-01

    In e-medicine system, the sharing of patients' medical histories scattered among medical institutions through the Internet is highly desirable. The most immediate cryptographic need certainly is an efficient key management method to solve dynamic access problems in a user hierarchy. In this paper, we propose a practical solution for dynamic access problem in a user hierarchy based on hybrid cryptosystems. When compared with Nikooghadam et al.'s scheme proposed most recently, the time complexity and the required storage space is reduced significantly. Moreover, it provides provable security, and is easy to implement. Therefore, our scheme is more suitable for e-medicine system.

  18. Equitable utilisation of Indian community based health insurance scheme among its rural membership: cluster randomised controlled trial

    PubMed Central

    Sinha, Tara; Chatterjee, Mirai; Gandhi, Fenil; Jayswal, Rupal; Patel, Falguni; Morris, Saul S; Mills, Anne J

    2007-01-01

    Objective To evaluate alternative strategies for improving the uptake of benefits of a community based health insurance scheme by its poorest members. Design Prospective cluster randomised controlled trial. Setting Self Employed Women's Association (SEWA) community based health insurance scheme in rural India. Participants 713 claimants at baseline (2003) and 1440 claimants two years later among scheme members in 16 rural sub-districts. Interventions After sales service with supportive supervision, prospective reimbursement, both packages, and neither package, randomised by sub-district. Main outcome measures The primary outcome was socioeconomic status of claimants relative to members living in the same sub-district. Secondary outcomes were enrolment rates in SEWA Insurance, mean socioeconomic status of the insured population relative to the general rural population, and rate of claim submission. Results Between 2003 and 2005, the mean socioeconomic status of SEWA Insurance members (relative to the rural population of Gujarat) increased significantly. Rates of claims also increased significantly, on average by 21.6 per 1000 members (P<0.001). However, differences between the intervention groups and the standard scheme were not significant. No systematic effect of time or interventions on the socioeconomic status of claimants relative to members in the same sub-district was found. Conclusions Neither intervention was sufficient to ensure that the poorer members in each sub-district were able to enjoy the greater share of the scheme benefits. Claim submission increased as a result of interventions that seem to have strengthened awareness of and trust in a community based health insurance scheme. Trial registration Clinical trials NCT00421629. PMID:17526594

  19. Developing Efficient Coordination Schemes to Control Over-Pumping in the Heihe River Basin, China

    NASA Astrophysics Data System (ADS)

    Pedrazzini, G.

    2015-12-01

    Many wicked water resources problems are approached in a social planner perspective. This not always matches the real institutional and policy-making context, where, rather, multiple decision-makers (DMs) can act independently, or weakly cooperate, ultimately producing system-wide inefficient trade-offs. The idea in this work is to adopt a more realistic approach, where the multi-DMs nature of the problem is preserved and the uncoordinated DMs are driven, thorough coordination mechanisms, towards a more system-wide efficient solution. An agent-based modelling framework linked to a surface and groundwater model is used to design these coordination mechanisms as constraints to the independent agents (i.e., DMs) behaviour. In the Heihe Basin the ongoing introduction of smart meter IC-card systems on farmers' pumping wells will soon allow monitoring and control of abstractions with the goal of preventing further depletion of the resource. The major interest of policy makers in the region concerns the development of new and the improvement of existing legislation on pricing schemes and/or groundwater quotas. The model outcome where agents act rationally but selfishly is compared to the optimal solution at system-level assuming perfect coordination and cooperation. The optimal solutions with respect to the given utility functions are computed using nonlinear optimization with a rolling out time horizon. The Pareto-Frontier is synthesized through an exhaustive sampling of the weight coefficient space and related to the current and to the historical management of the last 4 decades. The best parameter values for the proposed coordination mechanisms are determined and the alternatives are compared with respect to their efficiency and acceptability. Preliminary results suggest that a regulatory tax on groundwater of about a factor 10 of the current resource fee is required to increase the elasticity of the groundwater demand curve such that reducing consumption becomes

  20. Desynchronization and rebound of beta oscillations during conscious and unconscious local neuronal processing in the macaque lateral prefrontal cortex.

    PubMed

    Panagiotaropoulos, Theofanis I; Kapoor, Vishal; Logothetis, Nikos K

    2013-01-01

    Accumulating evidence indicates that control mechanisms are not tightly bound to conscious perception since both conscious and unconscious information can trigger control processes, probably through the activation of higher-order association areas like the prefrontal cortex. Studying the modulation of control-related prefrontal signals in a microscopic, neuronal level during conscious and unconscious neuronal processing, and under control-free conditions could provide an elementary understanding of these interactions. Here we performed extracellular electrophysiological recordings in the macaque lateral prefrontal cortex (LPFC) during monocular physical alternation (PA) and binocular flash suppression (BFS) and studied the local scale relationship between beta (15-30 Hz) oscillations, a rhythmic signal believed to reflect the current sensory, motor, or cognitive state (status-quo), and conscious or unconscious neuronal processing. First, we show that beta oscillations are observed in the LPFC during resting state. Both PA and BFS had a strong impact on the power of this spontaneous rhythm with the modulation pattern of beta power being identical across these two conditions. Specifically, both perceptual dominance and suppression of local neuronal populations in BFS were accompanied by a transient beta desynchronization followed by beta activity rebound, a pattern also observed when perception occurred without any underlying visual competition in PA. These results indicate that under control-free conditions, at least one rhythmic signal known to reflect control processes in the LPFC (i.e., beta oscillations) is not obstructed by local neuronal, and accordingly perceptual, suppression, thus being independent from temporally co-existing conscious and unconscious local neuronal representations. Future studies could reveal the additive effects of motor or cognitive control demands on prefrontal beta oscillations during conscious and unconscious processing.

  1. Modeling of a Segmented Electrode for Desynchronizing Deep Brain Stimulation

    PubMed Central

    Buhlmann, J.; Hofmann, L.; Tass, P. A.; Hauptmann, C.

    2011-01-01

    Deep brain stimulation (DBS) is an effective therapy for medically refractory movement disorders like Parkinson’s disease. The electrodes, implanted in the target area within the human brain, generate an electric field which activates nerve fibers and cell bodies in the vicinity. Even though the different target nuclei display considerable differences in their anatomical structure, only few types of electrodes are currently commercially available. It is desirable to adjust the electric field and in particular the volume of tissue activated around the electrode with respect to the corresponding target nucleus in a such way that side effects can be reduced. Furthermore, a more selective and partial activation of the target structure is desirable for an optimal application of novel stimulation strategies, e.g., coordinated reset neuromodulation. Hence we designed a DBS electrode with a segmented design allowing a more selective activation of the target structure. We created a finite element model (FEM) of the electrode and analyzed the volume of tissue activated for this electrode design. The segmented electrode activated an area in a targeted manner, of which the dimension and position relative to the electrode could be controlled by adjusting the stimulation parameters for each electrode contact. According to our computational analysis, this directed stimulation might be superior with respect to the occurrence of side effects and it enables the application of coordinated reset neuromodulation under optimal conditions. PMID:22163220

  2. Altered Rolandic Gamma-Band Activation Associated with Motor Impairment and Ictal Network Desynchronization in Childhood Epilepsy

    PubMed Central

    Doesburg, Sam M.; Ibrahim, George M.; Smith, Mary Lou; Sharma, Rohit; Viljoen, Amrita; Chu, Bill; Rutka, James T.; Snead, O. Carter; Pang, Elizabeth W.

    2013-01-01

    Epilepsy is associated with an abnormal expression of neural oscillations and their synchronization across brain regions. Oscillatory brain activation and synchronization also play an important role in cognition, perception and motor control. Childhood epilepsy is associated with a variety of cognitive and motor deficits, but the relationship between altered functional brain responses in various frequency ranges and functional impairment in these children remains poorly understood. We investigated functional magnetoencephalographic (MEG) responses from motor cortex in multiple functionally relevant frequency bands following median nerve stimulation in twelve children with epilepsy, including four children with motor impairments. We demonstrated that children with motor impairments exhibit an excessive gamma-band response from Rolandic cortex, and that the magnitude of this Rolandic gamma response is negatively associated with motor function. Abnormal responses from motor cortex were also associated with ictal desynchronization of oscillations within Rolandic cortex measured using intracranial EEG (iEEG). These results provide the evidence that ictal disruption of motor networks is associated with an altered functional response from motor cortex, which is in turn associated with motor impairment. PMID:23383007

  3. Evaluating the event-related synchronization and desynchronization by means of a statistical frequency test.

    PubMed

    Miranda de Sá, Antonio Mauricio F L; Infantosi, Antonio Fernando C; Lazarev, Vladimir V

    2007-01-01

    In the present work, a commonly used index for evaluating the Event-Related Synchronization and Desynchronization (ERS/ERD) in the EEG was expressed as a function of the Spectral F-Test (SFT), which is a statistical test for assessing if two sample spectra are from populations with identical theoretical spectra. The sampling distribution of SFT has been derived, allowing hence ERS/ERD to be evaluated under a statistical basis. An example of the technique was also provided in the EEG signals from 10 normal subjects during intermittent photic stimulation.

  4. The Simulium control scheme at Abuja, Northern Nigeria, and its effect on the prevalence of onchocerciasis in the area

    PubMed Central

    Davies, John B.

    1968-01-01

    This account of the conduct of the Similium Control Scheme at Abuja, Northern Nigeria, over the period 1956-66 shows that, by larvicide treatment of some 160 km of rivers with DDT in the early wet season, the Simulium damnosum density has been reduced by about 90% of its precontrol level each year over an area of more than 3000 km2. A skin-snip survey, in which 6748 persons were examined (of whom 5700 lived within the controlled area and 1048 in a comparison area) during 1966, indicates that there has been no obvious decrease in prevalence of onchocerciasis, particularly among children born since the commencement of the scheme, that could be attributed solely to the effects of the control measures, although there are indications that a drop in severity of infection has been achieved. Dissections of wild-caught S. damnosum suggest that, although the fly-density was greatly reduced by the control measures, the proportion of infective flies increased half-way through the period, probably owing to the greater proportion of older flies in the post-control populations; as a result, the estimated number of infective bites was only halved. By 1966, however, the infective bite rate was down to about 1/30th of its original level. It is concluded that the control scheme has demonstrated that the S. damnosum population in a small area within a larger endemic area can be substantially reduced by treating the rivers with DDT during the first 12 weeks of the wet season. It appears, however, that onchocerciasis may be transmitted by a very low density of S. damnosum. The author suggests that an ophthalmic survey would reveal whether there has been any change in the incidence of onchocercal blindness due to the control measures, and that an entomological investigation might show whether the continued transmission is due to residual, resident or immigrant fly populations or whether a second vector is involved. PMID:4972620

  5. Analog-model simulations for secondary canal controls and forward pumping water-management schemes in southeast Florida

    USGS Publications Warehouse

    Cordes, E.H.; Gardner, Richard Alfred

    1976-01-01

    The analog model of the Biscayne aquifer of southeast Florida was used to approximate the effects of two proposed water-management schemes. One involved adding a secondary control structure in a major canal which is controlled near the coast. In the model the controls were operated in accordance with canal water level both above and below the secondary control. Although the model could not differentiate between control openings of 1 foot or 5 feet, it showed that the secondary control is a viable method of conserving ground water. The second scheme involved pumping ground water ('forward pumping') from the Biscayne aquifer in inland areas during the dry season to: (1) augment canal flows toward the coast to sustain ground-water levels there, and (2) generate additional ground-water storage space for recharge in the wet season. Several sites on the model were programmed for forward pumping wells and the storage change was noted as a percentage of the ground-water withdrawal. (Woodard-USGS)

  6. Control of tripod-scheme cold-atom wavepackets by manipulating a non-Abelian vector potential

    SciTech Connect

    Zhang Qi; Gong Jiangbin; Oh, C.H.

    2010-06-15

    Tripod-scheme cold atoms interacting with laser beams have attracted considerable interest for their role in synthesizing effective non-Abelian vector potentials. Such effective vector potentials can be exploited to realize an all-optical imprinting of geometric phases onto matter waves. By working on carefully designed extensions of our previous work, we show that coherent lattice structure of cold-atom sub-wavepackets can be formed and that the non-Abelian Aharonov-Bohm effect can be easily manifested via the translational motion of cold atoms. We also show that by changing the frame of reference, effects due to a non-Abelian vector potential may be connected with a simple dynamical phase effect, and that under certain conditions it can be understood as an Abelian geometric phase in a different frame of reference. Results should help design better schemes for the control of cold-atom matter waves.

  7. Risk of Performance Decrements and Adverse Health Outcomes Resulting from Sleep Loss, Circadian Desynchronization, and Work Overload

    NASA Technical Reports Server (NTRS)

    Evans-Flynn, Erin; Gregory, Kevin; Arsintescu, Lucia; Whitmire, Alexandra; Leveton, Lauren B.; Vessey, William

    2015-01-01

    Sleep loss, circadian desynchronization, and work overload occur to some extent for ground and flight crews, prior to and during spaceflight missions. Ground evidence indicates that such risk factors may lead to performance decrements and adverse health outcomes, which could potentially compromise mission objectives. Efforts are needed to identify the environmental and mission conditions that interfere with sleep and circadian alignment, as well as individual differences in vulnerability and resiliency to sleep loss and circadian desynchronization. Specifically, this report highlights a collection of new evidence to better characterize the risk and reveals new gaps in this risk.

  8. Mu desynchronization during observation and execution of facial expressions in 30-month-old children.

    PubMed

    Rayson, Holly; Bonaiuto, James John; Ferrari, Pier Francesco; Murray, Lynne

    2016-06-01

    Simulation theories propose that observing another's facial expression activates sensorimotor representations involved in the execution of that expression, facilitating recognition processes. The mirror neuron system (MNS) is a potential mechanism underlying simulation of facial expressions, with like neural processes activated both during observation and performance. Research with monkeys and adult humans supports this proposal, but so far there have been no investigations of facial MNS activity early in human development. The current study used electroencephalography (EEG) to explore mu rhythm desynchronization, an index of MNS activity, in 30-month-old children as they observed videos of dynamic emotional and non-emotional facial expressions, as well as scrambled versions of the same videos. We found significant mu desynchronization in central regions during observation and execution of both emotional and non-emotional facial expressions, which was right-lateralized for emotional and bilateral for non-emotional expressions during observation. These findings support previous research suggesting movement simulation during observation of facial expressions, and are the first to provide evidence for sensorimotor activation during observation of facial expressions, consistent with a functioning facial MNS at an early stage of human development.

  9. Event-related EEG desynchronization and synchronization during an auditory memory task.

    PubMed

    Krause, C M; Lang, A H; Laine, M; Kuusisto, M; Pörn, B

    1996-04-01

    Event-related desynchronization (ERD) and synchronization (ERS) of the lower (8-10 Hz) and upper (10-12 Hz) alpha bands of background EEG were studied in 10 subjects during an auditory memory scanning paradigm. Each experimental trial started with the presentation of a visual warning signal, after which an auditory 4-vowel memory set was presented for memorization. Thereafter the probe, a fifth vowel, was presented and identified by the subject as belonging or not belonging to the memorized set. In 50% of the cases, the probe was among the previously presented memory set. The presentation of the memory set elicited a significant ERS in the both alpha frequency bands. In contrast, the presentation of the probe elicited a significant bilateral ERD in both alpha frequency bands studied. The results suggest that the ERD phenomenon is closely associated with higher cortical processes such as memory functions rather than with auditory stimulus processing per se. Event-related desynchronization provides a potentially valuable tool for studying cortical activity during cognitive processing in the auditory stimulus modality.

  10. Mu desynchronization during observation and execution of facial expressions in 30-month-old children.

    PubMed

    Rayson, Holly; Bonaiuto, James John; Ferrari, Pier Francesco; Murray, Lynne

    2016-06-01

    Simulation theories propose that observing another's facial expression activates sensorimotor representations involved in the execution of that expression, facilitating recognition processes. The mirror neuron system (MNS) is a potential mechanism underlying simulation of facial expressions, with like neural processes activated both during observation and performance. Research with monkeys and adult humans supports this proposal, but so far there have been no investigations of facial MNS activity early in human development. The current study used electroencephalography (EEG) to explore mu rhythm desynchronization, an index of MNS activity, in 30-month-old children as they observed videos of dynamic emotional and non-emotional facial expressions, as well as scrambled versions of the same videos. We found significant mu desynchronization in central regions during observation and execution of both emotional and non-emotional facial expressions, which was right-lateralized for emotional and bilateral for non-emotional expressions during observation. These findings support previous research suggesting movement simulation during observation of facial expressions, and are the first to provide evidence for sensorimotor activation during observation of facial expressions, consistent with a functioning facial MNS at an early stage of human development. PMID:27261926

  11. Phase Synchronization and Desynchronization of Structural Response Induced by Turbulent and External Sound

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    2002-01-01

    Acoustic and turbulent boundary layer flow loadings over a flexible structure are used to study the spatial-temporal dynamics of the response of the structure. The stability of the spatial synchronization and desynchronization by an active external force is investigated with an array of coupled transducers on the structure. In the synchronous state, the structural phase is locked, which leads to the formation of spatial patterns while the amplitude peaks exhibit chaotic behaviors. Large amplitude, spatially symmetric loading is superimposed on broadband, but in the desynchronized state, the spectrum broadens and the phase space is lost. The resulting pattern bears a striking resemblance to phase turbulence. The transition is achieved by using a low power external actuator to trigger broadband behaviors from the knowledge of the external acoustic load inducing synchronization. The changes are made favorably and efficiently to alter the frequency distribution of power, not the total power level. Before synchronization effects are seen, the panel response to the turbulent boundary layer loading is discontinuously spatio-temporally correlated. The stability develops from different competing wavelengths; the spatial scale is significantly shorter than when forced with the superimposed external sound. When the external sound level decreases and the synchronized phases are lost, changes in the character of the spectra can be linked to the occurrence of spatial phase transition. These changes can develop broadband response. Synchronized responses of fuselage structure panels have been observed in subsonic and supersonic aircraft; results from two flights tests are discussed.

  12. Living with a large reduction in permited loading by using a hydrograph-controlled release scheme

    USGS Publications Warehouse

    Conrads, P.A.; Martello, W.P.; Sullins, N.R.

    2003-01-01

    The Total Maximum Daily Load (TMDL) for ammonia and biochemical oxygen demand for the Pee Dee, Waccamaw, and Atlantic Intracoastal Waterway system near Myrtle Beach, South Carolina, mandated a 60-percent reduction in point-source loading. For waters with a naturally low background dissolved-oxygen concentrations, South Carolina anti-degradation rules in the water-quality regulations allows a permitted discharger a reduction of dissolved oxygen of 0.1 milligrams per liter (mg/L). This is known as the "0.1 rule." Permitted dischargers within this region of the State operate under the "0.1 rule" and cannot cause a cumulative impact greater than 0.1 mg/L on dissolved-oxygen concentrations. For municipal water-reclamation facilities to serve the rapidly growing resort and retirement community near Myrtle Beach, a variable loading scheme was developed to allow dischargers to utilize increased assimilative capacity during higher streamflow conditions while still meeting the requirements of a recently established TMDL. As part of the TMDL development, an extensive real-time data-collection network was established in the lower Waccamaw and Pee Dee River watershed where continuous measurements of streamflow, water level, dissolved oxygen, temperature, and specific conductance are collected. In addition, the dynamic BRANCH/BLTM models were calibrated and validated to simulate the water quality and tidal dynamics of the system. The assimilative capacities for various streamflows were also analyzed. The variable-loading scheme established total loadings for three streamflow levels. Model simulations show the results from the additional loading to be less than a 0.1 mg/L reduction in dissolved oxygen. As part of the loading scheme, the real-time network was redesigned to monitor streamflow entering the study area and water-quality conditions in the location of dissolved-oxygen "sags." The study reveals how one group of permit holders used a variable-loading scheme to implement

  13. A proposed transition scheme for the longitudinal emittance control in the Fermilab Booster

    SciTech Connect

    Yang, Xi; Ankenbrandt, Charles M.; MacLachlan, James; Lebedev, Valeri A.; /Fermilab

    2005-08-01

    Instead of applying the {gamma}{sub T} jump at the designed value of 1.0, which never can be used in the operation due to the quad steering, the combination of the rf manipulation and a 0.2-unit {gamma}{sub T} jump can reduce the longitudinal emittance growth nearly 40% during transition. Especially, a 0.2-unit {gamma}{sub T} jump can help in reducing the rf manipulating voltage from 1000 kV to 850 kV, and makes the transition scheme operationally feasible.

  14. 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.

  15. Lipoic acid entrains the hepatic circadian clock and lipid metabolic proteins that have been desynchronized with advanced age

    SciTech Connect

    Keith, Dove; Finlay, Liam; Butler, Judy; Gómez, Luis; Smith, Eric; Moreau, Régis; Hagen, Tory

    2014-07-18

    Highlights: • 24 month old rats were supplemented with 0.2% lipoic acid in the diet for 2 weeks. • Lipoic acid shifts phase of core circadian clock proteins. • Lipoic acid corrects age-induced desynchronized lipid metabolism rhythms. - Abstract: It is well established that lipid metabolism is controlled, in part, by circadian clocks. However, circadian clocks lose temporal precision with age and correlates with elevated incidence in dyslipidemia and metabolic syndrome in older adults. Because our lab has shown that lipoic acid (LA) improves lipid homeostasis in aged animals, we hypothesized that LA affects the circadian clock to achieve these results. We fed 24 month old male F344 rats a diet supplemented with 0.2% (w/w) LA for 2 weeks prior to sacrifice and quantified hepatic circadian clock protein levels and clock-controlled lipid metabolic enzymes. LA treatment caused a significant phase-shift in the expression patterns of the circadian clock proteins Period (Per) 2, Brain and Muscle Arnt-Like1 (BMAL1), and Reverse Erythroblastosis virus (Rev-erb) β without altering the amplitude of protein levels during the light phase of the day. LA also significantly altered the oscillatory patterns of clock-controlled proteins associated with lipid metabolism. The level of peroxisome proliferator-activated receptor (PPAR) α was significantly increased and acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) were both significantly reduced, suggesting that the LA-supplemented aged animals are in a catabolic state. We conclude that LA remediates some of the dyslipidemic processes associated with advanced age, and this mechanism may be at least partially through entrainment of circadian clocks.

  16. Biventricular stimulation to prevent cardiac desynchronization: rationale, design, and endpoints of the 'Biventricular Pacing for Atrioventricular Block to Prevent Cardiac Desynchronization (BioPace)' study.

    PubMed

    Funck, Reinhard C; Blanc, Jean-Jacques; Mueller, Hans-Helge; Schade-Brittinger, Carmen; Bailleul, Christophe; Maisch, Bernhard

    2006-08-01

    Despite the deleterious effects of cardiac dyssynchrony and the positive effects of cardiac resynchronization therapy, patients with high-degree atrioventricular block continue to receive desynchronizing right ventricular (RV) pacing systems. Although it is unclear whether the negative effects of RV pacing and left bundle branch block (LBBB) are comparable, and whether they depend on the presence and the degree of structural heart disease, one may hypothesize that RV pacing may have similar effects to LBBB. In the BioPace trial, the long-term effects of RV pacing vs. biventricular pacing will be prospectively compared in 1200 pacemaker patients with high likelihood of mostly paced ventricular events, regardless of whether in sinus rhythm or in atrial fibrillation (AF). After echocardiographic examination of left ventricular (LV) function, patients will be randomly assigned to the implantation of an RV vs. a biventricular pacing system and followed for up to 5 years. Primary study endpoints are survival, quality of life (QoL), and the distance covered in a 6-min hall walk (6-MHW) at 24 months after implantation. Secondary endpoints are QoL and the 6-MHW result at 12 months after implantation, hospitalization rate, LV dimensions, LV ejection fraction, and the development of chronic AF and other adverse events. PMID:16864616

  17. A Muscle Synergy-Inspired Adaptive Control Scheme for a Hybrid Walking Neuroprosthesis

    PubMed Central

    Alibeji, Naji A.; Kirsch, Nicholas Andrew; Sharma, Nitin

    2015-01-01

    A hybrid neuroprosthesis that uses an electric motor-based wearable exoskeleton and functional electrical stimulation (FES) has a promising potential to restore walking in persons with paraplegia. A hybrid actuation structure introduces effector redundancy, making its automatic control a challenging task because multiple muscles and additional electric motor need to be coordinated. Inspired by the muscle synergy principle, we designed a low dimensional controller to control multiple effectors: FES of multiple muscles and electric motors. The resulting control system may be less complex and easier to control. To obtain the muscle synergy-inspired low dimensional control, a subject-specific gait model was optimized to compute optimal control signals for the multiple effectors. The optimal control signals were then dimensionally reduced by using principal component analysis to extract synergies. Then, an adaptive feedforward controller with an update law for the synergy activation was designed. In addition, feedback control was used to provide stability and robustness to the control design. The adaptive-feedforward and feedback control structure makes the low dimensional controller more robust to disturbances and variations in the model parameters and may help to compensate for other time-varying phenomena (e.g., muscle fatigue). This is proven by using a Lyapunov stability analysis, which yielded semi-global uniformly ultimately bounded tracking. Computer simulations were performed to test the new controller on a 4-degree of freedom gait model. PMID:26734606

  18. Efficient congestion control scheme for providing QoS to I-VPN

    NASA Astrophysics Data System (ADS)

    De Marco, Martino; Trabucchi, Sara

    1998-12-01

    In this paper we outline an overall network architecture for the Internet Service Providers who want offer an Internet- Virtual Private Network service with QoS guarantees and, at the same time, with a high-level of efficiency in the network resource usage. The proposed approach is based on the negotiation of a service level agreement, which includes the definition of profile of traffic the user is allowed to emit. The ingress nodes perform an adaptive shaping of the user traffic entering the network, driven by a fast congestion notification scheme. In this scenario, the adoption of a service architecture based on a class-of- service concept enables the Internet Service Provider to offer different level of network performance according to the customer needs.

  19. Injection control of an XeF (C-A) laser - A simple scheme

    NASA Astrophysics Data System (ADS)

    Hollins, R. C.; Jordan, D. J.; Feltman, A.

    1987-07-01

    Enhancement of the efficiency of a blue-green discharge laser is demonstrated using a simple dye laser which is excited by the UV output of the XeF medium itself. The 350-nm output is harnessed to excite a small dye laser which acts as an injection source. The occurrence of optical gain on the C-A transition (440-520 nm) is delayed with respect to the UV output due to the initial presence of visible absorbing species, resulting in the automatic injection of dye-laser radiation into the XeF laser cavity at the appropriate time. With selection of the oscillation wavelength by the choice of dye, improvement of the efficiency by a factor of 30 is possible with the present self-excited injection scheme.

  20. Mask roughness induced LER control and mitigation: aberrations sensitivity study and alternate illumination scheme

    SciTech Connect

    McClinton, Brittany M.; Naulleau, Patrick P.

    2011-03-11

    Here we conduct a mask-roughness-induced line-edge-roughness (LER) aberrations sensitivity study both as a random distribution amongst the first 16 Fringe Zernikes (for overall aberration levels of 0.25, 0.50, and 0.75nm rms) as well as an individual aberrations sensitivity matrix over the first 37 Fringe Zernikes. Full 2D aerial image modeling for an imaging system with NA = 0.32 was done for both the 22-nm and 16-nm half-pitch nodes on a rough mask with a replicated surface roughness (RSR) of 100 pm and a correlation length of 32 nm at the nominal extreme-ultraviolet lithography (EUVL) wavelength of 13.5nm. As the ideal RSR value for commercialization of EUVL is 50 pm and under, and furthermore as has been shown elsewhere, a correlation length of 32 nm of roughness on the mask sits on the peak LER value for an NA = 0.32 imaging optic, these mask roughness values and consequently the aberration sensitivity study presented here, represent a worst-case scenario. The illumination conditions were chosen based on the possible candidates for the 22-nm and 16-nm half-pitch nodes, respectively. In the 22-nm case, a disk illumination setting of {sigma} = 0.50 was used, and for the 16-nm case, crosspole illumination with {sigma} = 0.10 at an optimum offset of dx = 0 and dy = .67 in sigma space. In examining how to mitigate mask roughness induced LER, we considered an alternate illumination scheme whereby a traditional dipole's angular spectrum is extended in the direction parallel to the line-and-space mask absorber pattern to represent a 'strip'. While this illumination surprisingly provides minimal improvement to the LER as compared to several alternate illumination schemes, the overall imaging quality in terms of image-log-slope (ILS) and contrast is improved.

  1. Neural Correlates of Action Observation and Execution in 14-Month-Old Infants: An Event-Related EEG Desynchronization Study

    ERIC Educational Resources Information Center

    Marshall, Peter J.; Young, Thomas; Meltzoff, Andrew N.

    2011-01-01

    There is increasing interest in neurobiological methods for investigating the shared representation of action perception and production in early development. We explored the extent and regional specificity of EEG desynchronization in the infant alpha frequency range (6-9 Hz) during action observation and execution in 14-month-old infants.…

  2. Visceral Leishmaniasis on the Indian Subcontinent: Modelling the Dynamic Relationship between Vector Control Schemes and Vector Life Cycles

    PubMed Central

    2016-01-01

    Background Visceral leishmaniasis (VL) is a disease caused by two known vector-borne parasite species (Leishmania donovani, L. infantum), transmitted to man by phlebotomine sand flies (species: Phlebotomus and Lutzomyia), resulting in ≈50,000 human fatalities annually, ≈67% occurring on the Indian subcontinent. Indoor residual spraying is the current method of sand fly control in India, but alternative means of vector control, such as the treatment of livestock with systemic insecticide-based drugs, are being evaluated. We describe an individual-based, stochastic, life-stage-structured model that represents a sand fly vector population within a village in India and simulates the effects of vector control via fipronil-based drugs orally administered to cattle, which target both blood-feeding adults and larvae that feed on host feces. Principle findings Simulation results indicated efficacy of fipronil-based control schemes in reducing sand fly abundance depended on timing of drug applications relative to seasonality of the sand fly life cycle. Taking into account cost-effectiveness and logistical feasibility, two of the most efficacious treatment schemes reduced population peaks occurring from April through August by ≈90% (applications 3 times per year at 2-month intervals initiated in March) and >95% (applications 6 times per year at 2-month intervals initiated in January) relative to no control, with the cumulative number of sand fly days occurring April-August reduced by ≈83% and ≈97%, respectively, and more specifically during the summer months of peak human exposure (June-August) by ≈85% and ≈97%, respectively. Conclusions Our model should prove useful in a priori evaluation of the efficacy of fipronil-based drugs in controlling leishmaniasis on the Indian subcontinent and beyond. PMID:27537774

  3. EEG Classification for Hybrid Brain-Computer Interface Using a Tensor Based Multiclass Multimodal Analysis Scheme

    PubMed Central

    Ji, Hongfei; Li, Jie; Lu, Rongrong; Gu, Rong; Cao, Lei; Gong, Xiaoliang

    2016-01-01

    Electroencephalogram- (EEG-) based brain-computer interface (BCI) systems usually utilize one type of changes in the dynamics of brain oscillations for control, such as event-related desynchronization/synchronization (ERD/ERS), steady state visual evoked potential (SSVEP), and P300 evoked potentials. There is a recent trend to detect more than one of these signals in one system to create a hybrid BCI. However, in this case, EEG data were always divided into groups and analyzed by the separate processing procedures. As a result, the interactive effects were ignored when different types of BCI tasks were executed simultaneously. In this work, we propose an improved tensor based multiclass multimodal scheme especially for hybrid BCI, in which EEG signals are denoted as multiway tensors, a nonredundant rank-one tensor decomposition model is proposed to obtain nonredundant tensor components, a weighted fisher criterion is designed to select multimodal discriminative patterns without ignoring the interactive effects, and support vector machine (SVM) is extended to multiclass classification. Experiment results suggest that the proposed scheme can not only identify the different changes in the dynamics of brain oscillations induced by different types of tasks but also capture the interactive effects of simultaneous tasks properly. Therefore, it has great potential use for hybrid BCI. PMID:26880873

  4. EEG Classification for Hybrid Brain-Computer Interface Using a Tensor Based Multiclass Multimodal Analysis Scheme.

    PubMed

    Ji, Hongfei; Li, Jie; Lu, Rongrong; Gu, Rong; Cao, Lei; Gong, Xiaoliang

    2016-01-01

    Electroencephalogram- (EEG-) based brain-computer interface (BCI) systems usually utilize one type of changes in the dynamics of brain oscillations for control, such as event-related desynchronization/synchronization (ERD/ERS), steady state visual evoked potential (SSVEP), and P300 evoked potentials. There is a recent trend to detect more than one of these signals in one system to create a hybrid BCI. However, in this case, EEG data were always divided into groups and analyzed by the separate processing procedures. As a result, the interactive effects were ignored when different types of BCI tasks were executed simultaneously. In this work, we propose an improved tensor based multiclass multimodal scheme especially for hybrid BCI, in which EEG signals are denoted as multiway tensors, a nonredundant rank-one tensor decomposition model is proposed to obtain nonredundant tensor components, a weighted fisher criterion is designed to select multimodal discriminative patterns without ignoring the interactive effects, and support vector machine (SVM) is extended to multiclass classification. Experiment results suggest that the proposed scheme can not only identify the different changes in the dynamics of brain oscillations induced by different types of tasks but also capture the interactive effects of simultaneous tasks properly. Therefore, it has great potential use for hybrid BCI. PMID:26880873

  5. A new method for high-capacity information hiding in video robust against temporal desynchronization

    NASA Astrophysics Data System (ADS)

    Mitekin, Vitaly; Fedoseev, Victor A.

    2015-02-01

    This paper presents a new method for high-capacity information hiding in digital video and algorithms of embedding and extraction of hidden information based on this method. These algorithms do not require temporal synchronization to provide robustness against both malicious and non-malicious frame dropping (temporal desynchronization). At the same time, due to randomized distribution of hidden information bits across the video frames, the proposed method allows to increase the hiding capacity proportionally to the number of frames used for information embedding. The proposed method is also robust against "watermark estimation" attack aimed at estimation of hidden information without knowing the embedding key or non-watermarked video. Presented experimental results demonstrate declared features of this method.

  6. Fractals properties of EEG during event-related desynchronization of motor imagery.

    PubMed

    Nguyen, Ngoc Quang; Truong, Quang Dang Khoa; Kondo, Toshiyuki

    2015-01-01

    Chaos and fractal dimension are emerging modalities for the research of electroencephalogram (EEG) signal processing. The capability of measuring non-linear characteristics of the fractal dimension enables new methodologies to identify distinct brain activities. Recent studies on the topic focus on utilizing various types of fractals as features in order to design better brain state classification system. However, we have little insight about the EEG signals projected in fractal dimension. In this paper, we investigate the relationship between the non-linear characteristics of ongoing EEG signals and event-related desynchronization (ERD) during motor imagery. We observed a considerable synchronization between ERD and fractal dimension. This finding suggests further usage of chaos and fractal theory in investigating brain activities. PMID:26737207

  7. Watermark Embedding and Recovery in the Presence of C-LPCD De-synchronization Attacks

    NASA Astrophysics Data System (ADS)

    Abrardo, Andrea; Barni, Mauro; Carretti, Cesare Maria

    The development of a watermarking system that is robust against de-synchronization attacks (DAs) is a major challenge. In this paper we make two steps towards the development of such a system by: i) proposing a fast algorithm for exhaustive watermark detection in the presence of C-LPCD DAs; ii) introducing a new watermarking system that by pre-distorting the watermark to be embedded greatly improves the performance of the exhaustive watermark detector. The validity of the proposed system is tested by means of Monte Carlo simulation on Gaussian white sequences. The results we obtained are rather promising thus suggesting to apply the newly proposed system to the watermarking of real audio sequences.

  8. Analysis of extrinsic and intrinsic factors affecting event related desynchronization production.

    PubMed

    Takata, Yohei; Kondo, Toshiyuki; Saeki, Midori; Izawa, Jun; Takeda, Kotaro; Otaka, Yohei; It, Koji

    2012-01-01

    Recently there has been an increase in the number of stroke patients with motor paralysis. Appropriate re-afferent sensory feedback synchronized with a voluntary motor intention would be effective for promoting neural plasticity in the stroke rehabilitation. Therefore, BCI technology is considered to be a promising approach in the neuro-rehabilitation. To estimate human motor intention, an event-related desynchronization (ERD), a feature of electroencephalogram (EEG) evoked by motor execution or motor imagery is usually used. However, there exists various factors that affect ERD production, and its neural mechanism is still an open question. As a preliminary stage, we evaluate mutual effects of intrinsic (voluntary motor imagery) and extrinsic (visual and somatosensory stimuli) factors on the ERD production. Experimental results indicate that these three factors are not always additively interacting with each other and affecting the ERD production.

  9. Tunable power law in the desynchronization events of coupled chaotic electronic circuits

    SciTech Connect

    Oliveira, Gilson F. de Lorenzo, Orlando di; Chevrollier, Martine; Passerat de Silans, Thierry; Oriá, Marcos; Souza Cavalcante, Hugo L. D. de

    2014-03-15

    We study the statistics of the amplitude of the synchronization error in chaotic electronic circuits coupled through linear feedback. Depending on the coupling strength, our system exhibits three qualitatively different regimes of synchronization: weak coupling yields independent oscillations; moderate to strong coupling produces a regime of intermittent synchronization known as attractor bubbling; and stronger coupling produces complete synchronization. In the regime of moderate coupling, the probability distribution for the sizes of desynchronization events follows a power law, with an exponent that can be adjusted by changing the coupling strength. Such power-law distributions are interesting, as they appear in many complex systems. However, most of the systems with such a behavior have a fixed value for the exponent of the power law, while here we present an example of a system where the exponent of the power law is easily tuned in real time.

  10. Stress-associated synchronization and desynchronization in geologic and biologic systems

    NASA Astrophysics Data System (ADS)

    Kluchevsky, A. V.; Kluchevskaya, A. A.

    2010-12-01

    Variations in the annual numbers of representative earthquakes in three areas and six districts of the Baikal rift zone in 1964-2002 were subjected to correlation analysis. Episodes of significant correlations of shock flow rates were found against the background of chaotic seismic activity. They followed the rearrangements (catastrophes) of stresses in the lithosphere, which are also stressing factors for the whole rift geodynamic system. The episode of the late 1970s-early 1980s was particularly long and showed the maximum correlation. Therefore, it can be considered the principal event in seismic process synchronization in the Baikal Rift Zone. The same approach to data analysis revealed similar synchronization and desynchronization phenomena in the behavior of Baikalian turbellaria when they deviated from homeostasis as a result of illumination, which is a stress for this biologic system. Possible reasons for the behavior of biologic and geodynamic systems are discussed in terms of the synergetic concept of phenomena in living and nonliving nature.

  11. Fractals properties of EEG during event-related desynchronization of motor imagery.

    PubMed

    Nguyen, Ngoc Quang; Truong, Quang Dang Khoa; Kondo, Toshiyuki

    2015-01-01

    Chaos and fractal dimension are emerging modalities for the research of electroencephalogram (EEG) signal processing. The capability of measuring non-linear characteristics of the fractal dimension enables new methodologies to identify distinct brain activities. Recent studies on the topic focus on utilizing various types of fractals as features in order to design better brain state classification system. However, we have little insight about the EEG signals projected in fractal dimension. In this paper, we investigate the relationship between the non-linear characteristics of ongoing EEG signals and event-related desynchronization (ERD) during motor imagery. We observed a considerable synchronization between ERD and fractal dimension. This finding suggests further usage of chaos and fractal theory in investigating brain activities.

  12. Online Motor Imagery Training Effect for the Appearance of Event Related Desynchronization (ERD)

    NASA Astrophysics Data System (ADS)

    Takahashi, Mitsuru; Gouko, Manabu; Ito, Koji

    Stroke patients have some motor deficits, but they can regain their motor abilities by rehabilitation. In the aspect of rehabilitation, voluntary movement is very important. We propose a system which can make a closed loop in brain for stroke patients like voluntary movement. Event Related Desynchronization (ERD) is used to extract patients' motor intention, and then Functional Electrical Stimulation (FES) stimuls their paralyzed muscles. In many Brain Computer Interface (BCI) researches, subjects are trained for several months or years to do the task, because of the difficulty to extract clear ERD without training. Thinking about applying for stroke patients, motor imagery training should be shorter, because of the brain plasticity. We did a pilot study about the effect of visual feedback training for three days with healthy subjects. The result indicated that ERD could be clearly extracted in three days, but the training effect differs in each subjects.

  13. Adaptive Training of Manual Control: 1. Comparison of Three Adaptive Variables and Two Logic Schemes.

    ERIC Educational Resources Information Center

    Norman, D. A.; And Others

    "Machine controlled adaptive training is a promising concept. In adaptive training the task presented to the trainee varies as a function of how well he performs. In machine controlled training, adaptive logic performs a function analogous to that performed by a skilled operator." This study looks at the ways in which gain-effective time constant…

  14. Control scheme of nonadiabatic transitions with the dynamical shift of potential curve crossing

    SciTech Connect

    Scheit, Simona; Arasaki, Yasuki Takatsuka, Kazuo

    2014-06-28

    We investigate how the nuclear dynamics at an avoided crossing is affected and can be controlled by the introduction of a laser field whose cycle is comparable to the time-scale of the nuclear dynamics. By introducing the concepts of light-induced effective potential energy curves and dynamical avoided crossing, we describe the laser controlled nuclear dynamics and present basic control scenarios, giving a detailed explanation of the underlying dynamical mechanisms. The scenarios presented allow for examples to understand from a different perspective the results of dynamic Stark control experiments. The proposed interpretation is applied to the laser-controlled nonadiabatic dynamics between the two lowest {sup 1}Σ{sup +} states of LiF, where the usefulness of the concepts developed is elucidated.

  15. Obesity and chronic stress are able to desynchronize the temporal pattern of serum levels of leptin and triglycerides.

    PubMed

    de Oliveira, Carla; Scarabelot, Vanessa Leal; de Souza, Andressa; de Oliveira, Cleverson Moraes; Medeiros, Liciane Fernandes; de Macedo, Isabel Cristina; Marques Filho, Paulo Ricardo; Cioato, Stefania Giotti; Caumo, Wolnei; Torres, Iraci L S

    2014-01-01

    Disruption of the circadian system can lead to metabolic dysfunction as a response to environmental alterations. This study assessed the effects of the association between obesity and chronic stress on the temporal pattern of serum levels of adipogenic markers and corticosterone in rats. We evaluated weekly weight, delta weight, Lee index, and weight fractions of adipose tissue (mesenteric, MAT; subcutaneous, SAT; and pericardial, PAT) to control for hypercaloric diet-induced obesity model efficacy. Wistar rats were divided into four groups: standard chow (C), hypercaloric diet (HD), stress plus standard chow (S), and stress plus hypercaloric diet (SHD), and analyzed at three time points: ZT0, ZT12, and ZT18. Stressed animals were subjected to chronic stress for 1h per day, 5 days per week, during 80 days. The chronic exposure to a hypercaloric diet was an effective model for the induction of obesity and metabolic syndrome, increasing delta weight, Lee index, weight fractions of adipose tissue, and triglycerides and leptin levels. We confirmed the presence of a temporal pattern in the release of triglycerides, corticosterone, leptin, and adiponectin in naïve animals. Chronic stress reduced delta weight, MAT weight, and levels of triglycerides, total cholesterol, and leptin. There were interactions between chronic stress and obesity and serum total cholesterol levels, between time points and obesity and adiponectin and corticosterone levels, and between time points and chronic stress and serum leptin levels. In conclusion, both parameters were able to desynchronize the temporal pattern of leptin and triglyceride release, which could contribute to the development of metabolic diseases such as obesity and metabolic syndrome.

  16. An on-line equivalent system identification scheme for adaptive control. Ph.D. Thesis - Stanford Univ.

    NASA Technical Reports Server (NTRS)

    Sliwa, S. M.

    1984-01-01

    A prime obstacle to the widespread use of adaptive control is the degradation of performance and possible instability resulting from the presence of unmodeled dynamics. The approach taken is to explicitly include the unstructured model uncertainty in the output error identification algorithm. The order of the compensator is successively increased by including identified modes. During this model building stage, heuristic rules are used to test for convergence prior to designing compensators. Additionally, the recursive identification algorithm as extended to multi-input, multi-output systems. Enhancements were also made to reduce the computational burden of an algorithm for obtaining minimal state space realizations from the inexact, multivariate transfer functions which result from the identification process. A number of potential adaptive control applications for this approach are illustrated using computer simulations. Results indicated that when speed of adaptation and plant stability are not critical, the proposed schemes converge to enhance system performance.

  17. Flow control simulations around a circular cylinder by a finite-volume scheme

    NASA Astrophysics Data System (ADS)

    Lin, San-Yih; Wu, Tsuen-Muh

    1993-07-01

    A numerical study is made of the flow past a circular cylinder with/without flow control devices. The Reynolds number ranges from 20 to 200. The numerical method for the solutions of the incompressible Navier-Stokes equations is based on an artificial compressibility approach and an upwind finite-volume method. Two kinds of the flow control devices are investigated: (1) placing an attached or a detached splitter plate in the wake behind the circular cylinder, and (2) placing a second small cylinder (control cylinder) behind the circular cylinder. The numerical investigations show that both of two are effective on the suppression of vortex shedding and the reduction of drag.

  18. The merits of ion cyclotron resonance heating schemes for sawtooth control in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Chapman, I. T.; Graves, J. P.; Lennholm, M.; Faustin, J.; Lerche, E.; Johnson, T.; Tholerus, S.; Tholerus

    2015-12-01

    > or dipole) has a destabilising effect on the sawteeth, meaning that dipole phasing can be employed, since this is preferable due to less plasma wall interaction from Resonant Frequency (RF) sheaths. Secondly, the resonance position of the low-field side ICRH does not have to be very accurately placed to achieve sawtooth control, relaxing the requirement for real-time control of the RF frequency. These empirical observations have been confirmed by hybrid kinetic-magnetohydrodynamic modelling, and suggest that the ICRH antenna design for ITER is well positioned to provide a control actuator capable of having a significant effect on the sawtooth behaviour.

  19. A direct torque control scheme for permanent magnet synchronous motors based on space vector modulation

    NASA Astrophysics Data System (ADS)

    Su, Xiao-hui; Xu, Shu-Ping

    2013-03-01

    In order to solve the problem of direct torque control (DTC) for permanent magnet synchronous motor (PMSM) related to the flux and the torque ripple and the uncertainty of switching frequency, A novel direct torque control system based on space vector modulation(SVM-DTC) for permanent magnet synchronous motor was proposed. In this method flux and torque are controlled through stator voltage components in stator flux linkage coordinate axes and space vector modulation is used to control inverters. Therefore, the errors of torque and flux linkage could be compensated accurately. The whole system has only one easily adjustable PI adjuster and needs no high for hardware and easy for realize. The simulation results verify the feasibility of this method, reduction of the flux and the torque ripple, and the good performance of DTC.

  20. Grey box modelling and advanced control scheme for building heating systems

    NASA Astrophysics Data System (ADS)

    Jassar, Surinder

    This dissertation is aimed at generating new knowledge on Recurrent Neuro-Fuzzy Inference Systems (RenFIS) and to explore its application in building automation. Inferential sensing is an attractive approach for modeling the behavior of dynamic processes. Inferential sensor based control strategies are applied to optimize the control of residential heating systems and demonstrate significant energy saving and comfort improvement. Despite the rapidly decreasing cost and improving accuracy of most temperature sensors, it is normally impractical to use a lot of sensors to measure the average air temperature because the wiring and instrumentation can be very expensive to install and maintain. To design a reliable inferential sensor, of fundamental importance is to build a simple and robust dynamic model of the system to be controlled. This dissertation presents the development of an innovative algorithm that is suitable for the robust black-box model. The algorithm is derived from ANFIS (Adaptive Neuro-Fuzzy Inference System) and is referred to as RenFIS. Like all other modeling techniques, RenFIS performance is sensitive to the training data. In this study, RenFIS is used to model two different heating systems, hot water heating system and forced warm-air heating system. The training data is collected under different operational conditions. RenFIS gives better performance if trained with the data set representing overall qualities of the whole universe of the experimental data. The robustness analysis is conducted by introducing simulated noise to the training data. Results show that RenFIS is less sensitive than ANFIS to the quality of training data. The RenFIS based inferential sensor is then applied to design an inferential control algorithm that can improve the operation of residential heating systems. In current practice, the control of heating systems is based on the measurement of air temperature at one point within the building. The inferential control

  1. An improved fault-tolerant control scheme for PWM inverter-fed induction motor-based EVs.

    PubMed

    Tabbache, Bekheïra; Benbouzid, Mohamed; Kheloui, Abdelaziz; Bourgeot, Jean-Matthieu; Mamoune, Abdeslam

    2013-11-01

    This paper proposes an improved fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. To increase the vehicle powertrain reliability regarding IGBT open-circuit failures, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed in a vehicle context. The proposed fault-tolerant topologies require only minimum hardware modifications to the conventional off-the-shelf six-switch three-phase drive, mitigating the IGBTs failures by specific inverter control. Indeed, the two topologies exploit the induction motor neutral accessibility for fault-tolerant purposes. The 4-wire topology uses then classical hysteresis controllers to account for the IGBT failures. The 4-leg topology, meanwhile, uses a specific 3D space vector PWM to handle vehicle requirements in terms of size (DC bus capacitors) and cost (IGBTs number). Experiments on an induction motor drive and simulations on an electric vehicle are carried-out using a European urban driving cycle to show that the proposed fault-tolerant control approach is effective and provides a simple configuration with high performance in terms of speed and torque responses. PMID:23916869

  2. Controlling Proton Conductivity with Light: A Scheme Based on Photoacid Doping of Materials.

    PubMed

    Haghighat, Shima; Ostresh, Sarah; Dawlaty, Jahan M

    2016-02-11

    Transducing light energy to changes in material properties is central to a large range of functional materials, including those used in light harvesting. In conventional semiconductors, photoconductivity arises due to generation of mobile electrons or holes with light. Here we demonstrate, to our knowledge for the first time, an analogue of this effect for protons in an organic polymer solution and in water. We show that when a material is doped with photoacids, light excitation generates extra mobile protons that change the low-frequency conductivity of the material. We measure such change both in poly(ethylene glycol) (PEG) and in water sandwiched between two transparent electrodes and doped with a well-known photoacid 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS). The complex impedance of the material is measured over a range of 0.1 Hz-1 MHz in both the presence and absence of light, and it is found that shining light changes the low frequency impedance significantly. We model the impedance spectra of the material with a minimal circuit composed of a diffusive impedance (Warburg element), a parallel capacitance, and a resistance. Fitting the light and dark impedance spectra to the model reveals that light reduces the low-frequency diffusive impedance of the material, which is consistent with generation of extra free carriers by light. We further suggest that the light-induced conductivity change arises mainly due to those photoreleased protons that manage to escape the zone of influence of the parent ion and avoid recapture. Such escape is more likely in materials with larger diffusion coefficient for protons and shorter electrostatic screening lengths for the parent ion. This explanation is consistent with our observed differences in the photoconductivity of solution of HPTS in water and in PEG. We anticipate that this scheme can be employed in protonic circuits where direct transduction of energy from light to protonic gradients or protonic currents is

  3. Stability Properties and Cross Coupling Performance of the Control Allocation Scheme CAPIO

    NASA Technical Reports Server (NTRS)

    Yildiz, Yildiray; Kolmanovsky, Ilya V.

    2010-01-01

    This paper presents a stability analysis and an application of a recently developed Control Allocator for recovery from Pilot Induced Oscillations (CAPIO). When actuators are rate-saturated due to either aggressive pilot commands, high gain ight control systems or some anomaly in the system, the effective delay in the control loop may increase. This effective delay increase manifests itself as a phase shift between the commanded and actual system signals and can instigate Pilot induced Oscillations (PIO). CAPIO reduces the e ective time delay by minimizing the phase shift between the commanded and the actual attitude accelerations. We present a stability analysis of CAPIO for a scalar system. In addition, we present simulation results for aircraft with cross-coupling which demonstrates the potential of CAPIO serving as an effective PIO handler in adverse conditions.

  4. Robust master-slave synchronization for general uncertain delayed dynamical model based on adaptive control scheme.

    PubMed

    Wang, Tianbo; Zhou, Wuneng; Zhao, Shouwei; Yu, Weiqin

    2014-03-01

    In this paper, the robust exponential synchronization problem for a class of uncertain delayed master-slave dynamical system is investigated by using the adaptive control method. Different from some existing master-slave models, the considered master-slave system includes bounded unmodeled dynamics. In order to compensate the effect of unmodeled dynamics and effectively achieve synchronization, a novel adaptive controller with simple updated laws is proposed. Moreover, the results are given in terms of LMIs, which can be easily solved by LMI Toolbox in Matlab. A numerical example is given to illustrate the effectiveness of the method.

  5. A Kalman filtering based control scheme for the improvement of dynamic performance of an AC/DC power system

    NASA Astrophysics Data System (ADS)

    Pecen, Recayi

    In this dissertation, two major accomplishments are achieved. First, the feasibility of a proposed Wyoming to California HVDC system having the ratings of 1000 MW, ±500 kV, 2 kA, 860 miles and 12-pulse bipolar lines is shown for exporting Wyoming's electrical power resources to the heavy loaded western states. The second and the main objective of this dissertation is the development of a Kalman filtering (KF) based control scheme applied to an ac/dc power system. It is shown that the use KF algorithm to estimate some of the system states and utilizing them in a proportional Integral (PI) controller which has a better performance for this specific control scheme have resulted in a better dynamic performance of the proposed system. A set of case studies has shown that the system dynamic performance is improved for most of the contingencies. Ac and dc noisy voltage and current measurements received from the simulated ac/dc power system are sent to the KF estimation algorithm. The noise-separated best estimates of measurable states are computed and sent to a PI controller-based current and firing angle control subsections in order to provide a set of optimum thyristor firing angles for both converter stations during and after contingencies until the normal operation is reached. To evaluate the dynamic performance of the system with the KF algorithm, the model is simulated by a well-known digital simulation package, Electromagnetic Transients DC Program (PSCAD/EMTDC) of Manitoba HVDC Research Center. To apply the KF algorithm, a general, linearized, state-space model of the proposed ac/dc system, appropriate for analyzing both the KF and the electromagnetics transients, is derived first. The derived model enables the representation of an ac power system with two ac sources and one HVDC line with a parallel ac line connecting the two systems. It is shown that system eigenvalues of the discretized system model for a normal operating point are inside the unit circle that

  6. Design of a new multiapertured diffraction interferometer scheme for small angular displacement control

    NASA Astrophysics Data System (ADS)

    Sokolov, Yu

    2016-08-01

    The compact diffraction circuit controlling small angular movements with small errors (2 ") and implementation simplicity is considered. The mathematical model describing the radiation intensity distribution in a receiver is obtained. The experiment results (at TU Ilmenau, Germany) confirmed the basic theoretical principles described in the paper.

  7. Determination of a control parameter of the r-modified Crank-Nicholson difference scheme for the Schrödinger equation

    NASA Astrophysics Data System (ADS)

    Ashyralyev, Allaberen; Urun, Mesut

    2016-08-01

    In the present paper, the second order of accuracy r-modified Crank-Nicholson difference schemes are presented for the numerical solution of the boundary value problem for the Schrödinger differential equation with parameter { i d/u (t ) d t +A u (t )+i u (t )=f (t )+p , 0 scheme is presented. The stability inequalities for the solution of difference schemes for three determination of a control parameter problems for the Schrödinger equation are given.

  8. A hybrid cascade control scheme for the VFA and COD regulation in two-stage anaerobic digestion processes.

    PubMed

    Méndez-Acosta, H O; Campos-Rodríguez, A; González-Álvarez, V; García-Sandoval, J P; Snell-Castro, R; Latrille, E

    2016-10-01

    A hybrid (continuous-discrete) cascade control is proposed to regulate both, volatile fatty acids (VFA) and chemical oxygen demand (COD) concentrations in two-stage (acidogenic-methanogenic) anaerobic digestion (TSAD) processes. The outer loop is a discrete controller that regulates the COD concentration of the methanogenic bioreactor by using a daily off-line measurement and that modifies the set-point tracked by inner loop, which manipulates the dilution rate to regulate the VFA concentration of the acidogenic bioreactor, estimated by continuous on-line conductivity measurements, avoiding acidification. The experimental validation was conducted in a TSAD process for the treatment of tequila vinasses during 110days. Results showed that the proposed cascade control scheme was able to achieve the VFA and COD regulation by using conventional measurements under different set-point values in spite of adverse common scenarios in full-scale anaerobic digestion processes. Microbial composition analysis showed that the controller also favors the abundance and diversity toward methane production.

  9. A hybrid cascade control scheme for the VFA and COD regulation in two-stage anaerobic digestion processes.

    PubMed

    Méndez-Acosta, H O; Campos-Rodríguez, A; González-Álvarez, V; García-Sandoval, J P; Snell-Castro, R; Latrille, E

    2016-10-01

    A hybrid (continuous-discrete) cascade control is proposed to regulate both, volatile fatty acids (VFA) and chemical oxygen demand (COD) concentrations in two-stage (acidogenic-methanogenic) anaerobic digestion (TSAD) processes. The outer loop is a discrete controller that regulates the COD concentration of the methanogenic bioreactor by using a daily off-line measurement and that modifies the set-point tracked by inner loop, which manipulates the dilution rate to regulate the VFA concentration of the acidogenic bioreactor, estimated by continuous on-line conductivity measurements, avoiding acidification. The experimental validation was conducted in a TSAD process for the treatment of tequila vinasses during 110days. Results showed that the proposed cascade control scheme was able to achieve the VFA and COD regulation by using conventional measurements under different set-point values in spite of adverse common scenarios in full-scale anaerobic digestion processes. Microbial composition analysis showed that the controller also favors the abundance and diversity toward methane production. PMID:27474953

  10. Novel control scheme for a high-speed metrological scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Vorbringer-Dorozhovets, N.; Hausotte, T.; Manske, E.; Shen, J. C.; Jäger, G.

    2011-09-01

    Some time ago, an interferometer-based metrological scanning probe microscope (SPM) was developed at the Institute of Process Measurement and Sensor Technology of the Ilmenau University of Technology, Germany. The specialty of this SPM is the combined deflection detection system that comprises an interferometer and a beam deflection. Due to this system it is possible to simultaneously measure the displacement, bending and torsion of the probe (cantilever). The SPM is integrated into a nanopositioning and nanomeasuring machine (NPM machine) and allows measurements with a resolution of 0.1 nm over a range of 25 mm × 25 mm × 5 mm. Excellent results were achieved for measurements of calibrated step height and lateral standards and these results are comparable to the calibration values from the Physikalisch-Technische Bundesanstalt (PTB) (Dorozhovets N et al 2007 Proc. SPIE 6616 661624-1-7). The disadvantage was a low attainable scanning speed and accordingly large expenditure of time. Control dynamics and scanning speed are limited because of the high masses of the stage and corner mirror of the machine. For the vertical axis an additional high-speed piezoelectric drive is integrated in the SPM in order to increase the measuring dynamics. The movement of the piezoelectric drive is controlled and traceable measured by the interferometer. Hence, nonlinearity and hysteresis in the actuator do not affect the measurement. The outcome of this is an improvement of the bending control of the cantilever and much higher scan speeds of up to 200 µm s-1.

  11. A general method for selecting quantum channel for bidirectional controlled state teleportation and other schemes of controlled quantum communication

    NASA Astrophysics Data System (ADS)

    Thapliyal, Kishore; Verma, Amit; Pathak, Anirban

    2015-12-01

    Recently, a large number of protocols for bidirectional controlled state teleportation (BCST) have been proposed using n-qubit entangled states (nin {5,6,7}) as quantum channel. Here, we propose a general method of selecting multiqubit (n>4) quantum channels suitable for BCST and show that all the channels used in the existing protocols of BCST can be obtained using the proposed method. Further, it is shown that the quantum channels used in the existing protocols of BCST form only a negligibly small subset of the set of all the quantum channels that can be constructed using the proposed method to implement BCST. It is also noted that all these quantum channels are also suitable for controlled bidirectional remote state preparation. Following the same logic, methods for selecting quantum channels for other controlled quantum communication tasks, such as controlled bidirectional joint remote state preparation and controlled quantum dialogue, are also provided.

  12. Access Scheme for Controlling Mobile Agents and its Application to Share Medical Information.

    PubMed

    Liao, Yu-Ting; Chen, Tzer-Shyong; Chen, Tzer-Long; Chung, Yu-Fang; Chen, Yu- Xin; Hwang, Jen-Hung; Wang, Huihui; Wei, Wei

    2016-05-01

    This study is showing the advantage of mobile agents to conquer heterogeneous system environments and contribute to a virtual integrated sharing system. Mobile agents will collect medical information from each medical institution as a method to achieve the medical purpose of data sharing. Besides, this research also provides an access control and key management mechanism by adopting Public key cryptography and Lagrange interpolation. The safety analysis of the system is based on a network attacker's perspective. The achievement of this study tries to improve the medical quality, prevent wasting medical resources and make medical resources access to appropriate configuration. PMID:27010391

  13. Sliding mode control scheme for a jumping robot with multi-joint based on floating basis

    NASA Astrophysics Data System (ADS)

    Jianjun, Yao; Duotao, Di; Shuang, Gao; Lei, He; Shenghai, Hu

    2012-01-01

    A jumping robot has different jumping characteristics. The emphasis of its motion characteristics is placed on the sagittal plane, and every phase of a whole jumping motion has different constraints, so it is a variable constraint system. Its kinematic and dynamic equations, both of the stance phase and of the flight phase are established. Furthermore, the floating basis method is applied to unify the dynamic equations of the stance phase and the flight phase. The generalised coordinate is found based on the union of the tiptoe translation and the joint variables to obtain dynamic equations with constraints. Since the jumping robot is a strongly coupled system and has great impact when it lands on the ground, a reaching law is applied in the development of sliding mode controller in task space such that the state trajectory starting from anywhere can move towards the switching surface, making the system tracking error converge exponentially to zero. Simulation results demonstrate the efficiency and validity of the proposed control system.

  14. Master-slave control scheme in electric vehicle smart charging infrastructure.

    PubMed

    Chung, Ching-Yen; Chynoweth, Joshua; Chu, Chi-Cheng; Gadh, Rajit

    2014-01-01

    WINSmartEV is a software based plug-in electric vehicle (PEV) monitoring, control, and management system. It not only incorporates intelligence at every level so that charge scheduling can avoid grid bottlenecks, but it also multiplies the number of PEVs that can be plugged into a single circuit. This paper proposes, designs, and executes many upgrades to WINSmartEV. These upgrades include new hardware that makes the level 1 and level 2 chargers faster, more robust, and more scalable. It includes algorithms that provide a more optimal charge scheduling for the level 2 (EVSE) and an enhanced vehicle monitoring/identification module (VMM) system that can automatically identify PEVs and authorize charging.

  15. Master-Slave Control Scheme in Electric Vehicle Smart Charging Infrastructure

    PubMed Central

    Chung, Ching-Yen; Chynoweth, Joshua; Chu, Chi-Cheng; Gadh, Rajit

    2014-01-01

    WINSmartEV is a software based plug-in electric vehicle (PEV) monitoring, control, and management system. It not only incorporates intelligence at every level so that charge scheduling can avoid grid bottlenecks, but it also multiplies the number of PEVs that can be plugged into a single circuit. This paper proposes, designs, and executes many upgrades to WINSmartEV. These upgrades include new hardware that makes the level 1 and level 2 chargers faster, more robust, and more scalable. It includes algorithms that provide a more optimal charge scheduling for the level 2 (EVSE) and an enhanced vehicle monitoring/identification module (VMM) system that can automatically identify PEVs and authorize charging. PMID:24982956

  16. A new classification scheme for deep geothermal systems based on geologic controls

    NASA Astrophysics Data System (ADS)

    Moeck, I.

    2012-04-01

    A key element in the characterization, assessment and development of geothermal energy systems is the resource classification. Throughout the past 30 years many classifications and definitions were published mainly based on temperature and thermodynamic properties. In the past classification systems, temperature has been the essential measure of the quality of the resource and geothermal systems have been divided into three different temperature (or enthalpy) classes: low-temperature, moderate-temperature and high-temperature. There are, however, no uniform temperature ranges for these classes. It is still a key requirement of a geothermal classification that resource assessment provides logical and consistent frameworks simplified enough to communicate important aspects of geothermal energy potential to both non-experts and general public. One possible solution may be to avoid classifying geothermal resources by temperature and simply state the range of temperatures at the individual site. Due to technological development, in particular in EGS (Enhanced Geothermal Systems or Engineered Geothermal Systems; both terms are considered synonymously in this thesis) technology, currently there are more geothermal systems potentially economic than 30 years ago. An alternative possibility is to classify geothermal energy systems by their geologic setting. Understanding and characterizing the geologic controls on geothermal systems has been an ongoing focus on different scales from plate tectonics to local tectonics/structural geology. In fact, the geologic setting has a fundamental influence on the potential temperature, on the fluid composition, the reservoir characteristics and whether the system is a predominantly convective or conductive system. The key element in this new classification for geothermal systems is the recognition that a geothermal system is part of a geological system. The structural geological and plate tectonic setting has a fundamental influence on

  17. A fast and efficient adaptive threshold rate control scheme for remote sensing images.

    PubMed

    Chen, Xiao; Xu, Xiaoqing

    2012-01-01

    The JPEG2000 image compression standard is ideal for processing remote sensing images. However, its algorithm is complex and it requires large amounts of memory, making it difficult to adapt to the limited transmission and storage resources necessary for remote sensing images. In the present study, an improved rate control algorithm for remote sensing images is proposed. The required coded blocks are sorted downward according to their numbers of bit planes prior to entropy coding. An adaptive threshold computed from the combination of the minimum number of bit planes, along with the minimum rate-distortion slope and the compression ratio, is used to truncate passes of each code block during Tier-1 encoding. This routine avoids the encoding of all code passes and improves the coding efficiency. The simulation results show that the computational cost and working buffer memory size of the proposed algorithm reach only 18.13 and 7.81%, respectively, of the same parameters in the postcompression rate distortion algorithm, while the peak signal-to-noise ratio across the images remains almost the same. The proposed algorithm not only greatly reduces the code complexity and buffer requirements but also maintains the image quality.

  18. A multilevel region-of-interest based rate control scheme for video communication

    NASA Astrophysics Data System (ADS)

    Zhou, QiLui; Liu, Jiaying; Guo, Zongming

    2009-10-01

    The ROI based video coding is widely applied in video communication. In this paper, we propose a multilevel ROI model, which includes the eye-mouth core region (CR), the face profile region (PR), the edge region (ER) and the background region (BR), to classify the subjective importance level of regions for the scene. Taking account of the proposed model, we first segment the current frame into four regions through skin color detection and feature location. Then, we improve the rate control algorithm in JVT-G012 proposal. We consider two factors, including subjective factor by our multi-level ROI model and objective factor by direct difference from reference frame, to model the complexity weight of each macroblock (MB).We allocate resources both at the frame layer and the basic unit layer, and adjust QP at MB layer. Finally, we restrict the QP of MB with three strategies to maintain the spatial and temporal smoothness. The experimental results illustrate that PSNR of ROI (CR plus PR) area using proposed method is in average over 0.5dB higher than JM8.6, while there are only slight changes in the PSNR of whole frame between two methods. Subjective quality based on our method also achieves much better performance.

  19. Using Actual and Imagined Walking Related Desynchronization Features in a BCI.

    PubMed

    Severens, Marianne; Perusquia-Hernandez, Monica; Nienhuis, Bart; Farquhar, Jason; Duysens, Jacques

    2015-09-01

    Recently, brain-computer interface (BCI) research has extended to investigate its possible use in motor rehabilitation. Most of these investigations have focused on the upper body. Only few studies consider gait because of the difficulty of recording EEG during gross movements. However, for stroke patients the rehabilitation of gait is of crucial importance. Therefore, this study investigates if a BCI can be based on walking related desynchronization features. Furthermore, the influence of complexity of the walking movements on the classification performance is investigated. Two BCI experiments were conducted in which healthy subjects performed a cued walking task, a more complex walking task (backward or adaptive walking), and imagination of the same tasks. EEG data during these tasks was classified into walking and no-walking. The results from both experiments show that despite the automaticity of walking and recording difficulties, brain signals related to walking could be classified rapidly and reliably. Classification performance was higher for actual walking movements than for imagined walking movements. There was no significant increase in classification performance for both the backward and adaptive walking tasks compared with the cued walking tasks. These results are promising for developing a BCI for the rehabilitation of gait.

  20. Cortical processing of vowels and tones as measured by event-related desynchronization.

    PubMed

    Krause, C M; Lang, H; Laine, M; Kuusisto, M; Pörn, B

    1995-01-01

    Event-Related Desynchronization (ERD) and Synchronization (ERS) were studied in 20 normal subjects during a Sternberg-type auditory memory-scanning paradigm. Half of the subjects performed the experiment with vowels and the other half with tones as stimuli. The stimuli consisted of 100 msec long synthesized vowels and 100 msec long tones produced by eight different synthesized instruments. In this paradigm each trial started with the presentation of a visual warning signal, after which a four-stimulus set was presented for memorization whether after a probe stimulus was presented and identified by the subject as belonging or not belonging to the memorized set. The ERD/ERS of the lower (8-10 Hz) and upper (10-12 Hz) alpha frequency bands differed in their reactivity to stimulus type; the differences between the two frequency bands reached statistical significance only in the case of vowels. The presentation of the memory set elicited ERS which was more pronounced in the 10-12 Hz frequency band and greater for vowels than for tones. On the other hand, the presentation of the probe elicited ERD which was greater for vowels than for tones, especially in the upper alpha frequency band. The results of this exploratory study suggest that ERD is closely related to memory process and that the ERD/ERS-technique might provide a valuable tool for future research encompassing more complex auditory stimulation like speech and music.

  1. Characteristics of alpha power event-related desynchronization in the discrimination of spontaneous deceptive responses.

    PubMed

    Kim, Sujin; Jung, Kyu Hee; Lee, Jang-Han

    2012-08-01

    Event-related desynchronization (ERD) occurs in the alpha frequency band when individuals are mentally active, and reflects increasing task demands. Lying involves a relatively greater cognitive load, and should be indicated by an increase of alpha power ERD. This study aimed to examine whether ERD discriminates deceptive responses from truthful responses. In the deception task, subjects made their own decision or were instructed either to type the presented numbers on the dice or input different numbers. Based on a subject's response and rule of the task, the type of response was determined. There were four types of responses: spontaneous deceptive, spontaneous truth, instructed deceptive, instructed truth. The findings of this study suggest that spontaneous deceptions produced significantly greater ERD than spontaneous truths, whereas ERD did not distinguish instructed deception from instructed truth. Different patterns between spontaneous and instructed deceptions may be due to different levels of cognitive load. Spontaneous lies require a greater cognitive load than other types of deceptions. The results of this study suggest that ERD has the potential to detect spontaneous deceptive responses. That is, ERD can detect deceptions that require cognitive effort in natural situations.

  2. Impaired odour discrimination on desynchronization of odour-encoding neural assemblies

    NASA Astrophysics Data System (ADS)

    Stopfer, Mark; Bhagavan, Seetha; Smith, Brian H.; Laurent, Gilles

    1997-11-01

    Stimulus-evoked oscillatory synchronization of neural assemblies has been described in the olfactory and visual systems of several vertebrates and invertebrates. In locusts, information about odour identity is contained in the timing of action potentials in an oscillatory population response, suggesting that oscillations may reflect a common reference for messages encoded in time. Although the stimulus-evoked oscillatory phenomenon is reliable, its roles in sensation, perception, memory formation and pattern recognition remain to be demonstrated - a task requiring a behavioural paradigm. Using honeybees, we now demonstrate that odour encoding involves, as it does in locusts, the oscillatory synchronization of assemblies of projection neurons and that this synchronization is also selectively abolished by picrotoxin, an antagonist of the GABAA (γ-aminobutyric acid) receptor. By using a behavioural learning paradigm, we show that picrotoxin-induced desynchronization impairs the discrimination of molecularly similar odorants, but not that of dissimilar odorants. It appears, therefore, that oscillatory synchronization of neuronal assemblies is functionally relevant, and essential for fine sensory discrimination. This suggests that oscillatory synchronization and the kind of temporal encoding it affords provide an additional dimension by which the brain could segment spatially overlapping stimulus representations.

  3. Body temperature predicts the direction of internal desynchronization in humans isolated from time cues.

    PubMed

    Daan, Serge; Honma, Sato; Honma, Ken-ichi

    2013-12-01

    This publication presents a new analysis of experiments that were carried out in human subjects in isolation from time cues, under supervision of Jürgen Aschoff and Rütger Wever at the Max Planck Institute for Behavioural Physiology (Erling-Andechs, Germany, 1964-1974). Mean rectal temperatures (tb) were compared between subjects who showed internal desynchronization (ID) and internal synchronization (IS) of the endogenous rhythms of sleep-wakefulness and of body temperature. The results showed that tb was reduced in long ID (circadian sleep-wake cycle length [τ(SW)] > 27 h) and increased in short ID (τ(SW) < 22 h) relative to IS. In subjects with both ID and IS sections in the complete record, these differences were also found when comparing only the IS sections: Low tb during IS predicts the later occurrence of long ID, and high tb predicts the incidence of short ID. While this association is associated with sex differences in tb, it also occurs within each sex. To the extent that the variation in tb reflects the variation in heat production (metabolic rate), the results are consistent with the proposition that the spontaneous frequency of the human sleep-wake oscillator is associated with the metabolic rate, as suggested on the basis of the proportionality of meal frequency and sleep-wake frequency. The finding thus has implications for our views on spontaneous sleep timing.

  4. Event-related desynchronization and synchronization quantification in motor-related EEG by Kolmogorov entropy

    NASA Astrophysics Data System (ADS)

    Gao, Lin; Wang, Jue; Chen, Longwei

    2013-06-01

    Objective. Various approaches have been applied for the quantification of event-related desynchronization/synchronization (ERD/ERS) in EEG/MEG data analysis, but most of them are based on band power analysis. In this paper, we sought a novel method using a nonlinear measurement to quantify the ERD/ERS time course of motor-related EEG. Approach. We applied Kolmogorov entropy to quantify the ERD/ERS time course of motor-related EEG in relation to hand movement imagination and execution for the first time. To further test the validity of the Kolmogorov entropy measure, we tested it on five human subjects for feature extraction to classify the left and right hand motor tasks. Main results. The results show that the relative increase and decrease of Kolmogorov entropy indicates the ERD and ERS respectively. An average classification accuracy of 87.3% was obtained for five subjects. Significance. The results prove that Kolmogorov entropy can effectively quantify the dynamic process of event-related EEG, and it also provides a novel method of classifying motor imagery tasks from scalp EEG by Kolmogorov entropy measurement with promising classification accuracy.

  5. Quantification of event-related desynchronization/synchronization at low frequencies in a semantic memory task.

    PubMed

    Gómez, Juan; Aguilar, Mónica; Horna, Eduardo; Minguez, Javier

    2012-01-01

    Although several techniques have been developed for the visualization of EEG event-related desynchronization/synchronization (ERD/ERS) in both time and frequency domains, none of the quantification methods takes advantage of the time and frequency resolution at the same time. Existing techniques for the quantification of the ERD/ERS changes compute the average EEG power increase/decrease relative to certain reference value, over fixed time intervals and/or frequency bands (either fixed or individualized). Inaccuracy in the computation of these frequency bands (where the process is actually measured) in combination with the averaging process over time may lead to errors in the computation of any ERD/ERS quantification parameter. In this paper, we present a novel method for the automatic, individual and exact quantification of the most significant ERD/ERS region within a given window of the time-frequency domain. The method is exemplified by quantifying the ERS at low frequencies of 10 subjects performing a semantic memory task, and compared with existing techniques. PMID:23366438

  6. Evaluation of two momentum control variable schemes and their impact on the variational assimilation of radarwind data: Case study of a squall line

    NASA Astrophysics Data System (ADS)

    Li, Xin; Zeng, Mingjian; Wang, Yuan; Wang, Wenlan; Wu, Haiying; Mei, Haixia

    2016-10-01

    Different choices of control variables in variational assimilation can bring about different influences on the analyzed atmospheric state. Based on the WRF model's three-dimensional variational assimilation system, this study compares the behavior of two momentum control variable options—streamfunction velocity potential ( ψ-χ) and horizontal wind components ( U-V)—in radar wind data assimilation for a squall line case that occurred in Jiangsu Province on 24 August 2014. The wind increment from the single observation test shows that the ψ-χ control variable scheme produces negative increments in the neighborhood around the observation point because streamfunction and velocity potential preserve integrals of velocity. On the contrary, the U-V control variable scheme objectively reflects the information of the observation itself. Furthermore, radial velocity data from 17 Doppler radars in eastern China are assimilated. As compared to the impact of conventional observation, the assimilation of radar radial velocity based on the U-V control variable scheme significantly improves the mesoscale dynamic field in the initial condition. The enhanced low-level jet stream, water vapor convergence and low-level wind shear result in better squall line forecasting. However, the ψ-χ control variable scheme generates a discontinuous wind field and unrealistic convergence/divergence in the analyzed field, which lead to a degraded precipitation forecast.

  7. On the Control of the Fixed Charge Densities in Al2O3-Based Silicon Surface Passivation Schemes.

    PubMed

    Simon, Daniel K; Jordan, Paul M; Mikolajick, Thomas; Dirnstorfer, Ingo

    2015-12-30

    A controlled field-effect passivation by a well-defined density of fixed charges is crucial for modern solar cell surface passivation schemes. Al2O3 nanolayers grown by atomic layer deposition contain negative fixed charges. Electrical measurements on slant-etched layers reveal that these charges are located within a 1 nm distance to the interface with the Si substrate. When inserting additional interface layers, the fixed charge density can be continuously adjusted from 3.5 × 10(12) cm(-2) (negative polarity) to 0.0 and up to 4.0 × 10(12) cm(-2) (positive polarity). A HfO2 interface layer of one or more monolayers reduces the negative fixed charges in Al2O3 to zero. The role of HfO2 is described as an inert spacer controlling the distance between Al2O3 and the Si substrate. It is suggested that this spacer alters the nonstoichiometric initial Al2O3 growth regime, which is responsible for the charge formation. On the basis of this charge-free HfO2/Al2O3 stack, negative or positive fixed charges can be formed by introducing additional thin Al2O3 or SiO2 layers between the Si substrate and this HfO2/Al2O3 capping layer. All stacks provide very good passivation of the silicon surface. The measured effective carrier lifetimes are between 1 and 30 ms. This charge control in Al2O3 nanolayers allows the construction of zero-fixed-charge passivation layers as well as layers with tailored fixed charge densities for future solar cell concepts and other field-effect based devices.

  8. A controlled evaluation of assessments by doctors and nurses in a magistrates' court mental health assessment and diversion scheme.

    PubMed

    Chambers, C; Rix, K J

    1999-01-01

    In this study, assessments of prisoners by doctors and nurses were compared in a provincial magistrates' court mental health assessment and diversion scheme, and outcomes were compared with the outcomes of those for whom no assessments were available during a control period. Substance misuse was relatively common and psychosis uncommon in the prisoners referred. Assessment by doctors enabled magistrates to reduce remands in custody of persons suspected of suffering from mental disorder and to grant bail in more cases. Only a small proportion of prisoners were admitted to hospital and although doctors and nurses recommended out-patient treatment in many cases, the attendance rate was low. Doctors were more likely than nurses to identify prisoners with medical needs that needed to be brought to the attention of the prison health care service, and to recommend out-patient psychiatric treatment and identify relevant medicolegal issues. Prisoners assessed by nurses were less likely than those assessed by doctors to attend alcohol or drug treatment services if recommended to do so. Prisoners who were admitted to hospital after a remand in custody spent longer on remand if assessed by nurses compared with those assessed by doctors.

  9. Event-related desynchronization reflects downregulation of intracortical inhibition in human primary motor cortex.

    PubMed

    Takemi, Mitsuaki; Masakado, Yoshihisa; Liu, Meigen; Ushiba, Junichi

    2013-09-01

    There is increasing interest in electroencephalogram (EEG)-based brain-computer interface (BCI) as a tool for rehabilitation of upper limb motor functions in hemiplegic stroke patients. This type of BCI often exploits mu and beta oscillations in EEG recorded over the sensorimotor areas, and their event-related desynchronization (ERD) following motor imagery is believed to represent increased sensorimotor cortex excitability. However, it remains unclear whether the sensorimotor cortex excitability is actually correlated with ERD. Thus we assessed the association of ERD with primary motor cortex (M1) excitability during motor imagery of right wrist movement. M1 excitability was tested by motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) with transcranial magnetic stimulation (TMS). Twenty healthy participants were recruited. The participants performed 7 s of rest followed by 5 s of motor imagery and received online visual feedback of the ERD magnitude of the contralateral hand M1 while performing the motor imagery task. TMS was applied to the right hand M1 when ERD exceeded predetermined thresholds during motor imagery. MEP amplitudes, SICI, and ICF were recorded from the agonist muscle of the imagined hand movement. Results showed that the large ERD during wrist motor imagery was associated with significantly increased MEP amplitudes and reduced SICI but no significant changes in ICF. Thus ERD magnitude during wrist motor imagery represents M1 excitability. This study provides electrophysiological evidence that a motor imagery task involving ERD may induce changes in corticospinal excitability similar to changes accompanying actual movements.

  10. Food web de-synchronization in England's largest lake: an assessment based on multiple phenological metrics.

    PubMed

    Thackeray, Stephen J; Henrys, Peter A; Feuchtmayr, Heidrun; Jones, Ian D; Maberly, Stephen C; Winfield, Ian J

    2013-12-01

    Phenological changes have been observed globally for marine, freshwater and terrestrial species, and are an important element of the global biological 'fingerprint' of climate change. Differences in rates of change could desynchronize seasonal species interactions within a food web, threatening ecosystem functioning. Quantification of this risk is hampered by the rarity of long-term data for multiple interacting species from the same ecosystem and by the diversity of possible phenological metrics, which vary in their ecological relevance to food web interactions. We compare phenological change for phytoplankton (chlorophyll a), zooplankton (Daphnia) and fish (perch, Perca fluviatilis) in two basins of Windermere over 40 years and determine whether change has differed among trophic levels, while explicitly accounting for among-metric differences in rates of change. Though rates of change differed markedly among the nine metrics used, seasonal events shifted earlier for all metrics and trophic levels: zooplankton advanced most, and fish least, rapidly. Evidence of altered synchrony was found in both lake basins, when combining information from all phenological metrics. However, comparisons based on single metrics did not consistently detect this signal. A multimetric approach showed that across trophic levels, earlier phenological events have been associated with increasing water temperature. However, for phytoplankton and zooplankton, phenological change was also associated with changes in resource availability. Lower silicate, and higher phosphorus, concentrations were associated with earlier phytoplankton growth, and earlier phytoplankton growth was associated with earlier zooplankton growth. The developing trophic mismatch detected between the dominant fish species in Windermere and important zooplankton food resources may ultimately affect fish survival and portend significant impacts upon ecosystem functioning. We advocate that future studies on phenological

  11. Direct aerosol chemical composition measurements to evaluate the physicochemical differences between controlled sea spray aerosol generation schemes

    NASA Astrophysics Data System (ADS)

    Collins, D. B.; Zhao, D. F.; Ruppel, M. J.; Laskina, O.; Grandquist, J. R.; Modini, R. L.; Stokes, M. D.; Russell, L. M.; Bertram, T. H.; Grassian, V. H.; Deane, G. B.; Prather, K. A.

    2014-07-01

    Controlled laboratory studies of the physical and chemical properties of sea spray aerosol (SSA) must be underpinned by a physically and chemically accurate representation of the bubble mediated production of nascent SSA particles. Since bubble bursting is sensitive to the physicochemical properties of seawater, any important differences in the SSA production mechanism are projected into SSA composition. Using direct chemical measurements of SSA at the single-particle level, this study presents an inter-comparison of three laboratory-based, bubble-mediated SSA production schemes: gas forced through submerged sintered glass filters ("frits"), a pulsed plunging waterfall apparatus, and breaking waves in a wave channel filled with natural seawater. The size-resolved chemical composition of SSA particles produced by breaking waves is more similar to particles produced by the plunging waterfall than sintered glass filters. Aerosol generated by disintegrating foam produced by sintered glass filters contained a larger fraction of organic enriched particles and a different size-resolved elemental composition, especially in the 0.8-2 μm size range. These particles, when dried, had more spherical morphologies compared to the more cubic structure expected for pure NaCl particles, which can be attributed to the presence of additional organic carbon. In addition to an inter-comparison of three SSA production methods, the role of the episodic or "pulsed" nature of the waterfall method utilized in this study on SSA composition was undertaken. In organic-enriched seawater, the continuous operation of the plunging waterfall mechanism resulted in the accumulation of surface foam and an over-expression of organic matter in SSA particles compared to pulsed plunging waterfall. Throughout this set of experiments, comparative differences in the SSA number size distribution were coincident with differences in aerosol composition, indicating that the production mechanism of SSA exerts

  12. Direct aerosol chemical composition measurements to evaluate the physicochemical differences between controlled sea spray aerosol generation schemes

    NASA Astrophysics Data System (ADS)

    Collins, D. B.; Zhao, D. F.; Ruppel, M. J.; Laskina, O.; Grandquist, J. R.; Modini, R. L.; Stokes, M. D.; Russell, L. M.; Bertram, T. H.; Grassian, V. H.; Deane, G. B.; Prather, K. A.

    2014-11-01

    Controlled laboratory studies of the physical and chemical properties of sea spray aerosol (SSA) must be under-pinned by a physically and chemically accurate representation of the bubble-mediated production of nascent SSA particles. Bubble bursting is sensitive to the physico-chemical properties of seawater. For a sample of seawater, any important differences in the SSA production mechanism are projected into the composition of the aerosol particles produced. Using direct chemical measurements of SSA at the single-particle level, this study presents an intercomparison of three laboratory-based, bubble-mediated SSA production schemes: gas forced through submerged sintered glass filters ("frits"), a pulsed plunging-waterfall apparatus, and breaking waves in a wave channel filled with natural seawater. The size-resolved chemical composition of SSA particles produced by breaking waves is more similar to particles produced by the plunging waterfall than those produced by sintered glass filters. Aerosol generated by disintegrating foam produced by sintered glass filters contained a larger fraction of organic-enriched particles and a different size-resolved elemental composition, especially in the 0.8-2 μm dry diameter range. Interestingly, chemical differences between the methods only emerged when the particles were chemically analyzed at the single-particle level as a function of size; averaging the elemental composition of all particles across all sizes masked the differences between the SSA samples. When dried, SSA generated by the sintered glass filters had the highest fraction of particles with spherical morphology compared to the more cubic structure expected for pure NaCl particles produced when the particle contains relatively little organic carbon. In addition to an intercomparison of three SSA production methods, the role of the episodic or "pulsed" nature of the waterfall method on SSA composition was under-taken. In organic-enriched seawater, the continuous

  13. A Novel Scheme for Optimal Control of a Nonlinear Delay Differential Equations Model to Determine Effective and Optimal Administrating Chemotherapy Agents in Breast Cancer

    PubMed Central

    Ramezanpour, HR; Setayeshi, S; Akbari, ME

    2011-01-01

    Background Determining the optimal and effective scheme for administrating the chemotherapy agents in breast cancer is the main goal of this scientific research. The most important issue here is the amount of drug or radiation administrated in chemotherapy and radiotherapy for increasing patient's survival. This is because in these cases, the therapy not only kills the tumor cells, but also kills some of the healthy tissues and causes serious damages. In this paper we investigate optimal drug scheduling effect for breast cancer model which consist of nonlinear ordinary differential time-delay equations. Methods In this paper, a mathematical model of breast cancer tumors is discussed and then optimal control theory is applied to find out the optimal drug adjustment as an input control of system. Finally we use Sensitivity Approach (SA) to solve the optimal control problem. Results The goal of this paper is to determine optimal and effective scheme for administering the chemotherapy agent, so that the tumor is eradicated, while the immune systems remains above a suitable level. Simulation results confirm the effectiveness of our proposed procedure. Conclusion In this paper a new scheme is proposed to design a therapy protocol for chemotherapy in Breast Cancer. In contrast to traditional pulse drug delivery, a continuous process is offered and optimized, according to the optimal control theory for time-delay systems. PMID:26322192

  14. Desynchronization of Noisy Multi-cellular Clocks Underlies the Population-level Singularity Behavior of Mammalian Circadian Clock

    NASA Astrophysics Data System (ADS)

    Kobayashi, Tetsuya J.; Ukai, Hideki; Ueda, Hiroki R.

    2007-07-01

    The singularity behavior of circadian clocks defined as the suppression of circadian oscillation by critical perturbation is one of the intriguing dynamical properties of circadian rhythms. Although the singularity behaviors have been observed in various organisms, its mechanism has not yet been elucidated, because the hierarchical structure of multi-cell-level circadian clocks exists behind the organism-level circadian rhythm. In vitro light-responsible circadian system is indispensable for extracting the underlying mechanism of the singularity behavior behind the hierarchical structure of multi-cell organisms. To obtain such in vitro system, we synthetically constructed light-responsible mammalian clock cells by exogenously introducing a photo-responsible receptor. By using this synthetic system and population-level high-throughput promoter activity assay, we found that a light pulse with critical timing and strength can induce population-level singularity behavior of the light-responsible mammalian clock cells. Subsequent single-cell measurement revealed that desynchronization of multi-cellular clocks underlies the population-level singularity. A mathematical model consistently explains our population-level and single-cell-level experimental data, and also demonstrates that the synchronization and desynchronization of cellular clocks is the underlying mechanism of population-level response of circadian clocks to external perturbation. In addition, our model suggests that fluctuation in single-cell-level behavior of the clock cells is the key determinant of the observable singularity behavior.

  15. SPHERE eXtreme AO control scheme: final performance assessment and on sky validation of the first auto-tuned LQG based operational system

    NASA Astrophysics Data System (ADS)

    Petit, C.; Sauvage, J.-F.; Fusco, T.; Sevin, A.; Suarez, M.; Costille, A.; Vigan, A.; Soenke, C.; Perret, D.; Rochat, S.; Barrufolo, A.; Salasnich, B.; Beuzit, J.-L.; Dohlen, K.; Mouillet, D.; Puget, P.; Wildi, F.; Kasper, M.; Conan, J.-M.; Kulcsár, C.; Raynaud, H.-F.

    2014-08-01

    The SPHERE (Spectro-Polarimetry High-contrast Exoplanet Research) instrument is an ESO project aiming at the direct detection of extra-solar planets. SPHERE has been successfully integrated and tested in Europe end 2013 and has been re-integrated at Paranal in Chile early 2014 for a first light at the beginning of May. The heart of the SPHERE instrument is its eXtreme Adaptive Optics (XAO) SAXO (SPHERE AO for eXoplanet Observation) subsystem that provides extremely high correction of turbulence and very accurate stabilization of images for coronagraphic purpose. However, SAXO, as well as the overall instrument, must also provide constant operability overnights, ensuring robustness and autonomy. An original control scheme has been developed to satisfy this challenging dichotomy. It includes in particular both an Optimized Modal Gain Integrator (OMGI) to control the Deformable Mirror (DM) and a Linear Quadratic Gaussian (LQG) control law to manage the tip-tilt (TT) mirror. LQG allows optimal estimation and prediction of turbulent angle of arrival but also of possible vibrations. A specific and unprecedented control scheme has been developed to continuously adapt and optimize LQG control ensuring a constant match to turbulence and vibrations characteristics. SPHERE is thus the first operational system implementing LQG, with automatic adjustment of its models. SAXO has demonstrated performance beyond expectations during tests in Europe, in spite of internal limitations. Very first results have been obtained on sky last May. We thus come back to SAXO control scheme, focusing in particular on the LQG based TT control and the various upgrades that have been made to enhance further the performance ensuring constant operability and robustness. We finally propose performance assessment based on in lab performance and first on sky results and discuss further possible improvements.

  16. The generation contract, pension schemes, birth control and economic growth: A European model for the third world?

    PubMed

    Diessenbacher, H

    1989-10-01

    The paper presents an analysis of the relationship between the generation contract, pension schemes, fertility decline and the process of economic growth. It is shown that there is a close connection between the reproductive behavior of a population and social security in old age i.e. the introduction and effects of retirement insurances. The proof of this assumption is given by a historical analysis of the developed and a systematic analysis of the developing countries. The paper postulates that the intention to create a higher level of economic growth in developing countries will become effective if a change of the family-bound generation contract is brought about. A modern economy is not compatible with the traditional system of extended families. This thesis includes the assumption that a statutory pension scheme is not an economic burden but the very starting point of a social machine which triggers economic growth.

  17. From randomized controlled trials to evidence grading schemes: current state of evidence-based practice in social sciences.

    PubMed

    Boruch, Robert; Rui, Ning

    2008-11-01

    With the advance of web search and navigation technology, enormous amount of information, non-information, and misinformation may be obtained in milliseconds in response to questions about 'what works' in social sciences. Today, policy makers in non-medical public service arenas are under increasing pressure to make sound decisions based on scientific evidence. Some of these decisions are a matter of legal requirement. This paper shows how such movements are closely aligned with the evolution of organizations that develop and apply evidence standards and evidence grading schemes within the social science communities. The current state of evidence-based practice in social sciences is examined by reviewing the latest development of randomized trials and evidence grading schemes in the fields of education, criminal justice, and social welfare. Studies conducted under the auspices of the Campbell Collaboration and What Works Clearinghouse are used to illustrate ingredients of evidence grading schemes, graphic display of results of systematic reviews, and discrepancies of evidence derived from randomized trials and non-experimental trials. Furthermore, it is argued that the use of evidence on 'what works' depends on the potential users' awareness, understanding of the evidence, as well as their capacity and willingness to use it. Awareness and understanding depends on the world wide web and its augmentations, while capacity and willingness depends more on incentives to use good evidence and on political and ethical values. Implications for the future development of evidence grading organizations are discussed.

  18. A Harmonic-Free All Digital Delay-Locked Loop Using an Improved Fast-Locking Successive Approximation Register-Controlled Scheme

    NASA Astrophysics Data System (ADS)

    Huang, Kai; Cai, Zhikuang; Chen, Xin; Shi, Longxing

    This paper proposes a novel delay-locked loop (DLL) with fast-locking property. The improved fast-locking successive approximation register-controlled (IFSAR) scheme can decrease the locking time to n+4 periods and be harmonic-free, where n is the bits' number of the control code for a delay line. According to the simulation result in 180nm CMOS technology, the DLL can cover the operating range from 70MHz to 500MHz and dissipate 10.44mW at 500MHz.

  19. Effective control parameters in a deep convection scheme for improved simulation of the Madden-Julian oscillation

    NASA Astrophysics Data System (ADS)

    Choi, Jin-Ho; Seo, Kyong-Hwan

    2016-07-01

    This work seeks to find the most effective parameters in a deep convection scheme (relaxed Arakawa-Schubert scheme) of the National Centers of Environmental Prediction Climate Forecast System model for improved simulation of the Madden-Julian Oscillation (MJO). A suite of sensitivity experiments are performed by changing physical components such as the relaxation parameter of mass flux for adjustment of the environment, the evaporation rate from large-scale precipitation, the moisture trigger threshold using relative humidity of the boundary layer, and the fraction of re-evaporation of convective (subgrid-scale) rainfall. Among them, the last two parameters are found to produce a significant improvement. Increasing the strength of these two parameters reduces light rainfall that inhibits complete formation of the tropical convective system or supplies more moisture that help increase a potential energy to large-scale environment in the lower troposphere (especially at 700 hPa), leading to moisture preconditioning favorable for further development and eastward propagation of the MJO. In a more humid environment, more organized MJO structure (i.e., space-time spectral signal, eastward propagation, and tilted vertical structure) is produced.

  20. MP2 energy and density for large molecular systems with internal error control using the Divide-Expand-Consolidate scheme.

    PubMed

    Kristensen, Kasper; Høyvik, Ida-Marie; Jansik, Branislav; Jørgensen, Poul; Kjærgaard, Thomas; Reine, Simen; Jakowski, Jacek

    2012-12-01

    Divide-Expand-Consolidate (DEC) is a local correlation method where the inherent locality of the electron correlation problem is used to express the correlated calculation on a large molecular system in terms of small independent fragment calculations employing small subsets of local HF orbitals. A crucial feature of the DEC scheme is that the sizes of the local orbital spaces are determined in a black box manner during the calculation. In this way it is ensured that the correlation energy has been determined to a predefined precision compared to a conventional calculation. In the present work we apply the DEC scheme to calculate the correlation energy as well as the electron density matrix for the insulin molecule using second order Møller-Plesset (MP2) theory. This is the first DEC calculation on a molecular system which is too large to be treated using a conventional MP2 implementation. The fragmentation errors for the insulin DEC calculation are carefully analyzed using internal consistency checks. It is demonstrated that size-intensive properties are determined to the same precision for small and large molecules. For example, the percentage of correlation energy recovered and the error per electron in the correlated density matrix depend only on the predefined precision and not on the molecular size.

  1. Alpha desynchronization and fronto­parietal connectivity during spatial working memory encoding deficits in ADHD: A simultaneous EEG­fMRI study

    PubMed Central

    Lenartowicz, Agatha; Lu, Steven; Rodriguez, Cameron; Lau, Edward P.; Walshaw, Patricia D.; McCracken, James T.; Cohen, Mark S.; Loo, Sandra K.

    2016-01-01

    The underlying mechanisms of alpha band (8–12 Hz) neural oscillations are of importance to the functioning of attention control systems as well as to neuropsychiatric conditions that are characterized by deficits of that system, such as attention deficit hyperactivity disorder (ADHD). The objectives of the present study were to test if visual encoding-related alpha event-related desynchronization (ERD) correlates with fronto-parieto-occipital connectivity, and whether this is disrupted in ADHD during spatial working memory (SWM) performance. We acquired EEG concurrently with fMRI in thirty boys (12–16 yrs. old, 15 with ADHD), during SWM encoding. Psychophysiological connectivity analyses indicated that alpha ERD during SWM encoding was associated with both occipital activation and fronto-parieto-occipital functional connectivity, a finding that expands on prior associations between alpha ERD and occipital activation. This finding provides novel support for the interpretation of alpha ERD (and the associated changes in occipital activation) as a phenomenon that involves, and perhaps arises as a result of, top-down network interactions. Alpha ERD was associated less strongly with occipital activity, but associated more strongly with fronto-parieto-occipital connectivity in ADHD, consistent with a compensatory attentional response. Additionally, we illustrate that degradation of EEG data quality by MRI-amplified motion artifacts is robust to existing cleaning algorithms and is significantly correlated with hyperactivity symptoms and the ADHD Combined Type diagnosis. We conclude that persistent motion-related MR artifacts in EEG data can increase variance and introduce bias in interpretation of group differences in populations characterized by hypermobility — a clear limitation of current-state EEG-fMRI methodology. PMID:26955516

  2. A pragmatic randomised controlled trial of the Welsh National Exercise Referral Scheme: protocol for trial and integrated economic and process evaluation

    PubMed Central

    2010-01-01

    Background The benefits to health of a physically active lifestyle are well established and there is evidence that a sedentary lifestyle plays a significant role in the onset and progression of chronic disease. Despite a recognised need for effective public health interventions encouraging sedentary people with a medical condition to become more active, there are few rigorous evaluations of their effectiveness. Following NICE guidance, the Welsh national exercise referral scheme was implemented within the context of a pragmatic randomised controlled trial. Methods/Design The randomised controlled trial, with nested economic and process evaluations, recruited 2,104 inactive men and women aged 16+ with coronary heart disease (CHD) risk factors and/or mild to moderate depression, anxiety or stress. Participants were recruited from 12 local health boards in Wales and referred directly by health professionals working in a range of health care settings. Consenting participants were randomised to either a 16 week tailored exercise programme run by qualified exercise professionals at community sports centres (intervention), or received an information booklet on physical activity (control). A range of validated measures assessing physical activity, mental health, psycho-social processes and health economics were administered at 6 and 12 months, with the primary 12 month outcome measure being 7 day Physical Activity Recall. The process evaluation explored factors determining the effectiveness or otherwise of the scheme, whilst the economic evaluation determined the relative cost-effectiveness of the scheme in terms of public spending. Discussion Evaluation of such a large scale national public health intervention presents methodological challenges in terms of trial design and implementation. This study was facilitated by early collaboration with social research and policy colleagues to develop a rigorous design which included an innovative approach to patient referral and

  3. A novel infinite-time optimal tracking control scheme for a class of discrete-time nonlinear systems via the greedy HDP iteration algorithm.

    PubMed

    Zhang, Huaguang; Wei, Qinglai; Luo, Yanhong

    2008-08-01

    In this paper, we aim to solve the infinite-time optimal tracking control problem for a class of discrete-time nonlinear systems using the greedy heuristic dynamic programming (HDP) iteration algorithm. A new type of performance index is defined because the existing performance indexes are very difficult in solving this kind of tracking problem, if not impossible. Via system transformation, the optimal tracking problem is transformed into an optimal regulation problem, and then, the greedy HDP iteration algorithm is introduced to deal with the regulation problem with rigorous convergence analysis. Three neural networks are used to approximate the performance index, compute the optimal control policy, and model the nonlinear system for facilitating the implementation of the greedy HDP iteration algorithm. An example is given to demonstrate the validity of the proposed optimal tracking control scheme.

  4. Thrust Removal Scheme for the FAST-MAC Circulation Control Model Tested in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    Chan, David T.; Milholen, William E., II; Jones, Gregory S.; Goodliff, Scott L.

    2014-01-01

    A second wind tunnel test of the FAST-MAC circulation control semi-span model was recently completed in the National Transonic Facility at the NASA Langley Research Center. The model allowed independent control of four circulation control plenums producing a high momentum jet from a blowing slot near the wing trailing edge that was directed over a 15% chord simple-hinged flap. The model was configured for transonic testing of the cruise configuration with 0deg flap deflection to determine the potential for drag reduction with the circulation control blowing. Encouraging results from analysis of wing surface pressures suggested that the circulation control blowing was effective in reducing the transonic drag on the configuration, however this could not be quantified until the thrust generated by the blowing slot was correctly removed from the force and moment balance data. This paper will present the thrust removal methodology used for the FAST-MAC circulation control model and describe the experimental measurements and techniques used to develop the methodology. A discussion on the impact to the force and moment data as a result of removing the thrust from the blowing slot will also be presented for the cruise configuration, where at some Mach and Reynolds number conditions, the thrust-removed corrected data showed that a drag reduction was realized as a consequence of the blowing.

  5. Coherently controlled emissions |4P3/2,1/2> ↔ |4S1/2> from a femtosecond Λ-type excitation scheme in potassium atom

    NASA Astrophysics Data System (ADS)

    Pentaris, D.; Damianos, D.; Papademetriou, G.; Lyras, A.; Steponkevičius, K.; Vaičaitis, V.; Efthimiopoulos, T.

    2016-07-01

    The combined excitation of high density potassium (K) vapour by 100 fs pump-coupling pulses is experimentally studied. The intense pump pulse excites the two-photon ? transition and internally generated emissions are initiated along the atomic paths: ? (path-1) and, ? (path-2). The temporally delayed coupling pulse coherently drives the ? transitions, in a Λ-type excitation scheme. The competing axial and conical emission components of the well-resolved ? transitions (D2 and D1 lines of K) are substantially enhanced and controlled, for appropriate detunings and pump-coupling temporal delays. The coherence relaxation time (CRT) of the two-photon excited ? state is determined by exploiting the temporal delay in the pulse sequence. The effect of the pulse delay and the fs pulse bandwidth on the system dynamics is discussed as well as the role of dephasing collisions between K and buffer gas atoms. The proposed scheme can be employed in radiative multi-level systems, for the direct estimation of coherence relaxation rates of various states.

  6. Alfvén mode stability and wave particle interaction in the JET tokamak: prospects for scenario development and control schemes in burning plasma experiments

    NASA Astrophysics Data System (ADS)

    Testa, D.; Fasoli, A.; Borba, D.; de Baar, M.; Bigi, M.; Brzozowski, J.; de Vries, P.; contributors, JET-EFDA

    2004-07-01

    We have investigated the effect of different ion cyclotron resonance frequency (ICRF) heating schemes, of error field modes, of the plasma shape and edge magnetic shear, and of the ion nablaB drift direction on the stability of Alfvén eigenmodes (AEs). The use of multi-frequency or 2nd harmonic minority ICRF heating at high plasma density gives rise to a lower fast ion pressure gradient in the plasma core and to a reduced mode activity in the Alfvén frequency range. Externally excited low-amplitude error fields lead to a much larger AE instability threshold, which we attribute to a moderate radial redistribution of the fast ions. The edge plasma shape has a clear stabilizing effect on high-n, radially localized AEs. The damping rate of n = 1 toroidal AEs is a factor 3 higher when the ion nablaB drift is directed towards the divertor. These results represent a useful step towards the extrapolation of current scenarios to the inclusion of fusion-born alpha particles in ITER, with possible application for feedback control schemes for the various ITER operating regimes. Based on an invited talk given at the 8th International Atomic Energy Agency Technical Meeting on Energetic Particles in Magnetic Confinement Systems San Diego, USA, 6-8 October 2003.

  7. (De)synchronization of advanced visual information and ball flight characteristics constrains emergent information-movement couplings during one-handed catching.

    PubMed

    Stone, J A; Maynard, I W; North, J S; Panchuk, D; Davids, K

    2015-02-01

    Advance visual information of a projection action and ball flight information is important for organizing dynamic interceptive actions like catching. However, how the central nervous system (CNS) manages the relationship between advance visual information and emerging ball flight information in regulating behavior is less well understood. Here, we sought to examine the extent that advance visual information to the CNS constrains regulation of catching actions by synchronizing and desynchronizing its relationship with ball trajectory characteristics. Novel technology was used to present video footage of an actor throwing a ball at three different speeds, integrated with information from a real ball projected by a machine set to the three speeds. The technology enabled three synchronized and six desynchronized conditions between advance visual information and subsequent ball flight trajectories. Catching performance, kinematic data from the catching hand and gaze behaviors were recorded. Findings revealed that desynchronization of video images of ball projection shaped emergent catching behaviors. Footage of slower throws, paired with faster ball projection speeds, caused catching performance decrements. Timing in early phases of action was organized by the CNS to match the advance visual information presented. In later phases, like the grasp, ball flight information constraints adapted and regulated behaviors. Gaze behaviors showed increased ball projection speed resulted in participants tracking the ball for a smaller percentage of ball flight. Findings highlighted the role of the two visual systems in perception and action, implicating the importance of coupling advanced visual information and ball flight to regulate emergent movement coordination tendencies during interceptive behaviors.

  8. Progress on the application of ELM control schemes to ITER scenarios from the non-active phase to DT operation

    NASA Astrophysics Data System (ADS)

    Loarte, A.; Huijsmans, G.; Futatani, S.; Baylor, L. R.; Evans, T. E.; Orlov, D. M.; Schmitz, O.; Becoulet, M.; Cahyna, P.; Gribov, Y.; Kavin, A.; Sashala Naik, A.; Campbell, D. J.; Casper, T.; Daly, E.; Frerichs, H.; Kischner, A.; Laengner, R.; Lisgo, S.; Pitts, R. A.; Saibene, G.; Wingen, A.

    2014-03-01

    Progress in the definition of the requirements for edge localized mode (ELM) control and the application of ELM control methods both for high fusion performance DT operation and non-active low-current operation in ITER is described. Evaluation of the power fluxes for low plasma current H-modes in ITER shows that uncontrolled ELMs will not lead to damage to the tungsten (W) divertor target, unlike for high-current H-modes in which divertor damage by uncontrolled ELMs is expected. Despite the lack of divertor damage at lower currents, ELM control is found to be required in ITER under these conditions to prevent an excessive contamination of the plasma by W, which could eventually lead to an increased disruptivity. Modelling with the non-linear MHD code JOREK of the physics processes determining the flow of energy from the confined plasma onto the plasma-facing components during ELMs at the ITER scale shows that the relative contribution of conductive and convective losses is intrinsically linked to the magnitude of the ELM energy loss. Modelling of the triggering of ELMs by pellet injection for DIII-D and ITER has identified the minimum pellet size required to trigger ELMs and, from this, the required fuel throughput for the application of this technique to ITER is evaluated and shown to be compatible with the installed fuelling and tritium re-processing capabilities in ITER. The evaluation of the capabilities of the ELM control coil system in ITER for ELM suppression is carried out (in the vacuum approximation) and found to have a factor of ˜2 margin in terms of coil current to achieve its design criterion, although such a margin could be substantially reduced when plasma shielding effects are taken into account. The consequences for the spatial distribution of the power fluxes at the divertor of ELM control by three-dimensional (3D) fields are evaluated and found to lead to substantial toroidal asymmetries in zones of the divertor target away from the separatrix

  9. Development of the Circulation Control Flow Scheme Used in the NTF Semi-Span FAST-MAC Model

    NASA Technical Reports Server (NTRS)

    Jones, Gregory S.; Milholen, William E., II; Chan, David T.; Allan, Brian G.; Goodliff, Scott L.; Melton, Latunia P.; Anders, Scott G.; Carter, Melissa B.; Capone, Francis J.

    2013-01-01

    The application of a circulation control system for high Reynolds numbers was experimentally validated with the Fundamental Aerodynamic Subsonic Transonic Modular Active Control semi-span model in the NASA Langley National Transonic Facility. This model utilized four independent flow paths to modify the lift and thrust performance of a representative advanced transport type of wing. The design of the internal flow paths highlights the challenges associated with high Reynolds number testing in a cryogenic pressurized wind tunnel. Weight flow boundaries for the air delivery system were identified at mildly cryogenic conditions ranging from 0.1 to 10 lbm/sec. Results from the test verified system performance and identified solutions associated with the weight-flow metering system that are linked to internal perforated plates used to achieve flow uniformity at the jet exit.

  10. Action-related semantic content and negation polarity modulate motor areas during sentence reading: an event-related desynchronization study.

    PubMed

    Alemanno, F; Houdayer, E; Cursi, M; Velikova, S; Tettamanti, M; Comi, G; Cappa, S F; Leocani, L

    2012-11-12

    Our study evaluated motor cortex involvement during silent reading of sentences referring to hand actions. We aimed at defining whether sentential polarity (affirmative vs. negative) would modulate motor cortex activation using the event-related desynchronization (ERD) analysis of the mu rhythm. Eleven healthy volunteers performed a reading task involving 160 sentences (80 affirmative: 40 hand-related, 40 abstract; 80 negative: 40 hand-related, 40 abstract). After reading each sentence, subjects had to decide whether the verb was high or low frequency in Italian. Electroencephalographic (EEG) activity was recorded with 32 surface electrodes and mu ERD analyses were performed for each subject. Hand-action related sentences induced a greater mu ERD over the left premotor and motor hand areas compared to abstract sentences. Mu ERD was greater and temporally delayed when the hand-related verbs were presented in the negative versus affirmative form. As predicted by the "embodied semantic" theory of language understanding, motor areas were activated during sentences referring to hand actions. In addition, motor cortex activation was larger for negative than affirmative motor sentences, a finding compatible with the hypothesis that comprehension is more demanding in the specific case of motor content negation.

  11. Biological Computation Indexes of Brain Oscillations in Unattended Facial Expression Processing Based on Event-Related Synchronization/Desynchronization

    PubMed Central

    Ma, Lin; Li, Haifeng; Zhao, Lun; Bo, Hongjian; Wang, Xunda

    2016-01-01

    Estimation of human emotions from Electroencephalogram (EEG) signals plays a vital role in affective Brain Computer Interface (BCI). The present study investigated the different event-related synchronization (ERS) and event-related desynchronization (ERD) of typical brain oscillations in processing Facial Expressions under nonattentional condition. The results show that the lower-frequency bands are mainly used to update Facial Expressions and distinguish the deviant stimuli from the standard ones, whereas the higher-frequency bands are relevant to automatically processing different Facial Expressions. Accordingly, we set up the relations between each brain oscillation and processing unattended Facial Expressions by the measures of ERD and ERS. This research first reveals the contributions of each frequency band for comprehension of Facial Expressions in preattentive stage. It also evidences that participants have emotional experience under nonattentional condition. Therefore, the user's emotional state under nonattentional condition can be recognized in real time by the ERD/ERS computation indexes of different frequency bands of brain oscillations, which can be used in affective BCI to provide the user with more natural and friendly ways. PMID:27471545

  12. Action-related semantic content and negation polarity modulate motor areas during sentence reading: an event-related desynchronization study.

    PubMed

    Alemanno, F; Houdayer, E; Cursi, M; Velikova, S; Tettamanti, M; Comi, G; Cappa, S F; Leocani, L

    2012-11-12

    Our study evaluated motor cortex involvement during silent reading of sentences referring to hand actions. We aimed at defining whether sentential polarity (affirmative vs. negative) would modulate motor cortex activation using the event-related desynchronization (ERD) analysis of the mu rhythm. Eleven healthy volunteers performed a reading task involving 160 sentences (80 affirmative: 40 hand-related, 40 abstract; 80 negative: 40 hand-related, 40 abstract). After reading each sentence, subjects had to decide whether the verb was high or low frequency in Italian. Electroencephalographic (EEG) activity was recorded with 32 surface electrodes and mu ERD analyses were performed for each subject. Hand-action related sentences induced a greater mu ERD over the left premotor and motor hand areas compared to abstract sentences. Mu ERD was greater and temporally delayed when the hand-related verbs were presented in the negative versus affirmative form. As predicted by the "embodied semantic" theory of language understanding, motor areas were activated during sentences referring to hand actions. In addition, motor cortex activation was larger for negative than affirmative motor sentences, a finding compatible with the hypothesis that comprehension is more demanding in the specific case of motor content negation. PMID:23010314

  13. Biological Computation Indexes of Brain Oscillations in Unattended Facial Expression Processing Based on Event-Related Synchronization/Desynchronization.

    PubMed

    Yu, Bo; Ma, Lin; Li, Haifeng; Zhao, Lun; Bo, Hongjian; Wang, Xunda

    2016-01-01

    Estimation of human emotions from Electroencephalogram (EEG) signals plays a vital role in affective Brain Computer Interface (BCI). The present study investigated the different event-related synchronization (ERS) and event-related desynchronization (ERD) of typical brain oscillations in processing Facial Expressions under nonattentional condition. The results show that the lower-frequency bands are mainly used to update Facial Expressions and distinguish the deviant stimuli from the standard ones, whereas the higher-frequency bands are relevant to automatically processing different Facial Expressions. Accordingly, we set up the relations between each brain oscillation and processing unattended Facial Expressions by the measures of ERD and ERS. This research first reveals the contributions of each frequency band for comprehension of Facial Expressions in preattentive stage. It also evidences that participants have emotional experience under nonattentional condition. Therefore, the user's emotional state under nonattentional condition can be recognized in real time by the ERD/ERS computation indexes of different frequency bands of brain oscillations, which can be used in affective BCI to provide the user with more natural and friendly ways.

  14. Biological Computation Indexes of Brain Oscillations in Unattended Facial Expression Processing Based on Event-Related Synchronization/Desynchronization.

    PubMed

    Yu, Bo; Ma, Lin; Li, Haifeng; Zhao, Lun; Bo, Hongjian; Wang, Xunda

    2016-01-01

    Estimation of human emotions from Electroencephalogram (EEG) signals plays a vital role in affective Brain Computer Interface (BCI). The present study investigated the different event-related synchronization (ERS) and event-related desynchronization (ERD) of typical brain oscillations in processing Facial Expressions under nonattentional condition. The results show that the lower-frequency bands are mainly used to update Facial Expressions and distinguish the deviant stimuli from the standard ones, whereas the higher-frequency bands are relevant to automatically processing different Facial Expressions. Accordingly, we set up the relations between each brain oscillation and processing unattended Facial Expressions by the measures of ERD and ERS. This research first reveals the contributions of each frequency band for comprehension of Facial Expressions in preattentive stage. It also evidences that participants have emotional experience under nonattentional condition. Therefore, the user's emotional state under nonattentional condition can be recognized in real time by the ERD/ERS computation indexes of different frequency bands of brain oscillations, which can be used in affective BCI to provide the user with more natural and friendly ways. PMID:27471545

  15. Importance of baseline in event-related desynchronization during a combination task of motor imagery and motor observation

    NASA Astrophysics Data System (ADS)

    Tangwiriyasakul, Chayanin; Verhagen, Rens; van Putten, Michel J. A. M.; Rutten, Wim L. C.

    2013-04-01

    Objective. Event-related desynchronization (ERD) or synchronization (ERS) refers to the modulation of any EEG rhythm in response to a particular event. It is typically quantified as the ratio between a baseline and a task condition (the event). Here, we focused on the sensorimotor mu-rhythm. We explored the effects of different baselines on mu-power and ERD of the mu-rhythm during a motor imagery task. Methods. Eighteen healthy subjects performed motor imagery tasks while EEGs were recorded. Five different baseline movies were shown. For the imagery task a right-hand opening/closing movie was shown. Power and ERD of the mu-rhythm recorded over C3 and C4 for the different baselines were estimated. Main Results. 50% of the subjects showed relatively high mu-power for specific baselines only, and ERDs of these subjects were strongly dependent on the baseline used. In 17% of the subjects no preference was found. Contralateral ERD of the mu-rhythm was found in about 67% of the healthy volunteers, with a significant baseline preference in about 75% of that subgroup. Significance. The sensorimotor ERD quantifies activity of the brain during motor imagery tasks. Selection of the optimal baseline increases ERD.

  16. The effect of air flow on the temperature distribution and the harmonic conversion efficiency of the ADP crystal with large aperture in the temperature control scheme

    NASA Astrophysics Data System (ADS)

    Sun, Fuzhong; Zhang, Peng; Lu, Lihua; Xiang, Yong; Bai, Qingshun

    2016-03-01

    This paper presented a temperature control scheme for ammonium dihydrogen phosphate (ADP) crystal of V80 mm in diameter, and the influence of the air flow was also studied. This research aims to obtain the high energy, high frequency laser with large aperture under the non-critical phase matching (NCPM). Firstly, thermal analysis was carried out to investigate the air flow property in the cavity, as well as the effect of ambient temperature was analyzed. Secondly, the temperature distributions of air flow were achieved using the Finite Volume Method (FVM), and this prediction was validated by the experiment results. Finally, the effect of air flow in the cavity was obtained from the heating method, and the variation of harmonic conversion efficiency caused by the ambient temperature was also highlighted.

  17. Circadian time organization of professional firemen: desynchronization-tau differing from 24.0 hours-documented by longitudinal self-assessment of 16 variables.

    PubMed

    Reinberg, Alain; Riedel, Marc; Brousse, Eric; Floc'h, Nadine Le; Clarisse, René; Mauvieux, Benoît; Touitou, Yvan; Smolensky, Michael H; Marlot, Michel; Berrez, Stéphane; Mechkouri, Mohamed

    2013-10-01

    We investigated the circadian synchronization/desynchronization (by field-study assessment of differences in period, τ, of 16 coexisting and well-documented rhythms) of 30 healthy firemen (FM) exposed to irregular, difficult, and stressful nocturnal work hours who demonstrated excellent clinical tolerance (allochronism). Three groups of FM were studied (A = 12 FM on 24-h duty at the fire station; B = 9 FM on 24-h duty at the emergency call center; C = 9 day-shift administrative FM) of mostly comparable average age, body mass index, career duration, chronotype-morningness/eveningness, and trait of field dependence/independence. The self-assessed 16 circadian rhythms were (i) physiological ones of sleep-wake (sleep log), activity-rest (actography), body temperature (internal transmitter pill probe), right- and left-hand grip strength (hand dynamometer), systolic and diastolic blood pressure (BP) plus heart rate (ambulatory BP monitoring device); (ii) psychological ones (visual analog self-rating scales) of sleepiness, fatigue, fitness for work, and capacity to cope with aggressive social behavior; and (iii) cognitive ones of eye-hand skill and letter cancellation, entailing performance speed (tasks completed/unit time) and accuracy (errors). Data (4-6 time points/24 h; 2 591 480 values in total) were gathered continuously throughout two 8-d spans, one in winter 2010-2011 and one in summer 2011. Each of the resulting 938 unequal-interval time series was analyzed by a special power spectrum analysis to objectively determine the prominent τ. The desynchronization ratio (DR: number of study variables with τ = 24.0 h/number of study variables × 100) served to ascertain the strength/weakness of each rhythm per individual, group, and season. The field study confirmed, independent of group and season, coexistence of rather strong and weak circadian oscillators. Interindividual differences in DR were detected between groups and seasons (χ(2), correlation tests, analysis

  18. Enhancing and controlling single-atom high-harmonic generation spectra: a time-dependent density-functional scheme

    NASA Astrophysics Data System (ADS)

    Castro, Alberto; Rubio, Angel; Gross, Eberhard K. U.

    2015-08-01

    High harmonic generation (HHG) provides a flexible framework for the development of coherent light sources in the extreme-ultraviolet and soft X-ray regimes. However it suffers from low conversion efficiencies as the control of the HHG spectral and temporal characteristics requires manipulating electron trajectories on attosecond time scale. The phase matching mechanism has been employed to selectively enhance specific quantum paths leading to HHG. A few important fundamental questions remain open, among those how much of the enhancement can be achieved by the single-emitter and what is the role of correlations (or the electronic structure) in the selectivity and control of HHG generation. Here we address those questions by examining computationally the possibility of optimizing the HHG spectrum of isolated hydrogen and helium atoms by shaping the slowly varying envelope of a 800 nm, 200-cycles long laser pulse. The spectra are computed with a fully quantum mechanical description, by explicitly computing the time-dependent dipole moment of the systems using a time-dependent density-functional approach (or the single-electron Schrödinger equation for the case of H), on top of a one-dimensional model. The sought optimization corresponds to the selective enhancement of single harmonics, which we find to be significant. This selectivity is entirely due to the single atom response, and not to any propagation or phase-matching effect. Moreover, we see that the electronic correlation plays a role in the determining the degree of optimization that can be obtained.

  19. A novel transient rotor current control scheme of a doubly-fed induction generator equipped with superconducting magnetic energy storage for voltage and frequency support

    NASA Astrophysics Data System (ADS)

    Shen, Yang-Wu; Ke, De-Ping; Sun, Yuan-Zhang; Daniel, Kirschen; Wang, Yi-Shen; Hu, Yuan-Chao

    2015-07-01

    A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator (DFIG) equipped with a superconducting magnetic energy storage (SMES) device to enhance its transient voltage and frequency support capacity during grid faults. The SMES connected to the DC-link capacitor of the DFIG is controlled to regulate the transient dc-link voltage so that the whole capacity of the grid side converter (GSC) is dedicated to injecting reactive power to the grid for the transient voltage support. However, the rotor-side converter (RSC) has different control tasks for different periods of the grid fault. Firstly, for Period I, the RSC injects the demagnetizing current to ensure the controllability of the rotor voltage. Then, since the dc stator flux degenerates rapidly in Period II, the required demagnetizing current is low in Period II and the RSC uses the spare capacity to additionally generate the reactive (priority) and active current so that the transient voltage capability is corroborated and the DFIG also positively responds to the system frequency dynamic at the earliest time. Finally, a small amount of demagnetizing current is provided after the fault clearance. Most of the RSC capacity is used to inject the active current to further support the frequency recovery of the system. Simulations are carried out on a simple power system with a wind farm. Comparisons with other commonly used control methods are performed to validate the proposed control method. Project supported by the National Natural Science Foundation of China (Grant No. 51307124) and the Major Program of the National Natural Science Foundation of China (Grant No. 51190105).

  20. Electrically controlled second-harmonic generation in silicon-compatible plasmonic slot waveguides: a new modulation scheme.

    PubMed

    Zhang, Jihua; Cassan, Eric; Zhang, Xinliang

    2014-07-01

    The possible realization of an active electro-optical control of the nonlinear second-harmonic generation (SHG) mechanism in a plasmonic slot waveguide is theoretically investigated. Both the conventional SHG and the electrically induced SHG are taken into account with a moderate pump power of 40 mW at the fundamental wavelength (1550 nm). The generated power of the second-harmonic frequency can be modulated by the applied voltage in a quadratic and almost linear form for centrosymmetric and noncentrosymmetric nonlinear polymers integrated in the slot, respectively. Converted power up to 140 μW within a short distance of only 16 μm is predicted for a voltage of 10 V. This mechanism may open a new route to realize high-speed advanced modulations or inversely to detect ultrafast electrical signals.

  1. Patients with mild cognitive impairment have an abnormal upper-alpha event-related desynchronization/synchronization (ERD/ERS) during a task of temporal attention.

    PubMed

    Caravaglios, Giuseppe; Muscoso, Emma Gabriella; Di Maria, Giulia; Costanzo, Erminio

    2015-03-01

    There are several evidences indicating that an impairment in attention-executive functions is present in prodromal Alzheimer's disease and predict future global cognitive decline. In particular, the issue of temporal orienting of attention in patients with mild cognitive impairment (MCI) due to Alzheimer's disease has been overlooked. The present research aimed to explore whether subtle deficits of cortical activation are present in these patients early in the course of the disease. We studied the upper-alpha event-related synchronization/desynchronization phenomenon during a paradigm of temporal orientation of attention. MCI patients (n = 27) and healthy elderly controls (n = 15) performed a task in which periodically omitted tones had to be predicted and their virtual onset time had to be marked by pressing a button. Single-trial responses were measured, respectively, before and after the motor response. Then, upper-alpha responses were compared to upper-alpha power during eyes-closed resting state. The time course of the task was characterized by two different behavioral conditions: (1) a pre-event epoch, in which the subject awaited the virtual onset of the omitted tone, (2) a post-event epoch (after button pressing), in which the subject was in a post-motor response condition. The principal findings are: (1) during the waiting epoch, only healthy elderly had an upper-alpha ERD at the level of both temporal and posterior brain regions; (2) during the post-motor epoch, the aMCI patients had a weaker upper-alpha ERS on prefrontal regions; (3) only healthy elderly showed a laterality effect: (a) during the waiting epoch, the upper-alpha ERD was greater at the level of the right posterior-temporal lead; during the post-motor epoch, the upper alpha ERS was greater on the left prefrontal lead. The relevance of these findings is that the weaker upper-alpha response observed in aMCI patients is evident even if the accuracy of the behavioral performance (i.e., button

  2. Weighted Score Tests Implementing Model-Averaging Schemes in Detection of Rare Variants in Case-Control Studies

    PubMed Central

    Coombes, Brandon; Basu, Saonli; Guha, Sharmistha; Schork, Nicholas

    2015-01-01

    Multi-locus effect modeling is a powerful approach for detection of genes influencing a complex disease. Especially for rare variants, we need to analyze multiple variants together to achieve adequate power for detection. In this paper, we propose several parsimonious branching model techniques to assess the joint effect of a group of rare variants in a case-control study. These models implement a data reduction strategy within a likelihood framework and use a weighted score test to assess the statistical significance of the effect of the group of variants on the disease. The primary advantage of the proposed approach is that it performs model-averaging over a substantially smaller set of models supported by the data and thus gains power to detect multi-locus effects. We illustrate these proposed approaches on simulated and real data and study their performance compared to several existing rare variant detection approaches. The primary goal of this paper is to assess if there is any gain in power to detect association by averaging over a number of models instead of selecting the best model. Extensive simulations and real data application demonstrate the advantage the proposed approach in presence of causal variants with opposite directional effects along with a moderate number of null variants in linkage disequilibrium. PMID:26436424

  3. A PWM Buck Converter With Load-Adaptive Power Transistor Scaling Scheme Using Analog-Digital Hybrid Control for High Energy Efficiency in Implantable Biomedical Systems.

    PubMed

    Park, Sung-Yun; Cho, Jihyun; Lee, Kyuseok; Yoon, Euisik

    2015-12-01

    We report a pulse width modulation (PWM) buck converter that is able to achieve a power conversion efficiency (PCE) of > 80% in light loads 100 μA) for implantable biomedical systems. In order to achieve a high PCE for the given light loads, the buck converter adaptively reconfigures the size of power PMOS and NMOS transistors and their gate drivers in accordance with load currents, while operating at a fixed frequency of 1 MHz. The buck converter employs the analog-digital hybrid control scheme for coarse/fine adjustment of power transistors. The coarse digital control generates an approximate duty cycle necessary for driving a given load and selects an appropriate width of power transistors to minimize redundant power dissipation. The fine analog control provides the final tuning of the duty cycle to compensate for the error from the coarse digital control. The mode switching between the analog and digital controls is accomplished by a mode arbiter which estimates the average of duty cycles for the given load condition from limit cycle oscillations (LCO) induced by coarse adjustment. The fabricated buck converter achieved a peak efficiency of 86.3% at 1.4 mA and > 80% efficiency for a wide range of load conditions from 45 μA to 4.1 mA, while generating 1 V output from 2.5-3.3 V supply. The converter occupies 0.375 mm(2) in 0.18 μm CMOS processes and requires two external components: 1.2 μF capacitor and 6.8 μH inductor.

  4. A PWM Buck Converter With Load-Adaptive Power Transistor Scaling Scheme Using Analog-Digital Hybrid Control for High Energy Efficiency in Implantable Biomedical Systems.

    PubMed

    Park, Sung-Yun; Cho, Jihyun; Lee, Kyuseok; Yoon, Euisik

    2015-12-01

    We report a pulse width modulation (PWM) buck converter that is able to achieve a power conversion efficiency (PCE) of > 80% in light loads 100 μA) for implantable biomedical systems. In order to achieve a high PCE for the given light loads, the buck converter adaptively reconfigures the size of power PMOS and NMOS transistors and their gate drivers in accordance with load currents, while operating at a fixed frequency of 1 MHz. The buck converter employs the analog-digital hybrid control scheme for coarse/fine adjustment of power transistors. The coarse digital control generates an approximate duty cycle necessary for driving a given load and selects an appropriate width of power transistors to minimize redundant power dissipation. The fine analog control provides the final tuning of the duty cycle to compensate for the error from the coarse digital control. The mode switching between the analog and digital controls is accomplished by a mode arbiter which estimates the average of duty cycles for the given load condition from limit cycle oscillations (LCO) induced by coarse adjustment. The fabricated buck converter achieved a peak efficiency of 86.3% at 1.4 mA and > 80% efficiency for a wide range of load conditions from 45 μA to 4.1 mA, while generating 1 V output from 2.5-3.3 V supply. The converter occupies 0.375 mm(2) in 0.18 μm CMOS processes and requires two external components: 1.2 μF capacitor and 6.8 μH inductor. PMID:26742139

  5. Risk of Performance Decrements and Adverse Health Outcomes Resulting from Sleep Loss, Circadian Desynchronization, and Work Overload

    NASA Technical Reports Server (NTRS)

    Flynn-Evans, Erin; Gregory, Kevin; Arsintescu, Lucia; Whitmire, Alexandra

    2016-01-01

    Sleep loss, circadian desynchronization, and work overload occur to some extent for ground and flight crews, prior to and during spaceflight missions. Ground evidence indicates that such risk factors may lead to performance decrements and adverse health outcomes, which could potentially compromise mission objectives. Efforts are needed to identify the environmental and mission conditions that interfere with sleep and circadian alignment, as well as individual differences in vulnerability and resiliency to sleep loss and circadian desynchronization. Specifically, this report highlights a collection of new evidence to better characterize the risk and reveals new gaps in this risk as follows: Sleep loss is apparent during spaceflight. Astronauts consistently average less sleep during spaceflight relative to on the ground. The causes of this sleep loss remain unknown, however ground-based evidence suggests that the sleep duration of astronauts is likely to lead to performance impairment and short and long-term health consequences. Further research is needed in this area in order to develop screening tools to assess individual astronaut sleep need in order to quantify the magnitude of sleep loss during spaceflight; current and planned efforts in BHP's research portfolio address this need. In addition, it is still unclear whether the conditions of spaceflight environment lead to sleep loss or whether other factors, such as work overload lead to the reduced sleep duration. Future data mining efforts and continued data collection on the ISS will help to further characterize factors contributing to sleep loss. Sleep inertia has not been evaluated during spaceflight. Ground-based studies confirm that it takes two to four hours to achieve optimal performance after waking from a sleep episode. Sleep inertia has been associated with increased accidents and reduced performance in operational environments. Sleep inertia poses considerable risk during spaceflight when emergency

  6. Experimental Validation of a Compound Control Scheme for a Two-Axis Inertially Stabilized Platform with Multi-Sensors in an Unmanned Helicopter-Based Airborne Power Line Inspection System

    PubMed Central

    Zhou, Xiangyang; Jia, Yuan; Zhao, Qiang; Yu, Ruixia

    2016-01-01

    A compound control scheme is proposed to achieve high control performance for a two-axis inertially stabilized platform (ISP) with multi-sensors applied to an unmanned helicopter (UH)-based airborne power line inspection (APLI) system. Compared with the traditional two closed-loop control scheme that is composed of a high-bandwidth rate loop and a lower bandwidth position loop, a new current loop inside rate loop is particularly designed to suppress the influences of voltage fluctuation from power supply and motor back electromotive force (BEMF) on control precision. In this way, the stabilization accuracy of the ISP is greatly improved. The rate loop, which is the middle one, is used to improve sensor’s stability precision through compensating for various disturbances. To ensure the pointing accuracy of the line of sight (LOS) of multi-sensors, the position loop is designed to be the outer one and acts as the main feedback path, by which the accurate pointing angular position is achieved. To validate the scheme, a series of experiments were carried out. The results show that the proposed compound control scheme can achieve reliable control precision and satisfy the requirements of real APLI tasks. PMID:26978371

  7. Experimental Validation of a Compound Control Scheme for a Two-Axis Inertially Stabilized Platform with Multi-Sensors in an Unmanned Helicopter-Based Airborne Power Line Inspection System.

    PubMed

    Zhou, Xiangyang; Jia, Yuan; Zhao, Qiang; Yu, Ruixia

    2016-01-01

    A compound control scheme is proposed to achieve high control performance for a two-axis inertially stabilized platform (ISP) with multi-sensors applied to an unmanned helicopter (UH)-based airborne power line inspection (APLI) system. Compared with the traditional two closed-loop control scheme that is composed of a high-bandwidth rate loop and a lower bandwidth position loop, a new current loop inside rate loop is particularly designed to suppress the influences of voltage fluctuation from power supply and motor back electromotive force (BEMF) on control precision. In this way, the stabilization accuracy of the ISP is greatly improved. The rate loop, which is the middle one, is used to improve sensor's stability precision through compensating for various disturbances. To ensure the pointing accuracy of the line of sight (LOS) of multi-sensors, the position loop is designed to be the outer one and acts as the main feedback path, by which the accurate pointing angular position is achieved. To validate the scheme, a series of experiments were carried out. The results show that the proposed compound control scheme can achieve reliable control precision and satisfy the requirements of real APLI tasks. PMID:26978371

  8. Improved Transient and Steady-State Performances of Series Resonant ZCS High-Frequency Inverter-Coupled Voltage Multiplier Converter with Dual Mode PFM Control Scheme

    NASA Astrophysics Data System (ADS)

    Chu, Enhui; Gamage, Laknath; Ishitobi, Manabu; Hiraki, Eiji; Nakaoka, Mutsuo

    The A variety of switched-mode high voltage DC power supplies using voltage-fed type or current-fed type high-frequency transformer resonant inverters using MOS gate bipolar power transistors; IGBTs have been recently developed so far for a medical-use X-ray high power generator. In general, the high voltage high power X-ray generator using voltage-fed high frequency inverter with a high voltage transformer link has to meet some performances such as (i) short rising period in start transient of X-ray tube voltage (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady-state under extremely wide load variations and filament heater current fluctuation conditions of the X-ray tube. This paper presents two lossless inductor snubber-assisted series resonant zero current soft switching high-frequency inverter using a diode-capacitor ladder type voltage multiplier called Cockcroft-Walton circuit, which is effectively implemented for a high DC voltage X-ray power generator. This DC high voltage generator which incorporates pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high frequency transformer linked voltage boost multiplier can efficiently work a novel selectively-changed dual mode PFM control scheme in order to improve the start transient and steady-state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent for wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively-changed dual-mode PFM for

  9. Implementation of an insecticide-treated net subsidy scheme under a public-private partnership for malaria control in Tanzania – challenges in implementation

    PubMed Central

    2009-01-01

    Background In the past decade there has been increasing visibility of malaria control efforts at the national and international levels. The factors that have enhanced this scenario are the availability of proven interventions such as artemisinin-based combination therapy, the wide scale use of insecticide-treated nets (ITNs) and a renewed emphasis in indoor residual house-spraying. Concurrently, there has been a window of opportunity of financial commitments from organizations such as the Global Fund for HIV/AIDS, Tuberculosis and Malaria (GFATM), the President's Malaria Initiative and the World Bank Booster programme. Methods The case study uses the health policy analysis framework to analyse the implementation of a public-private partnership approach embarked upon by the government of Tanzania in malaria control – 'The Tanzania National Voucher Scheme'- and in this synthesis, emphasis is on the challenges faced by the scheme during the pre-implementation (2001 – 2004) and implementation phases (2004 – 2005). Qualitative research tools used include: document review, interview with key informants, stakeholder's analysis, force-field analysis, time line of events, policy characteristic analysis and focus group discussions. The study is also complemented by a cross-sectional survey, which was conducted at the Rufiji Health Demographic Surveillance Site, where a cohort of women of child-bearing age were followed up regarding access and use of ITNs. Results The major challenges observed include: the re-introduction of taxes on mosquito nets and related products, procurement and tendering procedures in the implementation of the GFATM, and organizational arrangements and free delivery of mosquito nets through a Presidential initiative. Conclusion The lessons gleaned from this synthesis include: (a) the consistency of the stakeholders with a common vision, was an important strength in overcoming obstacles, (b) senior politicians often steered the policy agenda when

  10. A bio-inspired stimulator to desynchronize epileptic cortical population models: A digital implementation framework.

    PubMed

    Piri, Mohsen; Amiri, Masoud; Amiri, Mahmood

    2015-07-01

    Pathophysiologic neural synchronization is a hallmark of several neurological disorders such as epilepsy. In addition, based on established neurophysiologic findings, astrocytes dynamically regulate the synaptic transmission and have key roles in stabilizing neural synchronization. Therefore, in the present study, based on the dynamic model of astrocyte, a digital bio-inspired stimulator is proposed to avoid the hyper-synchronous seizure-like activities in a cortical population model. The complete digital circuit of the close loop system that is the bio-inspired stimulator and the cortical population model are implemented in hardware on the ZedBoard development kit. Based on the results of MATLAB simulations, hardware synthesis and FPGA implementation, it is demonstrated that the digital bio-inspired stimulator can effectively prevent the occurrence of spontaneous paroxysmal episodes with a demand-controlled characteristic. In this way, the designed digital stimulator successfully maintains the normal ongoing activity. PMID:25888932

  11. Robust synchronization control scheme of a population of nonlinear stochastic synthetic genetic oscillators under intrinsic and extrinsic molecular noise via quorum sensing

    PubMed Central

    2012-01-01

    the help of LMI toolbox in MATLAB easily. Conclusion If the synchronization robustness criterion, i.e. the synchronization robustness ≥ intrinsic robustness + extrinsic robustness, then the stochastic coupled synthetic oscillators can be robustly synchronized in spite of intrinsic parameter fluctuation and extrinsic noise. If the synchronization robustness criterion is violated, external control scheme by adding inducer can be designed to improve synchronization robustness of coupled synthetic genetic oscillators. The investigated robust synchronization criteria and proposed external control method are useful for a population of coupled synthetic networks with emergent synchronization behavior, especially for multi-cellular, engineered networks. PMID:23101662

  12. Controlling synchrony in oscillatory networks with a separate stimulation-registration setup

    NASA Astrophysics Data System (ADS)

    Pyragas, K.; Popovych, O. V.; Tass, P. A.

    2007-11-01

    We present a demand-controlled method for desynchronization of globally coupled oscillatory networks utilizing a configuration with an observed and stimulated subsystem. The stimulated subsystem is subjected to a proportional-integro-differential (PID) feedback derived from the mean field of the observed subsystem. Our method enables to restore desynchronized states in both subsystems in a robust way. We develop an analytical theory for the Kuramoto model and analytically derive a threshold of the stimulation parameters for the desynchronization transition in ensembles of phase and van der Pol oscillators. We also numerically demonstrate the efficacy of the approach for ensembles of globally coupled Landau-Stuart and relaxation van der Pol oscillators. Our approach is particularly important for applications to physical and biological systems which do not allow for a simultaneous registration and stimulation of the whole network, as in the case of electrical brain stimulation.

  13. Top-Down Control of MEG Alpha-Band Activity in Children Performing Categorical N-Back Task

    ERIC Educational Resources Information Center

    Ciesielski, Kristina T.; Ahlfors, Seppo P.; Bedrick, Edward J.; Kerwin, Audra A.; Hamalainen, Matti S.

    2010-01-01

    Top-down cognitive control has been associated in adults with the prefrontal-parietal network. In children the brain mechanisms of top-down control have rarely been studied. We examined developmental differences in top-down cognitive control by monitoring event-related desynchronization (ERD) and event-related synchronization (ERS) of alpha-band…

  14. On Tenth Order Central Spatial Schemes

    SciTech Connect

    Sjogreen, B; Yee, H C

    2007-05-14

    This paper explores the performance of the tenth-order central spatial scheme and derives the accompanying energy-norm stable summation-by-parts (SBP) boundary operators. The objective is to employ the resulting tenth-order spatial differencing with the stable SBP boundary operators as a base scheme in the framework of adaptive numerical dissipation control in high order multistep filter schemes of Yee et al. (1999), Yee and Sj{umlt o}green (2002, 2005, 2006, 2007), and Sj{umlt o}green and Yee (2004). These schemes were designed for multiscale turbulence flows including strong shock waves and combustion.

  15. Amyloid-β-induced action potential desynchronization and degradation of hippocampal gamma oscillations is prevented by interference with peptide conformation change and aggregation.

    PubMed

    Kurudenkandy, Firoz Roshan; Zilberter, Misha; Biverstål, Henrik; Presto, Jenny; Honcharenko, Dmytro; Strömberg, Roger; Johansson, Jan; Winblad, Bengt; Fisahn, André

    2014-08-20

    The amyloid-β hypothesis of Alzheimer's Disease (AD) focuses on accumulation of amyloid-β peptide (Aβ) as the main culprit for the myriad physiological changes seen during development and progression of AD including desynchronization of neuronal action potentials, consequent development of aberrant brain rhythms relevant for cognition, and final emergence of cognitive deficits. The aim of this study was to elucidate the cellular and synaptic mechanisms underlying the Aβ-induced degradation of gamma oscillations in AD, to identify aggregation state(s) of Aβ that mediate the peptides neurotoxicity, and to test ways to prevent the neurotoxic Aβ effect. We show that Aβ(1-42) in physiological concentrations acutely degrades mouse hippocampal gamma oscillations in a concentration- and time-dependent manner. The underlying cause is an Aβ-induced desynchronization of action potential generation in pyramidal cells and a shift of the excitatory/inhibitory equilibrium in the hippocampal network. Using purified preparations containing different aggregation states of Aβ, as well as a designed ligand and a BRICHOS chaperone domain, we provide evidence that the severity of Aβ neurotoxicity increases with increasing concentration of fibrillar over monomeric Aβ forms, and that Aβ-induced degradation of gamma oscillations and excitatory/inhibitory equilibrium is prevented by compounds that interfere with Aβ aggregation. Our study provides correlative evidence for a link between Aβ-induced effects on synaptic currents and AD-relevant neuronal network oscillations, identifies the responsible aggregation state of Aβ and proofs that strategies preventing peptide aggregation are able to prevent the deleterious action of Aβ on the excitatory/inhibitory equilibrium and on the gamma rhythm. PMID:25143621

  16. On-Going Frontal Alpha Rhythms Are Dominant in Passive State and Desynchronize in Active State in Adult Gray Mouse Lemurs

    PubMed Central

    Rahman, Anisur; Lamberty, Yves; Bordet, Regis; Richardson, Jill C.; Forloni, Gianluigi; Drinkenburg, Wilhelmus; Lopez, Susanna; Aujard, Fabienne; Babiloni, Claudio; Pifferi, Fabien

    2015-01-01

    The gray mouse lemur (Microcebus murinus) is considered a useful primate model for translational research. In the framework of IMI PharmaCog project (Grant Agreement n°115009, www.pharmacog.org), we tested the hypothesis that spectral electroencephalographic (EEG) markers of motor and locomotor activity in gray mouse lemurs reflect typical movement-related desynchronization of alpha rhythms (about 8–12 Hz) in humans. To this aim, EEG (bipolar electrodes in frontal cortex) and electromyographic (EMG; bipolar electrodes sutured in neck muscles) data were recorded in 13 male adult (about 3 years) lemurs. Artifact-free EEG segments during active state (gross movements, exploratory movements or locomotor activity) and awake passive state (no sleep) were selected on the basis of instrumental measures of animal behavior, and were used as an input for EEG power density analysis. Results showed a clear peak of EEG power density at alpha range (7–9 Hz) during passive state. During active state, there was a reduction in alpha power density (8–12 Hz) and an increase of power density at slow frequencies (1–4 Hz). Relative EMG activity was related to EEG power density at 2–4 Hz (positive correlation) and at 8–12 Hz (negative correlation). These results suggest for the first time that the primate gray mouse lemurs and humans may share basic neurophysiologic mechanisms of synchronization of frontal alpha rhythms in awake passive state and their desynchronization during motor and locomotor activity. These EEG markers may be an ideal experimental model for translational basic (motor science) and applied (pharmacological and non-pharmacological interventions) research in Neurophysiology. PMID:26618512

  17. On-Going Frontal Alpha Rhythms Are Dominant in Passive State and Desynchronize in Active State in Adult Gray Mouse Lemurs.

    PubMed

    Infarinato, Francesco; Rahman, Anisur; Del Percio, Claudio; Lamberty, Yves; Bordet, Regis; Richardson, Jill C; Forloni, Gianluigi; Drinkenburg, Wilhelmus; Lopez, Susanna; Aujard, Fabienne; Babiloni, Claudio; Pifferi, Fabien

    2015-01-01

    The gray mouse lemur (Microcebus murinus) is considered a useful primate model for translational research. In the framework of IMI PharmaCog project (Grant Agreement n°115009, www.pharmacog.org), we tested the hypothesis that spectral electroencephalographic (EEG) markers of motor and locomotor activity in gray mouse lemurs reflect typical movement-related desynchronization of alpha rhythms (about 8-12 Hz) in humans. To this aim, EEG (bipolar electrodes in frontal cortex) and electromyographic (EMG; bipolar electrodes sutured in neck muscles) data were recorded in 13 male adult (about 3 years) lemurs. Artifact-free EEG segments during active state (gross movements, exploratory movements or locomotor activity) and awake passive state (no sleep) were selected on the basis of instrumental measures of animal behavior, and were used as an input for EEG power density analysis. Results showed a clear peak of EEG power density at alpha range (7-9 Hz) during passive state. During active state, there was a reduction in alpha power density (8-12 Hz) and an increase of power density at slow frequencies (1-4 Hz). Relative EMG activity was related to EEG power density at 2-4 Hz (positive correlation) and at 8-12 Hz (negative correlation). These results suggest for the first time that the primate gray mouse lemurs and humans may share basic neurophysiologic mechanisms of synchronization of frontal alpha rhythms in awake passive state and their desynchronization during motor and locomotor activity. These EEG markers may be an ideal experimental model for translational basic (motor science) and applied (pharmacological and non-pharmacological interventions) research in Neurophysiology. PMID:26618512

  18. Evaluation and application of a hybrid brain computer interface for real wheelchair parallel control with multi-degree of freedom.

    PubMed

    Li, Jie; Ji, Hongfei; Cao, Lei; Zang, Di; Gu, Rong; Xia, Bin; Wu, Qiang

    2014-06-01

    There have been many attempts to design brain-computer interfaces (BCIs) for wheelchair control based on steady state visual evoked potential (SSVEP), event-related desynchronization/synchronization (ERD/ERS) during motor imagery (MI) tasks, P300 evoked potential, and some hybrid signals. However, those BCI systems cannot implement the wheelchair navigation flexibly and effectively. In this paper, we propose a hybrid BCI scheme based on two-class MI and four-class SSVEP tasks. It cannot only provide multi-degree control for its user, but also allow the user implement the different types of commands in parallel. In order for the subject to learn the hybrid mental strategies effectively, we design a visual and auditory cues and feedback-based training paradigm. Furthermore, an algorithm based on entropy of classification probabilities is proposed to detect intentional control (IC) state for hybrid tasks, and ensure that multi-degree control commands are accurately and quickly generated. The experiment results attest to the efficiency and flexibility of the hybrid BCI for wheelchair control in the real-world. PMID:24694169

  19. Invisibly Sanitizable Digital Signature Scheme

    NASA Astrophysics Data System (ADS)

    Miyazaki, Kunihiko; Hanaoka, Goichiro; Imai, Hideki

    A digital signature does not allow any alteration of the document to which it is attached. Appropriate alteration of some signed documents, however, should be allowed because there are security requirements other than the integrity of the document. In the disclosure of official information, for example, sensitive information such as personal information or national secrets is masked when an official document is sanitized so that its nonsensitive information can be disclosed when it is requested by a citizen. If this disclosure is done digitally by using the current digital signature schemes, the citizen cannot verify the disclosed information because it has been altered to prevent the leakage of sensitive information. The confidentiality of official information is thus incompatible with the integrity of that information, and this is called the digital document sanitizing problem. Conventional solutions such as content extraction signatures and digitally signed document sanitizing schemes with disclosure condition control can either let the sanitizer assign disclosure conditions or hide the number of sanitized portions. The digitally signed document sanitizing scheme we propose here is based on the aggregate signature derived from bilinear maps and can do both. Moreover, the proposed scheme can sanitize a signed document invisibly, that is, no one can distinguish whether the signed document has been sanitized or not.

  20. Computing with high-resolution upwind schemes for hyperbolic equations

    NASA Technical Reports Server (NTRS)

    Chakravarthy, S. R.; Osher, S.

    1985-01-01

    Computational aspects of modern high-resolution upwind finite-difference schemes for hyperbolic systems of conservation laws are examined. An operational unification is demonstrated for constructing a wide class of flux-difference-split and flux-split schemes based on the design principles underlying total variation diminishing (TVD) schemes. Consideration is also given to TVD scheme design by preprocessing, the extension of preprocessing and postprocessing approaches to general control volumes, the removal of expansion shocks and 'glitches', relaxation methods for implicit TVD schemes, and a new family of high-accuracy TVD schemes.

  1. Tabled Execution in Scheme

    SciTech Connect

    Willcock, J J; Lumsdaine, A; Quinlan, D J

    2008-08-19

    Tabled execution is a generalization of memorization developed by the logic programming community. It not only saves results from tabled predicates, but also stores the set of currently active calls to them; tabled execution can thus provide meaningful semantics for programs that seemingly contain infinite recursions with the same arguments. In logic programming, tabled execution is used for many purposes, both for improving the efficiency of programs, and making tasks simpler and more direct to express than with normal logic programs. However, tabled execution is only infrequently applied in mainstream functional languages such as Scheme. We demonstrate an elegant implementation of tabled execution in Scheme, using a mix of continuation-passing style and mutable data. We also show the use of tabled execution in Scheme for a problem in formal language and automata theory, demonstrating that tabled execution can be a valuable tool for Scheme users.

  2. The NEC Link Scheme

    ERIC Educational Resources Information Center

    Noakes, Peter

    1976-01-01

    Describes the operation of the National Electronics Council (NEC) Link Scheme for schools in Great Britain. The service is intended to provide technical assistance, information concerning surplus equipment, and guest speakers for school aspiring professional electronic counsel. (CP)

  3. D-MSR: A Distributed Network Management Scheme for Real-Time Monitoring and Process Control Applications in Wireless Industrial Automation

    PubMed Central

    Zand, Pouria; Dilo, Arta; Havinga, Paul

    2013-01-01

    Current wireless technologies for industrial applications, such as WirelessHART and ISA100.11a, use a centralized management approach where a central network manager handles the requirements of the static network. However, such a centralized approach has several drawbacks. For example, it cannot cope with dynamicity/disturbance in large-scale networks in a real-time manner and it incurs a high communication overhead and latency for exchanging management traffic. In this paper, we therefore propose a distributed network management scheme, D-MSR. It enables the network devices to join the network, schedule their communications, establish end-to-end connections by reserving the communication resources for addressing real-time requirements, and cope with network dynamicity (e.g., node/edge failures) in a distributed manner. According to our knowledge, this is the first distributed management scheme based on IEEE 802.15.4e standard, which guides the nodes in different phases from joining until publishing their sensor data in the network. We demonstrate via simulation that D-MSR can address real-time and reliable communication as well as the high throughput requirements of industrial automation wireless networks, while also achieving higher efficiency in network management than WirelessHART, in terms of delay and overhead. PMID:23807687

  4. D-MSR: a distributed network management scheme for real-time monitoring and process control applications in wireless industrial automation.

    PubMed

    Zand, Pouria; Dilo, Arta; Havinga, Paul

    2013-01-01

    Current wireless technologies for industrial applications, such as WirelessHART and ISA100.11a, use a centralized management approach where a central network manager handles the requirements of the static network. However, such a centralized approach has several drawbacks. For example, it cannot cope with dynamicity/disturbance in large-scale networks in a real-time manner and it incurs a high communication overhead and latency for exchanging management traffic. In this paper, we therefore propose a distributed network management scheme, D-MSR. It enables the network devices to join the network, schedule their communications, establish end-to-end connections by reserving the communication resources for addressing real-time requirements, and cope with network dynamicity (e.g., node/edge failures) in a distributed manner. According to our knowledge, this is the first distributed management scheme based on IEEE 802.15.4e standard, which guides the nodes in different phases from joining until publishing their sensor data in the network. We demonstrate via simulation that D-MSR can address real-time and reliable communication as well as the high throughput requirements of industrial automation wireless networks, while also achieving higher efficiency in network management than WirelessHART, in terms of delay and overhead.

  5. [The comparative analysis of changes of short pieces of EEG at perception of music on the basis of the event-related synchronization/desynchronization and wavelet-synchrony].

    PubMed

    Oknina, L B; Kuptsova, S V; Romanov, A S; Masherov, E L; Kuznetsova, O A; Sharova, E V

    2012-01-01

    The going of present pilot study is an analysis of features changes of EEG short pieces registered from 32 sites, at perception of musical melodies healthy examinees depending on logic (cognizance) and emotional (it was pleasant it was not pleasant) melody estimations. For this purpose changes of event-related synchronization/desynchronization, and also wavelet-synchrony of EEG-responses at 31 healthy examinees at the age from 18 till 60 years were compared. It is shown that at a logic estimation of music the melody cognizance is accompanied the event-related desynchronization in the left fronto-parietal-temporal area. At an emotional estimation of a melody the event-related synchronization in left fronto - temporal area for the pleasant melodies, desynchronization in temporal area for not pleasant and desynchronization in occipital area for the melodies which are not causing the emotional response is typical. At the analysis of wavelet-synchrony of EEG characterizing jet changes of interaction of cortical zones, it is revealed that the most distinct topographical distinctions concern type of processing of the heard music: logic (has learned-hasn't learned) or emotional (it was pleasant-it was not pleasant). If at an emotional estimation changes interhemispheric communications between associative cortical zones (central, frontal, temporal), are more expressed at logic - between inter - and intrahemispheric communications of projective zones of the acoustic analyzer (temporal area). It is supposed that the revealed event-related synchronization/desynhronization reflects, most likely, an activation component of an estimation of musical fragments whereas the wavelet-analysis provides guidance on character of processing of musical stimulus. PMID:23101360

  6. A Spatial Domain Quantum Watermarking Scheme

    NASA Astrophysics Data System (ADS)

    Wei, Zhan-Hong; Chen, Xiu-Bo; Xu, Shu-Jiang; Niu, Xin-Xin; Yang, Yi-Xian

    2016-07-01

    This paper presents a spatial domain quantum watermarking scheme. For a quantum watermarking scheme, a feasible quantum circuit is a key to achieve it. This paper gives a feasible quantum circuit for the presented scheme. In order to give the quantum circuit, a new quantum multi-control rotation gate, which can be achieved with quantum basic gates, is designed. With this quantum circuit, our scheme can arbitrarily control the embedding position of watermark images on carrier images with the aid of auxiliary qubits. Besides reversely acting the given quantum circuit, the paper gives another watermark extracting algorithm based on quantum measurements. Moreover, this paper also gives a new quantum image scrambling method and its quantum circuit. Differ from other quantum watermarking schemes, all given quantum circuits can be implemented with basic quantum gates. Moreover, the scheme is a spatial domain watermarking scheme, and is not based on any transform algorithm on quantum images. Meanwhile, it can make sure the watermark be secure even though the watermark has been found. With the given quantum circuit, this paper implements simulation experiments for the presented scheme. The experimental result shows that the scheme does well in the visual quality and the embedding capacity. Supported by the National Natural Science Foundation of China under Grant Nos. 61272514, 61170272, 61373131, 61121061, 61411146001, the program for New Century Excellent Talents under Grant No. NCET-13-0681, the National Development Foundation for Cryptological Research (Grant No. MMJJ201401012) and the Fok Ying Tung Education Foundation under Grant No. 131067, and the Shandong Provincial Natural Science Foundation of China under Grant No. ZR2013FM025

  7. Compact Spreader Schemes

    SciTech Connect

    Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.

    2014-07-25

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  8. Compact spreader schemes

    NASA Astrophysics Data System (ADS)

    Placidi, M.; Jung, J.-Y.; Ratti, A.; Sun, C.

    2014-12-01

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  9. Symmetric weak ternary quantum homomorphic encryption schemes

    NASA Astrophysics Data System (ADS)

    Wang, Yuqi; She, Kun; Luo, Qingbin; Yang, Fan; Zhao, Chao

    2016-03-01

    Based on a ternary quantum logic circuit, four symmetric weak ternary quantum homomorphic encryption (QHE) schemes were proposed. First, for a one-qutrit rotation gate, a QHE scheme was constructed. Second, in view of the synthesis of a general 3 × 3 unitary transformation, another one-qutrit QHE scheme was proposed. Third, according to the one-qutrit scheme, the two-qutrit QHE scheme about generalized controlled X (GCX(m,n)) gate was constructed and further generalized to the n-qutrit unitary matrix case. Finally, the security of these schemes was analyzed in two respects. It can be concluded that the attacker can correctly guess the encryption key with a maximum probability pk = 1/33n, thus it can better protect the privacy of users’ data. Moreover, these schemes can be well integrated into the future quantum remote server architecture, and thus the computational security of the users’ private quantum information can be well protected in a distributed computing environment.

  10. A nonconservative scheme for isentropic gas dynamics

    SciTech Connect

    Chen, Gui-Qiang |; Liu, Jian-Guo

    1994-05-01

    In this paper, we construct a second-order nonconservative for the system of isentropic gas dynamics to capture the physical invariant regions for preventing negative density, to treat the vacuum singularity, and to control the local entropy from dramatically increasing near shock waves. The main difference in the construction of the scheme discussed here is that we use piecewise linear functions to approximate the Riemann invariants w and z instead of the physical variables {rho} and m. Our scheme is a natural extension of the schemes for scalar conservation laws and it can be numerical implemented easily because the system is diagonalized in this coordinate system. Another advantage of using Riemann invariants is that the Hessian matrix of any weak entropy has no singularity in the Riemann invariant plane w-z, whereas the Hessian matrices of the weak entropies have singularity at the vacuum points in the physical plane p-m. We prove that this scheme converges to an entropy solution for the Cauchy problem with L{sup {infinity}} initial data. By convergence here we mean that there is a subsequent convergence to a generalized solution satisfying the entrophy condition. As long as the entropy solution is unique, the whole sequence converges to a physical solution. This shows that this kind of scheme is quite reliable from theoretical view of point. In addition to being interested in the scheme itself, we wish to provide an approach to rigorously analyze nonconservative finite difference schemes.

  11. Histamine H3 receptor activation decreases kainate-induced hippocampal gamma oscillations in vitro by action potential desynchronization in pyramidal neurons

    PubMed Central

    Andersson, Richard; Lindskog, Maria; Fisahn, André

    2010-01-01

    The study of rhythmic electrical activity in slice preparations has generated important insights into neural network function. While the synaptic mechanisms involved in the generation of in vitro network oscillations have been studied widely, little is known about the modulatory influence exerted on rhythmic activity in neuronal networks by neuropeptides and biogenic amines. Gamma oscillations play an important role in cognitive processes and are altered or disrupted in disorders such as Alzheimer's disease (AD) and schizophrenia. Given the importance of gamma oscillations for learning, memory and cognition processes as well as the recent interest in histamine H3 receptors in the development of pro-cognitive drugs to treat disorders such as AD and schizophrenia, it is relevant to study the impact of histaminergic mechanisms on network gamma oscillations. Here we show for the first time a modulation of gamma oscillation by histaminergic mechanisms. Selective activation of the H3 receptor by R-α-methylhistamine significantly reduces the power of kainate-induced gamma oscillations, but not carbachol-induced gamma oscillations, in the rat hippocampal slice preparation without affecting oscillation frequency. This effect is neither caused by a decrease in excitatory or inhibitory postsynaptic currents, nor a decrease in cellular excitability. Instead, we find that the decrease in oscillation power following H3 receptor activation results from a desynchronization of pyramidal neuron action potential firing with regard to the local field potential oscillation cycle. Our data provide a possible mechanism of action for histamine in regulating gamma oscillations in the hippocampal network. PMID:20156850

  12. Event-related desynchronization and synchronization in MEG: Framework for analysis and illustrative datasets related to discrimination of frequency-modulated tones.

    PubMed

    Zygierewicz, J; Sieluzycki, C; König, R; Durka, P J

    2008-02-15

    We introduce a complete framework for the calculation of statistically significant event-related desynchronization and synchronization (ERD/ERS) in the time-frequency plane for magnetoencephalographic (MEG) data, and provide free Internet access to software and illustrative datasets related to a classification task of frequency-modulated (FM) tones. Event-related changes in MEG were analysed on the basis of the normal component of the magnetic field acquired by the 148 magnetometers of the hardware configuration of our whole-head MEG device, and by computing planar gradients in longitudinal and latitudinal direction. Time-frequency energy density for the magnetometer as well as the two gradient configurations is first approximated using short-time Fourier transform. Subsequently, detailed information is obtained from high-resolution time-frequency maps for the most interesting sensors by means of the computationally much more demanding matching pursuit parametrization. We argue that the ERD/ERS maps are easier to interpret in the gradient approaches and discuss the superior resolution of the matching pursuit time-frequency representation compared to short-time Fourier and wavelet transforms. Experimental results are accompanied by the following resources, available from http://brain.fuw.edu.pl/MEG: (a) 48 high-resolution figures presenting the results of four subjects in all applicable settings, (b) raw datasets, and (c) complete software environment, allowing to recompute these figures from the raw datasets. PMID:17983663

  13. Check-Digit Schemes.

    ERIC Educational Resources Information Center

    Wheeler, Mary L.

    1994-01-01

    Discusses the study of identification codes and check-digit schemes as a way to show students a practical application of mathematics and introduce them to coding theory. Examples include postal service money orders, parcel tracking numbers, ISBN codes, bank identification numbers, and UPC codes. (MKR)

  14. Secure Wake-Up Scheme for WBANs

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Wei; Ameen, Moshaddique Al; Kwak, Kyung-Sup

    Network life time and hence device life time is one of the fundamental metrics in wireless body area networks (WBAN). To prolong it, especially those of implanted sensors, each node must conserve its energy as much as possible. While a variety of wake-up/sleep mechanisms have been proposed, the wake-up radio potentially serves as a vehicle to introduce vulnerabilities and attacks to WBAN, eventually resulting in its malfunctions. In this paper, we propose a novel secure wake-up scheme, in which a wake-up authentication code (WAC) is employed to ensure that a BAN Node (BN) is woken up by the correct BAN Network Controller (BNC) rather than unintended users or malicious attackers. The scheme is thus particularly implemented by a two-radio architecture. We show that our scheme provides higher security while consuming less energy than the existing schemes.

  15. A flexible gridding scheme for reservoir simulation

    SciTech Connect

    Verma, S.

    1995-12-31

    This paper describes a new control volume based finite difference scheme for petroleum reservoir simulation which can be used with unstructured grids. The numerical scheme to model fluid flow is shown to be easily used for Voronoi grids in 2D. It can also be used with certain geometrical limitations for 3D Voronoi grids. The scheme can be used without any significant limitations for triangle or tetrahedron based grids where control volumes are constructed around their vertices. It assumes uniform properties inside such control volumes. Full, anisotropic and asymmetric permeability tensor can be easily handled with the proposed method. The permeability tensor can vary from block to block. Thus it will be of great value in modeling fluid flow in reservoirs where principal directions of permeability varies between beds or within a bed. The paper also presents an analysis of some of the published flexible gridding schemes which use a control volume type algebraic approximation and demonstrate the advantages of the method presented here. The technique for grid construction is also discussed. Test results presented here demonstrate the need for proper representation of reservoir geometry to predict the correct flow behavior. The gridding scheme described in this paper achieves that purpose.

  16. A lethal ovitrap-based mass trapping scheme for dengue control in Australia: I. Public acceptability and performance of lethal ovitraps.

    PubMed

    Ritchie, S A; Rapley, L P; Williams, C; Johnson, P H; Larkman, M; Silcock, R M; Long, S A; Russell, R C

    2009-12-01

    We report on the first field evaluation of the public acceptability and performance of two types of lethal ovitrap (LO) in three separate trials in Cairns, Australia. Health workers were able to set standard lethal ovitraps (SLOs) in 75 and 71% of premise yards in the wet and dry season, respectively, and biodegradable lethal ovitraps (BLOs) in 93% of yards. Public acceptance, measured as retention of traps by residents, was high for both trap types, with <9% of traps missing after 4 weeks. Traps retaining water after 4 weeks were 78 and 34% for the two SLO trials and 58% for the BLOs. The 'failure rate' in the 535 BLOs set in the field for 4 weeks was 47%, of which 19% were lost, 51% had holes from probable insect chewing, 23% were knocked over, 7% had dried by evaporation and 1% were split. There was no significant difference in the failure rate of BLOs set on porous (grass, soil and mulch) versus solid (tiles, concrete, wood and stone) substrates. The SLOs and the BLOs were readily acceptable to ovipositing Aedes aegypti L. (Diptera: Culicidae); the mean number of eggs/trap was 6 and 15, for the dry season and wet season SLO trial, respectively, and 15 for the BLO wet season trial. Indeed, 84-94% of premise yards had egg positive SLOs or BLOs. A high percentage of both wet and dry season SLOs (29 and 70%, respectively) and BLOs (62%) that were dry after 4 weeks were egg positive, indicating the traps had functioned. Lethal strips from SLOs and BLOs that had been exposed for 4 weeks killed 83 and 74%, respectively, of gravid Ae. aegypti in laboratory assays. These results indicate that mass trapping schemes using SLOs and BLOs are not rejected by the public and effectively target gravid Ae. aegypti. The impact of the interventions on mosquito populations is described in a companion paper. PMID:19941595

  17. A lethal ovitrap-based mass trapping scheme for dengue control in Australia: II. Impact on populations of the mosquito Aedes aegypti.

    PubMed

    Rapley, L P; Johnson, P H; Williams, C R; Silcock, R M; Larkman, M; Long, S A; Russell, R C; Ritchie, S A

    2009-12-01

    In Cairns, Australia, the impacts on Aedes aegypti L. (Diptera: Culicidae) populations of two types of 'lure & kill' (L&K) lethal ovitraps (LOs), the standard lethal ovitrap (SLO) and the biodegradable lethal ovitrap (BLO) were measured during three mass-trapping interventions. To assess the efficacy of the SLO, two interventions (one dry season and one wet season) were conducted in three discrete areas, each lasting 4 weeks, with the following treatments: (i) SLOs (>200 traps, approximately 4/premise), BG-sentinel traps (BGSs; approximately 15, 1/premise) and larval control (container reduction and methoprene treatment) and (ii) larval control alone, and (iii) untreated control. Female Ae. aegypti populations were monitored for 4 weeks pre- and post-treatment in all three areas using BGSs and sticky ovitraps (SOs) or non-lethal regular ovitraps (ROs). In the dry season, 206 SLOs and 15 BGSs set at 54 and 15 houses, respectively, caught and killed an estimated 419 and 73 female Ae. aegypti, respectively. No significant decrease in collection size of female Ae. aegypti could be attributed to the treatments. In the wet season, 243 SLOs and 15 BGSs killed approximately 993 and 119 female Ae. aegypti, respectively. The mean number of female Ae. aegypti collected after 4 weeks with SOs and BGSs was significantly less than the control (LSD post-hoc test). The third mass-trapping intervention was conducted using the BLO during the wet season in Cairns. For this trial, three treatment areas were each provided with BLOs (>500, approximately 4/premise) plus larval control, and an untreated control area was designated. Adult female Ae. aegypti were collected for 4 weeks pre- and post-treatment using 15 BGSs and 20 SOs. During this period, 53.2% of BLOs contained a total of 6654 Ae. aegypti eggs. Over the intervention period, collections of Ae. aegypti in the treatment areas were significantly less than in the control area for BGSs but not SOs. An influx of relatively large

  18. Beyond Scheme F

    SciTech Connect

    Elliott, C.J.; Fisher, H.; Pepin, J.; Gillmann, R.

    1996-07-01

    Traffic classification techniques were evaluated using data from a 1993 investigation of the traffic flow patterns on I-20 in Georgia. First we improved the data by sifting through the data base, checking against the original video for questionable events and removing and/or repairing questionable events. We used this data base to critique the performance quantitatively of a classification method known as Scheme F. As a context for improving the approach, we show in this paper that scheme F can be represented as a McCullogh-Pitts neural network, oar as an equivalent decomposition of the plane. We found that Scheme F, among other things, severely misrepresents the number of vehicles in Class 3 by labeling them as Class 2. After discussing the basic classification problem in terms of what is measured, and what is the desired prediction goal, we set forth desirable characteristics of the classification scheme and describe a recurrent neural network system that partitions the high dimensional space up into bins for each axle separation. the collection of bin numbers, one for each of the axle separations, specifies a region in the axle space called a hyper-bin. All the vehicles counted that have the same set of in numbers are in the same hyper-bin. The probability of the occurrence of a particular class in that hyper- bin is the relative frequency with which that class occurs in that set of bin numbers. This type of algorithm produces classification results that are much more balanced and uniform with respect to Classes 2 and 3 and Class 10. In particular, the cancellation of errors of classification that occurs is for many applications the ideal classification scenario. The neural network results are presented in the form of a primary classification network and a reclassification network, the performance matrices for which are presented.

  19. New User Support in the University Network with DACS Scheme

    ERIC Educational Resources Information Center

    Odagiri, Kazuya; Yaegashi, Rihito; Tadauchi, Masaharu; Ishii, Naohiro

    2007-01-01

    Purpose: The purpose of this paper is to propose and examine the new user support in university network. Design/methodology/approach: The new user support is realized by use of DACS (Destination Addressing Control System) Scheme which manages a whole network system through communication control on a client computer. This DACS Scheme has been…

  20. Novel Control Scheme of Power Assisted Wheelchair for Preventing Overturn (Part I)-Adjustment of Assisted Torque and Performance Evaluation From Field Test-

    NASA Astrophysics Data System (ADS)

    Seki, Hirokazu; Hata, Naoki; Koyasu, Yuichi; Hori, Yoichi

    Aged people and disabled people who have difficulty in walking are increasing. As one of mobility support, significance of power assisted wheelchair which assists driving force using electric motors and spreads their living areas has been enhanced. However, the increased driving force often causes a dangerous overturn of wheelchair. In this paper, control method to prevent power assisted wheelchair from overturning is proposed. It is found the front wheels rising is caused by magnitude and rapid increase of assisted torque. Therefore, feedforward control method to limit the assisted torque by tuning its magnitude or time constant is proposed. In order to emphasize safety and feeling of security, these methods make the front wheels no rise. The effectiveness of the proposed method is verified by the practical experiments and field test based performance evaluation using many trial subjects.

  1. Robust pre-specified time synchronization of chaotic systems by employing time-varying switching surfaces in the sliding mode control scheme

    NASA Astrophysics Data System (ADS)

    Khanzadeh, Alireza; Pourgholi, Mahdi

    2016-08-01

    In the conventional chaos synchronization methods, the time at which two chaotic systems are synchronized, is usually unknown and depends on initial conditions. In this work based on Lyapunov stability theory a sliding mode controller with time-varying switching surfaces is proposed to achieve chaos synchronization at a pre-specified time for the first time. The proposed controller is able to synchronize chaotic systems precisely at any time when we want. Moreover, by choosing the time-varying switching surfaces in a way that the reaching phase is eliminated, the synchronization becomes robust to uncertainties and exogenous disturbances. Simulation results are presented to show the effectiveness of the proposed method of stabilizing and synchronizing chaotic systems with complete robustness to uncertainty and disturbances exactly at a pre-specified time.

  2. Lipoic acid entrains the hepatic circadian clock and lipid metabolic proteins that have been desynchronized with advanced age.

    PubMed

    Keith, Dove; Finlay, Liam; Butler, Judy; Gómez, Luis; Smith, Eric; Moreau, Régis; Hagen, Tory

    2014-07-18

    It is well established that lipid metabolism is controlled, in part, by circadian clocks. However, circadian clocks lose temporal precision with age and correlates with elevated incidence in dyslipidemia and metabolic syndrome in older adults. Because our lab has shown that lipoic acid (LA) improves lipid homeostasis in aged animals, we hypothesized that LA affects the circadian clock to achieve these results. We fed 24 month old male F344 rats a diet supplemented with 0.2% (w/w) LA for 2 weeks prior to sacrifice and quantified hepatic circadian clock protein levels and clock-controlled lipid metabolic enzymes. LA treatment caused a significant phase-shift in the expression patterns of the circadian clock proteins Period (Per) 2, Brain and Muscle Arnt-Like1 (BMAL1), and Reverse Erythroblastosis virus (Rev-erb) β without altering the amplitude of protein levels during the light phase of the day. LA also significantly altered the oscillatory patterns of clock-controlled proteins associated with lipid metabolism. The level of peroxisome proliferator-activated receptor (PPAR) α was significantly increased and acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) were both significantly reduced, suggesting that the LA-supplemented aged animals are in a catabolic state. We conclude that LA remediates some of the dyslipidemic processes associated with advanced age, and this mechanism may be at least partially through entrainment of circadian clocks. PMID:24944020

  3. Beta event-related desynchronization as an index of individual differences in processing human facial expression: further investigations of autistic traits in typically developing adults

    PubMed Central

    Cooper, Nicholas R.; Simpson, Andrew; Till, Amy; Simmons, Kelly; Puzzo, Ignazio

    2013-01-01

    The human mirror neuron system (hMNS) has been associated with various forms of social cognition and affective processing including vicarious experience. It has also been proposed that a faulty hMNS may underlie some of the deficits seen in the autism spectrum disorders (ASDs). In the present study we set out to investigate whether emotional facial expressions could modulate a putative EEG index of hMNS activation (mu suppression) and if so, would this differ according to the individual level of autistic traits [high versus low Autism Spectrum Quotient (AQ) score]. Participants were presented with 3 s films of actors opening and closing their hands (classic hMNS mu-suppression protocol) while simultaneously wearing happy, angry, or neutral expressions. Mu-suppression was measured in the alpha and low beta bands. The low AQ group displayed greater low beta event-related desynchronization (ERD) to both angry and neutral expressions. The high AQ group displayed greater low beta ERD to angry than to happy expressions. There was also significantly more low beta ERD to happy faces for the low than for the high AQ group. In conclusion, an interesting interaction between AQ group and emotional expression revealed that hMNS activation can be modulated by emotional facial expressions and that this is differentiated according to individual differences in the level of autistic traits. The EEG index of hMNS activation (mu suppression) seems to be a sensitive measure of the variability in facial processing in typically developing individuals with high and low self-reported traits of autism. PMID:23630489

  4. A Comparison of Independent Event-Related Desynchronization Responses in Motor-Related Brain Areas to Movement Execution, Movement Imagery, and Movement Observation.

    PubMed

    Duann, Jeng-Ren; Chiou, Jin-Chern

    2016-01-01

    Electroencephalographic (EEG) event-related desynchronization (ERD) induced by movement imagery or by observing biological movements performed by someone else has recently been used extensively for brain-computer interface-based applications, such as applications used in stroke rehabilitation training and motor skill learning. However, the ERD responses induced by the movement imagery and observation might not be as reliable as the ERD responses induced by movement execution. Given that studies on the reliability of the EEG ERD responses induced by these activities are still lacking, here we conducted an EEG experiment with movement imagery, movement observation, and movement execution, performed multiple times each in a pseudorandomized order in the same experimental runs. Then, independent component analysis (ICA) was applied to the EEG data to find the common motor-related EEG source activity shared by the three motor tasks. Finally, conditional EEG ERD responses associated with the three movement conditions were computed and compared. Among the three motor conditions, the EEG ERD responses induced by motor execution revealed the alpha power suppression with highest strengths and longest durations. The ERD responses of the movement imagery and movement observation only partially resembled the ERD pattern of the movement execution condition, with slightly better detectability for the ERD responses associated with the movement imagery and faster ERD responses for movement observation. This may indicate different levels of involvement in the same motor-related brain circuits during different movement conditions. In addition, because the resulting conditional EEG ERD responses from the ICA preprocessing came with minimal contamination from the non-related and/or artifactual noisy components, this result can play a role of the reference for devising a brain-computer interface using the EEG ERD features of movement imagery or observation. PMID:27636359

  5. A Comparison of Independent Event-Related Desynchronization Responses in Motor-Related Brain Areas to Movement Execution, Movement Imagery, and Movement Observation

    PubMed Central

    Duann, Jeng-Ren; Chiou, Jin-Chern

    2016-01-01

    Electroencephalographic (EEG) event-related desynchronization (ERD) induced by movement imagery or by observing biological movements performed by someone else has recently been used extensively for brain-computer interface-based applications, such as applications used in stroke rehabilitation training and motor skill learning. However, the ERD responses induced by the movement imagery and observation might not be as reliable as the ERD responses induced by movement execution. Given that studies on the reliability of the EEG ERD responses induced by these activities are still lacking, here we conducted an EEG experiment with movement imagery, movement observation, and movement execution, performed multiple times each in a pseudorandomized order in the same experimental runs. Then, independent component analysis (ICA) was applied to the EEG data to find the common motor-related EEG source activity shared by the three motor tasks. Finally, conditional EEG ERD responses associated with the three movement conditions were computed and compared. Among the three motor conditions, the EEG ERD responses induced by motor execution revealed the alpha power suppression with highest strengths and longest durations. The ERD responses of the movement imagery and movement observation only partially resembled the ERD pattern of the movement execution condition, with slightly better detectability for the ERD responses associated with the movement imagery and faster ERD responses for movement observation. This may indicate different levels of involvement in the same motor-related brain circuits during different movement conditions. In addition, because the resulting conditional EEG ERD responses from the ICA preprocessing came with minimal contamination from the non-related and/or artifactual noisy components, this result can play a role of the reference for devising a brain-computer interface using the EEG ERD features of movement imagery or observation. PMID:27636359

  6. Comparison of the Efficacy and Safety of a Pharmacokinetic Model-Based Dosing Scheme Versus a Conventional Fentanyl Dosing Regimen For Patient-Controlled Analgesia Immediately Following Robot-Assisted Laparoscopic Prostatectomy: A Randomized Clinical Trial.

    PubMed

    Jin, Seok-Joon; Lim, Hyeong-Seok; Kwon, Youn-Ju; Park, Se-Ung; Yi, Jung-Min; Chin, Ji-Hyun; Hwang, Jai-Hyun; Kim, Young-Kug

    2016-01-01

    Conventional, intravenous, patient-controlled analgesia, which is only administered by demand bolus without basal continuous infusion, is closely associated with inappropriate analgesia. Pharmacokinetic model-based dosing schemes can quantitatively describe the time course of drug effects and achieve optimal drug therapy. We compared the efficacy and safety of a conventional dosing regimen for intravenous patient-controlled analgesia that was administered by demand bolus without basal continuous infusion (group A) versus a pharmacokinetic model-based dosing scheme performed by decreasing the dosage of basal continuous infusion according to the model-based simulation used to achieve a targeted concentration (group B) following robot-assisted laparoscopic prostatectomy.In total, 70 patients were analyzed: 34 patients in group A and 36 patients in group B. The postoperative opioid requirements, pain scores assessed by the visual analog scale, and adverse events (eg, nausea, vomiting, pruritis, respiratory depression, desaturation, sedation, confusion, and urinary retention) were compared on admission to the postanesthesia care unit and at 0.5, 1, 4, 24, and 48 h after surgery between the 2 groups. All patients were kept for close observation in the postanesthesia care unit for 1 h, and then transferred to the general ward.The fentanyl requirements in the postanesthesia care unit for groups A and B were 110.0 ± 46.4 μg and 77.5 ± 35.3 μg, respectively. The pain scores assessed by visual analog scale at 0.5, 1, 4, and 24 h after surgery in group B were significantly lower than in group A (all P < 0.05). There were no differences in the adverse events between the 2 groups.We found that the pharmacokinetic model-based dosing scheme resulted in lower opioid requirements, lower pain scores, and no significant adverse events in the postanesthesia care unit following robot-assisted laparoscopic prostatectomy in comparison with conventional dosing

  7. ESCAP mobile training scheme.

    PubMed

    Yasas, F M

    1977-01-01

    In response to a United Nations resolution, the Mobile Training Scheme (MTS) was set up to provide training to the trainers of national cadres engaged in frontline and supervisory tasks in social welfare and rural development. The training is innovative in its being based on an analysis of field realities. The MTS team consisted of a leader, an expert on teaching methods and materials, and an expert on action research and evaluation. The country's trainers from different departments were sent to villages to work for a short period and to report their problems in fulfilling their roles. From these grass roots experiences, they made an analysis of the job, determining what knowledge, attitude and skills it required. Analysis of daily incidents and problems were used to produce indigenous teaching materials drawn from actual field practice. How to consider the problems encountered through government structures for policy making and decisions was also learned. Tasks of the students were to identify the skills needed for role performance by job analysis, daily diaries and project histories; to analyze the particular community by village profiles; to produce indigenous teaching materials; and to practice the role skills by actual role performance. The MTS scheme was tried in Nepal in 1974-75; 3 training programs trained 25 trainers and 51 frontline workers; indigenous teaching materials were created; technical papers written; and consultations were provided. In Afghanistan the scheme was used in 1975-76; 45 participants completed the training; seminars were held; and an ongoing Council was created. It is hoped that the training program will be expanded to other countries. PMID:12265562

  8. New LNG process scheme

    SciTech Connect

    Foglietta, J.H.

    1999-07-01

    A new LNG cycle has been developed for base load liquefaction facilities. This new design offers a different technical and economical solution comparing in efficiency with the classical technologies. The new LNG scheme could offer attractive business opportunities to oil and gas companies that are trying to find paths to monetize gas sources more effectively; particularly for remote or offshore locations where smaller scale LNG facilities might be applicable. This design offers also an alternative route to classic LNG projects, as well as alternative fuel sources. Conceived to offer simplicity and access to industry standard equipment, This design is a hybrid result of combining a standard refrigeration system and turboexpander technology.

  9. Community-applied research of a traditional Chinese medicine rehabilitation scheme on Broca’s aphasia after stroke: study protocol for a randomized controlled trial

    PubMed Central

    2014-01-01

    Background Aphasia is a common and severely disabling complication in stroke patients. It usually brings about lower rates of functional recovery, longer rehabilitation length of stay (LOS), and significantly poorer LOS efficiency (LOS-Eff), resulting in higher rehabilitation costs compared to patients without aphasia. It also decreases the quality of life and increases the mortality of stroke patients. The evidence currently available suggests that the effect of acupuncture combined with language training for apoplectic aphasia is statistically better than speech and language therapy (SLT) alone, but there remains a lack of high-quality randomized controlled trials. Acupuncture combined with language training is relatively low-cost and especially suitable for community-based rehabilitation for aphasia patients after stroke, taking its medical and health facilities which are always deficient in manpower and material resources into account. The aim of the present study is to develop an effective standard therapeutic program for apoplectic aphasia in communities. Methods/Design In a randomized controlled clinical trial with blinded assessment, 290 eligible patients with aphasia due to stroke will be randomly allocated into a control group or an experimental group. The course of this trial will comprise a 4-week intervention and a 12-week follow-up period. Five assessment points, including baseline, 2 and 4 weeks after treatment, 6 and 12 weeks after follow-up, are set to dynamically observe the changes of curative effects. Primary outcome measures are the differences in the score on both the China rehabilitation research center aphasia examination (CRRCAE) and Boston diagnostic aphasia examination - Chinese version (BDAE-C) after intervention and follow-up. The Modified Barthel Index (MBI), 36-Item Short Form Health Survey (SF-36), and results of blood oxygen level dependent-functional magnetic resonance imaging (BOLD-fMRI) examination are considered as the

  10. Characterization of dynamic thermal control schemes and heat transfer pathways for incorporating variable emissivity electrochromic materials into a space suit heat rejection system

    NASA Astrophysics Data System (ADS)

    Massina, Christopher James

    The feasibility of conducting long duration human spaceflight missions is largely dependent on the provision of consumables such as oxygen, water, and food. In addition to meeting crew metabolic needs, water sublimation has long served as the primary heat rejection mechanism in space suits during extravehicular activity (EVA). During a single eight hour EVA, approximately 3.6 kg (8 lbm) of water is lost from the current suit. Reducing the amount of expended water during EVA is a long standing goal of space suit life support systems designers; but to date, no alternate thermal control mechanism has demonstrated the ability to completely eliminate the loss. One proposed concept is to convert the majority of a space suit's surface area into a radiator such that the local environment can be used as a radiative thermal sink for rejecting heat without mass loss. Due to natural variations in both internal (metabolic) loads and external (environmental) sink temperatures, radiative transport must be actively modulated in order to maintain an acceptable thermal balance. Here, variable emissivity electrochromic devices are examined as the primary mechanism for enabling variable heat rejection. This dissertation focuses on theoretical and empirical evaluations performed to determine the feasibility of using a full suit, variable emissivity radiator architecture for space suit thermal control. Operational envelopes are described that show where a given environment and/or metabolic load combination may or may not be supported by the evaluated thermal architecture. Key integration considerations and guidelines include determining allowable thermal environments, defining skin-to-radiator heat transfer properties, and evaluating required electrochromic performance properties. Analysis also considered the impacts of dynamic environmental changes and the architecture's extensibility to EVA on the Martian surface. At the conclusion of this work, the full suit, variable emissivity

  11. Dynamics and controls of urban heat sink and island phenomena in a desert city: Development of a local climate zone scheme using remotely-sensed inputs

    NASA Astrophysics Data System (ADS)

    Nassar, Ahmed K.; Blackburn, G. Alan; Whyatt, J. Duncan

    2016-09-01

    This study aims to determine the dynamics and controls of Surface Urban Heat Sinks (SUHS) and Surface Urban Heat Islands (SUHI) in desert cities, using Dubai as a case study. A Local Climate Zone (LCZ) schema was developed to subdivide the city into different zones based on similarities in land cover and urban geometry. Proximity to the Gulf Coast was also determined for each LCZ. The LCZs were then used to sample seasonal and daily imagery from the MODIS thermal sensor to determine Land Surface Temperature (LST) variations relative to desert sand. Canonical correlation techniques were then applied to determine which factors explained the variability between urban and desert LST. Our results indicate that the daytime SUHS effect is greatest during the summer months (typically ∼3.0 °C) with the strongest cooling effects in open high-rise zones of the city. In contrast, the night-time SUHI effect is greatest during the winter months (typically ∼3.5 °C) with the strongest warming effects in compact mid-rise zones of the city. Proximity to the Arabian Gulf had the largest influence on both SUHS and SUHI phenomena, promoting daytime cooling in the summer months and night-time warming in the winter months. However, other parameters associated with the urban environment such as building height had an influence on daytime cooling, with larger buildings promoting shade and variations in airflow. Likewise, other parameters such as sky view factor contributed to night-time warming, with higher temperatures associated with limited views of the sky.

  12. A New Hybrid Scheme for Preventing Channel Interference and Collision in Mobile Networks

    NASA Astrophysics Data System (ADS)

    Kim, Kyungjun; Han, Kijun

    This paper proposes a new hybrid scheme based on a given set of channels for preventing channel interference and collision in mobile networks. The proposed scheme is designed for improving system performance, focusing on enhancement of performance related to path breakage and channel interference. The objective of this scheme is to improve the performance of inter-node communication. Simulation results from this paper show that the new hybrid scheme can reduce a more control message overhead than a conventional random scheme.

  13. Electronic entanglement purification scheme enhanced by charge detections

    SciTech Connect

    Feng Xunli; Kwek, L. C.; Oh, C.H.

    2005-06-15

    We present an entanglement purification scheme for the mixed entangled states of electrons with the aid of charge detections. Our scheme adopts the electronic polarizing beam splitters rather than the controlled-NOT (CNOT) operations, but the total successful probability of our scheme can reach the quantity as large as that of the the CNOT-operation-based protocol and twice as large as that of linear-optics-based protocol for the purification of photonic entangled states. Thus our scheme can achieve a high successful probability without the usage of CNOT operations.

  14. Desynchronization in diluted neural networks

    SciTech Connect

    Zillmer, Ruediger; Livi, Roberto; Politi, Antonio; Torcini, Alessandro

    2006-09-15

    The dynamical behavior of a weakly diluted fully inhibitory network of pulse-coupled spiking neurons is investigated. Upon increasing the coupling strength, a transition from regular to stochasticlike regime is observed. In the weak-coupling phase, a periodic dynamics is rapidly approached, with all neurons firing with the same rate and mutually phase locked. The strong-coupling phase is characterized by an irregular pattern, even though the maximum Lyapunov exponent is negative. The paradox is solved by drawing an analogy with the phenomenon of 'stable chaos', i.e., by observing that the stochasticlike behavior is 'limited' to an exponentially long (with the system size) transient. Remarkably, the transient dynamics turns out to be stationary.

  15. Virtual Cortical Resection Reveals Push-Pull Network Control Preceding Seizure Evolution.

    PubMed

    Khambhati, Ankit N; Davis, Kathryn A; Lucas, Timothy H; Litt, Brian; Bassett, Danielle S

    2016-09-01

    In ∼20 million people with drug-resistant epilepsy, focal seizures originating in dysfunctional brain networks will often evolve and spread to surrounding tissue, disrupting function in otherwise normal brain regions. To identify network control mechanisms that regulate seizure spread, we developed a novel tool for pinpointing brain regions that facilitate synchronization in the epileptic network. Our method measures the impact of virtually resecting putative control regions on synchronization in a validated model of the human epileptic network. By applying our technique to time-varying functional networks, we identified brain regions whose topological role is to synchronize or desynchronize the epileptic network. Our results suggest that greater antagonistic push-pull interaction between synchronizing and desynchronizing brain regions better constrains seizure spread. These methods, while applied here to epilepsy, are generalizable to other brain networks and have wide applicability in isolating and mapping functional drivers of brain dynamics in health and disease.

  16. Virtual Cortical Resection Reveals Push-Pull Network Control Preceding Seizure Evolution.

    PubMed

    Khambhati, Ankit N; Davis, Kathryn A; Lucas, Timothy H; Litt, Brian; Bassett, Danielle S

    2016-09-01

    In ∼20 million people with drug-resistant epilepsy, focal seizures originating in dysfunctional brain networks will often evolve and spread to surrounding tissue, disrupting function in otherwise normal brain regions. To identify network control mechanisms that regulate seizure spread, we developed a novel tool for pinpointing brain regions that facilitate synchronization in the epileptic network. Our method measures the impact of virtually resecting putative control regions on synchronization in a validated model of the human epileptic network. By applying our technique to time-varying functional networks, we identified brain regions whose topological role is to synchronize or desynchronize the epileptic network. Our results suggest that greater antagonistic push-pull interaction between synchronizing and desynchronizing brain regions better constrains seizure spread. These methods, while applied here to epilepsy, are generalizable to other brain networks and have wide applicability in isolating and mapping functional drivers of brain dynamics in health and disease. PMID:27568515

  17. Plotting and Scheming

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1 [figure removed for brevity, see original site] Figure 2 Click for larger view

    These two graphics are planning tools used by Mars Exploration Rover engineers to plot and scheme the perfect location to place the rock abrasion tool on the rock collection dubbed 'El Capitan' near Opportunity's landing site. 'El Capitan' is located within a larger outcrop nicknamed 'Opportunity Ledge.'

    The rover visualization team from NASA Ames Research Center, Moffett Field, Calif., initiated the graphics by putting two panoramic camera images of the 'El Capitan' area into their three-dimensional model. The rock abrasion tool team from Honeybee Robotics then used the visualization tool to help target and orient their instrument on the safest and most scientifically interesting locations. The blue circle represents one of two current targets of interest, chosen because of its size, lack of dust, and most of all its distinct and intriguing geologic features. To see the second target location, see the image titled 'Plotting and Scheming.'

    The rock abrasion tool is sensitive to the shape and texture of a rock, and must safely sit within the 'footprint' indicated by the blue circles. The rock area must be large enough to fit the contact sensor and grounding mechanism within the area of the outer blue circle, and the rock must be smooth enough to get an even grind within the abrasion area of the inner blue circle. If the rock abrasion tool were not grounded by its support mechanism or if the surface were uneven, it could 'run away' from its target. The rock abrasion tool is location on the rover's instrument deployment device, or arm.

    Over the next few martian days, or sols, the rover team will use these and newer, similar graphics created with more recent, higher-resolution panoramic camera images and super-spectral data from the miniature thermal emission spectrometer. These data will be used to pick the best

  18. Classification schemes for arteriovenous malformations.

    PubMed

    Davies, Jason M; Kim, Helen; Young, William L; Lawton, Michael T

    2012-01-01

    The wide variety of arteriovenous malformation (AVM) anatomy, size, location, and clinical presentation makes patient selection for surgery a difficult process. Neurosurgeons have identified key factors that determine the risks of surgery and then devised classification schemes that integrate these factors, predict surgical results, and help select patients for surgery. These classification schemes have value because they transform complex decisions into simpler algorithms. In this review, the important grading schemes that have contributed to management of patients with brain AVMs are described, and our current approach to patient selection is outlined.

  19. A Randomised, Double-Blinded, Placebo-Controlled, Parallel Study of Vitamin D3 Supplementation with Different Schemes Based on Multiples of 25,000 IU Doses.

    PubMed

    Cavalier, Etienne; Faché, Werner; Souberbielle, Jean-Claude

    2013-01-01

    Vitamin D (VTD) treatment is recommended in patients presenting different causes of diseases. To treat these patients, physicians rely on the different available pharmaceutical forms present in their country. Unfortunately, even in a given country, there is no consensus on the best way to treat the patients. In Belgium, VTD is mostly prescribed as ampoules containing 25,000 IU of VTD. In this randomised controlled study, we evaluated whether four therapeutic schemes using multiples of 25,000 IU of VTD according to basal vitamin D concentration were able to increase or maintain the 25(OH)D serum level above 30 ng/mL. We randomized 175 subjects who received the drug (n = 140) or placebo (n = 35). Total duration of the study was 12 weeks. Doses ranged from 4167 to 1667 IU/day. Blood sampling was performed at baseline and each 4 visits. In the treated (placebo) subjects, mean 25(OH)D serum concentration was 18.7 (19.1) ng/mL at baseline and 31.5 (20.7) ng/mL at w-12. At the end of the study, 57.1% of the subjects treated with VTD presented 25(OH)D serum concentration ≥30 ng/mL, whereas 94.3% were ≥20 ng/mL. In conclusion, the doses administered were safe and increased or maintained the 25(OH)D concentration ≥20 ng/mL. However, concentrations ≥30 ng/mL were only achieved in 57.1% of the subjects.

  20. A Randomised, Double-Blinded, Placebo-Controlled, Parallel Study of Vitamin D3 Supplementation with Different Schemes Based on Multiples of 25,000 IU Doses

    PubMed Central

    Cavalier, Etienne; Faché, Werner; Souberbielle, Jean-Claude

    2013-01-01

    Vitamin D (VTD) treatment is recommended in patients presenting different causes of diseases. To treat these patients, physicians rely on the different available pharmaceutical forms present in their country. Unfortunately, even in a given country, there is no consensus on the best way to treat the patients. In Belgium, VTD is mostly prescribed as ampoules containing 25,000 IU of VTD. In this randomised controlled study, we evaluated whether four therapeutic schemes using multiples of 25,000 IU of VTD according to basal vitamin D concentration were able to increase or maintain the 25(OH)D serum level above 30 ng/mL. We randomized 175 subjects who received the drug (n = 140) or placebo (n = 35). Total duration of the study was 12 weeks. Doses ranged from 4167 to 1667 IU/day. Blood sampling was performed at baseline and each 4 visits. In the treated (placebo) subjects, mean 25(OH)D serum concentration was 18.7 (19.1) ng/mL at baseline and 31.5 (20.7) ng/mL at w-12. At the end of the study, 57.1% of the subjects treated with VTD presented 25(OH)D serum concentration ≥30 ng/mL, whereas 94.3% were ≥20 ng/mL. In conclusion, the doses administered were safe and increased or maintained the 25(OH)D concentration ≥20 ng/mL. However, concentrations ≥30 ng/mL were only achieved in 57.1% of the subjects. PMID:23431293

  1. Relaxation schemes for Chebyshev spectral multigrid methods

    NASA Technical Reports Server (NTRS)

    Kang, Yimin; Fulton, Scott R.

    1993-01-01

    Two relaxation schemes for Chebyshev spectral multigrid methods are presented for elliptic equations with Dirichlet boundary conditions. The first scheme is a pointwise-preconditioned Richardson relaxation scheme and the second is a line relaxation scheme. The line relaxation scheme provides an efficient and relatively simple approach for solving two-dimensional spectral equations. Numerical examples and comparisons with other methods are given.

  2. A Quantum Multi-proxy Blind Signature Scheme Based on Genuine Four-Qubit Entangled State

    NASA Astrophysics Data System (ADS)

    Tian, Juan-Hong; Zhang, Jian-Zhong; Li, Yan-Ping

    2016-02-01

    In this paper, we propose a multi-proxy blind signature scheme based on controlled teleportation. Genuine four-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to implement delegation, signature and verification. The security analysis shows the scheme satisfies the security features of multi-proxy signature, unforgeability, undeniability, blindness and unconditional security.

  3. New communication schemes based on adaptive synchronization

    NASA Astrophysics Data System (ADS)

    Yu, Wenwu; Cao, Jinde; Wong, Kwok-Wo; Lü, Jinhu

    2007-09-01

    In this paper, adaptive synchronization with unknown parameters is discussed for a unified chaotic system by using the Lyapunov method and the adaptive control approach. Some communication schemes, including chaotic masking, chaotic modulation, and chaotic shift key strategies, are then proposed based on the modified adaptive method. The transmitted signal is masked by chaotic signal or modulated into the system, which effectively blurs the constructed return map and can resist this return map attack. The driving system with unknown parameters and functions is almost completely unknown to the attackers, so it is more secure to apply this method into the communication. Finally, some simulation examples based on the proposed communication schemes and some cryptanalysis works are also given to verify the theoretical analysis in this paper.

  4. A CDMA synchronisation scheme

    NASA Technical Reports Server (NTRS)

    Soprano, C.

    1993-01-01

    CDMA (Code Division Multiple Access) is known to decrease inter-service interference in Satellite Communication Systems. Its performance is increased by chip quasi-synchronous operation which virtually eliminates the self-noise; however, the theory shows that the time error on the synchronization has to be kept at less than one tenth of a chip which, for 1 Mchip/sec. spreading rate, corresponds to 10(exp -7) sec. This, on the return-link, may only be achieved by means of a closed loop control system which, for mobile communication systems, has to be capable of autonomous operation. Until now some results have been reported on the feasibility of chip quasi-synchronous operation for mobile communication systems only including satellites on GEO (Geostationary Earth Orbit). In what follows, the basic principles are exposed, and results are presented showing how low chip synchronism error may be achieved by means of an autonomous control loop operating through satellites on any Earth orbit.

  5. The salivary testosterone and cortisol response to three loading schemes.

    PubMed

    Crewther, Blair; Cronin, John; Keogh, Justin; Cook, Christian

    2008-01-01

    This aim of this study was to examine the free hormone (in saliva) responses to squat workouts performed by recreationally weight-trained males, using either a power (8 sets of 6 reps, 45% 1 repetition maximum [1RM], 3-minute rest periods, ballistic movements), hypertrophy (10 sets of 10 reps, 75% 1RM, 2-minute rest periods, controlled movements), or maximal strength scheme (6 sets of 4 reps, 88% 1RM, 4-minute rest periods, explosive intent). To determine the relative importance of the different training variables, these schemes were equated by workout duration with the power and strength schemes also equated by load volume. Salivary testosterone (T) and cortisol (C) both increased following the hypertrophy scheme (P < 0.05), with little to no hormonal change across the power and maximal strength schemes (P > 0.05). In general, the postexercise T and C responses to the hypertrophy scheme exceeded the other two schemes (P < 0.05). The greater volume of load lifted in the hypertrophy protocol over the same workout duration may explain the endocrine differences observed. The similar T and C responses to the power and maximal strength schemes (of equal volume) support such a view and suggest that differences in load intensity, rest periods, and technique are secondary to volume. Because the acute hormonal responses to resistance exercise contribute to protein metabolism, then load volume may be the most important workout variable activating the endocrine system and stimulating muscle growth.

  6. Novel Control Scheme of Power Assisted Wheelchair for Preventing Overturn (Part II)-Variable Assistance Ratio Control Based on Estimation of Center-of-Gravity Angle and Phase Plane-

    NASA Astrophysics Data System (ADS)

    Hata, Naoki; Seki, Hirokazu; Koyasu, Yuichi; Hori, Yoichi

    Aged people and disabled people who have difficulty in walking are increasing. As one of mobility support, significance of a power assisted wheelchair which assists driving force using electric motors and spreads their living areas has been enhanced. However, the increased driving force often causes a dangerous overturn of wheelchair. This paper proposes a novel control method to prevent power assisted wheelchair from overturning. The man-wheelchair system can be regarded as an inverse pendulum model when the front wheels are rising. The center-of-gravity (COG) angle of the model is the most important information directly-linked to overturn. Behavior of the system can be analyzed using phase plane as shown in this paper. The COG angle cannot be directly measured using a sensor, therefore, COG observer based on its velocity is proposed. On the basis of the analysis on phase plane, a novel control method with variable assistance ratio to prevent a dangerous overturn is proposed. The effectiveness of the proposed method is verified by the practical experiments on the flat ground and uphill slope.

  7. High resolution schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Harten, A.

    1983-01-01

    A class of new explicit second order accurate finite difference schemes for the computation of weak solutions of hyperbolic conservation laws is presented. These highly nonlinear schemes are obtained by applying a nonoscillatory first order accurate scheme to an appropriately modified flux function. The so-derived second order accurate schemes achieve high resolution while preserving the robustness of the original nonoscillatory first order accurate scheme. Numerical experiments are presented to demonstrate the performance of these new schemes.

  8. Performance of hashed cache data migration schemes on multicomputers

    NASA Technical Reports Server (NTRS)

    Hiranandani, Seema; Saltz, Joel; Mehrotra, Piyush; Berryman, Harry

    1991-01-01

    After conducting an examination of several data-migration mechanisms which permit an explicit and controlled mapping of data to memory, a set of schemes for storage and retrieval of off-processor array elements is experimentally evaluated and modeled. All schemes considered have their basis in the use of hash tables for efficient access of nonlocal data. The techniques in question are those of hashed cache, partial enumeration, and full enumeration; in these, nonlocal data are stored in hash tables, so that the operative difference lies in the amount of memory used by each scheme and in the retrieval mechanism used for nonlocal data.

  9. Comparison of the AUSM(+) and H-CUSP Schemes for Turbomachinery Applications

    NASA Technical Reports Server (NTRS)

    Chima, Rodrick V.; Liou, Meng-Sing

    2003-01-01

    Many turbomachinery CFD codes use second-order central-difference (C-D) schemes with artificial viscosity to control point decoupling and to capture shocks. While C-D schemes generally give accurate results, they can also exhibit minor numerical problems including overshoots at shocks and at the edges of viscous layers, and smearing of shocks and other flow features. In an effort to improve predictive capability for turbomachinery problems, two C-D codes developed by Chima, RVCQ3D and Swift, were modified by the addition of two upwind schemes: the AUSM+ scheme developed by Liou, et al., and the H-CUSP scheme developed by Tatsumi, et al. Details of the C-D scheme and the two upwind schemes are described, and results of three test cases are shown. Results for a 2-D transonic turbine vane showed that the upwind schemes eliminated viscous layer overshoots. Results for a 3-D turbine vane showed that the upwind schemes gave improved predictions of exit flow angles and losses, although the HCUSP scheme predicted slightly higher losses than the other schemes. Results for a 3-D supersonic compressor (NASA rotor 37) showed that the AUSM+ scheme predicted exit distributions of total pressure and temperature that are not generally captured by C-D codes. All schemes showed similar convergence rates, but the upwind schemes required considerably more CPU time per iteration.

  10. An Orbit And Dispersion Correction Scheme for the PEP II

    SciTech Connect

    Cai, Y.; Donald, M.; Shoaee, H.; White, G.; Yasukawa, L.A.; /SLAC

    2011-09-01

    To achieve optimum luminosity in a storage ring it is vital to control the residual vertical dispersion. In the original PEP storage ring, a scheme to control the residual dispersion function was implemented using the ring orbit as the controlling element. The 'best' orbit not necessarily giving the lowest vertical dispersion. A similar scheme has been implemented in both the on-line control code and in the simulation code LEGO. The method involves finding the response matrices (sensitivity of orbit/dispersion at each Beam-Position-Monitor (BPM) to each orbit corrector) and solving in a least squares sense for minimum orbit, dispersion function or both. The optimum solution is usually a subset of the full least squares solution. A scheme of simultaneously correcting the orbits and dispersion has been implemented in the simulation code and on-line control system for PEP-II. The scheme is based on the eigenvector decomposition method. An important ingredient of the scheme is to choose the optimum eigenvectors that minimize the orbit, dispersion and corrector strength. Simulations indicate this to be a very effective way to control the vertical residual dispersion.

  11. Direct plasma injection scheme with various ion beams

    SciTech Connect

    Okamura, M.

    2010-09-15

    The laser ion source is one of the most powerful heavy ion sources. However, it is difficult to obtain good stability and to control its intense current. To overcome these difficulties, we proposed a new beam injection scheme called 'direct plasma injection scheme'. Following this it was established to provide various species with desired charge state as an intense accelerated beam. Carbon, aluminum and iron beams have been tested.

  12. Energy partitioning schemes: a dilemma.

    PubMed

    Mayer, I

    2007-01-01

    Two closely related energy partitioning schemes, in which the total energy is presented as a sum of atomic and diatomic contributions by using the "atomic decomposition of identity", are compared on the example of N,N-dimethylformamide, a simple but chemically rich molecule. Both schemes account for different intramolecular interactions, for instance they identify the weak C-H...O intramolecular interactions, but give completely different numbers. (The energy decomposition scheme based on the virial theorem is also considered.) The comparison of the two schemes resulted in a dilemma which is especially striking when these schemes are applied for molecules distorted from their equilibrium structures: one either gets numbers which are "on the chemical scale" and have quite appealing values at the equilibrium molecular geometries, but exhibiting a counter-intuitive distance dependence (the two-center energy components increase in absolute value with the increase of the interatomic distances)--or numbers with too large absolute values but "correct" distance behaviour. The problem is connected with the quick decay of the diatomic kinetic energy components.

  13. Nonlinear secret image sharing scheme.

    PubMed

    Shin, Sang-Ho; Lee, Gil-Je; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2 m⌉ bit-per-pixel (bpp), respectively.

  14. Nonlinear secret image sharing scheme.

    PubMed

    Shin, Sang-Ho; Lee, Gil-Je; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2 m⌉ bit-per-pixel (bpp), respectively. PMID:25140334

  15. Energy partitioning schemes: a dilemma.

    PubMed

    Mayer, I

    2007-01-01

    Two closely related energy partitioning schemes, in which the total energy is presented as a sum of atomic and diatomic contributions by using the "atomic decomposition of identity", are compared on the example of N,N-dimethylformamide, a simple but chemically rich molecule. Both schemes account for different intramolecular interactions, for instance they identify the weak C-H...O intramolecular interactions, but give completely different numbers. (The energy decomposition scheme based on the virial theorem is also considered.) The comparison of the two schemes resulted in a dilemma which is especially striking when these schemes are applied for molecules distorted from their equilibrium structures: one either gets numbers which are "on the chemical scale" and have quite appealing values at the equilibrium molecular geometries, but exhibiting a counter-intuitive distance dependence (the two-center energy components increase in absolute value with the increase of the interatomic distances)--or numbers with too large absolute values but "correct" distance behaviour. The problem is connected with the quick decay of the diatomic kinetic energy components. PMID:17328441

  16. Nonlinear Secret Image Sharing Scheme

    PubMed Central

    Shin, Sang-Ho; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2⁡m⌉ bit-per-pixel (bpp), respectively. PMID:25140334

  17. Upwind Compact Finite Difference Schemes

    NASA Astrophysics Data System (ADS)

    Christie, I.

    1985-07-01

    It was shown by Ciment, Leventhal, and Weinberg ( J. Comput. Phys.28 (1978), 135) that the standard compact finite difference scheme may break down in convection dominated problems. An upwinding of the method, which maintains the fourth order accuracy, is suggested and favorable numerical results are found for a number of test problems.

  18. On symmetric and upwind TVD schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1985-01-01

    A class of explicit and implicit total variation diminishing (TVD) schemes for the compressible Euler and Navier-Stokes equations was developed. They do not generate spurious oscillations across shocks and contact discontinuities. In general, shocks can be captured within 1 to 2 grid points. For the inviscid case, these schemes are divided into upwind TVD schemes and symmetric (nonupwind) TVD schemes. The upwind TVD scheme is based on the second-order TVD scheme. The symmetric TVD scheme is a generalization of Roe's and Davis' TVD Lax-Wendroff scheme. The performance of these schemes on some viscous and inviscid airfoil steady-state calculations is investigated. The symmetric and upwind TVD schemes are compared.

  19. A blind reversible robust watermarking scheme for relational databases.

    PubMed

    Chang, Chin-Chen; Nguyen, Thai-Son; Lin, Chia-Chen

    2013-01-01

    Protecting the ownership and controlling the copies of digital data have become very important issues in Internet-based applications. Reversible watermark technology allows the distortion-free recovery of relational databases after the embedded watermark data are detected or verified. In this paper, we propose a new, blind, reversible, robust watermarking scheme that can be used to provide proof of ownership for the owner of a relational database. In the proposed scheme, a reversible data-embedding algorithm, which is referred to as "histogram shifting of adjacent pixel difference" (APD), is used to obtain reversibility. The proposed scheme can detect successfully 100% of the embedded watermark data, even if as much as 80% of the watermarked relational database is altered. Our extensive analysis and experimental results show that the proposed scheme is robust against a variety of data attacks, for example, alteration attacks, deletion attacks, mix-match attacks, and sorting attacks.

  20. A Blind Reversible Robust Watermarking Scheme for Relational Databases

    PubMed Central

    Chang, Chin-Chen; Nguyen, Thai-Son; Lin, Chia-Chen

    2013-01-01

    Protecting the ownership and controlling the copies of digital data have become very important issues in Internet-based applications. Reversible watermark technology allows the distortion-free recovery of relational databases after the embedded watermark data are detected or verified. In this paper, we propose a new, blind, reversible, robust watermarking scheme that can be used to provide proof of ownership for the owner of a relational database. In the proposed scheme, a reversible data-embedding algorithm, which is referred to as “histogram shifting of adjacent pixel difference” (APD), is used to obtain reversibility. The proposed scheme can detect successfully 100% of the embedded watermark data, even if as much as 80% of the watermarked relational database is altered. Our extensive analysis and experimental results show that the proposed scheme is robust against a variety of data attacks, for example, alteration attacks, deletion attacks, mix-match attacks, and sorting attacks. PMID:24223033

  1. Subranging scheme for SQUID sensors

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin I. (Inventor)

    2008-01-01

    A readout scheme for measuring the output from a SQUID-based sensor-array using an improved subranging architecture that includes multiple resolution channels (such as a coarse resolution channel and a fine resolution channel). The scheme employs a flux sensing circuit with a sensing coil connected in series to multiple input coils, each input coil being coupled to a corresponding SQUID detection circuit having a high-resolution SQUID device with independent linearizing feedback. A two-resolution configuration (course and fine) is illustrated with a primary SQUID detection circuit for generating a fine readout, and a secondary SQUID detection circuit for generating a course readout, both having feedback current coupled to the respective SQUID devices via feedback/modulation coils. The primary and secondary SQUID detection circuits function and derive independent feedback. Thus, the SQUID devices may be monitored independently of each other (and read simultaneously) to dramatically increase slew rates and dynamic range.

  2. Stable maps and Quot schemes

    NASA Astrophysics Data System (ADS)

    Popa, Mihnea; Roth, Mike

    2003-06-01

    In this paper we study the relationship between two different compactifications of the space of vector bundle quotients of an arbitrary vector bundle on a curve. One is Grothendieck's Quot scheme, while the other is a moduli space of stable maps to the relative Grassmannian. We establish an essentially optimal upper bound on the dimension of the two compactifications. Based on that, we prove that for an arbitrary vector bundle, the Quot schemes of quotients of large degree are irreducible and generically smooth. We precisely describe all the vector bundles for which the same thing holds in the case of the moduli spaces of stable maps. We show that there are in general no natural morphisms between the two compactifications. Finally, as an application, we obtain new cases of a conjecture on effective base point freeness for pluritheta linear series on moduli spaces of vector bundles.

  3. A biometric signcryption scheme without bilinear pairing

    NASA Astrophysics Data System (ADS)

    Wang, Mingwen; Ren, Zhiyuan; Cai, Jun; Zheng, Wentao

    2013-03-01

    How to apply the entropy in biometrics into the encryption and remote authentication schemes to simplify the management of keys is a hot research area. Utilizing Dodis's fuzzy extractor method and Liu's original signcryption scheme, a biometric identity based signcryption scheme is proposed in this paper. The proposed scheme is more efficient than most of the previous proposed biometric signcryption schemes for that it does not need bilinear pairing computation and modular exponentiation computation which is time consuming largely. The analysis results show that under the CDH and DL hard problem assumption, the proposed scheme has the features of confidentiality and unforgeability simultaneously.

  4. Control of parallel manipulators using force feedback

    NASA Technical Reports Server (NTRS)

    Nanua, Prabjot

    1994-01-01

    Two control schemes are compared for parallel robotic mechanisms actuated by hydraulic cylinders. One scheme, the 'rate based scheme', uses the position and rate information only for feedback. The second scheme, the 'force based scheme' feeds back the force information also. The force control scheme is shown to improve the response over the rate control one. It is a simple constant gain control scheme better suited to parallel mechanisms. The force control scheme can be easily modified for the dynamic forces on the end effector. This paper presents the results of a computer simulation of both the rate and force control schemes. The gains in the force based scheme can be individually adjusted in all three directions, whereas the adjustment in just one direction of the rate based scheme directly affects the other two directions.

  5. Implicit Block ACK Scheme for IEEE 802.11 WLANs

    PubMed Central

    Sthapit, Pranesh; Pyun, Jae-Young

    2016-01-01

    The throughput of IEEE 802.11 standard is significantly bounded by the associated Medium Access Control (MAC) overhead. Because of the overhead, an upper limit exists for throughput, which is bounded, including situations where data rates are extremely high. Therefore, an overhead reduction is necessary to achieve higher throughput. The IEEE 802.11e amendment introduced the block ACK mechanism, to reduce the number of control messages in MAC. Although the block ACK scheme greatly reduces overhead, further improvements are possible. In this letter, we propose an implicit block ACK method that further reduces the overhead associated with IEEE 802.11e’s block ACK scheme. The mathematical analysis results are presented for both the original protocol and the proposed scheme. A performance improvement of greater than 10% was achieved with the proposed implementation.

  6. The CSIRO Mk3L climate system model v1.0 coupled to the CABLE land surface scheme v1.4b: evaluation of the control climatology

    SciTech Connect

    Mao, Jiafu; Phipps, S.J.; Pitman, A.J.; Wang, Yingping; Abramowitz, G.; Pak, B.

    2011-01-01

    The CSIRO Mk3L climate system model, a reduced-resolution coupled general circulation model, has previously been described in this journal. The model is configured for millennium scale or multiple century scale simulations. This paper reports the impact of replacing the relatively simple land surface scheme that is the default parameterisation in Mk3L with a sophisticated land surface model that simulates the terrestrial energy, water and carbon balance in a physically and biologically consistent way. An evaluation of the new model s near-surface climatology highlights strengths and weaknesses, but overall the atmospheric variables, including the near-surface air temperature and precipitation, are simulated well. The impact of the more sophisticated land surface model on existing variables is relatively small, but generally positive. More significantly, the new land surface scheme allows an examination of surface carbon-related quantities including net primary productivity which adds significantly to the capacity of Mk3L. Overall, results demonstrate that this reduced-resolution climate model is a good foundation for exploring long time scale phenomena. The addition of the more sophisticated land surface model enables an exploration of important Earth System questions including land cover change and abrupt changes in terrestrial carbon storage.

  7. The "Kluge-Lüttge Kammer": a preliminary evaluation of an enclosed, Crassulacean acid metabolism (CAM) Mesocosm that allows separation of synchronized and desynchronized contributions of plants to whole system gas exchange.

    PubMed

    Rascher, U; Bobich, E G; Osmond, C B

    2006-01-01

    Crassulacean acid metabolism (CAM) is recognized as a photosynthetic adaptation of plants to arid habitats. This paper presents a proof-of-concept evaluation of partitioning net CO2 exchanges for soil and plants in an arid, exclusively CAM mesocosm, with soil depth and succulent plant biomass approximating that of natural Sonoran Desert ecosystems. We present the first evidence that an enclosed CAM-dominated soil and plant community exposed to a substantial day/night temperature difference (30/20 degrees C), exhibits a diel gas exchange pattern consisting of four consecutive phases with a distinct nocturnal CO2 uptake. These phases were modulated by plant assimilation and soil respiration processes. Day-time stomatal closure of the CAM cycle during phase III was used to eliminate aboveground photosynthetic assimilation and respiration and thereby to estimate belowground plant plus soil respiration. Rapid changes in temperature appeared to synchronize single plant gas exchange but individual plant gas exchange patterns were desynchronized at constant day/night temperatures (25 degrees C), masking the distinct mesocosm pattern. Overall, the mean carbon budget of this CAM model Sonoran Desert system was negative, releasing an average of 22.5 mmol CO2 m-2 d-1. The capacity for nocturnal CO2 assimilation in this exclusively CAM mesocosm was inadequate to recycle CO2 released by plant and soil respiration.

  8. An evaluation of three spatial differencing schemes for the discrete ordinates method in participating media

    NASA Technical Reports Server (NTRS)

    Chai, John C.; Lee, Haeok S.; Patankar, Suhas V.

    1993-01-01

    Three popular spatial differencing schemes for the discrete ordinates method are examined for two-dimensional Cartesian coordinates system. These are a positive, the step, and the diamond schemes. Contrary to the common belief that negative intensities will not occur when fine spatial discretization is used with the diamond scheme, under certain conditions, the diamond scheme will produce negative intensities irrespective of the number of control volums employed. The positive scheme can produce physically unrealistic trends. The diamond and positive schemes are also capable of producing physically unrealistic overshoots. In absorbing-emitting or absorbing-emitting-scattering media, grid refinement can result in negative intensities when the diamond or positive scheme is used.

  9. TVD schemes for open channel flow

    NASA Astrophysics Data System (ADS)

    Delis, A. I.; Skeels, C. P.

    1998-04-01

    The Saint Venant equations for modelling flow in open channels are solved in this paper, using a variety of total variation diminishing (TVD) schemes. The performance of second- and third-order-accurate TVD schemes is investigated for the computation of free-surface flows, in predicting dam-breaks and extreme flow conditions created by the river bed topography. Convergence of the schemes is quantified by comparing error norms between subsequent iterations. Automatically calculated time steps and entropy corrections allow high CFL numbers and smooth transition between different conditions. In order to compare different approaches with TVD schemes, the most accurate of each type was chosen. All four schemes chosen proved acceptably accurate. However, there are important differences between the schemes in the occurrence of clipping, overshooting and oscillating behaviour and in the highest CFL numbers allowed by a scheme. These variations in behaviour stem from the different orders and inherent properties of the four schemes.

  10. Contemplation on marking scheme for Type X multiple choice questions, and an illustration of a practically applicable scheme

    PubMed Central

    Siddiqui, Nazeem Ishrat; Bhavsar, Vinayak H.; Bhavsar, Arnav V.; Bose, Sukhwant

    2016-01-01

    Ever since its inception 100 years back, multiple choice items have been widely used as a method of assessment. It has certain inherent limitations such as inability to test higher cognitive skills, element of guesswork while answering, and issues related with marking schemes. Various marking schemes have been proposed in the past but they are not balanced, skewed, and complex, which are based on mathematical calculations which are typically not within the grasp of medical personnel. Type X questions has many advantages being easy to construct, can test multiple concepts/application/facets of a topic, cognitive skill of various level of hierarchy can be tested, and unlike Type K items, they are free from complicated coding. In spite of these advantages, they are not in common use due to complicated marking schemes. This is the reason we explored the aspects of methods of evaluation of multiple correct options multiple choice questions and came up with the simple, practically applicable, nonstringent but logical scoring system for the same. The rationale of the illustrated marking scheme is that it takes into consideration the distracter recognition ability of the examinee rather than relying on the ability only to select the correct response. Thus, examinee's true knowledge is tested, and he is rewarded accordingly for selecting a correct answer and omitting a distracter. The scheme also penalizes for not recognizing a distracter thus controlling guessing behavior. It is emphasized that if the illustrated scoring scheme is adopted, then Type X questions would come in common practice. PMID:27127312

  11. Privacy protection schemes for fingerprint recognition systems

    NASA Astrophysics Data System (ADS)

    Marasco, Emanuela; Cukic, Bojan

    2015-05-01

    The deployment of fingerprint recognition systems has always raised concerns related to personal privacy. A fingerprint is permanently associated with an individual and, generally, it cannot be reset if compromised in one application. Given that fingerprints are not a secret, potential misuses besides personal recognition represent privacy threats and may lead to public distrust. Privacy mechanisms control access to personal information and limit the likelihood of intrusions. In this paper, image- and feature-level schemes for privacy protection in fingerprint recognition systems are reviewed. Storing only key features of a biometric signature can reduce the likelihood of biometric data being used for unintended purposes. In biometric cryptosystems and biometric-based key release, the biometric component verifies the identity of the user, while the cryptographic key protects the communication channel. Transformation-based approaches only a transformed version of the original biometric signature is stored. Different applications can use different transforms. Matching is performed in the transformed domain which enable the preservation of low error rates. Since such templates do not reveal information about individuals, they are referred to as cancelable templates. A compromised template can be re-issued using a different transform. At image-level, de-identification schemes can remove identifiers disclosed for objectives unrelated to the original purpose, while permitting other authorized uses of personal information. Fingerprint images can be de-identified by, for example, mixing fingerprints or removing gender signature. In both cases, degradation of matching performance is minimized.

  12. Comparative study of numerical schemes of TVD3, UNO3-ACM and optimized compact scheme

    NASA Technical Reports Server (NTRS)

    Lee, Duck-Joo; Hwang, Chang-Jeon; Ko, Duck-Kon; Kim, Jae-Wook

    1995-01-01

    Three different schemes are employed to solve the benchmark problem. The first one is a conventional TVD-MUSCL (Monotone Upwind Schemes for Conservation Laws) scheme. The second scheme is a UNO3-ACM (Uniformly Non-Oscillatory Artificial Compression Method) scheme. The third scheme is an optimized compact finite difference scheme modified by us: the 4th order Runge Kutta time stepping, the 4th order pentadiagonal compact spatial discretization with the maximum resolution characteristics. The problems of category 1 are solved by using the second (UNO3-ACM) and third (Optimized Compact) schemes. The problems of category 2 are solved by using the first (TVD3) and second (UNO3-ACM) schemes. The problem of category 5 is solved by using the first (TVD3) scheme. It can be concluded from the present calculations that the Optimized Compact scheme and the UN03-ACM show good resolutions for category 1 and category 2 respectively.

  13. Pay scheme preferences and health policy objectives.

    PubMed

    Abelsen, Birgit

    2011-04-01

    This paper studies the preferences among healthcare workers towards pay schemes involving different levels of risk. It identifies which pay scheme individuals would prefer for themselves, and which they think is best in furthering health policy objectives. The paper adds, methodologically, a way of defining pay schemes that include different levels of risk. A questionnaire was mailed to a random sample of 1111 dentists. Respondents provided information about their current and preferred pay schemes, and indicated which pay scheme, in their opinion, would best further overall health policy objectives. A total of 504 dentists (45%) returned the questionnaire, and there was no indication of systematic non-response bias. All public dentists had a current pay scheme based on a fixed salary and the majority of individuals preferred a pay scheme with more income risk. Their preferred pay schemes coincided with the ones believed to further stabilise healthcare personnel. The predominant current pay scheme among private dentists was based solely on individual output, and the majority of respondents preferred this pay scheme. In addition, their preferred pay schemes coincided with the ones believed to further efficiency objectives. Both public and private dentists believed that pay schemes, furthering efficiency objectives, had to include more performance-related pay than the ones believed to further stability and quality objectives. PMID:20565995

  14. Quantum Signature Scheme with Weak Arbitrator

    NASA Astrophysics Data System (ADS)

    Luo, Ming-Xing; Chen, Xiu-Bo; Yun, Deng; Yang, Yi-Xian

    2012-07-01

    In this paper, we propose one quantum signature scheme with a weak arbitrator to sign classical messages. This scheme can preserve the merits in the original arbitrated scheme with some entanglement resources, and provide a higher efficiency in transmission and reduction the complexity of implementation. The arbitrator is costless and only involved in the disagreement case.

  15. The Spanish external quality assessment scheme for lead in blood.

    PubMed

    Marcuello, D

    1996-01-01

    In 1985 the Instituto Nacional de Seguridad e Higiene en el Trabajo (INSHT) established the "Programa Interlaboratorios de Control de Calidad de Plomo en Sangre (PICC-PbS)". The operation of this scheme is explained, criteria for evaluation of laboratory performance are defined and some results obtained are reviewed.

  16. The design and application of upwind schemes on unstructured meshes

    NASA Technical Reports Server (NTRS)

    Barth, Timothy J.; Jespersen, Dennis C.

    1989-01-01

    Solution and mesh generation algorithms for solving the Euler equations on unstructured meshes consisting of triangle and quadrilateral control volumes are presented. Cell-centered and mesh-vertex upwind finite-volume schemes are developed which utilize multi-dimensional monotone linear reconstruction procedures. These algorithms differ from existing algorithms (even on structured meshes). Numerical results in two dimensions are presented.

  17. The upgraded scheme of Hefei Light Source

    SciTech Connect

    Li Weimin; Xu Hongliang; Wang Lin; Feng Guangyao; Zhang Shancai; Hao Hao

    2010-06-23

    To enhance the performance of Hefei Light Source, which was designed and constructed two decades ago, an upgrade project would be carried out in the near future. The detail upgrade scheme was described in this paper. Firstly, the magnet lattice of storage ring should be reconstructed with 4 DBA cells, whose advantages are lower beam emittance and more straight section available for insertion devices. Secondly, the beam diagnostics, main power supply, transverse and longitudinal multi-bunch feedback, beam control and manipulation system would be upgrade to improve the beam orbit stability. Finally, the injection system of storage ring and injector, which is composed of electron linac and beam transfer line, would be updated in order to assure smooth beam accumulation process under new low emittance lattice. With above improvement, it is hopeful to increase the brilliance of Hefei Light Source by two orders approximately. After three-year upgrade project, the performance of HLS would meet the demands of advanced SR users.

  18. A New Quantum Proxy Multi-signature Scheme Using Maximally Entangled Seven-Qubit States

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Jing; Zhang, Jia-Fu; Liu, Jian; Li, Zeng-You

    2016-02-01

    In this paper, we propose a new secure quantum proxy multi-signature scheme using seven-qubit entangled quantum state as quantum channels, which may have applications in e-payment system, e-government, e-business, etc. This scheme is based on controlled quantum teleportation. The scheme uses the physical characteristics of quantum mechanics to guarantee its anonymity, verifiability, traceability, unforgetability and undeniability.

  19. On symmetric and upwind TVD schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1986-01-01

    The performance of the upwind and symmetric total variation diminishing (TVD) schemes in viscous and inviscid airfoil steady-state calculations is considered, and the extension of the implicit second-order-accurate TVD scheme for hyperbolic systems of conservative laws in curvilinear coordinates is discussed. For two-dimensional steady-state applications, schemes are implemented in a conservative noniterative alternating direction implicit form, and results illustrate that the algorithm produces a fairly good solution for an RAE2822 airfoil calculation. The study demonstrates that the symmetric TVD scheme is as accurate as the upwind TVD scheme, while requiring less computational effort than it.

  20. Construction of weighted upwind compact scheme

    NASA Astrophysics Data System (ADS)

    Wang, Zhengjie

    Enormous endeavor has been devoted in spatial high order high resolution schemes in more than twenty five years previously, like total variation diminishing (TVD), essentially non-oscillatory scheme, weighted essentially non-oscillatory scheme for finite difference, and Discontinuous Galerkin methods for finite element and the finite volume. In this dissertation, a high order finite difference Weighted Upwind Compact Scheme has been constructed by dissipation and dispersion analysis. Secondly, a new method to construct global weights has been tested. Thirdly, a methodology to compromise dissipation and dispersion in constructing Weighted Upwind Compact Scheme has been derived. Finally, several numerical test cases have been shown.

  1. The Spanish external quality assessment scheme for mercury in urine.

    PubMed

    Quintana, M J; Mazarrasa, O

    1996-01-01

    In 1986 the Instituto Nacional de Seguridad e Higiene en el Trabajo (INSHT), established the "Programa interlaboratorios de control de calidad de mercurio en orina (PICC-HgU)". The operation of this scheme is explained, criteria for evaluation of laboratory performance are defined and some results obtained are reviewed. Since the scheme started, an improvement in the overall performance of laboratories has been observed. The differences in the analytical methods used by laboratories do not seem to have a clear influence on the results.

  2. Scheme of IMSF-EP for matrix video display

    NASA Astrophysics Data System (ADS)

    Liu, Bin; He, Zhuyuan; Liu, Shicai

    1996-09-01

    The wide commercial utilization of varied matrix display systems provides a promising development of matrix display techniques. Some methods, which are addressed in this paper, have existed for matrix systems to display video (dynamic) pictures with colors and multi-level brightness. A novel scheme, referred to as the integration of multi-sub-frames with equal period (IMSF-EP), is proposed. With this scheme, the implement of display control is simplified. A proof-in- principle LED matrix display system of 64 X 48 pixels, with the breadboard-based circuits, is constructed.

  3. High-Order Energy Stable WENO Schemes

    NASA Technical Reports Server (NTRS)

    Yamaleev, Nail K.; Carpenter, Mark H.

    2008-01-01

    A new third-order Energy Stable Weighted Essentially NonOscillatory (ESWENO) finite difference scheme for scalar and vector linear hyperbolic equations with piecewise continuous initial conditions is developed. The new scheme is proven to be stable in the energy norm for both continuous and discontinuous solutions. In contrast to the existing high-resolution shock-capturing schemes, no assumption that the reconstruction should be total variation bounded (TVB) is explicitly required to prove stability of the new scheme. A rigorous truncation error analysis is presented showing that the accuracy of the 3rd-order ESWENO scheme is drastically improved if the tuning parameters of the weight functions satisfy certain criteria. Numerical results show that the new ESWENO scheme is stable and significantly outperforms the conventional third-order WENO finite difference scheme of Jiang and Shu in terms of accuracy, while providing essentially nonoscillatory solutions near strong discontinuities.

  4. A reactive coordination scheme for a many-robot system.

    PubMed

    Evans, K S; Unsal, C; Bay, J S

    1997-01-01

    This paper presents a novel approach for coordinating a homogeneous system of mobile robots using implicit communication in the form of broadcasts. The broadcast-based coordination scheme was developed for the Army Ant swarm-a system of small, relatively inexpensive mobile robots that can accomplish complex tasks by cooperating as a team. The primary drawback, however, of the Army Ant system is that the absence of a central supervisor poses difficulty in the coordination and control of the agents. Our coordination scheme provides a global "group dynamic" that controls the actions of each robot using only local interactions. Coordination of the swarm is achieved with signals we call "heartbeats". Each agent broadcasts a unique heartbeat and responds to the collective behavior of all other heartbeats. We generate heartbeats with van der Pol oscillators. In this application, we use the known properties of coupled van der Pol oscillators to create predictable group behavior. Some of the properties and behaviors of coupled van der Pol oscillators are discussed in detail. We emphasize the use of this scheme to allow agents to simultaneously perform an action such as lifting, steering, or changing speed. The results of experiments performed on three actual heartbeat circuits are presented and the behavior of the realized system is compared to simulated results. We also demonstrate the application of the coordination scheme to global speed control. PMID:18255900

  5. Secure SCADA communication by using a modified key management scheme.

    PubMed

    Rezai, Abdalhossein; Keshavarzi, Parviz; Moravej, Zahra

    2013-07-01

    This paper presents and evaluates a new cryptographic key management scheme which increases the efficiency and security of the Supervisory Control And Data Acquisition (SCADA) communication. In the proposed key management scheme, two key update phases are used: session key update and master key update. In the session key update phase, session keys are generated in the master station. In the master key update phase, the Elliptic Curve Diffie-Hellman (ECDH) protocol is used. The Poisson process is also used to model the Security Index (SI) and Quality of Service (QoS). Our analysis shows that the proposed key management not only supports the required speed in the MODBUS implementation but also has several advantages compared to other key management schemes for secure communication in SCADA networks.

  6. Secure SCADA communication by using a modified key management scheme.

    PubMed

    Rezai, Abdalhossein; Keshavarzi, Parviz; Moravej, Zahra

    2013-07-01

    This paper presents and evaluates a new cryptographic key management scheme which increases the efficiency and security of the Supervisory Control And Data Acquisition (SCADA) communication. In the proposed key management scheme, two key update phases are used: session key update and master key update. In the session key update phase, session keys are generated in the master station. In the master key update phase, the Elliptic Curve Diffie-Hellman (ECDH) protocol is used. The Poisson process is also used to model the Security Index (SI) and Quality of Service (QoS). Our analysis shows that the proposed key management not only supports the required speed in the MODBUS implementation but also has several advantages compared to other key management schemes for secure communication in SCADA networks. PMID:23528753

  7. Environmental endocrine disruptors: A proposed classification scheme

    SciTech Connect

    Fur, P.L. de; Roberts, J.

    1995-12-31

    A number of chemicals known to act on animal systems through the endocrine system have been termed environmental endocrine disruptors. This group includes some of the PCBs and TCDDs, as well as lead, mercury and a large number of pesticides. The common feature is that the chemicals interact with endogenous endocrine systems at the cellular and/or molecular level to alter normal processes that are controlled or regulated by hormones. Although the existence of artificial or environmental estrogens (e.g. chlordecone and DES) has been known for some time, recent data indicate that this phenomenon is widespread. Indeed, anti-androgens have been held responsible for reproductive dysfunction in alligator populations in Florida. But the significance of endocrine disruption was recognized by pesticide manufacturers when insect growth regulators were developed to interfere with hormonal control of growth. Controlling, regulating or managing these chemicals depends in no small part on the ability to identify, screen or otherwise know that a chemical is an endocrine disrupter. Two possible classifications schemes are: using the effects caused in an animal, or animals as an exposure indicator; and using a known screen for the point of contact with the animal. The former would require extensive knowledge of cause and effect relationships in dozens of animal groups; the latter would require a screening tool comparable to an estrogen binding assay. The authors present a possible classification based on chemicals known to disrupt estrogenic, androgenic and ecdysone regulated hormonal systems.

  8. Improved Readout Scheme for SQUID-Based Thermometry

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin

    2007-01-01

    An improved readout scheme has been proposed for high-resolution thermometers, (HRTs) based on the use of superconducting quantum interference devices (SQUIDs) to measure temperature- dependent magnetic susceptibilities. The proposed scheme would eliminate counting ambiguities that arise in the conventional scheme, while maintaining the superior magnetic-flux sensitivity of the conventional scheme. The proposed scheme is expected to be especially beneficial for HRT-based temperature control of multiplexed SQUIDbased bolometer sensor arrays. SQUID-based HRTs have become standard for measuring and controlling temperatures in the sub-nano-Kelvin temperature range in a broad range of low-temperature scientific and engineering applications. A typical SQUIDbased HRT that utilizes the conventional scheme includes a coil wound on a core made of a material that has temperature- dependent magnetic susceptibility in the temperature range of interest. The core and the coil are placed in a DC magnetic field provided either by a permanent magnet or as magnetic flux inside a superconducting outer wall. The aforementioned coil is connected to an input coil of a SQUID. Changes in temperature lead to changes in the susceptibility of the core and to changes in the magnetic flux detected by the SQUID. The SQUID readout instrumentation is capable of measuring magnetic-flux changes that correspond to temperature changes down to a noise limit .0.1 nK/Hz1/2. When the flux exceeds a few fundamental flux units, which typically corresponds to a temperature of .100 nK, the SQUID is reset. The temperature range can be greatly expanded if the reset events are carefully tracked and counted, either by a computer running appropriate software or by a dedicated piece of hardware.

  9. External quality assessment scheme and laboratory accreditation in Indonesia.

    PubMed

    Timan, Ina S; Aulia, Diana; Santoso, Witono

    2002-02-01

    The National Program on External Quality Assessment Scheme (NEQAS) in Indonesia was first started in 1979, organized by the Indonesian Ministry of Health collaborating with professional bodies. The first trial was for clinical chemistry test with 2 cycles per year, followed by the hematology NEQAS in 1986 in collaboration with WHO-Royal Post Graduate Medical School London. After that, the schemes for serology, microbiology and parasitology were also organized. Around 500-600 laboratories throughout Indonesia participated each year in these quality control schemes, 2-4 cycles per year. Samples would be sent to participants and results will be given back to each laboratory. Poor performers should participate in the workshop or training course conducted by the Central Health Laboratory to improve their results. Participation in this NEQAS is mandatory for obtaining the laboratory license, and the Ministry of Health uses these schemes as one of the means for monitoring and coordinating the performance of laboratories throughout Indonesia. There are also some other EQAS (External Quality Assessment Scheme) programs conducted by professional bodies, such as for hemostasis, clinical chemistry and serology. During the course of conducting these schemes, it could be observed that manual methods were gradually changed to the automatic methods, especially for the clinical chemistry and hematology laboratories, which counts also for improvements of their results. Since the last 6 years, the Ministry of Health also began to conduct the Accreditation System evaluation for hospitals, including the laboratory departments. There are 7 standards that were evaluated, such as the aspect of the organization, administration and management, staffing, facilities and equipment, standard operating procedures, research and developments and quality control. This accreditation program is still in progress for all public and private hospital laboratories.

  10. A 24-Week, Randomized, Controlled Study to Evaluate the Tolerability, Safety and Efficacy of 2 Different Titration Schemes of the Rivastigmine Patch in Japanese Patients with Mild to Moderate Alzheimer's Disease

    PubMed Central

    Nakamura, Yu; Strohmaier, Christine; Tamura, Kaoru; Kataoka, Naoko; Nakano, Masayuki; Oda, Shoichiro; Nishimura, Kazuma; Homma, Akira

    2015-01-01

    Aim To investigate whether 1-step titration of the rivastigmine patch (initiated at 5 cm2 and titrated to 10 cm2 after 4 weeks) is well tolerated in Japanese patients with Alzheimer's disease (AD) as compared to 3-step titration (initiated at 2.5 cm2 and titrated by 2.5 cm2 every 4 weeks to 10 cm2). Methods A 24-week, multicenter, randomized, double-blind study was conducted in Japan between July 2012 and May 2014. Patients with mild to moderate AD aged 50-85 years were randomized 1:1 to 1-step or 3-step titration of the rivastigmine once-daily patch. The primary endpoint was the proportion of patients with adverse events leading to discontinuation. Results Of 216 patients randomized, 215 (1-step, n = 107; 3-step, n = 108) were included in the safety analysis. The primary endpoint outcome was 15.0% in the 1-step group and 18.5% in the 3-step group. The observed treatment difference was −3.6% (95% confidence interval: −17.0, 9.6), falling within the prespecified acceptance range. Conclusion The tolerability of two different titration schemes was similar in Japanese patients with AD. PMID:26557135

  11. The impact of loss of control on movement BCIs.

    PubMed

    Reuderink, Boris; Poel, Mannes; Nijholt, Anton

    2011-12-01

    Brain-computer interfaces (BCIs) are known to suffer from spontaneous changes in the brain activity. If changes in the mental state of the user are reflected in the brain signals used for control, the behavior of a BCI is directly influenced by these states. We investigate the influence of a state of loss of control in a variant of Pacman on the performance of BCIs based on motor control. To study the effect a temporal loss of control has on the BCI performance, BCI classifiers were trained on electroencephalography (EEG) recorded during the normal control condition, and the classification performance on segments of EEG from the normal and loss of control condition was compared. Classifiers based on event-related desynchronization unexpectedly performed significantly better during the loss of control condition; for the event-related potential classifiers there was no significant difference in performance.

  12. Matroids and quantum-secret-sharing schemes

    SciTech Connect

    Sarvepalli, Pradeep; Raussendorf, Robert

    2010-05-15

    A secret-sharing scheme is a cryptographic protocol to distribute a secret state in an encoded form among a group of players such that only authorized subsets of the players can reconstruct the secret. Classically, efficient secret-sharing schemes have been shown to be induced by matroids. Furthermore, access structures of such schemes can be characterized by an excluded minor relation. No such relations are known for quantum secret-sharing schemes. In this paper we take the first steps toward a matroidal characterization of quantum-secret-sharing schemes. In addition to providing a new perspective on quantum-secret-sharing schemes, this characterization has important benefits. While previous work has shown how to construct quantum-secret-sharing schemes for general access structures, these schemes are not claimed to be efficient. In this context the present results prove to be useful; they enable us to construct efficient quantum-secret-sharing schemes for many general access structures. More precisely, we show that an identically self-dual matroid that is representable over a finite field induces a pure-state quantum-secret-sharing scheme with information rate 1.

  13. High resolution TVD schemes for interface tracking

    NASA Astrophysics Data System (ADS)

    Nandi, K.; Walker, S. P.; Date, A. W.

    2016-06-01

    A first order upwind difference scheme (UDS) is routinely adopted for representing convection terms in a discretised space. UDS provides stable solutions. However it also introduces false diffusion in situations in which the flow direction is oblique relative to the numerical grid or when the cell-Peclet number is large. In order to predict sharp interface, higher order upwind schemes are preferred because of they reduce numerical dissipation. In interfacial flows, density and viscosity vary sharply in space. Representation of convective terms by Total variation diminishing (TVD) schemes ensures reduced smearing without impairing convergence property. TVD schemes develop formulae for interpolation of a cell-face value of the transported variable. If the interpolated value is bounded by the neighbouring nodal values then the scheme is `Bounded'. However, not all TVD schemes possess this property of `Boundedness'. The Normalised Variable Diagram (NVD) defines a domain within which the TVD scheme is bounded. Thus by combining the features of both TVD schemes and ensuring that they fall with the defined area of NVD, the convergence as well as the boundedness of a computational scheme can be ensured. In this paper, six different higher order schemes are considered some which are TVD bounded or unbounded, to solve the well known interface tracking problem of Rayleigh-Taylor Instability. To the best of our knowledge, a comparison of combined TVD/NVD principles in the case of interface tracking problems has not been reported in published literature.

  14. Attendance of Exercise Referral Schemes in the UK: A Systematic Review

    ERIC Educational Resources Information Center

    Gidlow, Christopher; Johnston, Lynne Halley; Crone, Diane; James, David

    2005-01-01

    Objective: The aim of this review was to explore attendance of UK exercise referral schemes (ERS), who attends them, why participants drop out of schemes and to compare evaluations of existing ERS with randomised controlled trials (RCTs). Design: Systematic review. Method: A search of major databases was conducted to identify studies investigating…

  15. An efficient and secure attribute based signcryption scheme with LSSS access structure.

    PubMed

    Hong, Hanshu; Sun, Zhixin

    2016-01-01

    Attribute based encryption (ABE) and attribute based signature (ABS) provide flexible access control with authentication for data sharing between users, but realizing both functions will bring about too much computation burden. In this paper, we combine the advantages of CP-ABE with ABS and propose a ciphertext policy attribute based signcryption scheme. In our scheme, only legal receivers can decrypt the ciphertext and verify the signature signed by data owner. Furthermore, we use linear secret sharing scheme instead of tree structure to avoid the frequent calls of recursive algorithm. By security and performance analysis, we prove that our scheme is secure as well as gains higher efficiency. PMID:27330910

  16. Coupling WRF double-moment 6-class microphysics schemes to RRTMG radiation scheme in weather research forecasting model

    SciTech Connect

    Bae, Soo Ya; Hong, Song -You; Lim, Kyo-Sun Sunny

    2016-01-01

    A method to explicitly calculate the effective radius of hydrometeors in the Weather Research Forecasting (WRF) double-moment 6-class (WDM6) microphysics scheme is designed to tackle the physical inconsistency in cloud properties between the microphysics and radiation processes. At each model time step, the calculated effective radii of hydrometeors from the WDM6 scheme are linked to the Rapid Radiative Transfer Model for GCMs (RRTMG) scheme to consider the cloud effects in radiative flux calculation. This coupling effect of cloud properties between the WDM6 and RRTMG algorithms is examined for a heavy rainfall event in Korea during 25–27 July 2011, and it is compared to the results from the control simulation in which the effective radius is prescribed as a constant value. It is found that the derived radii of hydrometeors in the WDM6 scheme are generally larger than the prescribed values in the RRTMG scheme. Consequently, shortwave fluxes reaching the ground (SWDOWN) are increased over less cloudy regions, showing a better agreement with a satellite image. The overall distribution of the 24-hour accumulated rainfall is not affected but its amount is changed. In conclusion, a spurious rainfall peak over the Yellow Sea is alleviated, whereas the local maximum in the central part of the peninsula is increased.

  17. Coupling WRF double-moment 6-class microphysics schemes to RRTMG radiation scheme in weather research forecasting model

    DOE PAGESBeta

    Bae, Soo Ya; Hong, Song -You; Lim, Kyo-Sun Sunny

    2016-01-01

    A method to explicitly calculate the effective radius of hydrometeors in the Weather Research Forecasting (WRF) double-moment 6-class (WDM6) microphysics scheme is designed to tackle the physical inconsistency in cloud properties between the microphysics and radiation processes. At each model time step, the calculated effective radii of hydrometeors from the WDM6 scheme are linked to the Rapid Radiative Transfer Model for GCMs (RRTMG) scheme to consider the cloud effects in radiative flux calculation. This coupling effect of cloud properties between the WDM6 and RRTMG algorithms is examined for a heavy rainfall event in Korea during 25–27 July 2011, and itmore » is compared to the results from the control simulation in which the effective radius is prescribed as a constant value. It is found that the derived radii of hydrometeors in the WDM6 scheme are generally larger than the prescribed values in the RRTMG scheme. Consequently, shortwave fluxes reaching the ground (SWDOWN) are increased over less cloudy regions, showing a better agreement with a satellite image. The overall distribution of the 24-hour accumulated rainfall is not affected but its amount is changed. In conclusion, a spurious rainfall peak over the Yellow Sea is alleviated, whereas the local maximum in the central part of the peninsula is increased.« less

  18. Extension of Low Dissipative High Order Hydrodynamics Schemes for MHD Equations

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Sjoegreen, Bjoern; Mansour, Nagi (Technical Monitor)

    2002-01-01

    The objective of this paper is to extend our recently developed highly parallelizable nonlinear stable high order schemes for complex multiscale hydrodynamic applications to the viscous MHD (magnetohydrodynamic) equations. These schemes employed multiresolution wavelets as adaptive numerical dissipation controls to limit the amount and to aid the selection and/or blending of the appropriate types of dissipation to be used. The new scheme is formulated for both the conservative and non-conservative form of the MHD equations in curvi-linear grids. The three features of the present MHD scheme over existing schemes in the open literature are as follows. First, the scheme is constructed for long-time integrations of shock/turbulence/combustion magnetized flows. Available schemes are too diffusive for long-time integrations and/or turbulence/combustion problems. Second, unlike existing schemes for the conservative MHD equations which suffer from ill-conditioned eigen-decompositions, the present scheme makes use of a well-conditioned eigen-decomposition to solve the conservative form of the MHD equations. This is due to, partly. the fact that the divergence of the magnetic field condition is a different type of constraint from its incompressible Navier-Stokes cousin. Third, a new approach to minimize the numerical error of the divergence free magnetic condition for high order scheme is introduced.

  19. On schemes of combinatorial transcription logic

    NASA Astrophysics Data System (ADS)

    Buchler, Nicolas E.; Gerland, Ulrich; Hwa, Terence

    2003-04-01

    Cells receive a wide variety of cellular and environmental signals, which are often processed combinatorially to generate specific genetic responses. Here we explore theoretically the potentials and limitations of combinatorial signal integration at the level of cis-regulatory transcription control. Our analysis suggests that many complex transcription-control functions of the type encountered in higher eukaryotes are already implementable within the much simpler bacterial transcription system. Using a quantitative model of bacterial transcription and invoking only specific protein-DNA interaction and weak glue-like interaction between regulatory proteins, we show explicit schemes to implement regulatory logic functions of increasing complexity by appropriately selecting the strengths and arranging the relative positions of the relevant protein-binding DNA sequences in the cis-regulatory region. The architectures that emerge are naturally modular and evolvable. Our results suggest that the transcription regulatory apparatus is a "programmable" computing machine, belonging formally to the class of Boltzmann machines. Crucial to our results is the ability to regulate gene expression at a distance. In bacteria, this can be achieved for isolated genes via DNA looping controlled by the dimerization of DNA-bound proteins. However, if adopted extensively in the genome, long-distance interaction can cause unintentional intergenic cross talk, a detrimental side effect difficult to overcome by the known bacterial transcription-regulation systems. This may be a key factor limiting the genome-wide adoption of complex transcription control in bacteria. Implications of our findings for combinatorial transcription control in eukaryotes are discussed. Abbreviations: TF, transcription factor RNAP, RNA polymerase DNF, disjunctive normal form CNF, conjunctive normal form

  20. Sequential Feedback Scheme Outperforms the Parallel Scheme for Hamiltonian Parameter Estimation

    NASA Astrophysics Data System (ADS)

    Yuan, Haidong

    2016-10-01

    Measurement and estimation of parameters are essential for science and engineering, where the main quest is to find the highest achievable precision with the given resources and design schemes to attain it. Two schemes, the sequential feedback scheme and the parallel scheme, are usually studied in the quantum parameter estimation. While the sequential feedback scheme represents the most general scheme, it remains unknown whether it can outperform the parallel scheme for any quantum estimation tasks. In this Letter, we show that the sequential feedback scheme has a threefold improvement over the parallel scheme for Hamiltonian parameter estimations on two-dimensional systems, and an order of O (d +1 ) improvement for Hamiltonian parameter estimation on d -dimensional systems. We also show that, contrary to the conventional belief, it is possible to simultaneously achieve the highest precision for estimating all three components of a magnetic field, which sets a benchmark on the local precision limit for the estimation of a magnetic field.

  1. How can conceptual schemes change teaching?

    NASA Astrophysics Data System (ADS)

    Wickman, Per-Olof

    2012-03-01

    Lundqvist, Almqvist and Östman describe a teacher's manner of teaching and the possible consequences it may have for students' meaning making. In doing this the article examines a teacher's classroom practice by systematizing the teacher's transactions with the students in terms of certain conceptual schemes, namely the epistemological moves, educational philosophies and the selective traditions of this practice. In connection to their study one may ask how conceptual schemes could change teaching. This article examines how the relationship of the conceptual schemes produced by educational researchers to educational praxis has developed from the middle of the last century to today. The relationship is described as having been transformed in three steps: (1) teacher deficit and social engineering, where conceptual schemes are little acknowledged, (2) reflecting practitioners, where conceptual schemes are mangled through teacher practice to aid the choices of already knowledgeable teachers, and (3) the mangling of the conceptual schemes by researchers through practice with the purpose of revising theory.

  2. Curvilinear bicubic spline fit interpolation scheme

    NASA Technical Reports Server (NTRS)

    Chi, C.

    1973-01-01

    Modification of the rectangular bicubic spline fit interpolation scheme so as to make it suitable for use with a polar grid pattern. In the proposed modified scheme the interpolation function is expressed in terms of the radial length and the arc length, and the shape of the patch, which is a wedge or a truncated wedge, is taken into account implicitly. Examples are presented in which the proposed interpolation scheme was used to reproduce the equations of a hemisphere.

  3. Quantum Authentication Scheme Based on Entanglement Swapping

    NASA Astrophysics Data System (ADS)

    Penghao, Niu; Yuan, Chen; Chong, Li

    2016-01-01

    Based on the entanglement swapping, a quantum authentication scheme with a trusted- party is proposed in this paper. With this scheme, two users can perform mutual identity authentication to confirm each other's validity. In addition, the scheme is proved to be secure under circumstances where a malicious attacker is capable of monitoring the classical and quantum channels and has the power to forge all information on the public channel.

  4. Simulation of the Australian Mobilesat signalling scheme

    NASA Technical Reports Server (NTRS)

    Rahman, Mushfiqur

    1990-01-01

    The proposed Australian Mobilesat system will provide a range of circuit switched voice/data services using the B-series satellites. The reliability of the signalling scheme between the Network Management Station (NMS) and the mobile terminal (MT) is of critical importance to the performance of the overall system. Simulation results of the performance of the signalling scheme under various channel conditions and coding schemes are presented.

  5. On central-difference and upwind schemes

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Turkel, Eli

    1990-01-01

    A class of numerical dissipation models for central-difference schemes constructed with second- and fourth-difference terms is considered. The notion of matrix dissipation associated with upwind schemes is used to establish improved shock capturing capability for these models. In addition, conditions are given that guarantee that such dissipation models produce a Total Variation Diminishing (TVD) scheme. Appropriate switches for this type of model to ensure satisfaction of the TVD property are presented. Significant improvements in the accuracy of a central-difference scheme are demonstrated by computing both inviscid and viscous transonic airfoil flows.

  6. Direct Eulerian MUSCL scheme for gas dynamics

    SciTech Connect

    Colella, P.

    1985-01-01

    The authors present a second order extension of Godunov's method for gas dynamics in Eulerian coordinates patterned after van Leer's MUSCL scheme for gas dynamics in Lagrangian coordinates. The present method performs the Eulerian calculation in a single step by solving Riemann problems and characteristic equations for the fluxes in the Eulerian frame. The authors also make several modifications in the formulation of MUSCL, applicable to both this scheme and to the original Lagrangian scheme, all aimed at making a more robust and accurate scheme. The authors present the results of test calculations in one and two space variables. 12 references, 5 figures.

  7. A comparison of two multi-variable integrator windup protection schemes

    NASA Technical Reports Server (NTRS)

    Mattern, Duane

    1993-01-01

    Two methods are examined for limit and integrator wind-up protection for multi-input, multi-output linear controllers subject to actuator constraints. The methods begin with an existing linear controller that satisfies the specifications for the nominal, small perturbation, linear model of the plant. The controllers are formulated to include an additional contribution to the state derivative calculations. The first method to be examined is the multi-variable version of the single-input, single-output, high gain, Conventional Anti-Windup (CAW) scheme. Except for the actuator limits, the CAW scheme is linear. The second scheme to be examined, denoted the Modified Anti-Windup (MAW) scheme, uses a scalar to modify the magnitude of the controller output vector while maintaining the vector direction. The calculation of the scalar modifier is a nonlinear function of the controller outputs and the actuator limits. In both cases the constrained actuator is tracked. These two integrator windup protection methods are demonstrated on a turbofan engine control system with five measurements, four control variables, and four actuators. The closed-loop responses of the two schemes are compared and contrasted during limit operation. The issue of maintaining the direction of the controller output vector using the Modified Anti-Windup scheme is discussed and the advantages and disadvantages of both of the IWP methods are presented.

  8. Modeling Students' Mathematics Using Steffe's Fraction Schemes

    ERIC Educational Resources Information Center

    Norton, Anderson H.; McCloskey, Andrea V.

    2008-01-01

    Each year, more teachers learn about the successful intervention program known as Math Recovery (USMRC 2008; Wright 2003). The program uses Steffe's whole-number schemes to model, understand, and support children's development of whole-number reasoning. Readers are probably less familiar with Steffe's fraction schemes, which have proven similarly…

  9. Finite volume renormalization scheme for fermionic operators

    SciTech Connect

    Monahan, Christopher; Orginos, Kostas

    2013-11-01

    We propose a new finite volume renormalization scheme. Our scheme is based on the Gradient Flow applied to both fermion and gauge fields and, much like the Schr\\"odinger functional method, allows for a nonperturbative determination of the scale dependence of operators using a step-scaling approach. We give some preliminary results for the pseudo-scalar density in the quenched approximation.

  10. An Accounting Scheme for Personality Study.

    ERIC Educational Resources Information Center

    Dillon, James J.; Feldman, S. Shirley

    Realizing the importance of human personality variables in comprehensive educational assessment structures, Operation PEP sought to develop a tool to assess specific human personality characteristics. The resulting accounting scheme is divided into three chapters: (1) an outline and definition of relevant terminology, (2) a scheme to account for…

  11. A novel key management scheme using biometrics

    NASA Astrophysics Data System (ADS)

    Sui, Yan; Yang, Kai; Du, Yingzi; Orr, Scott; Zou, Xukai

    2010-04-01

    Key management is one of the most important issues in cryptographic systems. Several important challenges in such a context are represented by secure and efficient key generation, key distribution, as well as key revocation. Addressing such challenges requires a comprehensive solution which is robust, secure and efficient. Compared to traditional key management schemes, key management using biometrics requires the presence of the user, which can reduce fraud and protect the key better. In this paper, we propose a novel key management scheme using iris based biometrics. Our newly proposed scheme outperforms traditional key management schemes as well as some existing key-binding biometric schemes in terms of security, diversity and/or efficiency.

  12. The basic function scheme of polynomial type

    SciTech Connect

    WU, Wang-yi; Lin, Guang

    2009-12-01

    A new numerical method---Basic Function Method is proposed. This method can directly discrete differential operator on unstructured grids. By using the expansion of basic function to approach the exact function, the central and upwind schemes of derivative are constructed. By using the second-order polynomial as basic function and applying the technique of flux splitting method and the combination of central and upwind schemes to suppress the non-physical fluctuation near the shock wave, the second-order basic function scheme of polynomial type for solving inviscid compressible flow numerically is constructed in this paper. Several numerical results of many typical examples for two dimensional inviscid compressible transonic and supersonic steady flow illustrate that it is a new scheme with high accuracy and high resolution for shock wave. Especially, combining with the adaptive remeshing technique, the satisfactory results can be obtained by these schemes.

  13. Efficient DSMC collision-partner selection schemes.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2010-07-01

    The effect of collision-partner selection schemes on the accuracy and the efficiency of the Direct Simulation Monte Carlo (DSMC) method of Bird is investigated. Several schemes to reduce the total discretization error as a function of the mean collision separation and the mean collision time are examined. These include the historically first sub-cell scheme, the more recent nearest-neighbor scheme, and various near-neighbor schemes, which are evaluated for their effect on the thermal conductivity for Fourier flow. Their convergence characteristics as a function of spatial and temporal discretization and the number of simulators per cell are compared to the convergence characteristics of the sophisticated and standard DSMC algorithms. Improved performance is obtained if the population from which possible collision partners are selected is an appropriate fraction of the population of the cell.

  14. Two level scheme solvers for nuclear spectroscopy

    NASA Astrophysics Data System (ADS)

    Jansson, Kaj; DiJulio, Douglas; Cederkäll, Joakim

    2011-10-01

    A program for building level schemes from γ-spectroscopy coincidence data has been developed. The scheme builder was equipped with two different algorithms: a statistical one based on the Metropolis method and a more logical one, called REMP (REcurse, Merge and Permute), developed from scratch. These two methods are compared both on ideal cases and on experimental γ-ray data sets. The REMP algorithm is based on coincidences and transition energies. Using correct and complete coincidence data, it has solved approximately half a million schemes without failures. Also, for incomplete data and data with minor errors, the algorithm produces consistent sub-schemes when it is not possible to obtain a complete scheme from the provided data.

  15. Efficient DSMC collision-partner selection schemes.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2010-05-01

    The effect of collision-partner selection schemes on the accuracy and the efficiency of the Direct Simulation Monte Carlo (DSMC) method of Bird is investigated. Several schemes to reduce the total discretization error as a function of the mean collision separation and the mean collision time are examined. These include the historically first sub-cell scheme, the more recent nearest-neighbor scheme, and various near-neighbor schemes, which are evaluated for their effect on the thermal conductivity for Fourier flow. Their convergence characteristics as a function of spatial and temporal discretization and the number of simulators per cell are compared to the convergence characteristics of the sophisticated and standard DSMC algorithms. Improved performance is obtained if the population from which possible collision partners are selected is an appropriate fraction of the population of the cell.

  16. Construction of Low Dissipative High Order Well-Balanced Filter Schemes for Non-Equilibrium Flows

    NASA Technical Reports Server (NTRS)

    Wang, Wei; Yee, H. C.; Sjogreen, Bjorn; Magin, Thierry; Shu, Chi-Wang

    2009-01-01

    The goal of this paper is to generalize the well-balanced approach for non-equilibrium flow studied by Wang et al. [26] to a class of low dissipative high order shock-capturing filter schemes and to explore more advantages of well-balanced schemes in reacting flows. The class of filter schemes developed by Yee et al. [30], Sjoegreen & Yee [24] and Yee & Sjoegreen [35] consist of two steps, a full time step of spatially high order non-dissipative base scheme and an adaptive nonlinear filter containing shock-capturing dissipation. A good property of the filter scheme is that the base scheme and the filter are stand alone modules in designing. Therefore, the idea of designing a well-balanced filter scheme is straightforward, i.e., choosing a well-balanced base scheme with a well-balanced filter (both with high order). A typical class of these schemes shown in this paper is the high order central difference schemes/predictor-corrector (PC) schemes with a high order well-balanced WENO filter. The new filter scheme with the well-balanced property will gather the features of both filter methods and well-balanced properties: it can preserve certain steady state solutions exactly; it is able to capture small perturbations, e.g., turbulence fluctuations; it adaptively controls numerical dissipation. Thus it shows high accuracy, efficiency and stability in shock/turbulence interactions. Numerical examples containing 1D and 2D smooth problems, 1D stationary contact discontinuity problem and 1D turbulence/shock interactions are included to verify the improved accuracy, in addition to the well-balanced behavior.

  17. A scheme for a topological insulator field effect transistor

    NASA Astrophysics Data System (ADS)

    Vali, Mehran; Dideban, Daryoosh; Moezi, Negin

    2015-05-01

    We propose a scheme for a topological insulator field effect transistor. The idea is based on the gate voltage control of the Dirac fermions in a ferromagnetic topological insulator channel with perpendicular magnetization connecting to two metallic topological insulator leads. Our theoretical analysis shows that the proposed device displays a switching effect with high on/off current ratio and a negative differential conductance with a good peak to valley ratio.

  18. Analysis of reaction schemes using maximum rates of constituent steps.

    PubMed

    Motagamwala, Ali Hussain; Dumesic, James A

    2016-05-24

    We show that the steady-state kinetics of a chemical reaction can be analyzed analytically in terms of proposed reaction schemes composed of series of steps with stoichiometric numbers equal to unity by calculating the maximum rates of the constituent steps, rmax,i, assuming that all of the remaining steps are quasi-equilibrated. Analytical expressions can be derived in terms of rmax,i to calculate degrees of rate control for each step to determine the extent to which each step controls the rate of the overall stoichiometric reaction. The values of rmax,i can be used to predict the rate of the overall stoichiometric reaction, making it possible to estimate the observed reaction kinetics. This approach can be used for catalytic reactions to identify transition states and adsorbed species that are important in controlling catalyst performance, such that detailed calculations using electronic structure calculations (e.g., density functional theory) can be carried out for these species, whereas more approximate methods (e.g., scaling relations) are used for the remaining species. This approach to assess the feasibility of proposed reaction schemes is exact for reaction schemes where the stoichiometric coefficients of the constituent steps are equal to unity and the most abundant adsorbed species are in quasi-equilibrium with the gas phase and can be used in an approximate manner to probe the performance of more general reaction schemes, followed by more detailed analyses using full microkinetic models to determine the surface coverages by adsorbed species and the degrees of rate control of the elementary steps.

  19. Analysis of reaction schemes using maximum rates of constituent steps

    NASA Astrophysics Data System (ADS)

    Hussain Motagamwala, Ali; Dumesic, James A.

    2016-05-01

    We show that the steady-state kinetics of a chemical reaction can be analyzed analytically in terms of proposed reaction schemes composed of series of steps with stoichiometric numbers equal to unity by calculating the maximum rates of the constituent steps, rmax,i, assuming that all of the remaining steps are quasi-equilibrated. Analytical expressions can be derived in terms of rmax,i to calculate degrees of rate control for each step to determine the extent to which each step controls the rate of the overall stoichiometric reaction. The values of rmax,i can be used to predict the rate of the overall stoichiometric reaction, making it possible to estimate the observed reaction kinetics. This approach can be used for catalytic reactions to identify transition states and adsorbed species that are important in controlling catalyst performance, such that detailed calculations using electronic structure calculations (e.g., density functional theory) can be carried out for these species, whereas more approximate methods (e.g., scaling relations) are used for the remaining species. This approach to assess the feasibility of proposed reaction schemes is exact for reaction schemes where the stoichiometric coefficients of the constituent steps are equal to unity and the most abundant adsorbed species are in quasi-equilibrium with the gas phase and can be used in an approximate manner to probe the performance of more general reaction schemes, followed by more detailed analyses using full microkinetic models to determine the surface coverages by adsorbed species and the degrees of rate control of the elementary steps.

  20. Analysis of reaction schemes using maximum rates of constituent steps.

    PubMed

    Motagamwala, Ali Hussain; Dumesic, James A

    2016-05-24

    We show that the steady-state kinetics of a chemical reaction can be analyzed analytically in terms of proposed reaction schemes composed of series of steps with stoichiometric numbers equal to unity by calculating the maximum rates of the constituent steps, rmax,i, assuming that all of the remaining steps are quasi-equilibrated. Analytical expressions can be derived in terms of rmax,i to calculate degrees of rate control for each step to determine the extent to which each step controls the rate of the overall stoichiometric reaction. The values of rmax,i can be used to predict the rate of the overall stoichiometric reaction, making it possible to estimate the observed reaction kinetics. This approach can be used for catalytic reactions to identify transition states and adsorbed species that are important in controlling catalyst performance, such that detailed calculations using electronic structure calculations (e.g., density functional theory) can be carried out for these species, whereas more approximate methods (e.g., scaling relations) are used for the remaining species. This approach to assess the feasibility of proposed reaction schemes is exact for reaction schemes where the stoichiometric coefficients of the constituent steps are equal to unity and the most abundant adsorbed species are in quasi-equilibrium with the gas phase and can be used in an approximate manner to probe the performance of more general reaction schemes, followed by more detailed analyses using full microkinetic models to determine the surface coverages by adsorbed species and the degrees of rate control of the elementary steps. PMID:27162366

  1. Resource Allocation and Power Management Schemes in an LTE-Advanced Femtocell Network

    NASA Astrophysics Data System (ADS)

    Lee, Byung-Bog; Yu, Jae-Hak; Lee, In-Hwan; Pyo, Cheol-Sig; Kim, Se-Jin

    In this letter, we introduce two different resource allocation and Tx power management schemes, called resource control and fixed power (RCFP) and fixed resource and power control (FRPC), in an LTE-Advanced femtocell network. We analyze and compare the two schemes in terms of the system throughput for downlink and energy consumption of home evolved NodeB (HeNB) Tx power according to the number of HeNBs and home user equipment (HUE)'s user traffic density (C). The simulation results show that the FRPC scheme has better performance in terms of system throughput for macro user equipments (MUEs) and energy consumption in low C.

  2. All possible coupling schemes in XY spin chains for perfect state transfer

    SciTech Connect

    Wang Yaoxiong; Shuang Feng; Rabitz, Herschel

    2011-07-15

    We investigate quantum state transfer in XY spin chains and propose a recursive procedure to construct the nonuniform couplings within these chains of arbitrary length in order to achieve perfect state transfer. We show that this method is capable of finding all possible coupling schemes for perfect state transfer. These schemes, without external control fields, involve analytically identified engineered couplings without the need for dynamical control. The analytical solutions provide all information for coupling design.

  3. Resource management scheme based on ubiquitous data analysis.

    PubMed

    Lee, Heung Ki; Jung, Jaehee; Yi, Gangman

    2014-01-01

    Resource management of the main memory and process handler is critical to enhancing the system performance of a web server. Owing to the transaction delay time that affects incoming requests from web clients, web server systems utilize several web processes to anticipate future requests. This procedure is able to decrease the web generation time because there are enough processes to handle the incoming requests from web browsers. However, inefficient process management results in low service quality for the web server system. Proper pregenerated process mechanisms are required for dealing with the clients' requests. Unfortunately, it is difficult to predict how many requests a web server system is going to receive. If a web server system builds too many web processes, it wastes a considerable amount of memory space, and thus performance is reduced. We propose an adaptive web process manager scheme based on the analysis of web log mining. In the proposed scheme, the number of web processes is controlled through prediction of incoming requests, and accordingly, the web process management scheme consumes the least possible web transaction resources. In experiments, real web trace data were used to prove the improved performance of the proposed scheme. PMID:25197692

  4. The interprocedural analysis and automatic parallelization of scheme programs

    SciTech Connect

    Harrison, W.L. III.

    1989-01-01

    Lisp and its descendants are among the most important and widely used of programming languages. At the same time, parallelism in the architecture of computer systems is becoming commonplace. There is a pressing need to extend the technology of automatic parallelization that has become available to Fortran programmers of parallel machines, to the realm of Lisp programs and symbolic computing. In this thesis the authors presents a comprehensive approach to the compilation of Scheme programs for share-memory multiprocessors. The strategy has two principal components: interprocedural analysis and program restructuring. He introduces procedure strings and stack configurations as a framework in which to reason about interprocedural side-effects and object lifetimes, and develop a system of interprocedural analysis, using abstract interpretation, that is used in the dependence analysis and memory management of Scheme programs. He introduces the transformations of exit-loop translation and recursion splitting to treat the control structures of iteration and recursion that arise commonly in Scheme programs. He proposes an alternative representation for s-expressions that facilitates the parallel creation and access of lists. He has implemented these ideas in a parallelizing scheme compiler and run-time system, and he complements the theory of the work with snapshots of programs during the restructuring process, and some preliminary performance results of the execution of object codes produced by the compiler.

  5. Date attachable offline electronic cash scheme.

    PubMed

    Fan, Chun-I; Sun, Wei-Zhe; Hau, Hoi-Tung

    2014-01-01

    Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling.

  6. Date attachable offline electronic cash scheme.

    PubMed

    Fan, Chun-I; Sun, Wei-Zhe; Hau, Hoi-Tung

    2014-01-01

    Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling. PMID:24982931

  7. Date Attachable Offline Electronic Cash Scheme

    PubMed Central

    Sun, Wei-Zhe; Hau, Hoi-Tung

    2014-01-01

    Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling. PMID:24982931

  8. A Real Quantum Designated Verifier Signature Scheme

    NASA Astrophysics Data System (ADS)

    Shi, Wei-Min; Zhou, Yi-Hua; Yang, Yu-Guang

    2015-09-01

    The effectiveness of most quantum signature schemes reported in the literature can be verified by a designated person, however, those quantum signature schemes aren't the real traditional designated verifier signature schemes, because the designated person hasn't the capability to efficiently simulate a signature which is indistinguishable from a signer, which cannot satisfy the requirements in some special environments such as E-voting, call for tenders and software licensing. For solving this problem, a real quantum designated verifier signature scheme is proposed in this paper. According to the property of unitary transformation and quantum one-way function, only a verifier designated by a signer can verify the "validity of a signature" and the designated verifier cannot prove to a third party that the signature was produced by the signer or by himself through a transcript simulation algorithm. Moreover, the quantum key distribution and quantum encryption algorithm guarantee the unconditional security of this scheme. Analysis results show that this new scheme satisfies the main security requirements of designated verifier signature scheme and the major attack strategies.

  9. Towards an "All Speed" Unstructured Upwind Scheme

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Jorgenson, Philip C.E.

    2009-01-01

    In the authors previous studies [1], a time-accurate, upwind finite volume method (ETAU scheme) for computing compressible flows on unstructured grids was proposed. The scheme is second order accurate in space and time and yields high resolution in the presence of discontinuities. The scheme features a multidimensional limiter and multidimensional numerical dissipation. These help to stabilize the numerical process and to overcome the annoying pathological behaviors of upwind schemes. In the present paper, it will be further shown that such multidimensional treatments also lead to a nearly all-speed or Mach number insensitive upwind scheme. For flows at very high Mach number, e.g., 10, local numerical instabilities or the pathological behaviors are suppressed, while for flows at very low Mach number, e.g., 0.02, computation can be directly carried out without invoking preconditioning. For flows in different Mach number regimes, i.e., low, medium, and high Mach numbers, one only needs to adjust one or two parameters in the scheme. Several examples with low and high Mach numbers are demonstrated in this paper. Thus, the ETAU scheme is applicable to a broad spectrum of flow regimes ranging from high supersonic to low subsonic, appropriate for both CFD (computational fluid dynamics) and CAA (computational aeroacoustics).

  10. A diagonally inverted LU implicit multigrid scheme

    NASA Technical Reports Server (NTRS)

    Yokota, Jeffrey W.; Caughey, David A.; Chima, Rodrick V.

    1988-01-01

    A new Diagonally Inverted LU Implicit scheme is developed within the framework of the multigrid method for the 3-D unsteady Euler equations. The matrix systems that are to be inverted in the LU scheme are treated by local diagonalizing transformations that decouple them into systems of scalar equations. Unlike the Diagonalized ADI method, the time accuracy of the LU scheme is not reduced since the diagonalization procedure does not destroy time conservation. Even more importantly, this diagonalization significantly reduces the computational effort required to solve the LU approximation and therefore transforms it into a more efficient method of numerically solving the 3-D Euler equations.

  11. Palmprint based multidimensional fuzzy vault scheme.

    PubMed

    Liu, Hailun; Sun, Dongmei; Xiong, Ke; Qiu, Zhengding

    2014-01-01

    Fuzzy vault scheme (FVS) is one of the most popular biometric cryptosystems for biometric template protection. However, error correcting code (ECC) proposed in FVS is not appropriate to deal with real-valued biometric intraclass variances. In this paper, we propose a multidimensional fuzzy vault scheme (MDFVS) in which a general subspace error-tolerant mechanism is designed and embedded into FVS to handle intraclass variances. Palmprint is one of the most important biometrics; to protect palmprint templates; a palmprint based MDFVS implementation is also presented. Experimental results show that the proposed scheme not only can deal with intraclass variances effectively but also could maintain the accuracy and meanwhile enhance security. PMID:24892094

  12. The GEMPAK Barnes objective analysis scheme

    NASA Technical Reports Server (NTRS)

    Koch, S. E.; Desjardins, M.; Kocin, P. J.

    1981-01-01

    GEMPAK, an interactive computer software system developed for the purpose of assimilating, analyzing, and displaying various conventional and satellite meteorological data types is discussed. The objective map analysis scheme possesses certain characteristics that allowed it to be adapted to meet the analysis needs GEMPAK. Those characteristics and the specific adaptation of the scheme to GEMPAK are described. A step-by-step guide for using the GEMPAK Barnes scheme on an interactive computer (in real time) to analyze various types of meteorological datasets is also presented.

  13. Renormalization schemes: Where do we stand

    SciTech Connect

    Ward, B.F.L.

    1989-07-01

    We consider the status of the current approaches to the application of the renormalization program to the standard SU/sub 2L/ /times/ U/sub 1/ theory from the standpoint of the interplay of the scheme chosen for such an application and the attendant high-precision tests of the respective loop effects. We thus review the available schemes and discuss their theoretical relationships. We also show how such schemes stand in numerical relation to one another in the context of high-precision Z/sup 0/ physics, as an illustration. 15 refs., 2 figs., 2 tabs.

  14. A classification scheme for chimera states

    NASA Astrophysics Data System (ADS)

    Kemeth, Felix P.; Haugland, Sindre W.; Schmidt, Lennart; Kevrekidis, Ioannis G.; Krischer, Katharina

    2016-09-01

    We present a universal characterization scheme for chimera states applicable to both numerical and experimental data sets. The scheme is based on two correlation measures that enable a meaningful definition of chimera states as well as their classification into three categories: stationary, turbulent, and breathing. In addition, these categories can be further subdivided according to the time-stationarity of these two measures. We demonstrate that this approach is both consistent with previously recognized chimera states and enables us to classify states as chimeras which have not been categorized as such before. Furthermore, the scheme allows for a qualitative and quantitative comparison of experimental chimeras with chimeras obtained through numerical simulations.

  15. Improved Quantum Signature Scheme with Weak Arbitrator

    NASA Astrophysics Data System (ADS)

    Su, Qi; Li, Wen-Min

    2013-09-01

    In this paper, we find a man-in-the-middle attack on the quantum signature scheme with a weak arbitrator (Luo et al., Int. J. Theor. Phys., 51:2135, 2012). In that scheme, the authors proposed a quantum signature based on quantum one way function which contains both verifying the signer phase and verifying the signed message phase. However, after our analysis we will show that Eve can adopt different strategies in respective phases to forge the signature without being detected. Then we present an improved scheme to increase the security.

  16. TVD finite difference schemes and artificial viscosity

    NASA Technical Reports Server (NTRS)

    Davis, S. F.

    1984-01-01

    The total variation diminishing (TVD) finite difference scheme can be interpreted as a Lax-Wendroff scheme plus an upwind weighted artificial dissipation term. If a particular flux limiter is chosen and the requirement for upwind weighting is removed, an artificial dissipation term which is based on the theory of TVD schemes is obtained which does not contain any problem dependent parameters and which can be added to existing MacCormack method codes. Numerical experiments to examine the performance of this new method are discussed.

  17. Application of high resolution NVD and TVD differencing schemes to the discrete ordinates method using unstructured grids

    NASA Astrophysics Data System (ADS)

    Coelho, Pedro J.

    2014-08-01

    High order resolution schemes based on the NVD and TVD boundedness criteria are applied to radiative transfer problems using the DOM in two-dimensional unstructured triangular grids. The implementation of these schemes in unstructured grids requires approximations, and two implementations reported in the literature are compared with a new one. Three different methods have been used to calculate the gradient of the radiation intensity at the center of the control volumes. The various schemes are applied to several test problems, the results are compared with those obtained using the step scheme, the mean flux interpolation scheme and another high order scheme based on a truncated Taylor series expansion, and the most accurate implementations are identified. It is concluded that although the high order schemes perform much better than the others, they are not as accurate as in Cartesian coordinates, and their order of convergence is lower than in that case.

  18. Structure-preserving desynchronization of minority games

    NASA Astrophysics Data System (ADS)

    Mosetti, G.; Challet, D.; Solomon, S.

    2009-10-01

    Perfect synchronicity in N-player games is a useful theoretical dream, but communication delays are inevitable and may result in asynchronous interactions. Some systems such as financial markets are asynchronous by design, and yet most theoretical models assume perfectly synchronized actions. We propose a general method to transform standard models of adaptive agents into asynchronous systems while preserving their global structure under some conditions. Using the minority game as an example, we find that the phase and fluctuations structure of the standard game subsists even in maximally asynchronous deterministic case, but that it disappears if too much stochasticity is added to the temporal structure of interaction. Allowing for heterogeneous communication speeds and activity patterns gives rise to a new information ecology that we study in details. in here

  19. Impact of nonlocal boundary-layer diffusion scheme on forecasts over Indian region

    NASA Astrophysics Data System (ADS)

    Sanjay, J.; Mukhopadhyay, P.; Singh, S. S.

    The results of incorporating a nonlocal boundary-layer diffusion scheme in a forecast model over Indian region are discussed. The simple formulation of atmospheric boundary layer height in the nonlocal diffusion scheme is examined in detail to understand how far the model simulated boundary layer height is realistic. Analyses of the temporal and spatial variability of the boundary height for three cases representing premonsoon, active monsoon and post monsoon conditions over Indian region show that it is comparable with the observational evidence. Further, for a case of active monsoon condition over Indian region, comparison of precipitation forecasts with the nonlocal scheme and the control local boundary-layer scheme clearly indicated that the model run with the nonlocal scheme is significantly more accurate in forecasting the intense precipitation locations.

  20. A solution scheme for the Euler equations based on a multi-dimensional wave model

    NASA Technical Reports Server (NTRS)

    Powell, Kenneth G.; Barth, Timothy J.; Parpia, Ijaz H.

    1993-01-01

    A scheme for the solution of scalar advection on an unstructured mesh has been developed, tested, and extended to the Euler equations. The scheme preserves a linear function exactly, and yields nearly monotone results. The flux function associated with the Euler scheme is based on a discrete 'wave model' for the system of equations. The wave model decomposes the solution gradient at a location into shear waves, entropy waves and acoustic waves and calculates the speeds, strengths and directions associated with the waves. The approach differs from typical flux-difference splitting schemes in that the waves are not assumed to propagate normal to the faces of the control volumes; directions of propagation of the waves are instead computed from solution-gradient information. Results are shown for three test cases, and two different wave models. The results are compared to those from other approaches, including MUSCL and Galerkin least squares schemes.

  1. Optimal Symmetric Ternary Quantum Encryption Schemes

    NASA Astrophysics Data System (ADS)

    Wang, Yu-qi; She, Kun; Huang, Ru-fen; Ouyang, Zhong

    2016-07-01

    In this paper, we present two definitions of the orthogonality and orthogonal rate of an encryption operator, and we provide a verification process for the former. Then, four improved ternary quantum encryption schemes are constructed. Compared with Scheme 1 (see Section 2.3), these four schemes demonstrate significant improvements in term of calculation and execution efficiency. Especially, under the premise of the orthogonal rate ɛ as secure parameter, Scheme 3 (see Section 4.1) shows the highest level of security among them. Through custom interpolation functions, the ternary secret key source, which is composed of the digits 0, 1 and 2, is constructed. Finally, we discuss the security of both the ternary encryption operator and the secret key source, and both of them show a high level of security and high performance in execution efficiency.

  2. ONU Power Saving Scheme for EPON System

    NASA Astrophysics Data System (ADS)

    Mukai, Hiroaki; Tano, Fumihiko; Tanaka, Masaki; Kozaki, Seiji; Yamanaka, Hideaki

    PON (Passive Optical Network) achieves FTTH (Fiber To The Home) economically, by sharing an optical fiber among plural subscribers. Recently, global climate change has been recognized as a serious near term problem. Power saving techniques for electronic devices are important. In PON system, the ONU (Optical Network Unit) power saving scheme has been studied and defined in XG-PON. In this paper, we propose an ONU power saving scheme for EPON. Then, we present an analysis of the power reduction effect and the data transmission delay caused by the ONU power saving scheme. According to the analysis, we propose an efficient provisioning method for the ONU power saving scheme which is applicable to both of XG-PON and EPON.

  3. A robust coding scheme for packet video

    NASA Technical Reports Server (NTRS)

    Chen, Y. C.; Sayood, Khalid; Nelson, D. J.

    1991-01-01

    We present a layered packet video coding algorithm based on a progressive transmission scheme. The algorithm provides good compression and can handle significant packet loss with graceful degradation in the reconstruction sequence. Simulation results for various conditions are presented.

  4. A robust coding scheme for packet video

    NASA Technical Reports Server (NTRS)

    Chen, Yun-Chung; Sayood, Khalid; Nelson, Don J.

    1992-01-01

    A layered packet video coding algorithm based on a progressive transmission scheme is presented. The algorithm provides good compression and can handle significant packet loss with graceful degradation in the reconstruction sequence. Simulation results for various conditions are presented.

  5. Consistency of homogenization schemes in linear poroelasticity

    NASA Astrophysics Data System (ADS)

    Pichler, Bernhard; Dormieux, Luc

    2008-08-01

    In view of extending classical micromechanics of poroelasticity to the non-saturated regime, one has to deal with different pore stresses which may be affected by the size and the shape of the pores. Introducing the macrostrain and these pore stresses as loading parameters, the macrostress of a representative volume element of a porous material can be derived by means of Levin's theorem or by means of the direct formulation of the stress average rule, respectively. A consistency requirement for a given homogenization scheme is obtained from the condition that the two approaches should yield identical results. Classical approaches (Mori-Tanaka scheme, self-consistent scheme) are shown to be only conditionally consistent. In contrast, the Ponte Castañeda-Willis scheme proves to provide consistent descriptions both of porous matrix-inclusion composites and of porous polycrystals. To cite this article: B. Pichler, L. Dormieux, C. R. Mecanique 336 (2008).

  6. High-Order Energy Stable WENO Schemes

    NASA Technical Reports Server (NTRS)

    Yamaleev, Nail K.; Carpenter, Mark H.

    2009-01-01

    A third-order Energy Stable Weighted Essentially Non-Oscillatory (ESWENO) finite difference scheme developed by Yamaleev and Carpenter was proven to be stable in the energy norm for both continuous and discontinuous solutions of systems of linear hyperbolic equations. Herein, a systematic approach is presented that enables 'energy stable' modifications for existing WENO schemes of any order. The technique is demonstrated by developing a one-parameter family of fifth-order upwind-biased ESWENO schemes; ESWENO schemes up to eighth order are presented in the appendix. New weight functions are also developed that provide (1) formal consistency, (2) much faster convergence for smooth solutions with an arbitrary number of vanishing derivatives, and (3) improved resolution near strong discontinuities.

  7. A positive finite-difference advection scheme

    SciTech Connect

    Hundsdorfer, W.; Koren, B.; Loon, M. van

    1995-03-01

    This paper examines a class of explicit finite-difference advection schemes derived along the method of lines. An important application field is large-scale atmospheric transport. The paper therefore focuses on the demand of positivity. For the spatial discretization, attention is confined to conservative schemes using five points per direction. The fourth-order central scheme and the family of {kappa}-schemes, comprising the second-order central, the second-order upwind, and the third-order upwind biased, are studied. Positivity is enforced through flux limiting. It is concluded that the limited third-order upwind discretization is the best candidate from the four examined. For the time integration attention is confined to a number of explicit Runge-Kutta methods of orders two to four. With regard to the demand of positivity, these integration methods turn out to behave almost equally and no best method could be identified. 16 refs., 4 figs., 4 tabs.

  8. Efficient Low Dissipative High Order Schemes for Multiscale MHD Flows, I: Basic Theory

    NASA Technical Reports Server (NTRS)

    Sjoegreen, Bjoern; Yee, H. C.

    2003-01-01

    The objective of this paper is to extend our recently developed highly parallelizable nonlinear stable high order schemes for complex multiscale hydrodynamic applications to the viscous MHD equations. These schemes employed multiresolution wavelets as adaptive numerical dissipation controls t o limit the amount of and to aid the selection and/or blending of the appropriate types of dissipation to be used. The new scheme is formulated for both the conservative and non-conservative form of the MHD equations in curvilinear grids. The four advantages of the present approach over existing MHD schemes reported in the open literature are as follows. First, the scheme is constructed for long-time integrations of shock/turbulence/combustion MHD flows. Available schemes are too diffusive for long-time integrations and/or turbulence/combustion problems. Second, unlike exist- ing schemes for the conservative MHD equations which suffer from ill-conditioned eigen- decompositions, the present scheme makes use of a well-conditioned eigen-decomposition obtained from a minor modification of the eigenvectors of the non-conservative MHD equations t o solve the conservative form of the MHD equations. Third, this approach of using the non-conservative eigensystem when solving the conservative equations also works well in the context of standard shock-capturing schemes for the MHD equations. Fourth, a new approach to minimize the numerical error of the divergence-free magnetic condition for high order schemes is introduced. Numerical experiments with typical MHD model problems revealed the applicability of the newly developed schemes for the MHD equations.

  9. Renormalization scheme dependence with renormalization group summation

    NASA Astrophysics Data System (ADS)

    McKeon, D. G. C.

    2015-08-01

    We consider all perturbative radiative corrections to the total e+e- annihilation cross section Re+e- showing how the renormalization group (RG) equation associated with the radiatively induced mass scale μ can be used to sum the logarithmic contributions in two ways. First of all, one can sum leading-log, next-to-leading-log, etc., contributions to Re+e- using in turn the one-loop, two-loop, etc., contributions to the RG function β . A second summation shows how all logarithmic corrections to Re+e- can be expressed entirely in terms of the log-independent contributions when one employs the full β -function. Next, using Stevenson's characterization of any choice of renormalization scheme by the use of the contributions to the β -function arising beyond two-loop order, we examine the RG scheme dependence in Re+e- when using the second way of summing logarithms. The renormalization scheme invariants that arise are then related to the renormalization scheme invariants found by Stevenson. We next consider two choices of the renormalization scheme, one which can be used to express Re+e- solely in terms of two powers of a running coupling, and the second which can be used to express Re+e- as an infinite series in the two-loop running coupling (i.e., a Lambert W -function). In both cases, Re+e- is expressed solely in terms of renormalization scheme invariant parameters that are to be computed by a perturbative evaluation of Re+e-. We then establish how in general the coupling constant arising in one renormalization scheme can be expressed as a power series of the coupling arising in any other scheme. We then establish how, by using a different renormalization mass scale at each order of perturbation theory, all renormalization scheme dependence can be absorbed into these mass scales when one uses the second way of summing logarithmic corrections to Re+e-. We then employ the approach to renormalization scheme dependency that we have applied to Re+e- to a RG summed

  10. Comparative study of signaling and routing schemes in ASTN

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Ma, Yuanyuan; Mao, Dongfeng; Zhang, Jie; Gu, Wanyi

    2005-02-01

    We have developed a GMPLS-based software platform with Intelligence Optical Network (ION) capabilities to simulate different technologies and protocols of ASTN. For optical transport network (OTN) based ASTN, usually named as automatically switched optical network (ASON), two signalling schemes, Explicit Label Control (ELC) and Backward Wavelength Reservation with N retries (BWR-N), are considered. The ELC is associated with two routing and wavelength assignment (RWA) policies, the shortest path first routing (Dijkstra algorithm) with first-fit (FF) wavelength assignment and the fixed path least congestion (FPLC) routing with FF wavelength assignment. For the BWR-N, the route is determined by Dijkstra's algorithm and the wavelength is selected through signalling process. For SDH/SONET-based ASTN, we also consider two signalling scheme, the ELC and the Forward Timeslot Reservation (FTR). Similar simulations have been performed. These signalling and routing schemes are evaluated by several crucial metrics, such as the blocking probability, the setup time, the average routing length of the connections and the control overhead. Some significant conclusions have been presented by this paper.

  11. A comparison of ENO and TVD schemes

    NASA Technical Reports Server (NTRS)

    Chang, Shih-Hung; Liou, Meng-Sing

    1988-01-01

    The numerical performance of a second-order upwind-based TVD scheme is compared with that of a uniform second-order ENO scheme on shock capturing. The cases considered include flows with Mach numbers of 2.9, 5.0, and 10.0. For cases with Mach numbers of 5.0 and 10.0, the computed ENO results are inferior to the corresponding TVD results.

  12. Signature scheme based on bilinear pairs

    NASA Astrophysics Data System (ADS)

    Tong, Rui Y.; Geng, Yong J.

    2013-03-01

    An identity-based signature scheme is proposed by using bilinear pairs technology. The scheme uses user's identity information as public key such as email address, IP address, telephone number so that it erases the cost of forming and managing public key infrastructure and avoids the problem of user private generating center generating forgery signature by using CL-PKC framework to generate user's private key.

  13. A modified scheme for biotyping Gardnerella vaginalis.

    PubMed

    Benito, R; Vazquez, J A; Berron, S; Fenoll, A; Saez-Neito, J A

    1986-06-01

    A scheme is proposed for biotyping Gardnerella vaginalis, based on detection of hippurate hydrolysis, beta-galactosidase (ONPG) and lipase, and fermentation of arabinose, galactose and xylose. Seventeen biotypes were found among 197 strains from asymptomatic women and patients with bacterial vaginosis (non-specific vaginitis). The distribution of biotypes was similar in both populations but some biotypes were found more frequently in patients. The proposed scheme is compared with those previously described.

  14. Binary Schemes of Vapor Bubble Growth

    NASA Astrophysics Data System (ADS)

    Zudin, Yu. B.

    2015-05-01

    A problem on spherically symmetric growth of a vapor bubble in an infi nite volume of a uniformly superheated liquid is considered. A description of the limiting schemes of bubble growth is presented. A binary inertial-thermal bubble growth scheme characterized by such specifi c features as the "three quarters" growth law and the effect of "pressure blocking" in a vapor phase is considered.

  15. Composite centered schemes for multidimensional conservation laws

    SciTech Connect

    Liska, R.; Wendroff, B.

    1998-05-08

    The oscillations of a centered second order finite difference scheme and the excessive diffusion of a first order centered scheme can be overcome by global composition of the two, that is by performing cycles consisting of several time steps of the second order method followed by one step of the diffusive method. The authors show the effectiveness of this approach on some test problems in two and three dimensions.

  16. Dynamic Restarting Schemes for Eigenvalue Problems

    SciTech Connect

    Wu, Kesheng; Simon, Horst D.

    1999-03-10

    In studies of restarted Davidson method, a dynamic thick-restart scheme was found to be excellent in improving the overall effectiveness of the eigen value method. This paper extends the study of the dynamic thick-restart scheme to the Lanczos method for symmetric eigen value problems and systematically explore a range of heuristics and strategies. We conduct a series of numerical tests to determine their relative strength and weakness on a class of electronic structure calculation problems.

  17. Asynchronous Communication Scheme For Hypercube Computer

    NASA Technical Reports Server (NTRS)

    Madan, Herb S.

    1988-01-01

    Scheme devised for asynchronous-message communication system for Mark III hypercube concurrent-processor network. Network consists of up to 1,024 processing elements connected electrically as though were at corners of 10-dimensional cube. Each node contains two Motorola 68020 processors along with Motorola 68881 floating-point processor utilizing up to 4 megabytes of shared dynamic random-access memory. Scheme intended to support applications requiring passage of both polled or solicited and unsolicited messages.

  18. On nonstandard finite difference schemes in biosciences

    NASA Astrophysics Data System (ADS)

    Anguelov, R.; Dumont, Y.; Lubuma, J. M.-S.

    2012-10-01

    We design, analyze and implement nonstandard finite difference (NSFD) schemes for some differential models in biosciences. The NSFD schemes are reliable in three directions. They are topologically dynamically consistent for onedimensional models. They can replicate the global asymptotic stability of the disease-free equilibrium of the MSEIR model in epidemiology whenever the basic reproduction number is less than 1. They preserve the positivity and boundedness property of solutions of advection-reaction and reaction-diffusion equations.

  19. FRESCO: flexible alignment with rectangle scoring schemes.

    PubMed

    Dalca, A V; Brudno, M

    2008-01-01

    While the popular DNA sequence alignment tools incorporate powerful heuristics to allow for fast and accurate alignment of DNA, most of them still optimize the classical Needleman Wunsch scoring scheme. The development of novel scoring schemes is often hampered by the difficulty of finding an optimizing algorithm for each non-trivial scheme. In this paper we define the broad class of rectangle scoring schemes, and describe an algorithm and tool that can align two sequences with an arbitrary rectangle scoring scheme in polynomial time. Rectangle scoring schemes encompass some of the popular alignment scoring metrics currently in use, as well as many other functions. We investigate a novel scoring function based on minimizing the expected number of random diagonals observed with the given scores and show that it rivals the LAGAN and Clustal-W aligners, without using any biological or evolutionary parameters. The FRESCO program, freely available at http://compbio.cs.toronto.edu/fresco, gives bioinformatics researchers the ability to quickly compare the performance of other complex scoring formulas without having to implement new algorithms to optimize them.

  20. Simplification of the unified gas kinetic scheme.

    PubMed

    Chen, Songze; Guo, Zhaoli; Xu, Kun

    2016-08-01

    The unified gas kinetic scheme (UGKS) is an asymptotic preserving (AP) scheme for kinetic equations. It is superior for transition flow simulation and has been validated in the past years. However, compared to the well-known discrete ordinate method (DOM), which is a classical numerical method solving the kinetic equations, the UGKS needs more computational resources. In this study, we propose a simplification of the unified gas kinetic scheme. It allows almost identical numerical cost as the DOM, but predicts numerical results as accurate as the UGKS. In the simplified scheme, the numerical flux for the velocity distribution function and the numerical flux for the macroscopic conservative quantities are evaluated separately. The equilibrium part of the UGKS flux is calculated by analytical solution instead of the numerical quadrature in velocity space. The simplification is equivalent to a flux hybridization of the gas kinetic scheme for the Navier-Stokes (NS) equations and the conventional discrete ordinate method. Several simplification strategies are tested, through which we can identify the key ingredient of the Navier-Stokes asymptotic preserving property. Numerical tests show that, as long as the collision effect is built into the macroscopic numerical flux, the numerical scheme is Navier-Stokes asymptotic preserving, regardless the accuracy of the microscopic numerical flux for the velocity distribution function. PMID:27627418

  1. Simplification of the unified gas kinetic scheme

    NASA Astrophysics Data System (ADS)

    Chen, Songze; Guo, Zhaoli; Xu, Kun

    2016-08-01

    The unified gas kinetic scheme (UGKS) is an asymptotic preserving (AP) scheme for kinetic equations. It is superior for transition flow simulation and has been validated in the past years. However, compared to the well-known discrete ordinate method (DOM), which is a classical numerical method solving the kinetic equations, the UGKS needs more computational resources. In this study, we propose a simplification of the unified gas kinetic scheme. It allows almost identical numerical cost as the DOM, but predicts numerical results as accurate as the UGKS. In the simplified scheme, the numerical flux for the velocity distribution function and the numerical flux for the macroscopic conservative quantities are evaluated separately. The equilibrium part of the UGKS flux is calculated by analytical solution instead of the numerical quadrature in velocity space. The simplification is equivalent to a flux hybridization of the gas kinetic scheme for the Navier-Stokes (NS) equations and the conventional discrete ordinate method. Several simplification strategies are tested, through which we can identify the key ingredient of the Navier-Stokes asymptotic preserving property. Numerical tests show that, as long as the collision effect is built into the macroscopic numerical flux, the numerical scheme is Navier-Stokes asymptotic preserving, regardless the accuracy of the microscopic numerical flux for the velocity distribution function.

  2. Dynamical Scheme for Interferometric Measurements of Full-Counting Statistics

    NASA Astrophysics Data System (ADS)

    Dasenbrook, David; Flindt, Christian

    2016-09-01

    We propose a dynamical scheme for measuring the full-counting statistics in a mesoscopic conductor using an electronic Mach-Zehnder interferometer. The conductor couples capacitively to one arm of the interferometer and causes a phase shift which is proportional to the number of transferred charges. Importantly, the full-counting statistics can be obtained from average current measurements at the outputs of the interferometer. The counting field can be controlled by varying the time delay between two separate voltage signals applied to the conductor and the interferometer, respectively. As a specific application, we consider measuring the entanglement entropy generated by partitioning electrons on a quantum point contact. Our scheme is robust against moderate environmental dephasing and may be realized thanks to recent advances in gigahertz quantum electronics.

  3. A pattern jitter free AFC scheme for mobile satellite systems

    NASA Technical Reports Server (NTRS)

    Yoshida, Shousei

    1993-01-01

    This paper describes a scheme for pattern jitter free automatic frequency control (AFC) with a wide frequency acquisition range. In this scheme, equalizing signals fed to the frequency discriminator allow pattern jitter free performance to be achieved for all roll-off factors. In order to define the acquisition range, frequency discrimination characateristics are analyzed on a newly derived frequency domain model. As a result, it is shown that a sufficiently wide acquisition range over a given system symbol rate can be achieved independent of symbol timing errors. Additionally, computer simulation demonstrates that frequency jitter performance improves in proportion to E(sub b)/N(sub 0) because pattern-dependent jitter is suppressed in the discriminator output. These results show significant promise for applciation to mobile satellite systems, which feature relatively low symbol rate transmission with an approximately 0.4-0.7 roll-off factor.

  4. A scheme for supporting distributed data structures on multicomputers

    NASA Technical Reports Server (NTRS)

    Hiranandani, Seema; Saltz, Joel; Berryman, Harry; Mehrotra, Piyush

    1990-01-01

    A data migration mechanism is proposed that allows an explicit and controlled mapping of data to memory. While read or write copies of each data element can be assigned to any processor's memory, longer term storage of each data element is assigned to a specific location in the memory of a particular processor. The proposed integration of a data migration scheme with a compiler is able to eliminate the migration of unneeded data that can occur in multiprocessor paging or caching. The overhead of adjudicating multiple concurrent writes to the same page or cache line is also eliminated. Data is presented that suggests that the scheme may be a pratical method for efficiently supporting data migration.

  5. Meal-feeding scheme: twenty years of research in Brazil.

    PubMed

    Bazotte, R B; Batista, M R; Curi, R

    2000-09-01

    Naomi Shinomiya Hell was the first researcher to investigate the physiological adaptations to a meal-feeding scheme (MFS) in Brazil. Over a period of 20 years, from 1979 to 1999, Naomi's group determined the physiological and metabolic adaptations induced by this feeding scheme in rats. The group showed the persistence of such adaptations even when MFS is associated with moderate exercise training and the performance to a session of intense physical effort. The metabolic changes induced by the feeding training were discriminated from those caused by the effective fasting period. Naomi made an important contribution to the understanding of the MFS but a lot still has to be done. One crucial question still remains to be satisfactorily answered: what is the ideal control for the MFS? PMID:10973128

  6. A color-coded vision scheme for robotics

    NASA Technical Reports Server (NTRS)

    Johnson, Kelley Tina

    1991-01-01

    Most vision systems for robotic applications rely entirely on the extraction of information from gray-level images. Humans, however, regularly depend on color to discriminate between objects. Therefore, the inclusion of color in a robot vision system seems a natural extension of the existing gray-level capabilities. A method for robot object recognition using a color-coding classification scheme is discussed. The scheme is based on an algebraic system in which a two-dimensional color image is represented as a polynomial of two variables. The system is then used to find the color contour of objects. In a controlled environment, such as that of the in-orbit space station, a particular class of objects can thus be quickly recognized by its color.

  7. Vorticity Preserving Flux Corrected Transport Scheme for the Acoustic Equations

    SciTech Connect

    Lung, Tyler B.; Roe, Phil; Morgan, Nathaniel R.

    2012-08-15

    Long term research goals are to develop an improved cell-centered Lagrangian Hydro algorithm with the following qualities: 1. Utilizes Flux Corrected Transport (FCT) to achieve second order accuracy with multidimensional physics; 2. Does not rely on the one-dimensional Riemann problem; and 3. Implements a form of vorticity control. Short term research goals are to devise and implement a 2D vorticity preserving FCT solver for the acoustic equations on an Eulerian mesh: 1. Develop a flux limiting mechanism for systems of governing equations with symmetric wave speeds; 2. Verify the vorticity preserving properties of the scheme; and 3. Compare the performance of the scheme to traditional MUSCL-Hancock and other algorithms.

  8. A Linearized Prognostic Cloud Scheme in NASAs Goddard Earth Observing System Data Assimilation Tools

    NASA Technical Reports Server (NTRS)

    Holdaway, Daniel; Errico, Ronald M.; Gelaro, Ronald; Kim, Jong G.; Mahajan, Rahul

    2015-01-01

    A linearized prognostic cloud scheme has been developed to accompany the linearized convection scheme recently implemented in NASA's Goddard Earth Observing System data assimilation tools. The linearization, developed from the nonlinear cloud scheme, treats cloud variables prognostically so they are subject to linearized advection, diffusion, generation, and evaporation. Four linearized cloud variables are modeled, the ice and water phases of clouds generated by large-scale condensation and, separately, by detraining convection. For each species the scheme models their sources, sublimation, evaporation, and autoconversion. Large-scale, anvil and convective species of precipitation are modeled and evaporated. The cloud scheme exhibits linearity and realistic perturbation growth, except around the generation of clouds through large-scale condensation. Discontinuities and steep gradients are widely used here and severe problems occur in the calculation of cloud fraction. For data assimilation applications this poor behavior is controlled by replacing this part of the scheme with a perturbation model. For observation impacts, where efficiency is less of a concern, a filtering is developed that examines the Jacobian. The replacement scheme is only invoked if Jacobian elements or eigenvalues violate a series of tuned constants. The linearized prognostic cloud scheme is tested by comparing the linear and nonlinear perturbation trajectories for 6-, 12-, and 24-h forecast times. The tangent linear model performs well and perturbations of clouds are well captured for the lead times of interest.

  9. Filtered schemes for Hamilton-Jacobi equations: A simple construction of convergent accurate difference schemes

    NASA Astrophysics Data System (ADS)

    Oberman, Adam M.; Salvador, Tiago

    2015-03-01

    We build a simple and general class of finite difference schemes for first order Hamilton-Jacobi (HJ) Partial Differential Equations. These filtered schemes are convergent to the unique viscosity solution of the equation. The schemes are accurate: we implement second, third and fourth order accurate schemes in one dimension and second order accurate schemes in two dimensions, indicating how to build higher order ones. They are also explicit, which means they can be solved using the fast sweeping method. The accuracy of the method is validated with computational results for the eikonal equation and other HJ equations in one and two dimensions, using filtered schemes made from standard centered differences, higher order upwinding and ENO interpolation.

  10. A Scalable Media Multicasting Scheme

    NASA Astrophysics Data System (ADS)

    Youwei, Zhang

    IP multicast has been proved to be unfeasible for deployment, Application Layer Multicast (ALM) Based on end multicast system is practical and more scalable than IP multicast in Internet. In this paper, an ALM protocol called Scalable multicast for High Definition streaming media (SHD) is proposed in which end to end transmission capability is fully cultivated for HD media transmission without increasing much control overhead. Similar to the transmission style of BiTtorrent, hosts only forward part of data piece according to the available bandwidth that improves the usage of bandwidth greatly. On the other hand, some novel strategies are adopted to overcome the disadvantages of BiTtorrent protocol in streaming media transmission. Data transmission between hosts is implemented in many-one transmission style in Hierarchical architecture in most circumstances. Simulations implemented on Internet-like topology indicate that SHD achieves low link stress, end to end latency and stability.

  11. Incoherent control of locally controllable quantum systems

    SciTech Connect

    Dong Daoyi; Zhang Chenbin; Rabitz, Herschel; Pechen, Alexander; Tarn, T.-J.

    2008-10-21

    An incoherent control scheme for state control of locally controllable quantum systems is proposed. This scheme includes three steps: (1) amplitude amplification of the initial state by a suitable unitary transformation, (2) projective measurement of the amplified state, and (3) final optimization by a unitary controlled transformation. The first step increases the amplitudes of some desired eigenstates and the corresponding probability of observing these eigenstates, the second step projects, with high probability, the amplified state into a desired eigenstate, and the last step steers this eigenstate into the target state. Within this scheme, two control algorithms are presented for two classes of quantum systems. As an example, the incoherent control scheme is applied to the control of a hydrogen atom by an external field. The results support the suggestion that projective measurements can serve as an effective control and local controllability information can be used to design control laws for quantum systems. Thus, this scheme establishes a subtle connection between control design and controllability analysis of quantum systems and provides an effective engineering approach in controlling quantum systems with partial controllability information.

  12. A scheme for tracking and pointing at small celestial bodies during high velocity encounters

    NASA Technical Reports Server (NTRS)

    Burdick, G. M.; Lin, H.-S.; Wong, E. C.

    1982-01-01

    A scheme has been developed and verified for closed-loop tracking and pointing space-borne science instruments at small celestial bodies, such as comets and asteroids, during high velocity encounters. To overcome ephemeris uncertainties for these bodies, the scheme involves sequential estimation of flyby model parameters. The design consists of a two-axis gimballed platform mounted on a three-axis stabilized spacecraft. A platform-mounted optical tracker provides closed-loop target measurements and precision micro-step actuators enable high-rate platform slewing. For comet missions which involve dust particle impact disturbances, a dual-mode attitude control scheme is presented for minimizing transient response time.

  13. Cavity QED scheme for realizing the optimal universal quantum cloning of the polarization state of photons

    SciTech Connect

    Zou Xubo; Mathis, W.

    2005-08-15

    We propose a scheme to realize the optimal universal quantum cloning of the polarization state of the photons in context of a microwave cavity quantum electrodynamics. The scheme is based on the resonant interaction of three-level {lambda}-type atoms with two cavity modes. The operation requires atoms to fly one by one through the cavity. The interaction time between each of the atoms and the cavity is appropriately controlled by using a velocity selector. The scheme is deterministic, and is feasible by the current experimental technology.

  14. Cavity QED scheme for realizing the optimal universal quantum cloning of the polarization state of photons

    NASA Astrophysics Data System (ADS)

    Zou, Xubo; Mathis, W.

    2005-08-01

    We propose a scheme to realize the optimal universal quantum cloning of the polarization state of the photons in context of a microwave cavity quantum electrodynamics. The scheme is based on the resonant interaction of three-level Λ -type atoms with two cavity modes. The operation requires atoms to fly one by one through the cavity. The interaction time between each of the atoms and the cavity is appropriately controlled by using a velocity selector. The scheme is deterministic, and is feasible by the current experimental technology.

  15. Adaptive Directional Multicast Scheme in mmWave WPANs with Directional Antennas

    NASA Astrophysics Data System (ADS)

    Shin, Kyungchul; Kim, Youngsun; Kang, Chul-Hee

    This letter considers problems with an efficient link layer multicasting technique in a wireless personal area network environment using a directional antenna. First, we propose an adaptive directional multicast scheme (ADMS) for delay-sensitive applications in mmWave WPAN with directional antenna. Second, the proposed ADMS aims to improve throughput as well as satisfy the application-specific delay requirements. We evaluate the performances of legacy Medium Access Control, Life Centric Approach, and adaptive directional multicast schemes via QualNet 5.0. Our results show that the proposed scheme provides better performance in terms of total network throughput, average transmission time, packet delivery ratio and decodable frame ratio.

  16. A key management scheme for tiered wireless sensor network with self-healing capability

    NASA Astrophysics Data System (ADS)

    Wang, Maoyu; Tang, Helen; Yu, F. R.

    2013-05-01

    This paper presents a novel key management scheme for a tiered self-healing wireless sensor network. A tiered wireless sensor network with self-healing features draws extensive attention because of its scalability, robustness and reliability. A tiered key management scheme to support the cluster membership and the self-healing features is proposed with emphasis on the control of a node's participation and re-keying when joining a new cluster. The security and overhead analysis demonstrates the proposed scheme is effective and efficient with respect to communication, computation, and memory overhead for operation in a hostile environment.

  17. Combining image-processing and image compression schemes

    NASA Technical Reports Server (NTRS)

    Greenspan, H.; Lee, M.-C.

    1995-01-01

    An investigation into the combining of image-processing schemes, specifically an image enhancement scheme, with existing compression schemes is discussed. Results are presented on the pyramid coding scheme, the subband coding scheme, and progressive transmission. Encouraging results are demonstrated for the combination of image enhancement and pyramid image coding schemes, especially at low bit rates. Adding the enhancement scheme to progressive image transmission allows enhanced visual perception at low resolutions. In addition, further progressing of the transmitted images, such as edge detection schemes, can gain from the added image resolution via the enhancement.

  18. An efficient authentication scheme for telecare medicine information systems.

    PubMed

    Zhu, Zhian

    2012-12-01

    To ensure patients' privacy, such as telephone number, medical record number, health information, etc., authentication schemes for telecare medicine information systems (TMIS) have been studied widely. Recently, Wei et al. proposed an efficient authentication scheme for TMIS. They claimed their scheme could resist various attacks. However, in this paper, we will show their scheme is vulnerable to an off-line password guessing attack when user's smart card is lost. To improve the security, we propose a new authentication scheme for TMIS. The analysis shows our scheme could overcome the weaknesses in Wei et al.'s scheme and has better performance than their scheme. PMID:22527784

  19. Establishing a Proficiency Testing Scheme for Drinking Water Radiochemistry

    SciTech Connect

    Brookman, Brian

    2008-08-14

    As part of its international water proficiency testing (PT) scheme, 'Aquacheck', the LGC Proficiency Testing Group has established a new water radiochemistry PT scheme. The PT scheme is aimed at laboratories who undertake radiochemical analysis on drinking water samples as part of an environmental monitoring programme. Following a scheme design and feasibility study, the new scheme was established to monitor the laboratory performance of participants undertaking the determination of gross alpha, gross beta and tritium activity. Three rounds of the new water radiochemistry PT scheme are now complete. This paper explains the process of establishing such a scheme, reviews the results so far, and addresses future development of the scheme.

  20. An Encryption Scheme for Communication Internet SCADA Components

    NASA Astrophysics Data System (ADS)

    Robles, Rosslin John; Kim, Tai-Hoon

    The trend in most systems is that they are connected through the Internet. Traditional Supervisory Control and Data Acquisition Systems (SCADA) is connected only in a limited private network. SCADA is considered a critical infrastructure, and connecting to the internet is putting the society on jeopardy, some operators hold back on connecting it to the internet. But since the internet Supervisory Control and Data Acquisition Systems (SCADA) facility has brought a lot of advantages in terms of control, data viewing and generation. Along with these advantages, are security issues regarding web SCADA, operators are pushed to connect Supervisory Control and Data Acquisition Systems (SCADA) through the internet. Because of this, many issues regarding security surfaced. In this paper, we discuss web SCADA and the issues regarding security. As a countermeasure, a web SCADA security solution using crossed-crypto-scheme is proposed to be used in the communication of SCADA components.

  1. A classification scheme for risk assessment methods.

    SciTech Connect

    Stamp, Jason Edwin; Campbell, Philip LaRoche

    2004-08-01

    This report presents a classification scheme for risk assessment methods. This scheme, like all classification schemes, provides meaning by imposing a structure that identifies relationships. Our scheme is based on two orthogonal aspects--level of detail, and approach. The resulting structure is shown in Table 1 and is explained in the body of the report. Each cell in the Table represent a different arrangement of strengths and weaknesses. Those arrangements shift gradually as one moves through the table, each cell optimal for a particular situation. The intention of this report is to enable informed use of the methods so that a method chosen is optimal for a situation given. This report imposes structure on the set of risk assessment methods in order to reveal their relationships and thus optimize their usage.We present a two-dimensional structure in the form of a matrix, using three abstraction levels for the rows and three approaches for the columns. For each of the nine cells in the matrix we identify the method type by name and example. The matrix helps the user understand: (1) what to expect from a given method, (2) how it relates to other methods, and (3) how best to use it. Each cell in the matrix represent a different arrangement of strengths and weaknesses. Those arrangements shift gradually as one moves through the table, each cell optimal for a particular situation. The intention of this report is to enable informed use of the methods so that a method chosen is optimal for a situation given. The matrix, with type names in the cells, is introduced in Table 2 on page 13 below. Unless otherwise stated we use the word 'method' in this report to refer to a 'risk assessment method', though often times we use the full phrase. The use of the terms 'risk assessment' and 'risk management' are close enough that we do not attempt to distinguish them in this report. The remainder of this report is organized as follows. In Section 2 we provide context for this report

  2. Performance of Improved High-Order Filter Schemes for Turbulent Flows with Shocks

    NASA Technical Reports Server (NTRS)

    Kotov, Dmitry Vladimirovich; Yee, Helen M C.

    2013-01-01

    The performance of the filter scheme with improved dissipation control ? has been demonstrated for different flow types. The scheme with local ? is shown to obtain more accurate results than its counterparts with global or constant ?. At the same time no additional tuning is needed to achieve high accuracy of the method when using the local ? technique. However, further improvement of the method might be needed for even more complex and/or extreme flows.

  3. Probability of undetected error after decoding for a concatenated coding scheme

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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 NASA telecommand system is analyzed.

  4. Geophysical Inversion through Hierarchical Genetic Algorithm Scheme

    NASA Astrophysics Data System (ADS)

    Furman, Alex; Huisman, Johan A.

    2010-05-01

    Geophysical investigation is a powerful tool that allows non-invasive and non-destructive mapping of subsurface states and properties. However, non-uniqueness associated with the inversion process halts these methods from becoming of more quantitative use. One major direction researchers are going is constraining the inverse problem by hydrological observations and models. An alternative to the commonly used direct inversion methods are global optimization schemes (such as genetic algorithms and Monte Carlo Markov Chain methods). However, the major limitation here is the desired high resolution of the tomographic image, which leads to a large number of parameters and an unreasonably high computational effort when using global optimization schemes. One way to overcome these problems is to combine the advantages of both direct and global inversion methods through hierarchical inversion. That is, starting the inversion with relatively coarse resolution of parameters, achieving good inversion using one of the two inversion schemes (global or direct), and then refining the resolution and applying a combination of global and direct inversion schemes for the whole domain or locally. In this work we explore through synthetic case studies the option of using a global optimization scheme for inversion of electrical resistivity tomography data through hierarchical refinement of the model resolution.

  5. Identification Schemes from Key Encapsulation Mechanisms

    NASA Astrophysics Data System (ADS)

    Anada, Hiroaki; Arita, Seiko

    We propose a generic conversion from a key encapsulation mechanism (KEM) to an identification (ID) scheme. The conversion derives the security for ID schemes against concurrent man-in-the-middle (cMiM) attacks from the security for KEMs against adaptive chosen ciphertext attacks on one-wayness (one-way-CCA2). Then, regarding the derivation as a design principle of ID schemes, we develop a series of concrete one-way-CCA2 secure KEMs. We start with El Gamal KEM and prove it secure against non-adaptive chosen ciphertext attacks on one-wayness (one-way-CCA1) in the standard model. Then, we apply a tag framework with the algebraic trick of Boneh and Boyen to make it one-way-CCA2 secure based on the Gap-CDH assumption. Next, we apply the CHK transformation or a target collision resistant hash function to exit the tag framework. And finally, as it is better to rely on the CDH assumption rather than the Gap-CDH assumption, we apply the Twin DH technique of Cash, Kiltz and Shoup. The application is not “black box” and we do it by making the Twin DH technique compatible with the algebraic trick. The ID schemes obtained from our KEMs show the highest performance in both computational amount and message length compared with previously known ID schemes secure against concurrent man-in-the-middle attacks.

  6. A patient privacy protection scheme for medical information system.

    PubMed

    Lu, Chenglang; Wu, Zongda; Liu, Mingyong; Chen, Wei; Guo, Junfang

    2013-12-01

    In medical information systems, there are a lot of confidential information about patient privacy. It is therefore an important problem how to prevent patient's personal privacy information from being disclosed. Although traditional security protection strategies (such as identity authentication and authorization access control) can well ensure data integrity, they cannot prevent system's internal staff (such as administrators) from accessing and disclosing patient privacy information. In this paper, we present an effective scheme to protect patients' personal privacy for a medical information system. In the scheme, privacy data before being stored in the database of the server of a medical information system would be encrypted using traditional encryption algorithms, so that the data even if being disclosed are also difficult to be decrypted and understood. However, to execute various kinds of query operations over the encrypted data efficiently, we would also augment the encrypted data with additional index, so as to process as much of the query as possible at the server side, without the need to decrypt the data. Thus, in this paper, we mainly explore how the index of privacy data is constructed, and how a query operation over privacy data is translated into a new query over the corresponding index so that it can be executed at the server side immediately. Finally, both theoretical analysis and experimental evaluation validate the practicality and effectiveness of our proposed scheme.

  7. A patient privacy protection scheme for medical information system.

    PubMed

    Lu, Chenglang; Wu, Zongda; Liu, Mingyong; Chen, Wei; Guo, Junfang

    2013-12-01

    In medical information systems, there are a lot of confidential information about patient privacy. It is therefore an important problem how to prevent patient's personal privacy information from being disclosed. Although traditional security protection strategies (such as identity authentication and authorization access control) can well ensure data integrity, they cannot prevent system's internal staff (such as administrators) from accessing and disclosing patient privacy information. In this paper, we present an effective scheme to protect patients' personal privacy for a medical information system. In the scheme, privacy data before being stored in the database of the server of a medical information system would be encrypted using traditional encryption algorithms, so that the data even if being disclosed are also difficult to be decrypted and understood. However, to execute various kinds of query operations over the encrypted data efficiently, we would also augment the encrypted data with additional index, so as to process as much of the query as possible at the server side, without the need to decrypt the data. Thus, in this paper, we mainly explore how the index of privacy data is constructed, and how a query operation over privacy data is translated into a new query over the corresponding index so that it can be executed at the server side immediately. Finally, both theoretical analysis and experimental evaluation validate the practicality and effectiveness of our proposed scheme. PMID:24166018

  8. Enhancement of protection against influenza by complex prophylactic schemes.

    PubMed

    Zykov, M P; Rudenko, L G; Subotina, T I

    1980-01-01

    A hundred percent protection against influenza was obtained by means of joined application of two antiinfluenza vaccines [inactivated and live ones]. At the same time complete mobilization of various specific mechanisms of protection against influenza [humoral, cellular and local] was observed. This mode of vaccination was designated for protection against influenza of persons exposed, in the course of influenza epidemics, to enhanced possibility of getting infected [medical personnel, teachers, employees of public transport, shop assistants and others]. The second complex scheme of protection - simultaneous vaccination against influenza and tuberculosis - showed and made possible nonspecific stimulation of a specific protection against influenza by BCG vaccine. As a result frequency of seroconversion with regard to influenza amounted to 96%, the increase of influenza antibodies was 21.2 fold, their mean geometrical titers [inverse value] being 182.0. Also other problems connected with elaboration of complex schemes of protection against influenza by means of inactivated vaccines were investigated. The author presents concrete proposals for enlarged mutual elaboration by specialists of member countries of CMEA [Council for mutual economic assistance] not only of new complex schemes for influenza control but also for cooperation on other problems. PMID:7462614

  9. Reconstruction of unsteady viscous flows using data assimilation schemes

    NASA Astrophysics Data System (ADS)

    Mons, V.; Chassaing, J.-C.; Gomez, T.; Sagaut, P.

    2016-07-01

    This paper investigates the use of various data assimilation (DA) approaches for the reconstruction of the unsteady flow past a cylinder in the presence of incident coherent gusts. Variational, ensemble Kalman filter-based and ensemble-based variational DA techniques are deployed along with a 2D compressible Navier-Stokes flow solver, which is also used to generate synthetic observations of a reference flow. The performance of these DA schemes is thoroughly analyzed for various types of observations ranging from the global aerodynamic coefficients of the cylinder to the full 2D flow field. Moreover, different reconstruction scenarios are investigated in order to assess the robustness of these methods for large scale DA problems with up to 105 control variables. In particular, we show how an iterative procedure can be used within the framework of ensemble-based methods to deal with both non-uniform unsteady boundary conditions and initial field reconstruction. The different methodologies developed and assessed in this work give a review of what can be done with DA schemes in computational fluid dynamics (CFD) paradigm. In the same time, this work also provides useful information which can also turn out to be rational arguments in the DA scheme choice dedicated to a specific CFD application.

  10. The Nonlinear Characteristic scheme in X-Y geometries

    SciTech Connect

    Walters, W.F.; Wareing, T.A.

    1994-08-01

    The Nonlinear Characteristic (NC) scheme for solving the discrete-ordinates form of the transport equation has recently been introduced and used to analyze one-dimensional slab transport problems. The purpose of this paper is to determine the accuracy and positivity of the NC scheme as extended to solve two-dimensional X-Y problems. We compare the results obtained using the NC scheme to those obtained using the Bilinear Discontinuous (BLD) scheme, the Bilinear Nodal (BLN) scheme, Linear Characteristic scheme, and the Diamond Difference with Fixup (DD/F) scheme. As was found in one-dimensional applications, the NC scheme is strictly positive and as accurate or more accurate than the other schemes for all meshes examined. The accuracy of the NC scheme for coarse meshes is particularity outstanding compared to that of the other schemes.

  11. A Comprehensive Study of Data Collection Schemes Using Mobile Sinks in Wireless Sensor Networks

    PubMed Central

    Khan, Abdul Waheed; Abdullah, Abdul Hanan; Anisi, Mohammad Hossein; Bangash, Javed Iqbal

    2014-01-01

    Recently sink mobility has been exploited in numerous schemes to prolong the lifetime of wireless sensor networks (WSNs). Contrary to traditional WSNs where sensory data from sensor field is ultimately sent to a static sink, mobile sink-based approaches alleviate energy-holes issues thereby facilitating balanced energy consumption among nodes. In mobility scenarios, nodes need to keep track of the latest location of mobile sinks for data delivery. However, frequent propagation of sink topological updates undermines the energy conservation goal and therefore should be controlled. Furthermore, controlled propagation of sinks' topological updates affects the performance of routing strategies thereby increasing data delivery latency and reducing packet delivery ratios. This paper presents a taxonomy of various data collection/dissemination schemes that exploit sink mobility. Based on how sink mobility is exploited in the sensor field, we classify existing schemes into three classes, namely path constrained, path unconstrained, and controlled sink mobility-based schemes. We also organize existing schemes based on their primary goals and provide a comparative study to aid readers in selecting the appropriate scheme in accordance with their particular intended applications and network dynamics. Finally, we conclude our discussion with the identification of some unresolved issues in pursuit of data delivery to a mobile sink. PMID:24504107

  12. Dropout--Mertonian or reproduction scheme?

    PubMed

    Horowitz, T R

    1992-01-01

    This article reports on dropouts in four schools in Israel. Two main research questions were addressed: (1) Is it possible to identify a potential dropout through examination of his/her attitudes and competence before the actual act of leaving school? (2) Is there a difference between dropouts and persistent students in different educational settings (academic, vocational, agricultural, and comprehensive high schools)? Significant differences were found in the attitudes of persistent students and dropouts even before the act of dropping out occurred. In the vocational, comprehensive, and agricultural schools, the dropouts scored more positively on the self-estrangement, meaninglessness, and misfeasance scales. In the academic school, the dropouts scored positively on the anxiety scale. Results were interpreted in light of the Mertonian scheme of ends and means as well as the reproduction scheme. The Mertonian scheme was deemed more applicable.

  13. Campylobacter biotyping scheme of epidemiological value.

    PubMed Central

    Bolton, F J; Holt, A V; Hutchinson, D N

    1984-01-01

    A biotyping scheme has been developed which utilises 12 tests, including growth at 28 degrees C, hippurate hydrolysis, and 10 resistotyping tests. These tests are arranged in groups of three, and by assigning a numerical value to each positive test a four figure code is produced for each strain. The order of the tests is such that campylobacters are both speciated and biotyped . This scheme recognises Campylobacter jejuni, C coli, "C laridis ," C fetus fetus, and C fetus subspecies venerealis. The reproducibility of the biotyping technique and the stability of the biotype code have been determined by testing campylobacter reference strains. The routine application of the scheme has also been evaluated by biotyping 1000 recent campylobacter isolates, and the epidemiological value has been confirmed by testing serotyped isolates from several milk borne outbreaks. PMID:6373839

  14. A compositional classification scheme for meteoritic chondrules

    NASA Technical Reports Server (NTRS)

    Sears, Derek W. G.; Jie, LU; Benoit, Paul H.; Dehart, John M.; Lofgren, Gary E.

    1992-01-01

    A compositionally based classification scheme for chondrules is proposed that will help in systematizing the wealth of data available and disentangling the effects of nebular and subsequent processes. The classification is not by texture or the composition of a single phase, or a mixture of these two, but rather is a comprehensive, systematic approach which uses the composition of the two main chondrule components. This scheme is applicable to over 95 percent of the chondrules and is easily applied using an electron microprobe. It stresses the original diversity of the chondrules and the complex yet facile way in which they respond to parent-body metamorphism. Results using this classification scheme suggest that arguments against an important role of chondrules in determining the compositional trends of the chondrites have been premature.

  15. Cooling scheme for turbine hot parts

    DOEpatents

    Hultgren, Kent Goran; Owen, Brian Charles; Dowman, Steven Wayne; Nordlund, Raymond Scott; Smith, Ricky Lee

    2000-01-01

    A closed-loop cooling scheme for cooling stationary combustion turbine components, such as vanes, ring segments and transitions, is provided. The cooling scheme comprises: (1) an annular coolant inlet chamber, situated between the cylinder and blade ring of a turbine, for housing coolant before being distributed to the turbine components; (2) an annular coolant exhaust chamber, situated between the cylinder and the blade ring and proximate the annular coolant inlet chamber, for collecting coolant exhaust from the turbine components; (3) a coolant inlet conduit for supplying the coolant to said coolant inlet chamber; (4) a coolant exhaust conduit for directing coolant from said coolant exhaust chamber; and (5) a piping arrangement for distributing the coolant to and directing coolant exhaust from the turbine components. In preferred embodiments of the invention, the cooling scheme further comprises static seals for sealing the blade ring to the cylinder and flexible joints for attaching the blade ring to the turbine components.

  16. Upwind and symmetric shock-capturing schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1987-01-01

    The development of numerical methods for hyperbolic conservation laws has been a rapidly growing area for the last ten years. Many of the fundamental concepts and state-of-the-art developments can only be found in meeting proceedings or internal reports. This review paper attempts to give an overview and a unified formulation of a class of shock-capturing methods. Special emphasis is on the construction of the basic nonlinear scalar second-order schemes and the methods of extending these nonlinear scalar schemes to nonlinear systems via the extact Riemann solver, approximate Riemann solvers, and flux-vector splitting approaches. Generalization of these methods to efficiently include real gases and large systems of nonequilibrium flows is discussed. The performance of some of these schemes is illustrated by numerical examples for one-, two- and three-dimensional gas dynamics problems.

  17. Compression scheme for geophysical electromagnetic inversions

    NASA Astrophysics Data System (ADS)

    Abubakar, A.

    2014-12-01

    We have developed a model-compression scheme for improving the efficiency of the regularized Gauss-Newton inversion algorithm for geophysical electromagnetic applications. In this scheme, the unknown model parameters (the conductivity/resistivity distribution) are represented in terms of a basis such as Fourier and wavelet (Haar and Daubechies). By applying a truncation criterion, the model may then be approximated by a reduced number of basis functions, which is usually much less than the number of the model parameters. Further, because the geophysical electromagnetic measurements have low resolution, it is sufficient for inversion to only keep the low-spatial frequency part of the image. This model-compression scheme accelerates the computational time and also reduces the memory usage of the Gauss-Newton method. We are able to significantly reduce the algorithm computational complexity without compromising the quality of the inverted models.

  18. A Quantum Multi-proxy Multi-blind-signature Scheme Based on Genuine Six-Qubit Entangled State

    NASA Astrophysics Data System (ADS)

    Shao, Ai-Xia; Zhang, Jian-Zhong; Xie, Shu-Cui

    2016-08-01

    In this paper, a very efficient and secure multi-proxy multi-blind-signature scheme is proposed which is based on controlled quantum teleportation. Genuine six-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to guarantee its unforgeability, undeniability, blindness and unconditional security.

  19. Matching multistage schemes to viscous flow

    NASA Astrophysics Data System (ADS)

    Kleb, William Leonard

    A method to accelerate convergence to steady state by explicit time-marching schemes for the compressible Navier-Stokes equations is presented. The combination of cell-Reynolds-number-based multistage time stepping and local preconditioning makes solving steady-state viscous flow problems competitive with the convergence rates typically associated with implicit methods, without the associated memory penalty. Initially, various methods are investigated to extend the range of multistage schemes to diffusion-dominated cases. It is determined that the Chebyshev polynomials are well suited to serve as amplification factors for these schemes; however, creating a method that can bridge the continuum from convection-dominated to diffusion-dominated regimes proves troublesome, until the Manteuffel family of polynomials is uncovered. This transformation provides a smooth transition between the two extremes; and armed with this information, sets of multistage coefficients are created for a given spatial discretization as a function of cell Reynolds number according to various design criteria. As part of this process, a precise definition for the numerical time step is hammered out, something which up to this time, has been set via algebraic arguments only. Next are numerical tests of these sets of variable multistage coefficients. To isolate the effects of the variable multistage coefficients, the test case chosen is very simple: circular advection-diffusion. The numerical results support the analytical analysis by demonstrating an order of magnitude improvement in convergence rate for single-grid relaxation and a factor of three for multigrid relaxation. Building upon the success of the scalar case, preconditioning is applied to make the Navier-Stokes system of equations behave more nearly as a single scalar equation. Then, by applying the variable multistage coefficient scheme to a typical boundary-layer flow problem, the results affirm the benefits of local preconditioning

  20. An Improved Bulk Microphysical Scheme for Studying Precipitation Processes: Comparisons with Other Schemes

    NASA Technical Reports Server (NTRS)

    Tao, W. K.; Shi, J. J.; Lang, S.; Chen, S.; Hong, S-Y.; Peters-Lidard, C.

    2007-01-01

    Cloud microphysical processes play an important role in non-hydrostatic high-resolution simulations. Over the past decade both research and operational numerical weather prediction models have started using more complex cloud microphysical schemes that were originally developed for high-resolution cloud-resolving models. An improved bulk microphysical parameterization (adopted from the Goddard microphysics schemes) has recently implemented into the Weather Research and Forecasting (WRF) model. This bulk microphysical scheme has three different options --- 2ICE (cloud ice & snow), 3ICE-graupel (cloud ice, snow & graupel) and 3ICE-hail (cloud ice, snow & hail). High-resolution model simulations are conducted to examine the impact of microphysical schemes on two different weather events (a midlatitude linear convective system and an Atlantic hurricane). In addition, this bulk microphysical parameterization is compared with WIRF's three other bulk microphysical schemes.