Sample records for asynchronous control

  1. Asynchronous control for networked systems

    CERN Document Server

    Rubio, Francisco; Bencomo, Sebastián


    This book sheds light on networked control systems; it describes different techniques for asynchronous control, moving away from the periodic actions of classical control, replacing them with state-based decisions and reducing the frequency with which communication between subsystems is required. The text focuses specially on event-based control. Split into two parts, Asynchronous Control for Networked Systems begins by addressing the problems of single-loop networked control systems, laying out various solutions which include two alternative model-based control schemes (anticipatory and predictive) and the use of H2/H∞ robust control to deal with network delays and packet losses. Results on self-triggering and send-on-delta sampling are presented to reduce the need for feedback in the loop. In Part II, the authors present solutions for distributed estimation and control. They deal first with reliable networks and then extend their results to scenarios in which delays and packet losses may occur. The novel ...

  2. Control of asynchronous motors. Volume 1. Modeling, vectorial control and direct torque control; Commande des moteurs asynchrones. Volume 1. Modelisation, controle vectoriel et DTC

    Energy Technology Data Exchange (ETDEWEB)

    Canudas de Wit, C. [Ecole Nationale Superieure d' Ingenieurs de Genie Chimique, ENSIGC, 31 - Toulouse (France)


    This first volume deals with the problems of control of asynchronous motors in industrial environments: industrial environment, variable speed, asynchronous motors and power supplies, modeling, direct torque control laws, control by controlled limit cycles under frequency constraints. (J.S.)

  3. Asynchronous machines. Direct torque control; Machines asynchrones. Commande par controle direct de couple

    Energy Technology Data Exchange (ETDEWEB)

    Fornel, B. de [Institut National Polytechnique, 31 - Toulouse (France)


    The asynchronous machine, with its low cost and robustness, is today the most widely used motor to make speed variators. However, its main drawback is that the same current generates both the magnetic flux and the torque, and thus any torque variation creates a flux variation. Such a coupling gives to the asynchronous machine a nonlinear behaviour which makes its control much more complex. The direct self control (DSC) method has been developed to improve the low efficiency of the scalar control method and for the specific railway drive application. The direct torque control (DTC) method is derived from the DSC method but corresponds to other type of applications. The DSC and DTC algorithms for asynchronous motors are presented in this article: 1 - direct control of the stator flux (DSC): principle, flux control, torque control, switching frequency of the inverter, speed estimation; 2 - direct torque control (DTC): principle, electromagnetic torque derivative, signals shape and switching frequency, some results, DTC speed variator without speed sensor, DTC application to multi-machine multi-converter systems; 3 - conclusion. (J.S.)

  4. Burst-Mode Asynchronous Controllers on FPGA

    Directory of Open Access Journals (Sweden)

    Duarte L. Oliveira


    Full Text Available FPGAs have been mainly used to design synchronous circuits. Asynchronous design on FPGAs is difficult because the resulting circuit may suffer from hazard problems. We propose a method that implements a popular class of asynchronous circuits, known as burst mode, on FPGAs based on look-up table architectures. We present two conditions that, if satisfied, guarantee essential hazard-free implementation on any LUT-based FPGA. By doing that, besides all the intrinsic advantages of asynchronous over synchronous circuits, they also take advantage of the shorter design time and lower cost associated with FPGA designs.

  5. Adaptive wavefront control with asynchronous stochastic parallel gradient descent clusters. (United States)

    Vorontsov, Mikhail A; Carhart, Gary W


    A scalable adaptive optics (AO) control system architecture composed of asynchronous control clusters based on the stochastic parallel gradient descent (SPGD) optimization technique is discussed. It is shown that subdivision of the control channels into asynchronous SPGD clusters improves the AO system performance by better utilizing individual and/or group characteristics of adaptive system components. Results of numerical simulations are presented for two different adaptive receiver systems based on asynchronous SPGD clusters-one with a single deformable mirror with Zernike response functions and a second with tip-tilt and segmented wavefront correctors. We also discuss adaptive wavefront control based on asynchronous parallel optimization of several local performance metrics-a control architecture referred to as distributed adaptive optics (DAO). Analysis of the DAO system architecture demonstrated the potential for significant increase of the adaptation process convergence rate that occurs due to partial decoupling of the system control clusters optimizing individual performance metrics.


    Directory of Open Access Journals (Sweden)



    Full Text Available In this work, we present the application of artificial neural networks to the identification and control of the asynchronous motor, which is a complex nonlinear system with variable internal dynamics.  We show that neural networks can be applied to control the stator currents of the induction motor.  The results of the different simulations are presented to evaluate the performance of the neural controller proposed.


    Directory of Open Access Journals (Sweden)

    B. I. Firago


    Full Text Available The paper considers the issue of one of the widespread types of vector control realization for the asynchronous motors with a short-circuited rotor. Of all more than 20 vector control types known presently, the following are applied most frequently: direct vector control with velocity pickup (VP, direct vector control without VP, indirect vector control with VP and indirect vector control without VP. Despite the fact that the asynchronous-motor indirect vector control without VP is the easiest and most spread, the absence of VP does not allow controlling the motor electromagnetic torque at zero velocity. This is the reason why for electric motor drives of such requirements they utilize the vector control with a velocity transducer. The systems of widest dissemination became the direct and indirect vector control systems with X-axis alignment of the synchronously rotating x–y-coordinate frame along the rotor flux-linkage vector inasmuch as this provides the simplest correlations for controlling variables. Although these two types of vector control are well presented in literature, a number of issues concerning their realization and practical application require further elaboration. These include: the block schemes adequate representation as consisted with the modern realization of vector control and clarification of the analytical expressions for evaluating the regulator parameters.The authors present a technique for evaluating the dynamics of an asynchronous electric motor drive with direct vector control and x-axis alignment along the vector of rotor flux linkage. The article offers a generalized structure of this vector control type with detailed description of its principal blocks: controlling system, frequency converter, and the asynchronous motor.The paper presents a direct vector control simulating model developed in the MatLab environment on the grounds of this structure. The authors illustrate the described technique with the results

  8. Experience with synchronous and asynchronous digital control systems (United States)

    Regenie, V. A.; Chacon, C. V.; Lock, W. P.


    Flight control systems have undergone a revolution since the days of simple mechanical linkages; presently the most advanced systems are full-authority, full-time digital systems controlling unstable aircraft. With the use of advanced control systems, the aerodynamic design can incorporate features that allow greater performance and fuel savings, as can be seen on the new Airbus design and advanced tactical fighter concepts. These advanced aircraft will be and are relying on the flight control system to provide the stability and handling qualities required for safe flight and to allow the pilot to control the aircraft. Various design philosophies have been proposed and followed to investigate system architectures for these advanced flight control systems. One major area of discussion is whether a multichannel digital control system should be synchronous or asynchronous. This paper addressed the flight experience at the Dryden Flight Research Facility of NASA's Ames Research Center with both synchronous and asynchronous digital flight control systems. Four different flight control systems are evaluated against criteria such as software reliability, cost increases, and schedule delays.

  9. Experience with synchronous and asynchronous digital control systems. [for flight (United States)

    Regenie, Victoria A.; Chacon, Claude V.; Lock, Wilton P.


    Flight control systems have undergone a revolution since the days of simple mechanical linkages; presently the most advanced systems are full-authority, full-time digital systems controlling unstable aircraft. With the use of advanced control systems, the aerodynamic design can incorporate features that allow greater performance and fuel savings, as can be seen on the new Airbus design and advanced tactical fighter concepts. These advanced aircraft will be and are relying on the flight control system to provide the stability and handling qualities required for safe flight and to allow the pilot to control the aircraft. Various design philosophies have been proposed and followed to investigate system architectures for these advanced flight control systems. One major area of discussion is whether a multichannel digital control system should be synchronous or asynchronous. This paper addressed the flight experience at the Dryden Flight Research Facility of NASA's Ames Research Center with both synchronous and asynchronous digital flight control systems. Four different flight control systems are evaluated against criteria such as software reliability, cost increases, and schedule delays.

  10. Vector control structure of an asynchronous motor at maximum torque (United States)

    Chioncel, C. P.; Tirian, G. O.; Gillich, N.; Raduca, E.


    Vector control methods offer the possibility to gain high performance, being widely used. Certain applications require an optimum control in limit operating conditions, as, at maximum torque, that is not always satisfied. The paper presents how the voltage and the frequency for an asynchronous machine (ASM) operating at variable speed are determinate, with an accent on the method that keeps the rotor flux constant. The simulation analyses consider three load types: variable torque and speed, variable torque and constant speed, constant torque and variable speed. The final values of frequency and voltage are obtained through the proposed control schemes with one controller using the simulation language based on the Maple module. The dynamic analysis of the system is done for the case with P and PI controller and allows conclusions on the proposed method, which can have different applications, as the ASM in wind turbines.

  11. Research on the displacement control method of asynchronous modular contactor (United States)

    He, Gong; Ming, Zong


    Ac contactor is a kind of low voltage electrical appliances with large usage and wide application. Because of the frequent operation, contactor life must be long enough to ensure the reliable operation of power system. The electrical life of the contactor, as the key to affect the service life of the contactor, is mainly affected by the arc developed in the breaking and closing course. This paper concentrates on a new type of asynchronous modular contactor. To get the contactor movement characteristics, the dynamic model of the electromagnetic system is established by MATLAB/SIMULINK. Then, according to the displacement curve of contactor, the breaking process and closing process is planned. The thought of closed loop control, by adjusting the parameters of PID controller, enables the contactor to operate as the planning displacement curve. In addition, to achieve no arc or micro arc breaking and no bounce or micro bounce closing , a displacement closed loop control system for contactor is designed.

  12. Asynchronous BCI control using high-frequency SSVEP

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    Laciar Leber Eric


    Full Text Available Abstract Background Steady-State Visual Evoked Potential (SSVEP is a visual cortical response evoked by repetitive stimuli with a light source flickering at frequencies above 4 Hz and could be classified into three ranges: low (up to 12 Hz, medium (12-30 and high frequency (> 30 Hz. SSVEP-based Brain-Computer Interfaces (BCI are principally focused on the low and medium range of frequencies whereas there are only a few projects in the high-frequency range. However, they only evaluate the performance of different methods to extract SSVEP. Methods This research proposed a high-frequency SSVEP-based asynchronous BCI in order to control the navigation of a mobile object on the screen through a scenario and to reach its final destination. This could help impaired people to navigate a robotic wheelchair. There were three different scenarios with different difficulty levels (easy, medium and difficult. The signal processing method is based on Fourier transform and three EEG measurement channels. Results The research obtained accuracies ranging in classification from 65% to 100% with Information Transfer Rate varying from 9.4 to 45 bits/min. Conclusions Our proposed method allows all subjects participating in the study to control the mobile object and to reach a final target without prior training.

  13. Mathematical Description of an Asynchronous Motor with the Indirect Control of the Output Mechanical Variables

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    Glazachev A.V.


    Full Text Available The article gives the mathematical description of an asynchronous motor with the indirect control of the output mechanical variables of an asynchronous motor in the electric drive. To determine the electromagnetic torque and angular velocity of the asynchronous motor in the electric drive the mathematical description is used in which the values are determined by the readings of the motor and easily measured values by means of known in practice devices. The proposed in the article the mathematical description for the indirect measuring the electromagnetic torque and angular velocity of the asynchronous motor in the electric drive does not contain the integral components that introduce the great error into the value of the controlled electromagnetic torque and angular velocity.

  14. Asynchronous control of discrete-time impulsive switched systems with mode-dependent average dwell time. (United States)

    Wang, Bo; Zhang, Hongbin; Wang, Gang; Dang, Chuangyin; Zhong, Sijun


    This paper mainly studies the asynchronous control problem for a class of discrete-time impulsive switched systems, where "asynchronous" means the switching of the controllers has a lag to the switching of system modes. By using multiple Lyapunov functions (MLFs), the much looser asymptotic stability result of closed-loop systems is derived with a mode-dependent average dwell time (MDADT) technique. Based on the stability result obtained, the problem of asynchronous control is solved under a proper switching law. Moreover, the stability and stabilization results are formulated in form of matrix inequalities that are numerically feasible. Finally, an illustrative numerical example is presented to show the effectiveness of the obtained stability results. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  15. H∞ Controller Design for Asynchronous Hybrid Systems with Multiple Delays

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    Xiaoqiang Sun


    Full Text Available Solutions for the H∞ synthesis problems of asynchronous hybrid systems with input-output delays are proposed. The continuous-time lifting approach of sampled-data systems is extended to a hybrid system with multiple delays, and some feasible formulas to calculate the operators of the equivalent discrete-time (DT system are given. Different from the existing methods derived from symplectic pair theory or by state augmentation, a Lyapunov-Krasovskii functional to solve the synthesis problem is explicitly constructed. The delay-dependent stability conditions we obtained can be described in terms of nonstrict linear matrix inequalities (LMIs, which are much more convenient to be solved by LMI tools.

  16. PID Neural Network Based Speed Control of Asynchronous Motor Using Programmable Logic Controller

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    MARABA, V. A.


    Full Text Available This paper deals with the structure and characteristics of PID Neural Network controller for single input and single output systems. PID Neural Network is a new kind of controller that includes the advantages of artificial neural networks and classic PID controller. Functioning of this controller is based on the update of controller parameters according to the value extracted from system output pursuant to the rules of back propagation algorithm used in artificial neural networks. Parameters obtained from the application of PID Neural Network training algorithm on the speed model of the asynchronous motor exhibiting second order linear behavior were used in the real time speed control of the motor. Programmable logic controller (PLC was used as real time controller. The real time control results show that reference speed successfully maintained under various load conditions.

  17. An Asynchronous P300 BCI With SSVEP-Based Control State Detection

    DEFF Research Database (Denmark)

    Panicker, Rajesh C.; Puthusserypady, Sadasivan; Sun, Ying


    In this paper, an asynchronous brain–computer interface (BCI) system combining the P300 and steady-state visually evoked potentials (SSVEPs) paradigms is proposed. The information transfer is accomplished using P300 event-related potential paradigm and the control state (CS) detection is achieved...

  18. Distributed embedded controller development with petri nets application to globally-asynchronous locally-synchronous systems

    CERN Document Server

    Moutinho, Filipe de Carvalho


    This book describes a model-based development approach for globally-asynchronous locally-synchronous distributed embedded controllers.  This approach uses Petri nets as modeling formalism to create platform and network independent models supporting the use of design automation tools.  To support this development approach, the Petri nets class in use is extended with time-domains and asynchronous-channels. The authors’ approach uses models not only providing a better understanding of the distributed controller and improving the communication among the stakeholders, but also to be ready to support the entire lifecycle, including the simulation, the verification (using model-checking tools), the implementation (relying on automatic code generators), and the deployment of the distributed controller into specific platforms. Uses a graphical and intuitive modeling formalism supported by design automation tools; Enables verification, ensuring that the distributed controller was correctly specified; Provides flex...

  19. Application of Artificial Intelligence Techniques for the Control of the Asynchronous Machine

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    F. Khammar


    Full Text Available The induction machine is experiencing a growing success for two decades by gradually replacing the DC machines and synchronous in many industrial applications. This paper is devoted to the study of advanced methods applied to the command of the asynchronous machine in order to obtain a system of control of high performance. While the criteria for response time, overtaking, and static error can be assured by the techniques of conventional control, the criterion of robustness remains a challenge for researchers. This criterion can be satisfied only by applying advanced techniques of command. After mathematical modeling of the asynchronous machine, it defines the control strategies based on the orientation of the rotor flux. The results of the different simulation tests highlight the properties of robustness of algorithms proposed and suggested to compare the different control strategies.

  20. Synchronization of Hierarchical Time-Varying Neural Networks Based on Asynchronous and Intermittent Sampled-Data Control. (United States)

    Xiong, Wenjun; Patel, Ragini; Cao, Jinde; Zheng, Wei Xing

    In this brief, our purpose is to apply asynchronous and intermittent sampled-data control methods to achieve the synchronization of hierarchical time-varying neural networks. The asynchronous and intermittent sampled-data controllers are proposed for two reasons: 1) the controllers may not transmit the control information simultaneously and 2) the controllers cannot always exist at any time . The synchronization is then discussed for a kind of hierarchical time-varying neural networks based on the asynchronous and intermittent sampled-data controllers. Finally, the simulation results are given to illustrate the usefulness of the developed criteria.In this brief, our purpose is to apply asynchronous and intermittent sampled-data control methods to achieve the synchronization of hierarchical time-varying neural networks. The asynchronous and intermittent sampled-data controllers are proposed for two reasons: 1) the controllers may not transmit the control information simultaneously and 2) the controllers cannot always exist at any time . The synchronization is then discussed for a kind of hierarchical time-varying neural networks based on the asynchronous and intermittent sampled-data controllers. Finally, the simulation results are given to illustrate the usefulness of the developed criteria.

  1. An Asynchronous Multi-Sensor Micro Control Unit for Wireless Body Sensor Networks (WBSNs

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    Ching-Hsing Luo


    Full Text Available In this work, an asynchronous multi-sensor micro control unit (MCU core is proposed for wireless body sensor networks (WBSNs. It consists of asynchronous interfaces, a power management unit, a multi-sensor controller, a data encoder (DE, and an error correct coder (ECC. To improve the system performance and expansion abilities, the asynchronous interface is created for handshaking different clock domains between ADC and RF with MCU. To increase the use time of the WBSN system, a power management technique is developed for reducing power consumption. In addition, the multi-sensor controller is designed for detecting various biomedical signals. To prevent loss error from wireless transmission, use of an error correct coding technique is important in biomedical applications. The data encoder is added for lossless compression of various biomedical signals with a compression ratio of almost three. This design is successfully tested on a FPGA board. The VLSI architecture of this work contains 2.68-K gate counts and consumes power 496-μW at 133-MHz processing rate by using TSMC 0.13-μm CMOS process. Compared with the previous techniques, this work offers higher performance, more functions, and lower hardware cost than other micro controller designs.

  2. Load frequency control of an asynchronous restructured power ...

    African Journals Online (AJOL)


    Abstract. This paper presents the analysis of load frequency control (LFC) of a two-area restructured power system interconnected via parallel ac/dc transmission links. Simulation results show that the limitations of PI controller can be overcome by including. Fuzzy logic concept and thereby the dynamic performance can be ...

  3. Asynchronous control of Distributed Energy Resources using behaviour descriptions

    DEFF Research Database (Denmark)

    Kullmann, Daniel; Gehrke, Oliver; Bindner, Henrik


    The activation of power system services from small DER is a key to building electrical power systems with a high penetrations of renewable generation. Reliable, real-time and low-cost communication to a large number of DER units is required for controlling these resources, but difficult to achieve....... This paper presents an alternative to traditional closed-loop control which has the potential to relax the real-time requirements on the communication link between supervisory controller and DER unit. Examples are given, and experimental results are provided as a proof-of-concept....


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    V. S. Petrushin


    Full Text Available Purpose. Working out of mathematical models of the speed-controlled induction electric drives ensuring joint consideration of transformers, motors and loadings, and also matching reducers and transformers, both in static, and in dynamic regimes for the analysis of their operating characteristics. Methodology. At mathematical modelling are considered functional, mass, dimensional and cost indexes of reducers and transformers that allows observing engineering and economic aspects of speed-controlled induction electric drives. The mathematical models used for examination of the transitive electromagnetic and electromechanical processes, are grounded on systems of nonlinear differential equations with nonlinear coefficients (parameters of equivalent circuits of motors, varying in each operating point, including owing to appearances of saturation of magnetic system and current displacement in a winding of a rotor of an induction motor. For the purpose of raise of level of adequacy of models a magnetic circuit iron, additional and mechanical losses are considered. Results. Modelling of the several speed-controlled induction electric drives, different by components, but working on a loading equal on character, magnitude and a demanded control range is executed. At use of characteristic families including mechanical, at various parameters of regulating on which performances of the load mechanism are superimposed, the adjusting characteristics representing dependences of a modification of electrical, energy and thermal magnitudes from an angular speed of motors are gained. Originality. The offered complex models of speed-controlled induction electric drives with matching reducers and transformers, give the chance to realize well-founded sampling of components of drives. They also can be used as the design models by working out of speed-controlled induction motors. Practical value. Operating characteristics of various speed-controlled induction electric

  5. On the Distribution of Control in Asynchronous Processor Architectures


    Rebello, Vinod


    The effective performance of computer systems is to a large measure determined by the synergy between the processor architecture, the instruction set and the compiler. In the past, the sequencing of information within processor architectures has normally been synchronous: controlled centrally by a clock. However, this global signal could possibly limit the future gains in performance that can potentially be achieved through improvements in implementation technology. T...

  6. A BMI-based occupational therapy assist suit: asynchronous control by SSVEP

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    Takeshi eSakurada


    Full Text Available A brain-machine interface (BMI is an interface technology that uses neurophysiological signals from the brain to control external machines. Recent invasive BMI technologies have succeeded in the asynchronous control of robot arms for a useful series of actions, such as reaching and grasping. In this study, we developed non-invasive BMI technologies aiming to make such useful movements using the subject's own hands by preparing a BMI-based occupational therapy assist suit (BOTAS. We prepared a pre-recorded series of useful actionsa grasping-a-ball movement and a carrying-the-ball movementand added asynchronous control using steady-state visual evoked potential (SSVEP signals. A SSVEP signal was used to trigger the grasping-a-ball movement and another SSVEP signal was used to trigger the carrying-the-ball movement. A support vector machine was used to classify EEG signals recorded from the visual cortex (Oz in real time. Untrained, able-bodied participants (n = 12 operated the system successfully. Classification accuracy and time required for SSVEP detection were approximately 88% and 3 s, respectively. We further recruited three patients with upper cervical spinal cord injuries; they also succeeded in operating the system without training. These data suggest that our BOTAS system is potentially useful in terms of rehabilitation of patients with upper limb disabilities.

  7. Asynchronous P300-based brain-computer interface to control a virtual environment: initial tests on end users. (United States)

    Aloise, Fabio; Schettini, Francesca; Aricò, Pietro; Salinari, Serenella; Guger, Christoph; Rinsma, Johanna; Aiello, Marco; Mattia, Donatella; Cincotti, Febo


    Motor disability and/or ageing can prevent individuals from fully enjoying home facilities, thus worsening their quality of life. Advances in the field of accessible user interfaces for domotic appliances can represent a valuable way to improve the independence of these persons. An asynchronous P300-based Brain-Computer Interface (BCI) system was recently validated with the participation of healthy young volunteers for environmental control. In this study, the asynchronous P300-based BCI for the interaction with a virtual home environment was tested with the participation of potential end-users (clients of a Frisian home care organization) with limited autonomy due to ageing and/or motor disabilities. System testing revealed that the minimum number of stimulation sequences needed to achieve correct classification had a higher intra-subject variability in potential end-users with respect to what was previously observed in young controls. Here we show that the asynchronous modality performed significantly better as compared to the synchronous mode in continuously adapting its speed to the users' state. Furthermore, the asynchronous system modality confirmed its reliability in avoiding misclassifications and false positives, as previously shown in young healthy subjects. The asynchronous modality may contribute to filling the usability gap between BCI systems and traditional input devices, representing an important step towards their use in the activities of daily living.

  8. On the asynchronously continuous control of mobile robot movement by motor cortical spiking activity. (United States)

    Xu, Zhiming; So, Rosa Q; Toe, Kyaw Kyar; Ang, Kai Keng; Guan, Cuntai


    This paper presents an asynchronously intracortical brain-computer interface (BCI) which allows the subject to continuously drive a mobile robot. This system has a great implication for disabled patients to move around. By carefully designing a multiclass support vector machine (SVM), the subject's self-paced instantaneous movement intents are continuously decoded to control the mobile robot. In particular, we studied the stability of the neural representation of the movement directions. Experimental results on the nonhuman primate showed that the overt movement directions were stably represented in ensemble of recorded units, and our SVM classifier could successfully decode such movements continuously along the desired movement path. However, the neural representation of the stop state for the self-paced control was not stably represented and could drift.

  9. Asynchronous control of vortex-induced acoustic cavity resonance using imbedded piezo-electric actuators. (United States)

    Zhang, M M; Cheng, L; Zhou, Y


    This paper presents an experimental investigation of the control of a vortex-induced acoustic cavity resonance from flow over a bluff body using embedded piezo-ceramic actuators in order to alter the resonant flow-acoustic interactions. The action of the actuators was asynchronous. Experiments were mainly conducted at the flow velocity of acoustic resonance, where the vortex shedding frequency from the upstream bluff body approached the frequency of the first acoustic mode of two downstream cavities. The fluctuating acoustic pressure was measured using a microphone. The perturbed flow field around the bluff body was monitored using two single hot wire anemometers and one X-wire. It was found that the induced transverse vibrations were effective to reduce the acoustic resonance. The cavity sound pressure level at resonance was reduced by 8.2 dB in presence of actuation. The physics behind the control mechanism is discussed.

  10. Control or non-control state: that is the question! An asynchronous visual P300-based BCI approach (United States)

    Pinegger, Andreas; Faller, Josef; Halder, Sebastian; Wriessnegger, Selina C.; Müller-Putz, Gernot R.


    Objective. Brain-computer interfaces (BCI) based on event-related potentials (ERP) were proven to be a reliable synchronous communication method. For everyday life situations, however, this synchronous mode is impractical because the system will deliver a selection even if the user is not paying attention to the stimulation. So far, research into attention-aware visual ERP-BCIs (i.e., asynchronous ERP-BCIs) has led to variable success. In this study, we investigate new approaches for detection of user engagement. Approach. Classifier output and frequency-domain features of electroencephalogram signals as well as the hybridization of them were used to detect the user's state. We tested their capabilities for state detection in different control scenarios on offline data from 21 healthy volunteers. Main results. The hybridization of classifier output and frequency-domain features outperformed the results of the single methods, and allowed building an asynchronous P300-based BCI with an average correct state detection accuracy of more than 95%. Significance. Our results show that all introduced approaches for state detection in an asynchronous P300-based BCI can effectively avoid involuntary selections, and that the hybrid method is the most effective approach.

  11. EEG-Based Asynchronous BCI Controls Functional Electrical Stimulation in a Tetraplegic Patient

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    Rüdiger Rupp


    Full Text Available The present study reports on the use of an EEG-based asynchronous (uncued, user-driven brain-computer interface (BCI for the control of functional electrical stimulation (FES. By the application of FES, noninvasive restoration of hand grasp function in a tetraplegic patient was achieved. The patient was able to induce bursts of beta oscillations by imagination of foot movement. These beta oscillations were recorded in a one EEG-channel configuration, bandpass filtered and squared. When this beta activity exceeded a predefined threshold, a trigger for the FES was generated. Whenever the trigger was detected, a subsequent switching of a grasp sequence composed of 4 phases occurred. The patient was able to grasp a glass with the paralyzed hand completely on his own without additional help or other technical aids.

  12. Control of Dynamic Limb Motion Using Fatigue-Resistant Asynchronous Intrafascicular Multi-Electrode Stimulation

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    Mitchell A. Frankel


    Full Text Available Asynchronous intrafascicular multi-electrode stimulation (aIFMS of small independent populations of peripheral nerve motor axons can evoke selective, fatigue-resistant muscle forces. We previously developed a real-time proportional closed-loop control method for aIFMS generation of isometric muscle force and the present work extends and adapts this closed-loop controller to the more demanding task of dynamically controlling joint position in the presence of opposing joint torque. A proportional-integral-velocity controller, with integrator anti-windup strategies, was experimentally validated as a means to evoke motion about the hind-limb ankle joint of an anesthetized feline via aIFMS stimulation of fast-twitch plantar-flexor muscles. The controller was successful in evoking steps in joint position with 2.4% overshoot, 2.3-s rise time, 4.5-s settling time, and near-zero steady-state error. Controlled step responses were consistent across changes in step size, stable against external disturbances, and reliable over time. The controller was able to evoke smooth eccentric motion at joint velocities up to 8 deg./s, as well as sinusoidal trajectories with frequencies up to 0.1 Hz, with time delays less than 1.5 s. These experiments provide important insights toward creating a robust closed-loop aIFMS controller that can evoke precise fatigue-resistant motion in paralyzed individuals, despite the complexities introduced by aIFMS.


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    V.A. Volkov


    Using the method of the calculus of variations to offer optimal and quasi-optimal types of energy-saving variable frequency control the position of the induction motor (FCIM, which provide basic minimization of electromagnetic energy loss (BEEL of the engine when developing an arbitrary value of a small displacement of the shaft in the required time. Obtained for the proposed types of energy-saving control analytical dependencies to change the position and speed of the time, as well as to determine the maximum value of the engine speed. Calculations of the time change process: position, speed, electromagnetic torque, modulus of the generalized vector of the stator current, general electromagnetic power loss and engine BEEL – relevant proposals and quasi optimal energy-saving type of control. A comparison between a proposed and known (parabolic and linear dependence of the velocity on the time change types of energy-saving position control with small movements FCIM. Proposed optimal and quasi-optimal types of energy-saving position control are recommended for use in positional variable frequency asynchronous electric drive (for example, lifting-transport mechanisms and rotary platforms, urban and railway electric transport, etc...

  14. A Performance Study on Synchronous and Asynchronous Update Rules for A Plug-In Direct Particle Swarm Repetitive Controller

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    Ufnalski Bartlomiej


    Full Text Available In this paper two different update schemes for the recently developed plug-in direct particle swarm repetitive controller (PDPSRC are investigated and compared. The proposed approach employs the particle swarm optimizer (PSO to solve in on-line mode a dynamic optimization problem (DOP related to the control task in the constant-amplitude constant-frequency voltage-source inverter (CACF VSI with an LC output filter. The effectiveness of synchronous and asynchronous update rules, both commonly used in static optimization problems (SOPs, is assessed and compared in the case of PDPSRC. The performance of the controller, when synthesized using each of the update schemes, is studied numerically.

  15. Asynchronous P300 BCI

    DEFF Research Database (Denmark)

    Panicker, Rajesh; Puthusserypady, Sadasivan; Sun, Ying


    An asynchronous hybrid brain-computer interface (BCI) system combining the P300 and steady-state visually evoked potentials (SSVEP) paradigms is introduced. A P300 base system is used for information transfer, and is augmented to include SSVEP for control state detection. The proposed system has...

  16. Generalized Asynchronous Systems

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    E. S. Kudryashova


    Full Text Available The paper consider a mathematical model of a concurrent system, the special case of which is an asynchronous system. Distributed asynchronous automata are introduced here. It is proved that Petri nets and transition systems with independence can be considered as distributed asynchronous automata. Time distributed asynchronous automata are defined in a standard way by correspondence which relates events with time intervals. It is proved that the time distributed asynchronous automata generalize time Petri nets and asynchronous systems.

  17. Influence of the braking power control of the traction asynchronous machine in the voltage vector control system under DC

    Directory of Open Access Journals (Sweden)

    Юлія Олександрівна Слободенюк


    Full Text Available At braking the traction motors are transferred to generator mode and produce electrical energy which passes to the contact mains or storage device in the DC mains for further use. Such braking is called regenerative. The resulting electrical energy can be spent by trains in traction mode. Regenerative braking reduces the consumption of electric power for traction. In electric railways of our country more than 3% of the consumed electrical energy is given back to contact mains annually. As this takes place there arises the task to control the braking of the traction motors with minimal impact on electric power quality and maintaining proper braking performance. Based on the analysis of the characteristics of the brake traction of an electric locomotive with asynchronous electric machines the main braking modes have been chosen: at a constant sliding speed and the stator constant voltage; at constant braking power and the stator constant voltage; at a power value more than the nominal braking power; at a constant load torque; at a constant frequency of the stator. The vector control system with the formation of the reactive component of the stator current and the EMF regulator was chosen, basing on the working conditions characteristics in the electric braking mode (recuperation; namely, that the characteristics are defined by the laws regulating the frequency and voltage across the stator windings. This control system can fully reproduce any predetermined trajectory of traction and braking performance and adjust braking power. The offered system with recuperation can be used as a means of compensation in emergency situations with a power failure

  18. A brain-actuated wheelchair: asynchronous and non-invasive Brain-computer interfaces for continuous control of robots. (United States)

    Galán, F; Nuttin, M; Lew, E; Ferrez, P W; Vanacker, G; Philips, J; Millán, J Del R


    To assess the feasibility and robustness of an asynchronous and non-invasive EEG-based Brain-Computer Interface (BCI) for continuous mental control of a wheelchair. In experiment 1 two subjects were asked to mentally drive both a real and a simulated wheelchair from a starting point to a goal along a pre-specified path. Here we only report experiments with the simulated wheelchair for which we have extensive data in a complex environment that allows a sound analysis. Each subject participated in five experimental sessions, each consisting of 10 trials. The time elapsed between two consecutive experimental sessions was variable (from 1h to 2months) to assess the system robustness over time. The pre-specified path was divided into seven stretches to assess the system robustness in different contexts. To further assess the performance of the brain-actuated wheelchair, subject 1 participated in a second experiment consisting of 10 trials where he was asked to drive the simulated wheelchair following 10 different complex and random paths never tried before. In experiment 1 the two subjects were able to reach 100% (subject 1) and 80% (subject 2) of the final goals along the pre-specified trajectory in their best sessions. Different performances were obtained over time and path stretches, what indicates that performance is time and context dependent. In experiment 2, subject 1 was able to reach the final goal in 80% of the trials. The results show that subjects can rapidly master our asynchronous EEG-based BCI to control a wheelchair. Also, they can autonomously operate the BCI over long periods of time without the need for adaptive algorithms externally tuned by a human operator to minimize the impact of EEG non-stationarities. This is possible because of two key components: first, the inclusion of a shared control system between the BCI system and the intelligent simulated wheelchair; second, the selection of stable user-specific EEG features that maximize the

  19. Coexisting synchronous and asynchronous states in locally coupled array of oscillators by partial self-feedback control (United States)

    Bera, Bidesh K.; Ghosh, Dibakar; Parmananda, Punit; Osipov, G. V.; Dana, Syamal K.


    We report the emergence of coexisting synchronous and asynchronous subpopulations of oscillators in one dimensional arrays of identical oscillators by applying a self-feedback control. When a self-feedback is applied to a subpopulation of the array, similar to chimera states, it splits into two/more sub-subpopulations coexisting in coherent and incoherent states for a range of self-feedback strength. By tuning the coupling between the nearest neighbors and the amount of self-feedback in the perturbed subpopulation, the size of the coherent and the incoherent sub-subpopulations in the array can be controlled, although the exact size of them is unpredictable. We present numerical evidence using the Landau-Stuart system and the Kuramoto-Sakaguchi phase model.

  20. Development of a mathematical model for a frequency-controlled asynchronous motor rotor temperature field on the basis of differential equations of heat conduction

    Directory of Open Access Journals (Sweden)

    N.A. Ostashevskiy


    Full Text Available A mathematical model of the temperature field of a frequency-controlled asynchronous motor rotor is made out on the basis of differential equations of heat conduction. The model developed is approved in the course of experimental research on the motors examined.

  1. Direct torque control of an asynchronous machine: observation structures: application to multi-machine/multi-converter systems; Commande directe en couple d'une machine asynchrone: structures d'observations: application aux systemes multimachines-multiconvertisseurs

    Energy Technology Data Exchange (ETDEWEB)

    Belhadj, J.


    The aim of this work is the development of an observation structure of the direct torque control (DTC) variables of an asynchronous machine. This structure has to solve the dilemma between its robustness and a minimum calculation time. The control law obtained will be used for the control of multi-machine/multi-converter systems. The new control laws based on direct stator flux control and electromagnetic torque control are studied first, in particular the DTC and the principles of flux and torque adjustment and the associated switching logic. Then, three observation structures are developed: the full order state observer, the sliding mode observer, and the decoupled observer. A comparative study between these three structures and the classical estimator shows that the decoupled observer is an interesting structure which answers the problem of very low-speed operation. In the case of the multi-machine application, two systems are studied: the single inverter/dual-machine system and the dual-inverter/dual-machine system. The control is performed with the DTC and the vectorial control. The DTC gives interesting results for the control of multi-machine systems. In the last part, an architecture is defined for the mono- and multi-machine validation. It consists in a pseudo-experimental validation of the control law associated to the observation structure developed. This validation is performed with a mixed analog/numerical simulation. (J.S.)

  2. Pipelined Asynchronous Cache Design


    Nyströem, Mika


    This thesis describes the development of pipelined asynchronous cache memories. The work is done in the context of the performance characteristics of memories and transistor logic of a late 1990's high-performance asynchronous microprocessor. We describe the general framework of asynchronous memory systems, caching, and those system characteristics that make caching of growing importance and keep it an interesting research topic. Finally, we present the main contribution of this work, whi...

  3. Asynchronous P300-Based Brain-Computer Interface to Control a Virtual Environment : Initial Tests on End Users

    NARCIS (Netherlands)

    Aloise, Fabio; Schettini, Francesca; Arico, Pietro; Salinari, Serenella; Guger, Christoph; Rinsma, Johanna; Aiello, Marco; Mattia, Donatella; Cincotti, Febo


    Motor disability and/or ageing can prevent individuals from fully enjoying home facilities, thus worsening their quality of life. Advances in the field of accessible user interfaces for domotic appliances can represent a valuable way to improve the independence of these persons. An asynchronous

  4. Control of frequency converters for wind power systems with doubly fed asynchronous generators; Regelung von Frequenzumrichtern fuer Windenergieanlagen mit doppelt gespeistem Asynchrongenerator

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Stephan [Woodward SEG GmbH und Co. KG, Kempen (Germany)


    Modern wind energy systems are characterized by an extensive use of power electronics. Using complex converter systems is technically and commercially very attractive as it allows an optimized operation of the wind turbine in regard to efficiency, reduced stress to the drive train due to variable speed and feeding wind power with high quality into the grid. For some years wind energy systems with frequency converter and doubly fed asynchronous generator have the biggest market share. The main requirements from grid codes regarding fault ride through operation will be summarized and enhanced control algorithms for this special type of system will be presented. (orig.)

  5. Asynchronized synchronous machines

    CERN Document Server

    Botvinnik, M M


    Asynchronized Synchronous Machines focuses on the theoretical research on asynchronized synchronous (AS) machines, which are "hybrids” of synchronous and induction machines that can operate with slip. Topics covered in this book include the initial equations; vector diagram of an AS machine; regulation in cases of deviation from the law of full compensation; parameters of the excitation system; and schematic diagram of an excitation regulator. The possible applications of AS machines and its calculations in certain cases are also discussed. This publication is beneficial for students and indiv

  6. Asynchronous Multiparty Computation

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Geisler, Martin; Krøigaard, Mikkel


    less than n/3 players. We also present a software framework for implementation of asynchronous protocols called VIFF (Virtual Ideal Functionality Framework), which allows automatic parallelization of primitive operations such as secure multiplications, without having to resort to complicated...

  7. Handbook of asynchronous machines with variable speed

    CERN Document Server

    Razik, Hubert


    This handbook deals with the asynchronous machine in its close environment. It was born from a reflection on this electromagnetic converter whose integration in industrial environments takes a wide part. Previously this type of motor operated at fixed speed, from now on it has been integrated more and more in processes at variable speed. For this reason it seemed useful, or necessary, to write a handbook on the various aspects from the motor in itself, via the control and while finishing by the diagnosis aspect. Indeed, an asynchronous motor is used nowadays in industry where variation speed a

  8. Multiparty Asynchronous Session Types

    DEFF Research Database (Denmark)

    Honda, Kohei; Yoshida, Nobuko; Carbone, Marco


    . This work extends the foregoing theories of binary session types to multiparty, asynchronous sessions, which often arise in practical communication-centered applications. Presented as a typed calculus for mobile processes, the theory introduces a new notion of types in which interactions involving multiple......Communication is a central elements in software development. As a potential typed foundation for structured communication-centered programming, session types have been studied over the past decade for a wide range of process calculi and programming languages, focusing on binary (two-party) sessions...... peers are directly abstracted as a global scenario. Global types retain the friendly type syntax of binary session types while specifying dependencies and capturing complex causal chains of multiparty asynchronous interactions. A global type plays the role of a shared agreement among communication peers...

  9. Injectable and Self-Healing Thermosensitive Magnetic Hydrogel for Asynchronous Control Release of Doxorubicin and Docetaxel to Treat Triple-Negative Breast Cancer. (United States)

    Xie, Wensheng; Gao, Qin; Guo, Zhenhu; Wang, Dan; Gao, Fei; Wang, Xiumei; Wei, Yen; Zhao, Lingyun


    Integration of two or more drugs into a multiagent delivery system has been considered to have profound impact on both in vitro and in vivo cancer treatment due to their efficient synergistic effect. This study presents a cheap and simple chitosan hydrogel cross-linked with telechelic difunctional poly(ethylene glycol) (DF-PEG-DF) for synthesis of an injectable and self-healing thermosensitive dual-drug-loaded magnetic hydrogel (DDMH), which contains both doxorubicin (DOX) and docetaxel (DTX) for chemotherapy and iron oxide for magnetic hyperthermia induced stimuli responsive drug release. The as-prepared DDMH not only have good biocompatibility but also exhibit unique self-healing, injectable, asynchronous control release properties. Meanwhile, it shows an excellent magnetic field responsive heat-inducing property, which means that DDMH will produce a large amount of heat to control the surrounding temperature under the alternative magnetic field (AMF). A remarkably improved synergistic effect to triple negative breast cancer cell line is obtained by comparing the therapeutic effect of codelivery of DOX and DTX/PLGA nanoparticles (DTX/PLGA NPs) with DOX or DTX/PLGA NPs alone. In vivo results showed that DDMH exhibited significant higher antitumor efficacy of reducing tumor size compared to single drug-loaded hydrogel. Meanwhile, the AMF-trigger control release of drugs in codelivery system has a more efficient antitumor effect of cancer chemotherapy, indicating that DDMH was a promising multiagent codelivery system for synergistic chemotherapy in the cancer treatment field.

  10. Asynchronous Gossip for Averaging and Spectral Ranking (United States)

    Borkar, Vivek S.; Makhijani, Rahul; Sundaresan, Rajesh


    We consider two variants of the classical gossip algorithm. The first variant is a version of asynchronous stochastic approximation. We highlight a fundamental difficulty associated with the classical asynchronous gossip scheme, viz., that it may not converge to a desired average, and suggest an alternative scheme based on reinforcement learning that has guaranteed convergence to the desired average. We then discuss a potential application to a wireless network setting with simultaneous link activation constraints. The second variant is a gossip algorithm for distributed computation of the Perron-Frobenius eigenvector of a nonnegative matrix. While the first variant draws upon a reinforcement learning algorithm for an average cost controlled Markov decision problem, the second variant draws upon a reinforcement learning algorithm for risk-sensitive control. We then discuss potential applications of the second variant to ranking schemes, reputation networks, and principal component analysis.

  11. The Effects of Instructor Control on Critical Thinking and Social Presence: Variations Within Three Online Asynchronous Learning Environments

    Directory of Open Access Journals (Sweden)

    Jamie Costley


    Full Text Available In a world in which online interactions are becoming the norm, an understanding of how three fundamental aspects of online learning (teaching presence, social presence and cognitive presence interact is important. This paper will look at how these three presences interact with each other in an online forum. More specifically it will describe the effects of instructional design on learners’ levels of critical thinking and social presence. The research involved taking 900 learner posts from differing experimental conditions and analyzing those posts for social presence and critical thinking. The experimental conditions varied in three different ways in regards to the level of instructor control over the learning environment. The first learning environment had a low level of instructor control while the second and third had progressively high levels of instructor control over the learners’ contributions to the forum. The results showed that increasing the amount of control an instructor has over a learning environment increases the amount of cognitive presence but decreases the amount of social presence within the learners’ posts. In general, these results are important because instructors must be aware of how their behavior may affect how learners interact (and therefore learn online. More specifically, many instructors are interested in the types of discourse their learners create. Therefore, the ways instructors can manipulate learner discourse is of great importance.

  12. Pro asynchronous programming with .NET

    CERN Document Server

    Blewett, Richard; Ltd, Rock Solid Knowledge


    Pro Asynchronous Programming with .NET teaches the essential skill of asynchronous programming in .NET. It answers critical questions in .NET application development, such as: how do I keep my program responding at all times to keep my users happy how do I make the most of the available hardware how can I improve performanceIn the modern world, users expect more and more from their applications and devices, and multi-core hardware has the potential to provide it. But it takes carefully crafted code to turn that potential into responsive, scalable applications.With Pro Asynchronous Programming

  13. Reducing energy with asynchronous circuits


    Rivas Barragan, Daniel


    Reducing energy consumption using asynchronous circuits. The elastic clocks approach has been implemented along with a closed-feedback loop in order to achieve a lower energy consumption along with more reliability in integrated circuits.

  14. Totally Asynchronous Interference Channels

    CERN Document Server

    Moshksar, Kamyar


    This paper addresses an interference channel consisting of $\\mathbf{n}$ active users sharing $u$ frequency sub-bands. Users are asynchronous meaning there exists a mutual delay between their transmitted codes. A stationary model for interference is considered by assuming the starting point of an interferer's data is uniformly distributed along the codeword of any user. The spectrum is divided to private and common bands each containing $v_{\\mathrm{p}}$ and $v_{\\mathrm{c}}$ frequency sub-bands respectively. We consider a scenario where all transmitters are unaware of the number of active users and the channel gains. The optimum $v_{\\mathrm{p}}$ and $v_{\\mathrm{c}}$ are obtained such that the so-called outage capacity per user is maximized. If $\\Pr\\{\\mathbf{n}\\leq 2\\}=1$, upper and lower bounds on the mutual information between the input and output of the channel for each user are derived using a genie-aided technique. The proposed bounds meet each other as the code length grows to infinity yielding a closed ex...

  15. Behavioral Synthesis of Asynchronous Circuits Using Syntax Directed Translation as Backend

    DEFF Research Database (Denmark)

    Nielsen, Sune Fallgaard; Sparsø, Jens; Madsen, Jan


    The current state-of-the art in high-level synthesis of asynchronous circuits is syntax directed translation, which performs a one-to-one mapping of a HDL-description into a corresponding circuit. This paper presents a method for behavioral synthesis of asynchronous circuits which builds on top...... of syntax directed translation, and which allows the designer to perform automatic design space exploration guided by area or speed constraints. The paper presents an asynchronous implementation template consisting of a data-path and a control unit and its implementation using the asynchronous hardware...

  16. Study of a centrifugal pump, asynchronous motor and inverter, using ...

    African Journals Online (AJOL)

    ... concept to the study of a three-phase inverter, asynchronous motor and centrifugal pump. It presents the realization of the rectangular control using a micro controller (ATMEGA 168). The signals generated by the micro controller have been used to program the parallel port of a computer. By reading the recorded bits of the ...

  17. Asynchronous Message Service Reference Implementation (United States)

    Burleigh, Scott C.


    This software provides a library of middleware functions with a simple application programming interface, enabling implementation of distributed applications in conformance with the CCSDS AMS (Consultative Committee for Space Data Systems Asynchronous Message Service) specification. The AMS service, and its protocols, implement an architectural concept under which the modules of mission systems may be designed as if they were to operate in isolation, each one producing and consuming mission information without explicit awareness of which other modules are currently operating. Communication relationships among such modules are self-configuring; this tends to minimize complexity in the development and operations of modular data systems. A system built on this model is a society of generally autonomous, inter-operating modules that may fluctuate freely over time in response to changing mission objectives, modules functional upgrades, and recovery from individual module failure. The purpose of AMS, then, is to reduce mission cost and risk by providing standard, reusable infrastructure for the exchange of information among data system modules in a manner that is simple to use, highly automated, flexible, robust, scalable, and efficient. The implementation is designed to spawn multiple threads of AMS functionality under the control of an AMS application program. These threads enable all members of an AMS-based, distributed application to discover one another in real time, subscribe to messages on specific topics, and to publish messages on specific topics. The query/reply (client/server) communication model is also supported. Message exchange is optionally subject to encryption (to support confidentiality) and authorization. Fault tolerance measures in the discovery protocol minimize the likelihood of overall application failure due to any single operational error anywhere in the system. The multi-threaded design simplifies processing while enabling application nodes to

  18. Developing asynchronous online interprofessional education. (United States)

    Sanborn, Heidi


    For many health programmes, developing interprofessional education (IPE) has been a challenge. Evidence on the best method for design and implementation of IPE has been slow to emerge, with little research on how to best incorporate IPE in the asynchronous online learning environment. This leaves online programmes with no clear guidance when embarking upon an initiative to integrate IPE into the curriculum. One tool that can be effective at guiding the incorporation of IPE across all learning platforms is the Interprofessional Education Collaborative (IPEC) competencies. A project was designed to integrate the nationally defined IPEC competencies throughout an asynchronous, online baccalaureate nursing completion programme. A programme-wide review led to targeted revision of course and unit-level objectives, learning experiences, and assessments based on the IPEC framework. As a result of this effort, the programme curriculum now provides interprofessional learning activities across all courses. This report provides a method for using the IPEC competencies to incorporate IPE within various asynchronous learning assessments, assuring students learn about, with, and from other professions.

  19. Phase Space Invertible Asynchronous Cellular Automata

    Directory of Open Access Journals (Sweden)

    Simon Wacker


    Full Text Available While for synchronous deterministic cellular automata there is an accepted definition of reversibility, the situation is less clear for asynchronous cellular automata. We first discuss a few possibilities and then investigate what we call phase space invertible asynchronous cellular automata in more detail. We will show that for each Turing machine there is such a cellular automaton simulating it, and that it is decidable whether an asynchronous cellular automaton has this property or not, even in higher dimensions.

  20. Commande directe de couple d’un moteur asynchrone à base de techniques intelligentes


    GDAIM, Soufien


    Design and Experimental Implementation of DTC of an Induction Machine Based on artificial intelligence Control on FPGA; Implémentation sur FPGA de la Commande directe de couple d’un moteur asynchrone à base de techniques intelligentes

  1. Selective distortion of body image by asynchronous visuotactile stimulation. (United States)

    Perez-Marcos, Daniel; Martini, Matteo; Fuentes, Christina T; Bellido Rivas, Anna I; Haggard, Patrick; Sanchez-Vives, Maria V


    In the rubber hand illusion (RHI), a rubber hand is felt as being part of one's body. This illusion is evoked by providing synchronous visuotactile stimulation to the fake and real hands. Asynchronous visuotactile stimulation is known not to produce such an illusion of ownership, being commonly used as the control condition. Here we explored the impact of synchronous and asynchronous visuotactile stimulation on the body image. We combined the induction of the RHI with a quantitative test for the internal representation of body metrics (i.e., the positions of key fiducial points on the body relative to each other). We found a significant recalibration of the upper/lower arm lengths following asynchronous visuotactile stimulation. In particular, we observed a selective elongation of the lower arm, a distortion typical of deafferentation. Conversely, synchronous visuotactile stimulation did not alter the estimation of the arm segments' length. Our findings are consistent with a dynamic internal representation of body image that is continuously updated based on incoming multisensory information. Furthermore, the use of asynchronous multisensory stimulation as a neutral condition should be reconsidered since it introduces changes in the body image. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Development of speech glimpsing in synchronously and asynchronously modulated noise. (United States)

    Hall, Joseph W; Buss, Emily; Grose, John H


    This study investigated development of the ability to integrate glimpses of speech in modulated noise. Noise was modulated synchronously across frequency or asynchronously such that when noise below 1300 Hz was "off," noise above 1300 Hz was "on," and vice versa. Asynchronous masking was used to examine the ability of listeners to integrate speech glimpses separated across time and frequency. The study used the Word Intelligibility by Picture Identification (WIPI) test and included adults, older children (age 8-10 yr) and younger children (5-7 yr). Results showed poorer masking release for the children than the adults for synchronous modulation but not for asynchronous modulation. It is possible that children can integrate cues relatively well when all intervals provide at least partial speech information (asynchronous modulation) but less well when some intervals provide little or no information (synchronous modulation). Control conditions indicated that children appeared to derive less benefit than adults from speech cues below 1300 Hz. This frequency effect was supported by supplementary conditions where the noise was unmodulated and the speech was low- or high-pass filtered. Possible sources of the developmental frequency effect include differences in frequency weighting, effective speech bandwidth, and the signal-to-noise ratio in the unmodulated noise condition.

  3. Asynchronous Parallelization of a CFD Solver

    Directory of Open Access Journals (Sweden)

    Daniel S. Abdi


    Full Text Available A Navier-Stokes equations solver is parallelized to run on a cluster of computers using the domain decomposition method. Two approaches of communication and computation are investigated, namely, synchronous and asynchronous methods. Asynchronous communication between subdomains is not commonly used in CFD codes; however, it has a potential to alleviate scaling bottlenecks incurred due to processors having to wait for each other at designated synchronization points. A common way to avoid this idle time is to overlap asynchronous communication with computation. For this to work, however, there must be something useful and independent a processor can do while waiting for messages to arrive. We investigate an alternative approach of computation, namely, conducting asynchronous iterations to improve local subdomain solution while communication is in progress. An in-house CFD code is parallelized using message passing interface (MPI, and scalability tests are conducted that suggest asynchronous iterations are a viable way of parallelizing CFD code.

  4. A novel asynchronous access method with binary interfaces

    Directory of Open Access Journals (Sweden)

    Torres-Solis Jorge


    Full Text Available Abstract Background Traditionally synchronous access strategies require users to comply with one or more time constraints in order to communicate intent with a binary human-machine interface (e.g., mechanical, gestural or neural switches. Asynchronous access methods are preferable, but have not been used with binary interfaces in the control of devices that require more than two commands to be successfully operated. Methods We present the mathematical development and evaluation of a novel asynchronous access method that may be used to translate sporadic activations of binary interfaces into distinct outcomes for the control of devices requiring an arbitrary number of commands to be controlled. With this method, users are required to activate their interfaces only when the device under control behaves erroneously. Then, a recursive algorithm, incorporating contextual assumptions relevant to all possible outcomes, is used to obtain an informed estimate of user intention. We evaluate this method by simulating a control task requiring a series of target commands to be tracked by a model user. Results When compared to a random selection, the proposed asynchronous access method offers a significant reduction in the number of interface activations required from the user. Conclusion This novel access method offers a variety of advantages over traditionally synchronous access strategies and may be adapted to a wide variety of contexts, with primary relevance to applications involving direct object manipulation.

  5. Psychophysiological effects of synchronous versus asynchronous music during cycling. (United States)

    Lim, Harry B T; Karageorghis, Costas I; Romer, Lee M; Bishop, Daniel T


    Synchronizing movement to a musical beat may reduce the metabolic cost of exercise, but findings to date have been equivocal. Our aim was to examine the degree to which the synchronous application of music moderates the metabolic demands of a cycle ergometer task. Twenty-three recreationally active men made two laboratory visits. During the first visit, participants completed a maximal incremental ramp test on a cycle ergometer. At the second visit, they completed four randomized 6-min cycling bouts at 90% of ventilatory threshold (control, metronome, synchronous music, and asynchronous music). Main outcome variables were oxygen uptake, HR, ratings of dyspnea and limb discomfort, affective valence, and arousal. No significant differences were evident for oxygen uptake. HR was lower under the metronome condition (122 ± 15 bpm) compared to asynchronous music (124 ± 17 bpm) and control (125 ± 16 bpm). Limb discomfort was lower while listening to the metronome (2.5 ± 1.2) and synchronous music (2.3 ± 1.1) compared to control (3.0 ± 1.5). Both music conditions, synchronous (1.9 ± 1.2) and asynchronous (2.1 ± 1.3), elicited more positive affective valence compared to metronome (1.2 ± 1.4) and control (1.2 ± 1.2), while arousal was higher with synchronous music (3.4 ± 0.9) compared to metronome (2.8 ± 1.0) and control (2.8 ± 0.9). Synchronizing movement to a rhythmic stimulus does not reduce metabolic cost but may lower limb discomfort. Moreover, synchronous music has a stronger effect on limb discomfort and arousal when compared to asynchronous music.

  6. Interpolation algorithm for asynchronous ADC-data (United States)

    Bramburger, Stefan; Zinke, Benny; Killat, Dirk


    This paper presents a modified interpolation algorithm for signals with variable data rate from asynchronous ADCs. The Adaptive weights Conjugate gradient Toeplitz matrix (ACT) algorithm is extended to operate with a continuous data stream. An additional preprocessing of data with constant and linear sections and a weighted overlap of step-by-step into spectral domain transformed signals improve the reconstruction of the asycnhronous ADC signal. The interpolation method can be used if asynchronous ADC data is fed into synchronous digital signal processing.

  7. Wind power systems in the MW range. Part 2. Digital control of a double-fed asynchronous generator without position control; Windkraftanlagen fuer den Megawatt-Bereich. Teil 2. Digitale Steuerung eines doppelt gespeisten Asynchrongenerators ohne Lagegeber

    Energy Technology Data Exchange (ETDEWEB)

    Ehrenberg, J. [sci-worx GmbH, Braunschweig (Germany); Andresen, B.; Rebsdorf, A.V. [Vestas Wind Systems A/S (Denmark)


    While the first part investigated the characteristics of synchronous and asynchronous generators for wind power system development and presented theoretical fundamentals, part 2 discusses practical problems of synchronisation with the network and interpretation of measurements as illustrated by a prototype 2 MW wind power plant. [German] Nach einem Vergleich der Eignung von Synchron- und Asynchrongeneratoren fuer die Konzeption von Windkraftanlagen und einer Darstellung der Theoretischen Grundlagen im Teil 1 widmet sich der zweite Teil des Beitrages den praktischen Fragen der Synchronisation zum Netz und der Interpretation der Messergebnisse an dem Prototyp einer 2-MW-Windkraftanlage. (org.)

  8. Asynchronous presynaptic glutamate release enhances neuronal excitability during the post-spike refractory period. (United States)

    Iremonger, Karl J; Bains, Jaideep S


    Many excitatory synapses in the brain release glutamate with both synchronous and asynchronous components. Immediately following an action potential, neurons display a reduced excitability due to the post-spike afterhyperpolarization (AHP). This gives rise to a relative refractory period. When an action potential is evoked by glutamate synaptic input possessing asynchronous release, the delayed glutamate release events act to depolarize the neuron during the AHP and overcome the relative refractory period. These results demonstrate a new role for asynchronous release in regulating post-spike excitability and the relative refractory period in central neurons. Post-spike afterhyperpolarizations (AHPs) functionally inhibit neuronal excitability for tens to hundreds of milliseconds following each action potential. This imposes a relative refractory period during which synaptic excitation is less effective at evoking spikes. Here we asked whether some synapses have mechanisms in place that allow them to overcome the AHP and drive spiking in target cells during this period of reduced excitability. We examined glutamate synapses onto oxytocin and vasopressin neurons in the paraventricular nucleus of the hypothalamus. These synapses can display pronounced asynchronous glutamate release following a single presynaptic spike, with the time course of release being similar to that of the post-spike AHP. To test whether asynchronous release is more effective at overcoming the relative refractory period, we evoked a single action potential with either a brief synchronous depolarization or an asynchronous potential and then assessed excitability at multiple time points following the spike. Neurons receiving asynchronous depolarizing synaptic inputs had a shorter relative refractory period than those receiving synchronous depolarizations. Our data demonstrate that synapses releasing glutamate in an asynchronous and delayed manner are ideally adapted to counter the AHP. By

  9. Wireless Networks with Asynchronous Users

    CERN Document Server

    Moshksar, Kamyar


    This paper addresses an interference channel consisting of $\\mathbf{n}$ active users sharing $u$ frequency sub-bands. Users are asynchronous meaning there exists a mutual delay between their transmitted codes. A stationary model for interference is considered by assuming the starting point of an interferer's data is uniformly distributed along the codeword of any user. This model is not ergodic, however, we show that the noise plus interference process satisfies an Asymptotic Equipartition Property (AEP) under certain conditions. This enables us to define achievable rates in the conventional Shannon sense. The spectrum is divided to private and common bands. Each user occupies its assigned private band and the common band upon activation. In a scenario where all transmitters are unaware of the number of active users and the channel gains, the optimum spectrum assignment is obtained such that the so-called outage capacity per user is maximized. If $\\Pr\\{\\mathbf{n}>2\\}>0$, all users follow a locally Randomized ...

  10. Non-linear control of a doubly fed induction machine; Commande non-lineaire d'une machine asynchrone a double alimentation

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, P.E.


    This study deals with linear and non-linear control strategies applied to the rotation speed feedback of a doubly fed induction machine (DFIM), whose stator and rotor windings are connected to two Pulse Width Modulation voltage source inverters. We choose to distribute the active powers between the stator and the rotor following a certain proportionality ratio. This leads to guarantee, in steady state operation, a stator and rotor angular frequencies sharing. This distribution is initially assured by two shared angular frequencies controllers, and in a second time by the means of the Park transformation angles directly. Two models are established: the first express the currents, and the second is linked with the fluxes. The simulations results of the linear control (field oriented control), and non-linear control (sliding mode control), show a good independence between the main flux and the torque. An experimental validation is also presented. The results presented show the satisfactory DFIM flux control. Special attention is paid to the active power dispatching. (author)

  11. Remote Asynchronous Message Service Gateway (United States)

    Wang, Shin-Ywan; Burleigh, Scott C.


    The Remote Asynchronous Message Service (RAMS) gateway is a special-purpose AMS application node that enables exchange of AMS messages between nodes residing in different AMS "continua," notionally in different geographical locations. JPL s implementation of RAMS gateway functionality is integrated with the ION (Interplanetary Overlay Network) implementation of the DTN (Delay-Tolerant Networking) bundle protocol, and with JPL s implementation of AMS itself. RAMS protocol data units are encapsulated in ION bundles and are forwarded to the neighboring RAMS gateways identified in the source gateway s AMS management information base. Each RAMS gateway has interfaces in two communication environments: the AMS message space it serves, and the RAMS network - the grid or tree of mutually aware RAMS gateways - that enables AMS messages produced in one message space to be forwarded to other message spaces of the same venture. Each gateway opens persistent, private RAMS network communication channels to the RAMS gateways of other message spaces for the same venture, in other continua. The interconnected RAMS gateways use these communication channels to forward message petition assertions and cancellations among themselves. Each RAMS gateway subscribes locally to all subjects that are of interest in any of the linked message spaces. On receiving its copy of a message on any of these subjects, the RAMS gateway node uses the RAMS network to forward the message to every other RAMS gateway whose message space contains at least one node that has subscribed to messages on that subject. On receiving a message via the RAMS network from some other RAMS gateway, the RAMS gateway node forwards the message to all subscribers in its own message space.

  12. A simple asynchronous replica-exchange implementation

    CERN Document Server

    Bussi, Giovanni


    We discuss the possibility of implementing asynchronous replica-exchange (or parallel tempering) molecular dynamics. In our scheme, the exchange attempts are driven by asynchronous messages sent by one of the computing nodes, so that different replicas are allowed to perform a different number of time-steps between subsequent attempts. The implementation is simple and based on the message-passing interface (MPI). We illustrate the advantages of our scheme with respect to the standard synchronous algorithm and we benchmark it for a model Lennard-Jones liquid on an IBM-LS21 blade center cluster.

  13. Asynchronous Discrete Control of Continuous Processes. (United States)


    COP1854C ELE’M ’ CIC CHARACTERISTICS at TA’ -40 is 2::*C VDD~t 1±51%. 116= m, VIH =0.7 VDD ViL-osVDD CL-A100 p e ig %CHARACTERISTIC .14OM& OMC WS...8217 % 1800-Series Peripherals N CDPI 854, CDPI854C A DYNAMIC ELECTRICAL CHARACTERISTICS at TA -40 to +61’ C. VDO t6%, trtfz20 noS, VIH 𔃺.? VDD VIL=0.3 VDD...complements alternate methods I hat draw upon more advanced ergodic theory and measure- theoretic treatments of the subject. Much of this- work

  14. Asynchronous parallel search in global optimization problems

    Energy Technology Data Exchange (ETDEWEB)

    Archetti, F.; Schoen, F.


    A class of asynchronous parallel search methods is proposed in order to solve the global optimization problem on a multiprocessor system, consisting of several processors which can communicate through a set of global variables contained in a memory shared by all processors. The speed-up ratio and memory contension effects are experimentally analyzed for some algorithms of this class. 6 references.

  15. Asynchronous stream processing with S-Net

    NARCIS (Netherlands)

    Grelck, C.; Scholz, S.-B.; Shafarenko, A.


    We present the rationale and design of S-Net, a coordination language for asynchronous stream processing. The language achieves a near-complete separation between the application code, written in any conventional programming language, and the coordination/communication code written in S-Net. Our

  16. Increasing Student Engagement Using Asynchronous Learning (United States)

    Northey, Gavin; Bucic, Tania; Chylinski, Mathew; Govind, Rahul


    Student engagement is an ongoing concern for educators because of its positive association with deep learning and educational outcomes. This article tests the use of a social networking site (Facebook) as a tool to facilitate asynchronous learning opportunities that complement face-to-face interactions and thereby enable a stronger learning…

  17. Asynchronous versus Synchronous Learning in Pharmacy Education (United States)

    Motycka, Carol A.; St. Onge, Erin L.; Williams, Jennifer


    Objective: To better understand the technology being used today in pharmacy education through a review of the current methodologies being employed at various institutions. Also, to discuss the benefits and difficulties of asynchronous and synchronous methodologies, which are being utilized at both traditional and distance education campuses.…

  18. Dynamic Performances of Asynchronous Machines | Ubeku ...

    African Journals Online (AJOL)

    The dynamic performance of electrical machines is affected by low and unbalanced voltages, frequency variations in its supply systems and pulsating load torques. In this paper the d-q axis model in the synchronous reference frame is used in the dynamic analysis on the performance of an asynchronous machine working ...

  19. Towards behavioral synthesis of asynchronous circuits - an implementation template targeting syntax directed compilation

    DEFF Research Database (Denmark)

    Nielsen, Sune Fallgaard; Sparsø, Jens; Madsen, Jan


    domain by introducing a computation model, which resembles the synchronous datapath and control architecture, but which is completely asynchronous. The datapath and control architecture is then expressed in the Balsa-language, and using syntax directed compilation a corresponding handshake circuit...


    Directory of Open Access Journals (Sweden)

    D. O. Kulagin


    Full Text Available Development of mathematical model of asynchronous machines in (d, q coordinate system with taking into account the saturation of magnetic circuits is performed. In the paper, we used the method of dynamic inductances, which is connected with the use of a systematic study of motor properties. An analytical model of asynchronous motor magnetic circuit, which is taken into account action of the tangential and radial dynamic inductances is created. On the basis of this the sensor dynamic inductances of rich machine, which was recorded in (d, q coordinate system of equations of rotor and stator circles of asynchronous motor with the saturation were built. The author suggests to use the method of dynamic inductances at construction of asynchronous engine mathematical model, that allows to take into account the saturation of the main magnetic path for the modes with a wide range of changes in the flow of mutual induction between the stator and the rotor, saturation flow path, the scattering modes that are characterized by large current circuits of the machine, induction, due to processes of saturation, between mutually perpendicular to the contours of the machine, as well as the joint saturation worker thread and threads scattering modes that are characterized by the significant size of the workflow and large values of currents contours of the machine. The mathematical model allows to take into account the change of the magnetic state of asynchronous motor as necessity to build adequate systems of control drives and driving

  1. The design of an asynchronous Tiny RISC TM/TR4101 microprocessor core

    DEFF Research Database (Denmark)

    Christensen, Kåre Tais; Jensen, P.; Korger, P.


    This paper presents the design of an asynchronous version of the TR4101 embedded microprocessor core developed by LSI Logic Inc. The asynchronous processor, called ARISC, was designed using the same CAD tools and the same standard cell library that was used to implement the TR4101. The paper...... reports on the design methodology, the architecture, the implementation, and the performance of the ARISC. This includes a comparison with the TR4101, and a detailed breakdown of the power consumption in the ARISC. ARISC is our first attempt at an asynchronous implementation and a number of simplifying...... decisions were made up front. Throughout the entire design we use four-phase handshaking in combination with a normally opaque latch controller. All logic is implemented using static logic standard cells. Despite this the ARISC performs surprisingly well: In 0.35 μm CMOS performance is 74-123 MIPS depending...

  2. Finite-time synchronization of uncertain coupled switched neural networks under asynchronous switching. (United States)

    Wu, Yuanyuan; Cao, Jinde; Li, Qingbo; Alsaedi, Ahmed; Alsaadi, Fuad E


    This paper deals with the finite-time synchronization problem for a class of uncertain coupled switched neural networks under asynchronous switching. By constructing appropriate Lyapunov-like functionals and using the average dwell time technique, some sufficient criteria are derived to guarantee the finite-time synchronization of considered uncertain coupled switched neural networks. Meanwhile, the asynchronous switching feedback controller is designed to finite-time synchronize the concerned networks. Finally, two numerical examples are introduced to show the validity of the main results. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Verification of Building Blocks for Asynchronous Circuits

    Directory of Open Access Journals (Sweden)

    Freek Verbeek


    Full Text Available Scalable formal verification constitutes an important challenge for the design of asynchronous circuits. Deadlock freedom is a property that is desired but hard to verify. It is an emergent property that has to be verified monolithically. We present our approach to using ACL2 to verify necessary and sufficient conditions over asynchronous delay-insensitive primitives. These conditions are used to derive SAT/SMT instances from circuits built out of these primitives. These SAT/SMT instances help in establishing absence of deadlocks. Our verification effort consists of building an executable checker in the ACL2 logic tailored for our purpose. We prove that this checker is correct. This approach enables us to prove ACL2 theorems involving defun-sk constructs and free variables fully automatically.

  4. Existence test for asynchronous interval iterations

    DEFF Research Database (Denmark)

    Madsen, Kaj; Caprani, O.; Stauning, Ole


    In the search for regions that contain fixed points ofa real function of several variables, tests based on interval calculationscan be used to establish existence ornon-existence of fixed points in regions that are examined in the course ofthe search. The search can e.g. be performed...... as a synchronous (sequential) interval iteration:In each iteration step all components of the iterate are calculatedbased on the previous iterate. In this case it is straight forward to base simple interval existence and non-existencetests on the calculations done in each step of the iteration. The search can also...... be performed as an asynchronous (parallel) iteration: Only a few components are changed in each stepand this calculation is in general based on components from differentprevious iterates. For the asynchronous iteration it turns out thatsimple tests of existence and non-existence can be based...

  5. Computing by Temporal Order: Asynchronous Cellular Automata

    Directory of Open Access Journals (Sweden)

    Michael Vielhaber


    Full Text Available Our concern is the behaviour of the elementary cellular automata with state set 0,1 over the cell set Z/nZ (one-dimensional finite wrap-around case, under all possible update rules (asynchronicity. Over the torus Z/nZ (n<= 11,we will see that the ECA with Wolfram rule 57 maps any v in F_2^n to any w in F_2^n, varying the update rule. We furthermore show that all even (element of the alternating group bijective functions on the set F_2^n = 0,...,2^n-1, can be computed by ECA57, by iterating it a sufficient number of times with varying update rules, at least for n <= 10. We characterize the non-bijective functions computable by asynchronous rules.

  6. Asynchronous Communication Scheme For Hypercube Computer (United States)

    Madan, Herb S.


    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.

  7. Blending Online Asynchronous and Synchronous Learning

    Directory of Open Access Journals (Sweden)

    Lisa C. Yamagata-Lynch


    Full Text Available In this article I will share a qualitative self-study about a 15-week blended 100% online graduate level course facilitated through synchronous meetings on Blackboard Collaborate and asynchronous discussions on Blackboard. I taught the course at the University of Tennessee (UT during the spring 2012 semester and the course topic was online learning environments. The primary research question of this study was: How can the designer/instructor optimize learning experiences for students who are studying about online learning environments in a blended online course relying on both synchronous and asynchronous technologies? I relied on student reflections of course activities during the beginning, middle, and the end of the semester as the primary data source to obtain their insights regarding course experiences. Through the experiences involved in designing and teaching the course and engaging in this study I found that there is room in the instructional technology research community to address strategies for facilitating online synchronous learning that complement asynchronous learning. Synchronous online whole class meetings and well-structured small group meetings can help students feel a stronger sense of connection to their peers and instructor and stay engaged with course activities. In order to provide meaningful learning spaces in synchronous learning environments, the instructor/designer needs to balance the tension between embracing the flexibility that the online space affords to users and designing deliberate structures that will help them take advantage of the flexible space.

  8. An Asynchronous IEEE Floating-Point Arithmetic Unit

    Directory of Open Access Journals (Sweden)

    Joel R. Noche


    Full Text Available An asynchronous floating-point arithmetic unit is designed and tested at the transistor level usingCadence software. It uses CMOS (complementary metal oxide semiconductor and DCVS (differentialcascode voltage switch logic in a 0.35 µm process using a 3.3 V supply voltage, with dual-rail data andsingle-rail control signals using four-phase handshaking.Using 17,085 transistors, the unit handles single-precision (32-bit addition/subtraction, multiplication,division, and remainder using the IEEE 754-1985 Standard for Binary Floating-Point Arithmetic, withrounding and other operations to be handled by separate hardware or software. Division and remainderare done using a restoring subtractive algorithm; multiplication uses an additive algorithm. Exceptionsare noted by flags (and not trap handlers and the output is in single-precision.Previous work on asynchronous floating-point arithmetic units have mostly focused on single operationssuch as division. This is the first work to the authors' knowledge that can perform floating-point addition,multiplication, division, and remainder using a common datapath.

  9. Realization of station for testing asynchronous three-phase motors (United States)

    Wróbel, A.; Surma, W.


    Nowadays, you cannot imagine the construction and operation of machines without the use of electric motors [13-15]. The proposed position is designed to allow testing of asynchronous three-phase motors. The position consists of a tested engine and the engine running as a load, both engines combined with a mechanical clutch [2]. The value of the load is recorded by measuring shaft created with Strain Gauge Bridge. This concept will allow to study the basic parameters of the engines, visualization motor parameters both vector and scalar controlled, during varying load drive system. In addition, registration during the variable physical parameters of the working electric motor, controlled by a frequency converter or controlled by a contactor will be possible. Position is designed as a teaching and research position to characterize the engines. It will be also possible selection of inverter parameters.

  10. Asynchronous gaze-independent event-related potential-based brain-computer interface. (United States)

    Aloise, Fabio; Aricò, Pietro; Schettini, Francesca; Salinari, Serenella; Mattia, Donatella; Cincotti, Febo


    In this study a gaze independent event related potential (ERP)-based brain computer interface (BCI) for communication purpose was combined with an asynchronous classifier endowed with dynamical stopping feature. The aim was to evaluate if and how the performance of such asynchronous system could be negatively affected in terms of communication efficiency and robustness to false positives during the intentional no-control state. The proposed system was validated with the participation of 9 healthy subjects. A comparison was performed between asynchronous and synchronous classification technique outputs while users were controlling the same gaze independent BCI interface. The performance of both classification techniques were assessed both off-line and on-line by means of the efficiency metric introduced by Bianchi et al. (2007). This latter metric allows to set a different misclassification cost for wrong classifications and abstentions. Robustness was evaluated as the rate of false positives occurring during voluntary no-control states. The asynchronous classifier did not exhibited significantly higher accuracy or lower error rate with respect to the synchronous classifier (accuracy: 74.66% versus 87.96%, error rate: 7.11% versus 12.04% respectively). However, the on-line and off-line analysis revealed that the communication efficiency was significantly improved (pinterface is a promising solution to be further explored in order to increase the general usability of ERP-based BCI systems designed for severely disabled people with an impairment of the voluntary control of eye movements. In fact, the asynchronous classifier can improve communication efficiency automatically adapting the number of stimulus repetitions to the current user's state and suspending the control if he/she does not intend to select an item. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Behavioral synthesis of asynchronous circuits

    DEFF Research Database (Denmark)

    Nielsen, Sune Fallgaard


    is idle. This reduces unnecessary switching activity in the individual functional units and therefore the energy consumption of the entire circuit. A collection of behavioral synthesis algorithms have been developed allowing the designer to perform time and power constrained design space exploration....... The datapath and control architecture is then expressed in the Balsa-language, and using syntax directed compilation a corresponding handshake circuit implementation (and eventually a layout) is produced....

  12. An Asynchronous Register Bypass Transformation


    Papadantonakis, Karl


    A register specification typically states that in each cycle there is a possible read followed by a possible write; the sequence is strict. A register core with a separate read and write port is more efficient, because it can read and write to different locations simultaneously, and hence in one cycle. In the Caltech MiniMIPS processor, a control structure was added to such a register core, so that it implements the desired specification.

  13. EPOS for Coordination of Asynchronous Sensor Webs Project (United States)

    National Aeronautics and Space Administration — Develop, integrate, and deploy software-based tools to coordinate asynchronous, distributed missions and optimize observation planning spanning simultaneous...

  14. Implementing e-Transactions with Asynchronous Replication


    Frolund, Svend; Guerraoui, Rachid


    An e-Transaction is one that executes exactly-once despite failures. This paper describes a distributed protocol that implements the abstraction of e-Transactionsin three-tier architectures. Three-tier architectures are typically Internet-oriented architectures, where the end-user interacts with front-end clients (e.g., browsers) that invoke middle-tier application servers (e.g., web servers) to access back-end databases. We implement the e-Transaction abstraction using an asynchronous replic...

  15. Characterization and synthesis of a 32-bit asynchronous microprocessor in synchronous reconfigurable devices

    Directory of Open Access Journals (Sweden)

    Adrian Pedroza de la Crúz


    Full Text Available This paper presents the design, implementation, and experimental results of 32-bit asynchronous microprocessor developed in a synchronous reconfigurable device (FPGA, taking advantage of a hard macro. It has support for floating point operations, such as addition, subtraction, and multiplication, and is based on the IEEE 754-2008 standard with 32-bit simple precision. This work describes the different blocks of the microprocessors as delay modules, needed to implement a Self-Timed (ST protocol in a synchronous system, and the operational analysis of the asynchronous central unit, according to the developed occupations and speeds. The ST control is based on a micropipeline used as a centralized generator of activation signals that permit the performance of the operations in the microprocessor without the need of a global clock. This work compares the asynchronous microprocessor with a synchronous version. The parameters evaluated are power consumption, area, and speed. Both circuits were designed and implemented in an FPGA Virtex 5. The performance obtained was 4 MIPS for the asynchronous microprocessor against 1.6 MIPS for the synchronous.

  16. Indoor Positioning for Smartphones Using Asynchronous Ultrasound Trilateration

    Directory of Open Access Journals (Sweden)

    James D. Carswell


    Full Text Available Modern smartphones are a great platform for Location Based Services (LBS. While outdoor LBS for smartphones has proven to be very successful, indoor LBS for smartphones has not yet fully developed due to the lack of an accurate positioning technology. In this paper we present an accurate indoor positioning approach for commercial off-the-shelf (COTS smartphones that uses the innate ability of mobile phones to produce ultrasound, combined with Time-Difference-of-Arrival (TDOA asynchronous trilateration. We evaluate our indoor positioning approach by describing its strengths and weaknesses, and determine its absolute accuracy. This is accomplished through a range of experiments that involve variables such as position of control point microphones, position of phone within the room, direction speaker is facing and presence of user in the signal path. Test results show that our Lok8 (locate mobile positioning system can achieve accuracies better than 10 cm in a real-world environment.

  17. Asynchronous machine rotor speed estimation using a tabulated numerical approach (United States)

    Nguyen, Huu Phuc; De Miras, Jérôme; Charara, Ali; Eltabach, Mario; Bonnet, Stéphane


    This paper proposes a new method to estimate the rotor speed of the asynchronous machine by looking at the estimation problem as a nonlinear optimal control problem. The behavior of the nonlinear plant model is approximated off-line as a prediction map using a numerical one-step time discretization obtained from simulations. At each time-step, the speed of the induction machine is selected satisfying the dynamic fitting problem between the plant output and the predicted output, leading the system to adopt its dynamical behavior. Thanks to the limitation of the prediction horizon to a single time-step, the execution time of the algorithm can be completely bounded. It can thus easily be implemented and embedded into a real-time system to observe the speed of the real induction motor. Simulation results show the performance and robustness of the proposed estimator.


    Directory of Open Access Journals (Sweden)



    Full Text Available The purpose of the study was to compare the influences of a training programme’s instructional delivery method (synchronous and asynchronous on Greek in-service physical educators’ cognitive understanding on student assessment. Forty nine participants were randomly divided into synchronous, asynchronous, and control group. The experimental groups participated in the same training programme with different online instructional method. The control group received no intervention. A 17-item questionnaire was completed before and after programme implementation by the entire sample. A two-way analysis of variance with repeated measures on the last factor was used for data analysis. The methods x measures interaction effect were significant. Both experimental groups, unlike the control, presented a similar significant increase in their understanding. Conclusively, synchronous and asynchronous instructional approaches of a training programme enhance equally Greek physical educators’ cognitive understanding.

  19. Two Studies Examining Argumentation in Asynchronous Computer Mediated Communication (United States)

    Joiner, Richard; Jones, Sarah; Doherty, John


    Asynchronous computer mediated communication (CMC) would seem to be an ideal medium for supporting development in student argumentation. This paper investigates this assumption through two studies. The first study compared asynchronous CMC with face-to-face discussions. The transactional and strategic level of the argumentation (i.e. measures of…

  20. Considerations regarding asynchronous motor rotor parameters determination by FEM

    Directory of Open Access Journals (Sweden)

    Olivian Chiver


    Full Text Available The paper presents some considerations about asynchronous motor rotor parameters determination, using software based on finite elements method (FEM. For this, 2D magnetostatic and time harmonic analysis will be realized, at different frequencies, in case of a three phase asynchronous motor.

  1. Integrating Asynchronous Digital Design Into the Computer Engineering Curriculum (United States)

    Smith, S. C.; Al-Assadi, W. K.; Di, J.


    As demand increases for circuits with higher performance, higher complexity, and decreased feature size, asynchronous (clockless) paradigms will become more widely used in the semiconductor industry, as evidenced by the International Technology Roadmap for Semiconductors' (ITRS) prediction of a likely shift from synchronous to asynchronous design…

  2. Designing Asynchronous Circuits for Low Power: An IFIR Filter

    DEFF Research Database (Denmark)

    Nielsen, Lars Skovby; Sparsø, Jens


    This paper addresses the design of asynchronous circuits for low power through an example: a filter bank for a digital hearing aid. The asynchronous design re-implements an existing synchronous circuit which is used in a commercial product. For comparison, both designs have been fabricated...

  3. Selective particle capture by asynchronously beating cilia (United States)

    Ding, Yang; Kanso, Eva


    Selective particle filtration is fundamental in many engineering and biological systems. For example, many aquatic microorganisms use filter feeding to capture food particles from the surrounding fluid, using motile cilia. One of the capture strategies is to use the same cilia to generate feeding currents and to intercept particles when the particles are on the downstream side of the cilia. Here, we develop a 3D computational model of ciliary bands interacting with flow suspended particles and calculate particle trajectories for a range of particle sizes. Consistent with experimental observations, we find optimal particle sizes that maximize capture rate. The optimal size depends nonlinearly on cilia spacing and cilia coordination, synchronous vs. asynchronous. These parameters affect the cilia-generated flow field, which in turn affects particle trajectories. The low capture rate of smaller particles is due to the particles' inability to cross the flow streamlines of neighboring cilia. Meanwhile, large particles have difficulty entering the sub-ciliary region once advected downstream, also resulting in low capture rates. The optimal range of particle sizes is enhanced when cilia beat asynchronously. These findings have potentially important implications on the design and use of biomimetic cilia in processes such as particle sorting in microfluidic devices.

  4. A newly proposed disease condition produced by light exposure during night: asynchronization. (United States)

    Kohyama, Jun


    The bedtime of preschoolers/pupils/students in Japan has become progressively later with the result sleep duration has become progressively shorter. With these changes, more than half of the preschoolers/pupils/students in Japan recently have complained of daytime sleepiness, while approximately one quarter of junior and senior high school students in Japan reportedly suffer from insomnia. These preschoolers/pupils/students may be suffering from behaviorally induced insufficient sleep syndrome due to inadequate sleep hygiene. If this diagnosis is correct, they should be free from these complaints after obtaining sufficient sleep by avoiding inadequate sleep hygiene. However, such a therapeutic approach often fails. Although social factors are often involved in these sleep disturbances, a novel clinical notion--asynchronization--can further a deeper understanding of the pathophysiology of these disturbances. The essence of asynchronization is a disturbance in various aspects (e.g., cycle, amplitude, phase and interrelationship) of the biological rhythms that normally exhibit circadian oscillation, presumably involving decreased activity of the serotonergic system. The major trigger of asynchronization is hypothesized to be a combination of light exposure during the night and a lack of light exposure in the morning. In addition to basic principles of morning light and an avoidance of nocturnal light exposure, presumable potential therapeutic approaches for asynchronization involve both conventional ones (light therapy, medications (hypnotics, antidepressants, melatonin, vitamin B12), physical activation, chronotherapy) and alternative ones (kampo, pulse therapy, direct contact, control of the autonomic nervous system, respiration (qigong, tanden breathing), chewing, crawling). A morning-type behavioral preference is described in several of the traditional textbooks for good health. The author recommends a morning-type behavioral lifestyle as a way to reduce


    Directory of Open Access Journals (Sweden)

    А.М. Galynovskiy


    Full Text Available The comparative analysis of direct frequency converters with artificial and natural- switching term of the cyclical control algorithm is presented; the recommendations for their using in brushless asynchronized machines with three-phase winding are developed. Converters with a limited number of full-controlled valves have large losses in safety circuits of gates, they can be used in system of automatic excitation control. The best quality of voltage and current load are provided by converters with natural commutation using modulated input voltage, the combined potential compounds windings supply and the combined method of thyristor controlling. When the load is divided into two three-phase groups, an even number of phases of the power supply for single phase of the load are applied the bridge converter circuit. Regulation of the load current is carried out by the excitation current of field exciters and by the control angle of thyristor. Converters can be used in high-power asynchronized motors and generators. In asynchronized compensators it is possible to use diode-thyristor converters without transmitting the control signals to the rotating part. The frequency converters without modulation of input voltage have the smallest increase in rated capacity of power supply. However, they have a low quality form of the output voltage at high power factor of load.

  6. Error characterization for asynchronous computations: Proxy equation approach (United States)

    Sallai, Gabriella; Mittal, Ankita; Girimaji, Sharath


    Numerical techniques for asynchronous fluid flow simulations are currently under development to enable efficient utilization of massively parallel computers. These numerical approaches attempt to accurately solve time evolution of transport equations using spatial information at different time levels. The truncation error of asynchronous methods can be divided into two parts: delay dependent (EA) or asynchronous error and delay independent (ES) or synchronous error. The focus of this study is a specific asynchronous error mitigation technique called proxy-equation approach. The aim of this study is to examine these errors as a function of the characteristic wavelength of the solution. Mitigation of asynchronous effects requires that the asynchronous error be smaller than synchronous truncation error. For a simple convection-diffusion equation, proxy-equation error analysis identifies critical initial wave-number, λc. At smaller wave numbers, synchronous error are larger than asynchronous errors. We examine various approaches to increase the value of λc in order to improve the range of applicability of proxy-equation approach.

  7. Commande adaptive d'une machine asynchrone


    Slama-Belkhodja, I.; De Fornel, B.


    Cat article décrit une stratégie de commande adaptive indirecte à Placement de Pôles (PP), appliquée à la commande en vitesse d'une machine asynchrone alimentée par un ensemble hacheur-filtre-onduleur de tension. L'algorithme des Moindres Carrés Récursifs (MCR) est utilisé pour l'identification des modèles de comportement type entrées/sorties. Un intérêt particulier est porté à la mise en oeuvre de cet algorithme et à la discussion de ses résultats, tenant compte des erreurs de modélisation e...

  8. Asynchronous parallel pattern search for nonlinear optimization

    Energy Technology Data Exchange (ETDEWEB)

    P. D. Hough; T. G. Kolda; V. J. Torczon


    Parallel pattern search (PPS) can be quite useful for engineering optimization problems characterized by a small number of variables (say 10--50) and by expensive objective function evaluations such as complex simulations that take from minutes to hours to run. However, PPS, which was originally designed for execution on homogeneous and tightly-coupled parallel machine, is not well suited to the more heterogeneous, loosely-coupled, and even fault-prone parallel systems available today. Specifically, PPS is hindered by synchronization penalties and cannot recover in the event of a failure. The authors introduce a new asynchronous and fault tolerant parallel pattern search (AAPS) method and demonstrate its effectiveness on both simple test problems as well as some engineering optimization problems

  9. A Block-Asynchronous Relaxation Method for Graphics Processing Units

    Energy Technology Data Exchange (ETDEWEB)

    Antz, Hartwig [Karlsruhe Inst. of Technology (KIT) (Germany); Tomov, Stanimire [Univ. of Tennessee, Knoxville, TN (United States); Dongarra, Jack [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Manchester (United Kingdom); Heuveline, Vincent [Karlsruhe Inst. of Technology (KIT) (Germany)


    In this paper, we analyze the potential of asynchronous relaxation methods on Graphics Processing Units (GPUs). For this purpose, we developed a set of asynchronous iteration algorithms in CUDA and compared them with a parallel implementation of synchronous relaxation methods on CPU-based systems. For a set of test matrices taken from the University of Florida Matrix Collection we monitor the convergence behavior, the average iteration time and the total time-to-solution time. Analyzing the results, we observe that even for our most basic asynchronous relaxation scheme, despite its lower convergence rate compared to the Gauss-Seidel relaxation (that we expected), the asynchronous iteration running on GPUs is still able to provide solution approximations of certain accuracy in considerably shorter time then Gauss- Seidel running on CPUs. Hence, it overcompensates for the slower convergence by exploiting the scalability and the good fit of the asynchronous schemes for the highly parallel GPU architectures. Further, enhancing the most basic asynchronous approach with hybrid schemes – using multiple iterations within the ”subdomain” handled by a GPU thread block and Jacobi-like asynchronous updates across the ”boundaries”, subject to tuning various parameters – we manage to not only recover the loss of global convergence but often accelerate convergence of up to two times (compared to the effective but difficult to parallelize Gauss-Seidel type of schemes), while keeping the execution time of a global iteration practically the same. This shows the high potential of the asynchronous methods not only as a stand alone numerical solver for linear systems of equations fulfilling certain convergence conditions but more importantly as a smoother in multigrid methods. Due to the explosion of parallelism in todays architecture designs, the significance and the need for asynchronous methods, as the ones described in this work, is expected to grow.

  10. TCDQ-TCT retraction and losses during asynchronous beam dump

    CERN Document Server

    Bracco, Chiara; Quaranta, Elena; CERN. Geneva. ATS Department


    The protection provided by the TCDQs in case of asynchronous beam dump depends strongly on their correct setup. They have to respect the strict hierarchy of the full collimation system and shield the tertiary collimators in the experimental regions. This MD aimed at performing asynchronous beam dump tests with different configurations, in order to assess the minimum allowed retraction between TCTs and TCDQs and, as a consequence, on the The protection provided by the TCDQs in case of asynchronous beam dump depends strongly on their correct setup. They have to respect the strict hierarchy of the full collimation system and shield the tertiary collimators in the experimental regions. This MD aimed at performing asynchronous beam dump tests with different configurations, in order to assess the minimum allowed retraction between TCTs and TCDQs and, as a consequence, on the β* reach.

  11. Verification and Planning for Stochastic Processes with Asynchronous Events

    National Research Council Canada - National Science Library

    Younes, Hakan L


    .... The most common assumption is that of history-independence: the Markov assumption. In this thesis, the author considers the problems of verification and planning for stochastic processes with asynchronous events, without relying on the Markov assumption...

  12. Asynchronous cellular automaton-based neuron: theoretical analysis and on-FPGA learning. (United States)

    Matsubara, Takashi; Torikai, Hiroyuki


    A generalized asynchronous cellular automaton-based neuron model is a special kind of cellular automaton that is designed to mimic the nonlinear dynamics of neurons. The model can be implemented as an asynchronous sequential logic circuit and its control parameter is the pattern of wires among the circuit elements that is adjustable after implementation in a field-programmable gate array (FPGA) device. In this paper, a novel theoretical analysis method for the model is presented. Using this method, stabilities of neuron-like orbits and occurrence mechanisms of neuron-like bifurcations of the model are clarified theoretically. Also, a novel learning algorithm for the model is presented. An equivalent experiment shows that an FPGA-implemented learning algorithm enables an FPGA-implemented model to automatically reproduce typical nonlinear responses and occurrence mechanisms observed in biological and model neurons.

  13. Eventual Leader Service in Unreliable Asynchronous Systems: Why? How?


    Raynal, Michel


    Providing processes with an {\\it eventual leader} service is an important issue when one has to design and implement a middleware layer on top of a failure-prone asynchronous distributed system. This invited lecture investigates this problem. It first shows that such a service cannot be built if the underlying system is fully asynchronous. Then, the paper visits several additional behavioral assumptions that have been proposed in the literature to cope with this impossibility and presents cor...

  14. Experimental 3D Asynchronous Field Programmable Gate Array (FPGA) (United States)



  15. A Low-Power Asynchronous Step-Down DC-DC Converter for Implantable Devices. (United States)

    Al-Terkawi Hasib, Omar; Sawan, M; Savaria, Y


    In this paper, we present a fully integrated asynchronous step-down switched capacitor dc-dc conversion structure suitable for supporting ultra-low-power circuits commonly found in biomedical implants. The proposed converter uses a fully digital asynchronous state machine as the heart of the control circuitry to generate the drive signals. To minimize the switching losses, the asynchronous controller scales the switching frequency of the drive signals according to the loading conditions. It also turns on additional parallel switches when needed and has a backup synchronous drive mode. This circuit regulates load voltages from 300 mV to 1.1 V derived from a 1.2-V input voltage. A total of 350 pF on-chip capacitance was implemented to support a maximum of 230-μ W load power, while providing efficiency up to 80%. The circuit validating the proposed concepts was fabricated in 0.13- μm complementary metal-oxide semiconductor technology. Experimental test results confirm the expected functionality and performance of the proposed circuit.

  16. Rapid, generalized adaptation to asynchronous audiovisual speech. (United States)

    Van der Burg, Erik; Goodbourn, Patrick T


    The brain is adaptive. The speed of propagation through air, and of low-level sensory processing, differs markedly between auditory and visual stimuli; yet the brain can adapt to compensate for the resulting cross-modal delays. Studies investigating temporal recalibration to audiovisual speech have used prolonged adaptation procedures, suggesting that adaptation is sluggish. Here, we show that adaptation to asynchronous audiovisual speech occurs rapidly. Participants viewed a brief clip of an actor pronouncing a single syllable. The voice was either advanced or delayed relative to the corresponding lip movements, and participants were asked to make a synchrony judgement. Although we did not use an explicit adaptation procedure, we demonstrate rapid recalibration based on a single audiovisual event. We find that the point of subjective simultaneity on each trial is highly contingent upon the modality order of the preceding trial. We find compelling evidence that rapid recalibration generalizes across different stimuli, and different actors. Finally, we demonstrate that rapid recalibration occurs even when auditory and visual events clearly belong to different actors. These results suggest that rapid temporal recalibration to audiovisual speech is primarily mediated by basic temporal factors, rather than higher-order factors such as perceived simultaneity and source identity. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  17. Managing Asynchronous Data in ATLAS's Concurrent Framework

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00100895; The ATLAS collaboration; Baines, John; Bold, Tomasz; Calafiura, Paolo; Cranshaw, Jack; Dotti, Andrea; Farrell, Steven; Malon, David; Stewart, Graeme; Snyder, Scott; van Gemmeren, Peter; Tsulaia, Vakhtang; Wynne, Benjamin


    In order to be able to make effective use of emerging hardware, where the amount of memory available to any CPU is rapidly decreasing as the core count continues to rise, ATLAS has begun a migration to a concurrent, multi-threaded software framework, known as AthenaMT. Significant progress has been made in implementing AthenaMT - we can currently run realistic Geant4 simulations on massively concurrent machines. the migration of realistic prototypes of reconstruction workflows is more difficult, given the large amounts of legacy code and the complexity and challenges of reconstruction software. These types of workflows, however, are the types that will most benefit from the memory reduction features of a multi-threaded framework. One of the challenges that we will report on in this paper is the re-design and implementation of several key asynchronous technologies whose behaviour is radically different in a concurrent environment than in a serial one, namely the management of Conditions data and the Detector D...

  18. Asynchronous Forums in EAP: Assessment Issues

    Directory of Open Access Journals (Sweden)

    Sara Kol


    Full Text Available This paper reports on a pilot and a subsequent study that focused on the assessment of student writing in asynchronous text-stimulated forum discussions. The study, which was conducted in advanced English for Academic Purposes (EAP courses, aimed at determining suitable assessment criteria for written academic discussions. In addition, the study tapped student attitudes toward forums, checked the effect of forum participation on student writing, and characterized the text-stimulated forum discussions.Based on a content analysis of the pilot data, the constructs of reflection and interaction were selected as assessment criteria to be evaluated in the main study. These criteria were found to be usable but insufficient for student assessment in the EAP courses. A questionnaire showed that the student attitudes were positive and that most students felt that their writing improved, even though an analysis of language complexity showed no significant improvement. A qualitative analysis of the transcripts revealed deep student involvement with the content and with their peers as well as an academic register interspersed with conversational interactions.

  19. Commande vectorielle d'un moteur asynchrone sans capteur (United States)

    Ourth, T.


    A field-oriented control strategy for induction machines which does not use mechanical sensors is presented. The rotor flux is observed by a reduced-order Luenberger-type observer based on a model using a stator-fixed reference frame. An estimate of the rotation speed is derived from the flux vector, the measured stator currents and the field orientation angle. Simulations demonstrate that this control strategy performs well even in the presence of parameter variations up to ± 50% (resistances). Ce papier présente la commande par flux orienté d'une machine asynchrone sans capteur de vitesse ou de position. Le flux rotorique est évalué grâce à un observateur d'ordre réduit d'un type voisin de Luenberger travaillant dans un repère fixe statorique. L'estimation de la vitesse est obtenue à partir du module du flux rotorique, des courants statoriques mesurés et de l'angle d'orientation du flux rotorique. Cette étude basée sur des simulations démontre un comportement acceptable de la commande malgré la variation des paramètres comme les résistances de la machine.


    Directory of Open Access Journals (Sweden)

    V. S. Safaryan


    Full Text Available The article considers experimental and analytical determination of the asynchronous machine equivalent-circuit parameters with application of the reference data. Transient processes investigation of the asynchronous machines necessitates the equivalent circuit parameters (resistance impedance, inductances and coefficient of the stator-rotor contours mutual inductance that help form the transitory-process mathematical simulation model. The reference books do not provide those parameters; they instead give the rated ones (active power, voltage, slide, coefficient of performance and capacity coefficient as well as the ratio of starting and nominal currents and torques. The noted studies on the asynchronous machine equivalent-circuits parametrization fail to solve the problems ad finem or solve them with admissions. The paper presents experimental and analytical determinations of the asynchronous machine equivalent-circuit parameters: the experimental one based on the results of two measurements and the analytical one where the problem boils down to solving a system of nonlineal algebraic equations. The authors investigate the equivalent asynchronous machine input-resistance properties and adduce the dependence curvatures of the input-resistances on the slide. They present a symbolic model for analytical parameterization of the asynchronous machine equivalent-circuit that represents a system of nonlineal equations and requires one of the rotor-parameters arbitrary assignment. The article demonstrates that for the asynchronous machine equivalent-circuit experimental parameterization the measures are to be conducted of the stator-circuit voltage, current and active power with two different slides and arbitrary assignment of one of the rotor parameters. The paper substantiates the fact that additional measurement does not discard the rotor-parameter choice arbitrariness. The authors establish that in motoring mode there is a critical slide by which the

  1. IHadoop: Asynchronous iterations for MapReduce

    KAUST Repository

    Elnikety, Eslam Mohamed Ibrahim


    MapReduce is a distributed programming frame-work designed to ease the development of scalable data-intensive applications for large clusters of commodity machines. Most machine learning and data mining applications involve iterative computations over large datasets, such as the Web hyperlink structures and social network graphs. Yet, the MapReduce model does not efficiently support this important class of applications. The architecture of MapReduce, most critically its dataflow techniques and task scheduling, is completely unaware of the nature of iterative applications; tasks are scheduled according to a policy that optimizes the execution for a single iteration which wastes bandwidth, I/O, and CPU cycles when compared with an optimal execution for a consecutive set of iterations. This work presents iHadoop, a modified MapReduce model, and an associated implementation, optimized for iterative computations. The iHadoop model schedules iterations asynchronously. It connects the output of one iteration to the next, allowing both to process their data concurrently. iHadoop\\'s task scheduler exploits inter-iteration data locality by scheduling tasks that exhibit a producer/consumer relation on the same physical machine allowing a fast local data transfer. For those iterative applications that require satisfying certain criteria before termination, iHadoop runs the check concurrently during the execution of the subsequent iteration to further reduce the application\\'s latency. This paper also describes our implementation of the iHadoop model, and evaluates its performance against Hadoop, the widely used open source implementation of MapReduce. Experiments using different data analysis applications over real-world and synthetic datasets show that iHadoop performs better than Hadoop for iterative algorithms, reducing execution time of iterative applications by 25% on average. Furthermore, integrating iHadoop with HaLoop, a variant Hadoop implementation that caches

  2. Gigabit Ethernet Asynchronous Clock Compensation FIFO (United States)

    Duhachek, Jeff


    Clock compensation for Gigabit Ethernet is necessary because the clock recovered from the 1.25 Gb/s serial data stream has the potential to be 200 ppm slower or faster than the system clock. The serial data is converted to 10-bit parallel data at a 125 MHz rate on a clock recovered from the serial data stream. This recovered data needs to be processed by a system clock that is also running at a nominal rate of 125 MHz, but not synchronous to the recovered clock. To cross clock domains, an asynchronous FIFO (first-in-first-out) is used, with the write pointer (wprt) in the recovered clock domain and the read pointer (rptr) in the system clock domain. Because the clocks are generated from separate sources, there is potential for FIFO overflow or underflow. Clock compensation in Gigabit Ethernet is possible by taking advantage of the protocol data stream features. There are two distinct data streams that occur in Gigabit Ethernet where identical data is transmitted for a period of time. The first is configuration, which happens during auto-negotiation. The second is idle, which occurs at the end of auto-negotiation and between every packet. The identical data in the FIFO can be repeated by decrementing the read pointer, thus compensating for a FIFO that is draining too fast. The identical data in the FIFO can also be skipped by incrementing the read pointer, which compensates for a FIFO draining too slowly. The unique and novel features of this FIFO are that it works in both the idle stream and the configuration streams. The increment or decrement of the read pointer is different in the idle and compensation streams to preserve disparity. Another unique feature is that the read pointer to write pointer difference range changes between compensation and idle to minimize FIFO latency during packet transmission.


    Directory of Open Access Journals (Sweden)

    Ch. I. Zhdanovich


    Full Text Available Nowadays the work is in progress to develop wheeled and caterpillar tractors with electromechanical transmission. Range of changes in transmission gear ratio while using propulsion electric motor depends on mechanical characteristics of a tractor propulsion electric motor which is equipped with electromechanical transmission. In case when the range is rather high then it is possible to minimize number of gearings in the tractor gearing box or exclude its usage at all. Type of the applied propulsion electric motor and regulation method specify type of mechanical characteristics (characteristics family of the propulsion electric motor.The paper considers a propulsion asynchronous electric motor with frequency control. While using frequency control it is possible to regulate electric motor revolutions by mutual changes in voltage and voltage frequency. There are various laws of mutual changes in voltage and frequency (regulation laws. Selection of a regulation law influences on type of mechanical characteristics of a propulsion electric motor. Application of any law can be admissible only for some specific range of voltage frequency otherwise it is possible to exceed some parameters (for example, admissible voltage in the winding of electric motor stator. It is necessary to ensure the required moment within wide range for a tractor propulsion electric motor. In this case losses in the electric motor must be minimal. Losses in the rotor of the propulsion asynchronous electric motor are directly proportional to its sliding and its best propulsion and mechanical properties of a mobile machine will be ensured in the case when sliding is preserved at a constant value. According to these reasons selection of regulation laws has been carried out for operation of the propulsion asynchronous electric motor with nominal sliding and mechanical characteristics at nominal sliding is conventionally called a nominal characteristics.The paper analyzes the possible

  4. A Binary Array Asynchronous Sorting Algorithm with Using Petri Nets (United States)

    Voevoda, A. A.; Romannikov, D. O.


    Nowadays the tasks of computations speed-up and/or their optimization are actual. Among the approaches on how to solve these tasks, a method applying approaches of parallelization and asynchronization to a sorting algorithm is considered in the paper. The sorting methods are ones of elementary methods and they are used in a huge amount of different applications. In the paper, we offer a method of an array sorting that based on a division into a set of independent adjacent pairs of numbers and their parallel and asynchronous comparison. And this one distinguishes the offered method from the traditional sorting algorithms (like quick sorting, merge sorting, insertion sorting and others). The algorithm is implemented with the use of Petri nets, like the most suitable tool for an asynchronous systems description.

  5. Molecular mechanisms for synchronous, asynchronous, and spontaneous neurotransmitter release. (United States)

    Kaeser, Pascal S; Regehr, Wade G


    Most neuronal communication relies upon the synchronous release of neurotransmitters, which occurs through synaptic vesicle exocytosis triggered by action potential invasion of a presynaptic bouton. However, neurotransmitters are also released asynchronously with a longer, variable delay following an action potential or spontaneously in the absence of action potentials. A compelling body of research has identified roles and mechanisms for synchronous release, but asynchronous release and spontaneous release are less well understood. In this review, we analyze how the mechanisms of the three release modes overlap and what molecular pathways underlie asynchronous and spontaneous release. We conclude that the modes of release have key fusion processes in common but may differ in the source of and necessity for Ca(2+) to trigger release and in the identity of the Ca(2+) sensor for release.

  6. A Loosely Synchronizing Asynchronous Router for TDM-Scheduled NOCs

    DEFF Research Database (Denmark)

    Kotleas, Ioannis; Humphreys, Dean; Sørensen, Rasmus Bo


    This paper presents an asynchronous router design for use in time-division-multiplexed (TDM) networks-on-chip. Unlike existing synchronous, mesochronous and asynchronous router designs with similar functionality, the router is able to silently skip over cycles/TDM-slots where no traffic...... is scheduled and hence avoid all switching activity in the idle links and router ports. In this way switching activity is reduced to the minimum possible amount. The fact that this relaxed synchronization is sufficient to implement TDM scheduling represents a contribution at the conceptual level. The idea can...... only be implemented using asynchronous circuit techniques. To this end, the paper explores the use of “click-element” templates. Click-element templates use only flipflops and conventional gates, and this greatly simplifies the design process when using conventional EDA tools and standard cell...

  7. Asynchronous glaciations in arid continental climate (United States)

    Batbaatar, Jigjidsurengiin; Gillespie, Alan R.; Fink, David; Matmon, Ari; Fujioka, Toshiyuki


    Mountain glaciers at ∼26-19 ka, during the global Last Glacial Maximum near the end of the last 105 yr glacial cycle, are commonly considered on the basis of dating and field mapping in several well-studied areas to have been the largest of the late Quaternary and to have advanced synchronously from region to region. However, a numerical sensitivity model (Rupper and Roe, 2008) predicts that the fraction of ablation due to melting varies across Central Asia in proportion to the annual precipitation. The equilibrium-line altitude of glaciers across this region likely varies accordingly: in high altitude, cold and arid regions sublimation can ablate most of the ice, whereas glaciers fed by high precipitation cannot ablate completely due to sublimation alone, but extend downhill until higher temperatures there cause them to melt. We have conducted field studies and 10Be dating at five glaciated sites along a precipitation gradient in Mongolia to test the Rupper/Roe model. The sites are located in nearby 1.875 × 1.875° cells of the Rupper/Roe model, each with a different melt fraction, in this little-studied region. The modern environment of the sites ranges from dry subhumid in the north (47.7° N) to arid in the south (45° N). Our findings show that the maximum local advances in the dry subhumid conditions predated the global Last Glacial Maximum and were likely from MIS 3. However, we also found that at ∼8-7 ka a cirque glacier in one mountain range of the arid Gobi desert grew to a magnitude comparable to that of the local maximum extent. This Holocene maximum occurred during a regional pluvial period thousands of years after the retreat of the Pleistocene glaciers globally. This asynchronous behavior is not predicted by the prevailing and generally correct presumption that glacier advances are dominantly driven by temperature, although precipitation also plays a role. Our findings are consistent with and support the Rupper/Roe model, which calls for

  8. Design issues in the semantics and scheduling of asynchronous tasks.

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, Stephen L.


    The asynchronous task model serves as a useful vehicle for shared memory parallel programming, particularly on multicore and manycore processors. As adoption of model among programmers has increased, support has emerged for the integration of task parallel language constructs into mainstream programming languages, e.g., C and C++. This paper examines some of the design decisions in Cilk and OpenMP concerning semantics and scheduling of asynchronous tasks with the aim of informing the efforts of committees considering language integration, as well as developers of new task parallel languages and libraries.

  9. On the theoretical gap between synchronous and asynchronous MPC protocols

    DEFF Research Database (Denmark)

    Beerliová-Trubíniová, Zuzana; Hirt, Martin; Nielsen, Jesper Buus


    that in the cryptographic setting (with setup), the sole reason for it is the distribution of inputs: given an oracle for input distribution, cryptographically-secure asynchronous MPC is possible with the very same condition as synchronous MPC, namely t ..., we show that such an input-distribution oracle can be reduced to an oracle that allows each party to synchronously broadcast one single message. This means that when one single round of synchronous broadcast is available, then asynchronous MPC is possible at the same condition as synchronous MPC...


    Directory of Open Access Journals (Sweden)

    Berzan V.


    Full Text Available The paper sets out the methodology of designing an asynchronous generator with capacitive self-excitation. It is known that its design is possible on the basis of serial synchronous motor with squirrel cage rotor. With this approach, the design reworked only the stator winding of electrical machines, making it cost-effectively implement the creation of the generator. Therefore, the methodology for the design, optimization calculations, the development scheme and the stator winding excitation system gain, not only of practical interest, and may also be useful for specialists in the field of electrical machines in the design of asynchronous generators.


    Directory of Open Access Journals (Sweden)

    Birladean A.A.


    Full Text Available An asynchronous machine with a massive ferromagnetic rotor of the various designs, improving its energy indicators is considered. Elaboration and experimental tests results of the asynchronous machine working in a generating mode at the lowered speed of rotation of a massive ferromagnetic rotor are presented. Conditions and possibilities of the asynchronous generator creation with capacitor excitation on the basis of the asynchronous machine with a massive rotor are shown as well.

  12. Commande optimale à flux libre des machines asynchrones (United States)

    Biedinger, J. M.; Poullain, S.; Yvon, J. P.


    The subject of this paper is the optimal control with unconstrained flux of an induction motor being considered as a distributed parameter system described by a nonlinear diffusion equation. This approach allows to describe the electrodynamic state of the motor by taking into account, in a natural way, the influence of saturation and eddy-currents, as well as the nonlinearities due to the variable flux operation. Equations are approximated via a finite element formulation which leads to a finite dimensional dynamical system to which the techniques of optimal control may be applied. The generality of the methodology allows to treat various criteria. The objective aimed in this paper is to force the motor torque to follow a given input, especially under initially demagnetized conditions and with, naturally, constraints on the currents. For this purpose the criterion will be chosen as a norm of the difference between the electromagnetic torque and a given reference torque. Numerical simulations are presented for the case of a squirrel-cage rotor and for a solid iron rotor. Results are compared with those deduced from strategies based on lumped-parameter models. Torque responses obtained with field-oriented control method adapted to the case of flux-variable operation are also presented. Finally a modification of the criterion is proposed for identifying the command which allows to obtain the larger torque during transient states. Dans cet article on traite le problème du contrôle optimal à flux libre d'un moteur asynchrone considéré comme un système à paramètres répartis gouverné par une équation de diffusion non linéaire. Cette approche permet de décrire l'état électrodynamique de la machine en prenant naturellement en compte les effets de la saturation et des courants induits, ainsi que les non-linéarités liées au fonctionnement à flux variable. La formulation éléments finis est utilisée pour traduire le problème continu sous la forme d

  13. Promoting and Scaffolding Argumentation through Reflective Asynchronous Discussions (United States)

    Lin, Huann-shyang; Hong, Zuway-R.; Lawrenz, Frances


    The purpose of this quasi-experimental study was to explore the impact of asynchronous discussion on the quality and complexity of college students' arguments. Three different cohorts of students registered in a physical science course in 2009 Fall, 2010 Spring, and 2010 Fall semesters were briefly supported with scaffolding in class and then…

  14. Asynchronous online foresight panels: the case of wildfire management (United States)

    David N. Bengston; Robert L. Olson


    Text-based asynchronous online conferencing involves structured online discussion and deliberation among multiple participants from multiple sites in which there is a delay in interaction between contributors. This method has been widely used for a variety of purposes in higher education and other settings, but has not been commonly used in futures research. This paper...

  15. Numerical simulation of three phase asynchronous motor to ...

    African Journals Online (AJOL)

    Numerical simulation of three phase asynchronous motor to diagnose precisely the stator unbalanced voltage anomaly. ... First, the stator currents data pattern is used as a preliminary diagnosis. ... This similarity leads to uncertainty in the detection of the fault, which makes imperative the use of complementary technique.

  16. Student Moderators in Asynchronous Online Discussion: A Question of Questions (United States)

    Zingaro, Daniel


    Much current research exalts the benefits of having students facilitate weekly discussions in asynchronous online courses. This study seeks to add to what is known about student moderation through an analysis of the types of questions students use to spur each discussion. Prior experimental work has demonstrated that the types of questions posed…

  17. Asynchronous updating of threshold-coupled chaotic neurons

    Indian Academy of Sciences (India)

    Abstract. We study a network of chaotic model neurons incorporating threshold- activated coupling. We obtain a wide range of spatiotemporal patterns under varying degrees of asynchronicity in the evolution of the neuronal components. For instance, we find that sequential updating of threshold-coupled chaotic neurons ...

  18. Asynchronous updating of threshold-coupled chaotic neurons

    Indian Academy of Sciences (India)

    We study a network of chaotic model neurons incorporating threshold activated coupling. We obtain a wide range of spatiotemporal patterns under varying degrees of asynchronicity in the evolution of the neuronal components. For instance, we find that sequential updating of threshold-coupled chaotic neurons can yield ...

  19. Designing Communities of Learners for Asynchronous Distance Education. (United States)

    Moller, Leslie


    Describes the need for learning communities within the context of asynchronous distance education. Highlights include the relationship of community and distance learners; community as social reinforcement and as information exchange; and types of communities, including academic support communities, intellectual support communities, and…

  20. Cyber Asynchronous versus Blended Cyber Approach in Distance English Learning (United States)

    Ge, Zi-Gang


    This study aims to compare the single cyber asynchronous learning approach with the blended cyber learning approach in distance English education. Two classes of 70 students participated in this study, which lasted one semester of about four months, with one class using the blended approach for their English study and the other only using the…

  1. Asynchronous Assessment in a Large Lecture Marketing Course (United States)

    Downey, W. Scott; Schetzsle, Stacey


    Asynchronous assessment, which includes quizzes or exams online or outside class, offers marketing educators an opportunity to make more efficient use of class time and to enhance students' learning experiences by giving them more flexibility and choice in their assessment environment. In this paper, we examine the performance difference between…

  2. Designing a Web-Based Asynchronous Innovation/Entrepreneurism Course (United States)

    Ghandforoush, Parviz


    Teaching an online fully asynchronous information technology course that requires students to ideate, build an e-commerce website, and develop an effective business plan involves a well-developed and highly engaging course design. This paper describes the design, development, and implementation of such a course and presents information on…

  3. Numerical simulation of three phase asynchronous motor to ...

    African Journals Online (AJOL)

    Simulation numérique du moteur asynchrone triphasé pour diagnostiquer précisément le défaut du déséquilibre de ..... carrying more energy [9]. This severity index assumes values ..... its spectrum in normal circumstance. It was theoretically predicted that in this condition, the EPVA signature would be free from any spectral.

  4. Reconceptualising Moderation in Asynchronous Online Discussions Using Grounded Theory (United States)

    Vlachopoulos, Panos; Cowan, John


    This article reports a grounded theory study of the moderation of asynchronous online discussions, to explore the processes by which tutors in higher education decide when and how to moderate. It aims to construct a theory of e-moderation based on some key factors which appear to influence e-moderation. It discusses previous research on the…

  5. Adding the Human Touch to Asynchronous Online Learning (United States)

    Glenn, Cynthia Wheatley


    For learners to actively accept responsibility in a virtual classroom platform, it is necessary to provide special motivation extending across the traditional classroom setting into asynchronous online learning. This article explores specific ways to do this that bridge the gap between ground and online students' learning experiences, and how…

  6. Miscellany of Students' Satisfaction in an Asynchronous Learning Environment (United States)

    Larbi-Siaw, Otu; Owusu-Agyeman, Yaw


    This study investigates the determinants of students' satisfaction in an asynchronous learning environment using seven key considerations: the e-learning environment, student-content interaction, student and student interaction, student-teacher interaction, group cohesion and timely participation, knowledge of Internet usage, and satisfaction. The…

  7. An improved modelling of asynchronous machine with skin-effect ...

    African Journals Online (AJOL)

    The conventional method of analysis of Asynchronous machine fails to give accurate results especially when the machine is operated under high rotor frequency. At high rotor frequency, skin-effect dominates causing the rotor impedance to be frequency dependant. This paper therefore presents an improved method of ...

  8. Control algorithms for single inverter dual induction motor system applied to railway traction; Commande algorithmique d'un systeme mono-onduleur bimachine asynchrone destine a la traction ferroviaire

    Energy Technology Data Exchange (ETDEWEB)

    Pena Eguiluz, R.


    The goal of this work concerns the modelling and the behaviour characterisation of a single inverter dual induction motor system applied to a railway traction bogie (BB36000) in order to concept its control. First part of this job is dedicated to the detailed description of overall system. The influence analysis of the internal perturbations (motor parameters variation) and, external perturbations (pantograph detachment, adherence loss, stick-slip) of the system have made considering the field oriented control applied to each motor of the bogie (classical traction structure). vi In a second part, a novel propulsion structure is proposed. It is composed by a single pulse-width modulated two level voltage source inverter. It supplies two parallel connected induction motors, which generate the transmitted traction force to the bogie wheels. The locomotive case represents the common load for the two motors. Several co-operative control strategies (CS) are studied. They are: the mean CS, the double mean CS, the master - slave switched CS and, the mean differential CS. In addition, an appropriated electric modes observer structure for these different controls has studied. These controls have validated applying the perturbations to the models using the solver SABER. This special approach is equivalent to quasi-experimentation, because the mechanical and the electrical system components have modelled using MAST language and, the sample control has created by a C code programme in the SABER environment. Third part is dedicated to the mechanical sensor suppression and, its adaptation in the cooperative control strategies. The partial speed reconstruction methods are: the fundamental frequency relation, the mechanical Kalman filter, the variable structure observer and the MRAS. Finally, the hardware system configuration of the experimental realisation is described. (author)

  9. Significance of microbial asynchronous anabolism to soil carbon dynamics driven by litter inputs (United States)

    Fan, Zhaosheng; Liang, Chao


    Soil organic carbon (SOC) plays an important role in the global carbon cycle. However, it remains largely unknown how plant litter inputs impact magnitude, composition and source configuration of the SOC stocks over long term through microbial catabolism and anabolism, mostly due to uncoupled research on litter decomposition and SOC formation. This limits our ability to predict soil system responses to changes in land-use and climate. Here, we examine how microbes act as a valve controlling carbon sequestrated from plant litters versus released to the atmosphere in natural ecosystems amended with plant litters varying in quantity and quality. We find that litter quality - not quantity - regulates long-term SOC dynamics under different plausible scenarios. Long-term changes in bulk SOC stock occur only when the quality of carbon inputs causes asynchronous change in a microbial physiological trait, defined as ``microbial biosynthesis acceleration'' (MBA). This is the first theoretical demonstration that the response of the SOC stocks to litter inputs is critically determined by the microbial physiology. Our work suggests that total SOC at an equilibrium state may be an intrinsic property of a given ecosystem, which ultimately is controlled by the asynchronous MBA between microbial functional groups.


    Directory of Open Access Journals (Sweden)

    V. O. Volkov


    Full Text Available Purpose. Obtaining analytical dependencies for the calculation of the main electromagnetic energy losses of a frequency-controlled induction motor in positioning modes with small displacements for various types (linear, parabolic and quasi-optimal of its velocity variation. Methodology. Similarity methods, differential and integral calculus, analytical interpolation, mathematical analysis. Findings. Analytical dependencies for calculation of current electromagnetic power losses and basic electromagnetic energy losses of a frequency-controlled asynchronous motor in the modes of positioning with small displacements for various types (linear, parabolic and quasi-optimal of its velocity are obtained. A universal form of the analytical dependence for calculating the optimal acceleration and deceleration times for a frequency-controlled asynchronous motor for positioning with small displacements, corresponding to minimization of the main electromagnetic energy losses of this engine with the indicated positioning for various species (linear, parabolic and quasi-optimal, is obtained. A comparative quantitative assessment of the change is made: the optimum values of the main electromagnetic energy losses of the frequency-controlled asynchronous engine and the corresponding maximum speed and optimal acceleration and deceleration times, in the function of the set prescribed small displacements for the various engine speed trajectories under consideration. Originality. For the first time, analytical dependencies for the calculation of the main electromagnetic energy losses of a frequency-controlled asynchronous motor are obtained for positioning with small displacements as a function of the set values of the movement of the motor shaft and the set values of its acceleration and deceleration times for the specified specified displacements. For the first time, dependences are obtained for a quantitative estimate of the minimum fundamental electromagnetic

  11. Pre-synthesis Optimization for Asynchronous Circuits Using Compiler Techniques (United States)

    Zamanzadeh, Sharareh; Najibi, Mehrdad; Pedram, Hossein

    The effectiveness of traditional compiler techniques employed in high-level synthesis of synchronous circuits aiming to present a generic code is studied for asynchronous synthesis by considering the special features of these circuits. The compiler methods can be used innovatively to improve the synthesis results in both power consumption and area. The compiler methods like speculation, loop invariant code motion and condition expansion are applicable in decreasing mass of handshaking circuits and intermediate modules. Moreover, they eliminate conditional access to variables and ports and reducing the amount of completion detection circuits. The approach is superimposed on to Persia synthesis toolset as a presynthesis source-to-source transformation phase, and results shows on average 22% improvement in terms of area and 24 % in power consumption for asynchronous benchmarks.

  12. Mixing rich and asynchronous communication for new service development performance


    Storey, Chris; Perks, Helen


    This article explores the nature of relationships between internal communication modes, new service development (NSD) competencies (specifically learning and development competencies) and NSD performance. To do so, it draws on and advances communication theory by comparing and contrasting the contingent approach, favoured by media richness theory and media synchronicity theory, with the multiplicative manner of dual coding theory. Antecedent roles of rich and asynchronous communication modes ...

  13. Asynchronous Multi-Party Computation with Quadratic Communication

    DEFF Research Database (Denmark)

    Hirt, Martin; Nielsen, Jesper Buus; Przydatek, Bartosz


    We present an efficient protocol for secure multi-party computation in the asynchronous model with optimal resilience. For n parties, up to t < n/3 of them being corrupted, and security parameter κ, a circuit with c gates can be securely computed with communication complexity O(cn^2k) bits, which...... circuit randomization due to Beaver (Crypto’91), and an abstraction of certificates, which can be of independent interest....

  14. Marine Forces Reserve: Accelerating Knowledge Flow through Asynchronous Learning Technologies (United States)


    Substantial evidence indicates that—with informed instruction design and appropriate pedagogy —the efficacy of online education and training is...efficacy of online education and training is at least 3 comparable to that of classroom teaching. Indeed, the educational psychology literature is...learning in an education environment, and we adapt such highly effective asynchronous learning techniques and technologies to the I-I training task

  15. Dynamic modeling of an asynchronous squirrel-cage machine; Modelisation dynamique d'une machine asynchrone a cage

    Energy Technology Data Exchange (ETDEWEB)

    Guerette, D.


    This document presented a detailed mathematical explanation and validation of the steps leading to the development of an asynchronous squirrel-cage machine. The MatLab/Simulink software was used to model a wind turbine at variable high speeds. The asynchronous squirrel-cage machine is an electromechanical system coupled to a magnetic circuit. The resulting electromagnetic circuit can be represented as a set of resistances, leakage inductances and mutual inductances. Different models were used for a comparison study, including the Munteanu, Boldea, Wind Turbine Blockset, and SimPowerSystem. MatLab/Simulink modeling results were in good agreement with the results from other comparable models. Simulation results were in good agreement with analytical calculations. 6 refs, 2 tabs, 9 figs.

  16. Asynchronous BCI control using high-frequency SSVEP

    National Research Council Canada - National Science Library

    Diez, Pablo F; Mut, Vicente A; Avila Perona, Enrique M; Laciar Leber, Eric


    ...) and high frequency (> 30 Hz). SSVEP-based Brain-Computer Interfaces (BCI) are principally focused on the low and medium range of frequencies whereas there are only a few projects in the high-frequency range...

  17. Asynchronous Distributed Control of Biogas Supply and Multienergy Demand

    NARCIS (Netherlands)

    Alkano, Desti; Scherpen, Jacquelien M.A.; Chorfi, Younes


    In this paper, we study the coordination between biogas producers who can use the biogas themselves, exchange biogas with their neighbors, or deliver it to the various energy grids, such as the low pressure gas grid or the power grid. These producers are called prosumers. In this setting, gas

  18. Pharmacists' perception of synchronous versus asynchronous distance learning for continuing education programs. (United States)

    Buxton, Eric C


    To evaluate and compare pharmacists' satisfaction with the content and learning environment of a continuing education program series offered as either synchronous or asynchronous webinars. An 8-lecture series of online presentations on the topic of new drug therapies was offered to pharmacists in synchronous and asynchronous webinar formats. Participants completed a 50-question online survey at the end of the program series to evaluate their perceptions of the distance learning experience. Eighty-two participants completed the survey instrument (41 participants from the live webinar series and 41 participants from the asynchronous webinar series.) Responses indicated that while both groups were satisfied with the program content, the asynchronous group showed greater satisfaction with many aspects of the learning environment. The synchronous and asynchronous webinar participants responded positively regarding the quality of the programming and the method of delivery, but asynchronous participants rated their experience more positively overall.

  19. Fusion of Asynchronous, Parallel, Unreliable Data Streams (United States)


    their place of origin) at the place of displacement. Ration cards are used for basic provisions, such as rice, beans, cooking oil , detergent, tea...relatively minor and concentrated along a few dimensions not under rigid social control. Outlier detection methodology may well provide guides to aid the...salt, flour , petrol, and other fuel products. They can only be used in a specific shop or store in the person’s neighborhood. But local Ministry

  20. Observation et Commande de la Machine Asynchrone


    Dib, Abdou


    The research work developed in this thesis has been mainly devoted to the observation and control problems of sensorless induction moteurs. Two contributions have been carried out thanks to the high gain concept. The first contribution consists in a high gain observer design that performs a relatively accurate estimation of both mechanical and magnetic state variable using the available measurements on stator currents and voltages. Of particular interest, the observation gain has been appropr...

  1. Moderating influence of dominant attentional style and exercise intensity on responses to asynchronous music. (United States)

    Hutchinson, Jasmin C; Karageorghis, Costas I


    We examined independent and combined influences of asynchronous music and dominant attentional style (DAS) on psychological and psychophysical variables during exercise using mixed methods. Participants (N = 34) were grouped according to DAS and completed treadmill runs at three intensities (low, moderate, high) crossed with three music conditions (motivational, oudeterous, no-music control). State attentional focus shifted from dissociative to associative with increasing intensity and was most aligned with DAS during moderate-intensity exercise. Both music conditions facilitated dissociation at low-to-moderate intensities. At high exercise intensity, both music conditions were associated with reduced RPE among participants with an associative DAS. Dissociators reported higher RPE overall during moderate and high intensities. Psychological responses were most positive in the motivational condition, followed by oudeterous and control. Findings illustrate the relevance of individual differences in DAS as well as task intensity and duration when selecting music for exercise.

  2. Real Time Control on Firewire

    NARCIS (Netherlands)

    Zhang, Yuchen


    The goal of this project is to get insight into the use of Firewire as a field bus for real-time control. A characterization of Firewire's asynchronous transmission has been made by testing the point-to-point roundtrip in a 3-node Firewire network. The results show Firewire's asynchronous

  3. Asynchronous parallel generating set search for linearly-constrained optimization.

    Energy Technology Data Exchange (ETDEWEB)

    Kolda, Tamara G.; Griffin, Joshua; Lewis, Robert Michael


    We describe an asynchronous parallel derivative-free algorithm for linearly-constrained optimization. Generating set search (GSS) is the basis of ourmethod. At each iteration, a GSS algorithm computes a set of search directionsand corresponding trial points and then evaluates the objective function valueat each trial point. Asynchronous versions of the algorithm have been developedin the unconstrained and bound-constrained cases which allow the iterations tocontinue (and new trial points to be generated and evaluated) as soon as anyother trial point completes. This enables better utilization of parallel resourcesand a reduction in overall runtime, especially for problems where the objec-tive function takes minutes or hours to compute. For linearly-constrained GSS,the convergence theory requires that the set of search directions conform to the3 nearby boundary. The complexity of developing the asynchronous algorithm forthe linearly-constrained case has to do with maintaining a suitable set of searchdirections as the search progresses and is the focus of this research. We describeour implementation in detail, including how to avoid function evaluations bycaching function values and using approximate look-ups. We test our imple-mentation on every CUTEr test problem with general linear constraints and upto 1000 variables. Without tuning to individual problems, our implementationwas able to solve 95% of the test problems with 10 or fewer variables, 75%of the problems with 11-100 variables, and nearly half of the problems with100-1000 variables. To the best of our knowledge, these are the best resultsthat have ever been achieved with a derivative-free method. Our asynchronousparallel implementation is freely available as part of the APPSPACK software.4

  4. a Beat Perioid Observation of the Asynchronous Polar by Cam. (United States)

    Rainger, Jonathan

    We propose to observe the hard X-ray bright asynchronous polar BY Cam throughout its beat cycle in order to investigate the changes in the magnetic capture of the accretion stream as the secondary star changes in azimuth with respect to the white dwarf. Regular snap-shots of the light curve will reveal the order behind the chaos. Previous observations have been taken in 3 days or less, our monitoring plan over 21 days offers the only real hope of understanding these difficult systems.

  5. Creating video-annotated discussions: An asynchronous alternative

    Directory of Open Access Journals (Sweden)

    Craig D. Howard


    Full Text Available In this article the authors illustrate the design and development of a pedagogical intervention using video annotations in a pre-service teacher education courrse. An annotation platform was selected and video was shot to create a video backdrop on which asynchronous discussions would take place. The article addresses design considerations in the selection of video, the editing process, and the development of a tutorial to lead learners through their first experience with this form of discussion. Learner participation samples were collected, and an analysis of the design process concludes the article.

  6. Positive semidefinite integrated covariance estimation, factorizations and asynchronicity

    DEFF Research Database (Denmark)

    Sauri, Orimar; Lunde, Asger; Laurent, Sébastien


    An estimator of the ex-post covariation of log-prices under asynchronicity and microstructure noise is proposed. It uses the Cholesky factorization of the covariance matrix in order to exploit the heterogeneity in trading intensities to estimate the different parameters sequentially with as many...... observations as possible. The estimator is positive semidefinite by construction. We derive asymptotic results and confirm their good finite sample properties by means of a Monte Carlo simulation. In the application we forecast portfolio Value-at-Risk and sector risk exposures for a portfolio of 52 stocks. We...

  7. The braided Ptolemy-Thompson group $T^*$ is asynchronously combable


    Funar, Louis; Kapoudjian, Christophe


    The braided Ptolemy-Thompson group $T^*$ is an extension of the Thompson group $T$ by the full braid group $B_{\\infty}$ on infinitely many strands. This group is a simplified version of the acyclic extension considered by Greenberg and Sergiescu, and can be viewed as a mapping class group of a certain infinite planar surface. In a previous paper we showed that $T^*$ is finitely presented. Our main result here is that $T^*$ (and $T$) is asynchronously combable. The method of proof is inspired ...

  8. Analysis and asynchronous detection of gradually unfolding errors during monitoring tasks (United States)

    Omedes, Jason; Iturrate, Iñaki; Minguez, Javier; Montesano, Luis


    Human studies on cognitive control processes rely on tasks involving sudden-onset stimuli, which allow the analysis of these neural imprints to be time-locked and relative to the stimuli onset. Human perceptual decisions, however, comprise continuous processes where evidence accumulates until reaching a boundary. Surpassing the boundary leads to a decision where measured brain responses are associated to an internal, unknown onset. The lack of this onset for gradual stimuli hinders both the analyses of brain activity and the training of detectors. This paper studies electroencephalographic (EEG)-measurable signatures of human processing for sudden and gradual cognitive processes represented as a trajectory mismatch under a monitoring task. Time-locked potentials and brain-source analysis of the EEG of sudden mismatches revealed the typical components of event-related potentials and the involvement of brain structures related to cognitive control processing. For gradual mismatch events, time-locked analyses did not show any discernible EEG scalp pattern, despite related brain areas being, to a lesser extent, activated. However, and thanks to the use of non-linear pattern recognition algorithms, it is possible to train an asynchronous detector on sudden events and use it to detect gradual mismatches, as well as obtaining an estimate of their unknown onset. Post-hoc time-locked scalp and brain-source analyses revealed that the EEG patterns of detected gradual mismatches originated in brain areas related to cognitive control processing. This indicates that gradual events induce latency in the evaluation process but that similar brain mechanisms are present in sudden and gradual mismatch events. Furthermore, the proposed asynchronous detection model widens the scope of applications of brain-machine interfaces to other gradual processes.

  9. Asynchronous and synchronous teleconsultation for diabetes care: a systematic literature review. (United States)

    Verhoeven, Fenne; Tanja-Dijkstra, Karin; Nijland, Nicol; Eysenbach, Gunther; van Gemert-Pijnen, Lisette


    A systematic literature review, covering publications from 1994 to 2009, was carried out to determine the effects of teleconsultation regarding clinical, behavioral, and care coordination outcomes of diabetes care compared to usual care. Two types of teleconsultation were distinguished: (1) asynchronous teleconsultation for monitoring and delivering feedback via email and cell phone, automated messaging systems, or other equipment without face-to-face contact; and (2) synchronous teleconsultation that involves real-time, face-to-face contact (image and voice) via videoconferencing equipment (television, digital camera, webcam, videophone, etc.) to connect caregivers and one or more patients simultaneously, e.g., for the purpose of education. Electronic databases were searched for relevant publications about asynchronous and synchronous tele-consultation [Medline, Picarta, Psychinfo, ScienceDirect, Telemedicine Information Exchange, Institute for Scientific Information Web of Science, Google Scholar]. Reference lists of identified publications were hand searched. The contribution to diabetes care was examined for clinical outcomes [e.g., hemoglobin A1c (HbA1c), dietary values, blood pressure, quality of life], for behavioral outcomes (patient-caregiver interaction, self-care), and for care coordination outcomes (usability of technology, cost-effectiveness, transparency of guidelines, equity of access to care). Randomized controlled trials with HbA1c as an outcome were pooled using standard meta-analytical methods. Of 2060 publications identified, 90 met inclusion criteria for electronic communication between (groups of) caregivers and patients with type 1 and 2 or gestational diabetes. Studies that evaluated teleconsultation not particularly aimed at diabetes were excluded, as were those that described interventions aimed solely at clinical improvements (e.g., HbA1c or lipid profiles). In 63 of 90 interventions, the interaction had an asynchronous teleconsultation

  10. Wind-powered asynchronous AC/DC/AC converter system. [for electric power supply regulation (United States)

    Reitan, D. K.


    Two asynchronous ac/dc/ac systems are modelled that utilize wind power to drive a variable or constant hertz alternator. The first system employs a high power 60-hertz inverter tie to the large backup supply of the power company to either supplement them from wind energy, storage, or from a combination of both at a preset desired current; rectifier and inverter are identical and operate in either mode depending on the silicon control rectifier firing angle. The second system employs the same rectification but from a 60-hertz alternator arrangement; it provides mainly dc output, some sinusoidal 60-hertz from the wind bus and some high harmonic content 60-hertz from an 800-watt inverter.

  11. A multi-host front end concentrator system for asynchronous consoles

    CERN Document Server

    Palandri, E M


    Describes a front end concentrator system for asynchronous time sharing consoles which has recently been put into operation at CERN. The concentrator will control up to 36 consoles at speeds up to 9600 bits per second and has the capability of dynamically connecting these consoles to several large Host processors. Features of the system include specially designed hardware and software to connect a wide range of different types of consoles in a flexible and expandable way, and the use of special purpose microcode to optimise console handling and facilitate the implementation of the system. The system runs in an HP2100 computer initially front-ending CDC 6000 series computers using the INTERCOM time sharing system. (6 refs).

  12. A Scheduling Discipline for Latency and Bandwidth Guarantees in Asynchronous Network-on-Chip

    DEFF Research Database (Denmark)

    Bjerregaard, Tobias; Sparsø, Jens


    Guaranteed services (GS) are important in that they provide predictability in the complex dynamics of shared communication structures. This paper discusses the implementation of GS in asynchronous Network-on-Chip. We present a novel scheduling discipline called Asynchronous Latency Guarantee (ALG...

  13. Adding effect of current displacement and magnetic circuit saturation in an asynchronous motor mathematical model

    Directory of Open Access Journals (Sweden)

    I.A. Tsodik


    Full Text Available A methodology of an asynchronous motor mathematical model synthesis is described. Experiments are suggested to be conducted in the following sequence. Geometrical models are first built in AutoCAD, then imported to Comsol Multiphysics, and further processed in Matlab with computation of coefficients and dependences applied in the asynchronous motor mathematical model.

  14. Using Television Sitcoms to Facilitate Asynchronous Discussions in the Online Communication Course (United States)

    Tolman, Elizabeth; Asbury, Bryan


    Asynchronous discussions are a useful instructional resource in the online communication course. In discussion groups students have the opportunity to actively participate and interact with students and the instructor. Asynchronous communication allows for flexibility because "participants can interact with significant amounts of time between…

  15. Analysing High School Students' Participation and Interaction in an Asynchronous Online Project-Based Learning Environment (United States)

    Lang, Quek Choon


    This study aims to replicate and extend a previous study which was conducted on primary school students' asynchronous online project-based learning. In this study, 276 high school students' participation and interaction in a project-based learning environment was mediated by an asynchronous computer-mediated communication (CMC) tool. The students'…

  16. The Role of Online Instructors in Asynchronous Discussion Forums (United States)

    Maddison, Sarah T.; Mazzolini, M. M.; Gay, P. L.


    We present qualitative results and advice on the role of online instructors in asynchronous discussion forums and the technologies used to support online interactive learning. Results are based on six years of designing, coordinating, evaluating and teaching into the distance learning program Swinburne Astronomy Online. We discuss why we chose to use asynchronous rather than synchronous discussion forums and how we have implemented them; how we train our online instructors and their role as a 'guide on the side'; techniques for moderating the volume of forum postings while ensuring a constructive learning environment; and methods for dealing with both mixed class preparedness and 'challenging' students within an online environment. Our research into the interaction between students and instructors in online forums provides some interesting (and often counter-intuitive) insights into the relationship between the number and length of student postings and the posting patterns of their instructors. We compare these results with qualitative feedback from both students and instructors on their perception of the online learning and teaching experience.

  17. Formation of the wide asynchronous binary asteroid population

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Seth A. [Department of Astrophysical and Planetary Science, UCB 391, University of Colorado, Boulder, CO 80309 (United States); Scheeres, Daniel J.; McMahon, Jay [Department of Aerospace Engineering Sciences, UCB 429, University of Colorado, Boulder, CO 80309 (United States)


    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semimajor axes relative to most near-Earth and main belt asteroid systems. Confirmed members have rapidly rotating primaries and satellites that are not tidally locked. Previously suggested formation mechanisms from impact ejecta, from planetary flybys, and directly from rotational fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (1) these systems are formed from rotational fission, (2) their satellites are tidally locked, (3) their orbits are expanded by the binary Yarkovsky-O'Keefe-Radzievskii-Paddack (BYORP) effect, (4) their satellites desynchronize as a result of the adiabatic invariance between the libration of the secondary and the mutual orbit, and (5) the secondary avoids resynchronization because of the YORP effect. This seemingly complex chain of events is a natural pathway for binaries with satellites that have particular shapes, which define the BYORP effect torque that acts on the system. After detailing the theory, we analyze each of the wide asynchronous binary members and candidates to assess their most likely formation mechanism. Finally, we suggest possible future observations to check and constrain our hypothesis.

  18. Asynchronous Detection of Trials Onset from Raw EEG Signals. (United States)

    Lopez-Gordo, M A; Grima Murcia, M D; Padilla, Pablo; Pelayo, F; Fernandez, E


    Clinical processing of event-related potentials (ERPs) requires a precise synchrony between the stimulation and the acquisition units that are guaranteed by means of a physical link between them. This precise synchrony is needed since temporal misalignments during trial averaging can lead to high deviations of peak times, thus causing error in diagnosis or inefficiency in classification in brain-computer interfaces (BCIs). Out of the laboratory, mobile EEG systems and BCI headsets are not provided with the physical link, thus being inadequate for acquisition of ERPs. In this study, we propose a method for the asynchronous detection of trials onset from raw EEG without physical links. We validate it with a BCI application based on the dichotic listening task. The user goal was to attend the cued auditory message and to report three keywords contained in it while ignoring the other message. The BCI goal was to detect the attended message from the analysis of auditory ERPs. The rate of successful onset detection in both synchronous (using the real onset) and asynchronous (blind detection of trial onset from raw EEG) was 73% with a synchronization error of less than 1[Formula: see text]ms. The level of synchronization provided by this proposal would allow home-based acquisition of ERPs with low cost BCI headsets and any media player unit without physical links between them.

  19. A Parallel Particle Swarm Optimization Algorithm Accelerated by Asynchronous Evaluations (United States)

    Venter, Gerhard; Sobieszczanski-Sobieski, Jaroslaw


    A parallel Particle Swarm Optimization (PSO) algorithm is presented. Particle swarm optimization is a fairly recent addition to the family of non-gradient based, probabilistic search algorithms that is based on a simplified social model and is closely tied to swarming theory. Although PSO algorithms present several attractive properties to the designer, they are plagued by high computational cost as measured by elapsed time. One approach to reduce the elapsed time is to make use of coarse-grained parallelization to evaluate the design points. Previous parallel PSO algorithms were mostly implemented in a synchronous manner, where all design points within a design iteration are evaluated before the next iteration is started. This approach leads to poor parallel speedup in cases where a heterogeneous parallel environment is used and/or where the analysis time depends on the design point being analyzed. This paper introduces an asynchronous parallel PSO algorithm that greatly improves the parallel e ciency. The asynchronous algorithm is benchmarked on a cluster assembled of Apple Macintosh G5 desktop computers, using the multi-disciplinary optimization of a typical transport aircraft wing as an example.

  20. Asynchronous Task-Based Polar Decomposition on Manycore Architectures

    KAUST Repository

    Sukkari, Dalal


    This paper introduces the first asynchronous, task-based implementation of the polar decomposition on manycore architectures. Based on a new formulation of the iterative QR dynamically-weighted Halley algorithm (QDWH) for the calculation of the polar decomposition, the proposed implementation replaces the original and hostile LU factorization for the condition number estimator by the more adequate QR factorization to enable software portability across various architectures. Relying on fine-grained computations, the novel task-based implementation is also capable of taking advantage of the identity structure of the matrix involved during the QDWH iterations, which decreases the overall algorithmic complexity. Furthermore, the artifactual synchronization points have been severely weakened compared to previous implementations, unveiling look-ahead opportunities for better hardware occupancy. The overall QDWH-based polar decomposition can then be represented as a directed acyclic graph (DAG), where nodes represent computational tasks and edges define the inter-task data dependencies. The StarPU dynamic runtime system is employed to traverse the DAG, to track the various data dependencies and to asynchronously schedule the computational tasks on the underlying hardware resources, resulting in an out-of-order task scheduling. Benchmarking experiments show significant improvements against existing state-of-the-art high performance implementations (i.e., Intel MKL and Elemental) for the polar decomposition on latest shared-memory vendors\\' systems (i.e., Intel Haswell/Broadwell/Knights Landing, NVIDIA K80/P100 GPUs and IBM Power8), while maintaining high numerical accuracy.

  1. Asynchronous cracking with dissimilar paths in multilayer graphene. (United States)

    Jang, Bongkyun; Kim, Byungwoon; Kim, Jae-Hyun; Lee, Hak-Joo; Sumigawa, Takashi; Kitamura, Takayuki


    Multilayer graphene consists of a stack of single-atomic-thick monolayer graphene sheets bound with π-π interactions and is a fascinating model material opening up a new field of fracture mechanics. In this study, fracture behavior of single-crystalline multilayer graphene was investigated using an in situ mode I fracture test under a scanning electron microscope, and abnormal crack propagation in multilayer graphene was identified for the first time. The fracture toughness of graphene was determined from the measured load-displacement curves and the realistic finite element modelling of specimen geometries. Nonlinear fracture behavior of the multilayer graphene is discussed based on nonlinear elastic fracture mechanics. In situ scanning electron microscope images obtained during the fracture test showed asynchronous crack propagation along independent paths, causing interlayer shear stress and slippages. We also found that energy dissipation by interlayer slippages between the graphene layers is the reason for the enhanced fracture toughness of multilayer graphene. The asynchronous cracking with independent paths is a unique cracking and toughening mechanism for single-crystalline multilayer graphene, which is not observed for the monolayer graphene. This could provide a useful insight for the design and development of graphene-based composite materials for structural applications.

  2. Asynchronous replica exchange software for grid and heterogeneous computing (United States)

    Gallicchio, Emilio; Xia, Junchao; Flynn, William F.; Zhang, Baofeng; Samlalsingh, Sade; Mentes, Ahmet; Levy, Ronald M.


    Parallel replica exchange sampling is an extended ensemble technique often used to accelerate the exploration of the conformational ensemble of atomistic molecular simulations of chemical systems. Inter-process communication and coordination requirements have historically discouraged the deployment of replica exchange on distributed and heterogeneous resources. Here we describe the architecture of a software (named ASyncRE) for performing asynchronous replica exchange molecular simulations on volunteered computing grids and heterogeneous high performance clusters. The asynchronous replica exchange algorithm on which the software is based avoids centralized synchronization steps and the need for direct communication between remote processes. It allows molecular dynamics threads to progress at different rates and enables parameter exchanges among arbitrary sets of replicas independently from other replicas. ASyncRE is written in Python following a modular design conducive to extensions to various replica exchange schemes and molecular dynamics engines. Applications of the software for the modeling of association equilibria of supramolecular and macromolecular complexes on BOINC campus computational grids and on the CPU/MIC heterogeneous hardware of the XSEDE Stampede supercomputer are illustrated. They show the ability of ASyncRE to utilize large grids of desktop computers running the Windows, MacOS, and/or Linux operating systems as well as collections of high performance heterogeneous hardware devices.

  3. Asynchronously sampled blind source separation for coherent optical links (United States)

    Detwiler, Thomas F.; Searcy, Steven M.; Stark, Andrew J.; Ralph, Stephen E.; Basch, Bert E.


    Polarization multiplexing is an integral technique for generating spectrally efficient 100 Gb/s and higher optical links. Post coherent detection DSP-based polarization demultiplexing of QPSK links is commonly performed after timing recovery. We propose and demonstrate a method of asynchronous blind source separation using the constant modulus algorithm (CMA) on the asynchronously sampled signal to initially separate energy from arbitrarily aligned polarization states. This method lends well to implementation as it allows for an open-loop sampling frequency for analog-to-digital conversion at less than twice the symbol rate. We show that the performance of subsequent receiver functions is enhanced by the initial pol demux operation. CMA singularity behavior is avoided through tap settling constraints. The method is applicable to QPSK transmissions and many other modulation formats as well, including general QAM signals, offset-QPSK, and CPM, or a combination thereof. We present the architecture and its performance under several different formats and link conditions. Comparisons of complexity and performance are drawn between the proposed architecture and conventional receivers.

  4. Emergence of Asynchronous Local Clocks in Excitable Media. (United States)

    Gerum, Richard Carl; Fabry, Ben; Metzner, Claus


    Excitable media such as the myocardium or the brain consist of arrays of coupled excitable elements, in which the local excitation of a single element can propagate to its neighbors in the form of a non-linear autowave. Since each element has to pass through a refractory period immediately after excitation, the frequency of autowaves is self-limiting. In this work, we consider the case where each element is spontaneously excited at a fixed average rate and thereby initiates a new autowave. Although these spontaneous self-excitation events are modelled as independent Poisson point processes with exponentially distributed waiting times, the travelling autowaves lead collectively to a non-exponential, unimodal waiting time distribution for the individual elements. With increasing system size, a global 'clock' period T emerges as the most probable waiting time for each element, which fluctuates around T with an increasingly small but non-zero variance. This apparent synchronization between asynchronous, temporally uncorrelated point processes differs from synchronization effects between perfect oscillators interacting in a phase-aligning manner. Finally, we demonstrate that asynchronous local clocks also emerge in non-homogeneous systems in which the rates of self-excitation are different for all individuals, suggesting that this novel mechanism can occur in a wide range of excitable media.

  5. Spatiotemporal Features for Asynchronous Event-based Data

    Directory of Open Access Journals (Sweden)

    Xavier eLagorce


    Full Text Available Bio-inspired asynchronous event-based vision sensors are currently introducing a paradigm shift in visual information processing. These new sensors rely on a stimulus-driven principle of light acquisition similar to biological retinas. They are event-driven and fully asynchronous, thereby reducing redundancy and encoding exact times of input signal changes, leading to a very precise temporal resolution. Approaches for higher-level computer vision often rely on the realiable detection of features in visual frames, but similar definitions of features for the novel dynamic and event-based visual input representation of silicon retinas have so far been lacking. This article addresses the problem of learning and recognizing features for event-based vision sensors, which capture properties of truly spatiotemporal volumes of sparse visual event information. A novel computational architecture for learning and encoding spatiotemporal features is introduced based on a set of predictive recurrent reservoir networks, competing via winner-take-all selection. Features are learned in an unsupervised manner from real-world input recorded with event-based vision sensors. It is shown that the networks in the architecture learn distinct and task-specific dynamic visual features, and can predict their trajectories over time.

  6. Frog: Asynchronous Graph Processing on GPU with Hybrid Coloring Model

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xuanhua; Luo, Xuan; Liang, Junling; Zhao, Peng; Di, Sheng; He, Bingsheng; Jin, Hai


    GPUs have been increasingly used to accelerate graph processing for complicated computational problems regarding graph theory. Many parallel graph algorithms adopt the asynchronous computing model to accelerate the iterative convergence. Unfortunately, the consistent asynchronous computing requires locking or atomic operations, leading to significant penalties/overheads when implemented on GPUs. As such, coloring algorithm is adopted to separate the vertices with potential updating conflicts, guaranteeing the consistency/correctness of the parallel processing. Common coloring algorithms, however, may suffer from low parallelism because of a large number of colors generally required for processing a large-scale graph with billions of vertices. We propose a light-weight asynchronous processing framework called Frog with a preprocessing/hybrid coloring model. The fundamental idea is based on Pareto principle (or 80-20 rule) about coloring algorithms as we observed through masses of realworld graph coloring cases. We find that a majority of vertices (about 80%) are colored with only a few colors, such that they can be read and updated in a very high degree of parallelism without violating the sequential consistency. Accordingly, our solution separates the processing of the vertices based on the distribution of colors. In this work, we mainly answer three questions: (1) how to partition the vertices in a sparse graph with maximized parallelism, (2) how to process large-scale graphs that cannot fit into GPU memory, and (3) how to reduce the overhead of data transfers on PCIe while processing each partition. We conduct experiments on real-world data (Amazon, DBLP, YouTube, RoadNet-CA, WikiTalk and Twitter) to evaluate our approach and make comparisons with well-known non-preprocessed (such as Totem, Medusa, MapGraph and Gunrock) and preprocessed (Cusha) approaches, by testing four classical algorithms (BFS, PageRank, SSSP and CC). On all the tested applications and

  7. An Asynchronous Cellular Automata-Based Adaptive Illumination Facility (United States)

    Bandini, Stefania; Bonomi, Andrea; Vizzari, Giuseppe; Acconci, Vito

    The term Ambient Intelligence refers to electronic environments that are sensitive and responsive to the presence of people; in the described scenario the environment itself is endowed with a set of sensors (to perceive humans or other physical entities such as dogs, bicycles, etc.), interacting with a set of actuators (lights) that choose their actions (i.e. state of illumination) in an attempt improve the overall experience of these users. The model for the interaction and action of sensors and actuators is an asynchronous Cellular Automata (CA) with memory, supporting a self-organization of the system as a response to the presence and movements of people inside it. The paper will introduce the model, as well as an ad hoc user interface for the specification of the relevant parameters of the CA transition rule that determines the overall system behaviour.

  8. Label-acquired magnetorotation for biosensing: An asynchronous rotation assay

    Energy Technology Data Exchange (ETDEWEB)

    Hecht, Ariel, E-mail: hecht@umich.ed [University of Michigan, Department of Biomedical Engineering, 2200 Bonisteel, Ann Arbor, MI 48109-2099 (United States); University of Michigan, Department of Chemistry, 930 North University, Ann Arbor, MI 48109-1055 (United States); Kinnunen, Paivo, E-mail: pkkinn@umich.ed [University of Michigan, Department of Chemistry, 930 North University, Ann Arbor, MI 48109-1055 (United States); University of Michigan, Applied Physics Program, 2477 Randall Laboratory, Ann Arbor, MI 48109-1120 (United States); McNaughton, Brandon, E-mail: bmcnaugh@umich.ed [University of Michigan, Department of Biomedical Engineering, 2200 Bonisteel, Ann Arbor, MI 48109-2099 (United States); University of Michigan, Department of Chemistry, 930 North University, Ann Arbor, MI 48109-1055 (United States); University of Michigan, Applied Physics Program, 2477 Randall Laboratory, Ann Arbor, MI 48109-1120 (United States); Kopelman, Raoul, E-mail: kopelman@umich.ed [University of Michigan, Department of Biomedical Engineering, 2200 Bonisteel, Ann Arbor, MI 48109-2099 (United States); University of Michigan, Department of Chemistry, 930 North University, Ann Arbor, MI 48109-1055 (United States); University of Michigan, Applied Physics Program, 2477 Randall Laboratory, Ann Arbor, MI 48109-1120 (United States)


    This paper presents a novel application of magnetic particles for biosensing, called label-acquired magnetorotation (LAM). This method is based on a combination of the traditional sandwich assay format with the asynchronous magnetic bead rotation (AMBR) method. In label-acquired magnetorotation, an analyte facilitates the binding of a magnetic label bead to a nonmagnetic solid phase sphere, forming a sandwich complex. The sandwich complex is then placed in a rotating magnetic field, where the rotational frequency of the sandwich complex is a function of the amount of analyte attached to the surface of the sphere. Here, we use streptavidin-coated beads and biotin-coated particles as analyte mimics, to be replaced by proteins and other biological targets in future work. We show this sensing method to have a dynamic range of two orders of magnitude.

  9. Estimation of delays in generalized asynchronous Boolean networks. (United States)

    Das, Haimabati; Layek, Ritwik Kumar


    A new generalized asynchronous Boolean network (GABN) model has been proposed in this paper. This continuous-time discrete-state model captures the biological reality of cellular dynamics without compromising the computational efficiency of the Boolean framework. The GABN synthesis procedure is based on the prior knowledge of the logical structure of the regulatory network, and the experimental transcriptional parameters. The novelty of the proposed methodology lies in considering different delays associated with the activation and deactivation of a particular protein (especially the transcription factors). A few illustrative examples of some well-studied network motifs have been provided to explore the scope of using the GABN model for larger networks. The GABN model of the p53-signaling pathway in response to γ-irradiation has also been simulated in the current paper to provide an indirect validation of the proposed schema.

  10. A parallel asynchronous decomposition for on-line contingency planning

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, V.C. [Illinois Inst. of Tech., Chicago, IL (United States). Electrical and Computer Engineering Dept.; Talukdar, S.N. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Engineering Design Research Center


    Traditional formulations of security-constrained-optimal-power-flows represent contingencies by hard constraints. The disadvantages are four-fold. First, the conflicts among contingencies must be arbitrated apriori, before their effects are known. Second, the feasible region shrinks with increase in the number of contingencies. Third, computational time increases with the number of contingencies. Fourth, hard constraints provide poor models of fuzzy quantities such as equipment ratings and operating guidelines. This paper develops a modeling framework without these disadvantages. Specifically, it allows for soft constraints and always has feasible solutions. The effects of conflicts among contingencies are displayed so system operators can arbitrate them in an informed manner. Moreover, each contingency can be handled asynchronously and in parallel. In other words, the computational time, for handling an arbitrarily large number of contingencies, remains the same as for performing an optimal power flow without any contingencies (provided that a computer is dedicated to each contingency).

  11. A parallel asynchronous decomposition for on-line contingency planning

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, V.C. [Illinois Inst. of Tech., Chicago, IL (United States). Electrical and Computer Engineering Dept.; Talukdar, S.N. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Engineering Design Research Center


    Traditional formulations of security-constrained-optimal-power-flows represent contingencies by hard constraints. The disadvantages are four-fold. First, the conflicts among contingencies must be arbitrated a priori, before their effects are known. Second, the feasible region shrinks with increase in the number of contingencies. Third, computational time increases with the number of contingencies. Fourth, hard constraints provide poor models of fuzzy quantities such as equipment ratings and operating guidelines. This paper develops a modeling framework without these disadvantages. Specifically, it allows for soft constraints and always has feasible solutions. The effects of conflicts among contingencies are displayed so system operators can arbitrate them in an informed manner. Moreover, each contingency can be handled asynchronously and in parallel. In other words, the computational time, for handling an arbitrarily large number of contingencies, remains the same as for performing an optimal power flow without any contingencies (provided that a computer is dedicated to each contingency).

  12. Sideband-Harmonic Instability of Paralleled Inverters with Asynchronous Carriers

    DEFF Research Database (Denmark)

    Yang, Dongsheng; Wang, Xiongfei; Blaabjerg, Frede


    Paralleled inverters with asynchronous carriers are increasingly emerging into renewable power plants and other power-electronic-based power systems. The sideband harmonics resulting from the pulse width modulation tend to be different from one inverter to another, which may trigger sideband-harmonic...... resonances among the paralleled inverters. To address the sideband-harmonic instability, the nonlinearity of the digital pulse width modulator is analyzed first in this paper based on the harmonic balance principle. It is revealed that the dynamic sideband components corresponding to a given small......-signal perturbation can be far below the Nyquist frequency, and they may not be effectively attenuated by anti-aliasing filters. A multi-frequency impedance model is then developed for the inverter, which characterizes the dynamic coupling between the perturbed frequency component and the sideband frequency component...

  13. Graduate Students' Experiences of Challenges in Online Asynchronous Discussions

    Directory of Open Access Journals (Sweden)

    Elizabeth Murphy


    Full Text Available This paper presents one of five categories of findings of a qualitative study of students' experiences of challenges encountered in a web-based graduate program. The findings relate to the category of experiences with online asynchronous discussions. Data collection relied on a discussion, questionnaire and interview all conducted within WebCTTM. The category's findings were grouped into four sub-categories of challenges as follows: student behaviour; text-only, online communication; purpose and quality of the discussion; and forum features. Challenges related to students' behaviour included domination of the discussion by individual students or groups of students resulting in feelings of exclusion, frustration and inadequacy. Text-only communication caused difficulties related to misinterpretation and conveying and deriving intent. Challenges related to the purpose and value of the discussion resulted from low quality and high quantities of postings to meet grade requirements. Technical features that presented challenges included the inability to delete messages.

  14. Exploring Asynchronous Many-Task Runtime Systems toward Extreme Scales

    Energy Technology Data Exchange (ETDEWEB)

    Knight, Samuel [O8953; Baker, Gavin Matthew; Gamell, Marc [Rutgers U; Hollman, David [08953; Sjaardema, Gregor [SNL; Kolla, Hemanth [SNL; Teranishi, Keita; Wilke, Jeremiah J; Slattengren, Nicole [SNL; Bennett, Janine Camille


    Major exascale computing reports indicate a number of software challenges to meet the dramatic change of system architectures in near future. While several-orders-of-magnitude increase in parallelism is the most commonly cited of those, hurdles also include performance heterogeneity of compute nodes across the system, increased imbalance between computational capacity and I/O capabilities, frequent system interrupts, and complex hardware architectures. Asynchronous task-parallel programming models show a great promise in addressing these issues, but are not yet fully understood nor developed su ciently for computational science and engineering application codes. We address these knowledge gaps through quantitative and qualitative exploration of leading candidate solutions in the context of engineering applications at Sandia. In this poster, we evaluate MiniAero code ported to three leading candidate programming models (Charm++, Legion and UINTAH) to examine the feasibility of these models that permits insertion of new programming model elements into an existing code base.

  15. Blow Flies Visiting Decaying Alligators: Is Succession Synchronous or Asynchronous?

    Directory of Open Access Journals (Sweden)

    Mark P. Nelder


    Full Text Available Succession patterns of adult blow flies (Diptera: Calliphoridae on decaying alligators were investigated in Mobile (Ala, USA during August 2002. The most abundant blow fly species visiting the carcasses were Chrysomya rufifacies (Macquart, Cochliomyia macellaria (Fabricus, Chrysomya megacephala (Fabricus, Phormia regina (Meigen, and Lucilia coeruleiviridis (Macquart. Lucilia coeruleiviridis was collected more often during the early stages of decomposition, followed by Chrysomya spp., Cochliomyia macellaria, and Phormia regina in the later stages. Lucilia coeruleiviridis was the only synchronous blow fly on the three carcasses; other blow fly species exhibited only site-specific synchrony. Using dichotomous correlations and analyses of variance, we demonstrated that blow fly-community succession was asynchronous among three alligators; however, Monte Carlo simulations indicate that there was some degree of synchrony between the carcasses.

  16. Asynchronous Messaging and Data Transfer in a Spacecraft: An Implementation (United States)

    Moholt, Joseph M.


    Data transfer and messaging is an important part of a spacecraft. Creating a standard protocol for messaging that can be used for a variety of applications is an extremely beneficial project at the Jet Propulsion Laboratory (JPL). The Asynchronous Messaging Service (AMS) is a protocol outlining how subsystems initialize and conduct communication between each other. There are currently two implementations of AMS in the works. At JPL, my task is to get a working implementation of AMS onto vxWorks as a proof of concept. An Autocoder, a program used to convert visually created state chart diagrams to C++, has also been created to accomplish a part of the implementation. I was assigned to make the program portable on any Unix type environment. Lastly, I was to develop a program to demonstrate messaging between two FireWire cards running vxworks.

  17. Reliable Asynchronous Image Transfer Protocol in Wireless Multimedia Sensor Networks

    Directory of Open Access Journals (Sweden)

    In-Bum Jung


    Full Text Available In the paper, we propose a reliable asynchronous image transfer protocol, RAIT. RAIT applies a double sliding window method to node-to-node transfer, with one sliding window for the receiving queue, which is used to prevent packet loss caused by communication failure between nodes, and another sliding window for the sending queue, which prevents packet loss caused by network congestion. The routing node prevents packet loss between nodes by preemptive scheduling of multiple packets for a given image. RAIT implements a double sliding window method by means of a cross-layer design between the RAIT layer, routing layer, and queue layer. We demonstrate that RAIT guarantees a higher reliability of image transmission compared to the existing protocols.

  18. Reliable asynchronous image transfer protocol in wireless multimedia sensor networks. (United States)

    Lee, Joa-Hyoung; Jung, In-Bum


    In the paper, we propose a reliable asynchronous image transfer protocol, RAIT. RAIT applies a double sliding window method to node-to-node transfer, with one sliding window for the receiving queue, which is used to prevent packet loss caused by communication failure between nodes, and another sliding window for the sending queue, which prevents packet loss caused by network congestion. The routing node prevents packet loss between nodes by preemptive scheduling of multiple packets for a given image. RAIT implements a double sliding window method by means of a cross-layer design between the RAIT layer, routing layer, and queue layer. We demonstrate that RAIT guarantees a higher reliability of image transmission compared to the existing protocols.

  19. Asynchronous learning: student utilization out of sync with their preference

    Directory of Open Access Journals (Sweden)

    Edward K. Lew


    Full Text Available Background: Asynchronous learning is gaining popularity. Data are limited regarding this learning method in medical students rotating in emergency medicine (EM. In EM, faculty time is limited to give in-person lectures. The authors sought to create an online curriculum that students could utilize as an additional learning modality. Objective: The goal was to evaluate effectiveness, participation, and preference for this mode of learning. Methods: We developed five online, narrated PowerPoint presentations. After orientation, access to the online curriculum was provided to the students, which they could review at their leisure. Results: One hundred and seven fourth-year medical students participated. They reported the curriculum to be of high quality. Pretest scores were similar for those that viewed all lectures – compliant group (CG (9.5 [CI 4.8–14.1] and those that did not view any – non-compliant group (NCG (9.6 [CI 5.9–13.4]. There was no statistical significant difference in posttest scores between the groups although there was improvement overall: CG 14.6 (CI 6.9–22.1; NCG 11.4 (CI 5.7–17.1. A majority (69.2% favored inclusion of asynchronous learning, but less than a quarter (22.4% reported viewing all five modules and more than a third (36.4% viewed none. Conclusion: Despite student-expressed preference for an online curriculum, they used the online resource less than expected. This should give pause to educators looking to convert core EM topics to an online format. However, when high-quality online lectures are utilized as a learning tool, this study demonstrates that they had neither a positive nor a negative impact on test scores.

  20. Mechanical characteristics of a double-fed machine in asynchronous mode and prospects of its application in the electric drive of mining machines (United States)

    Ostrovlyanchik, V. Yu; Popolzin, I. Yu; Kubarev, V. A.; Marshev, D. A.


    The concept of a double-fed machine as an asynchronous motor with a phase rotor and a source of additional voltage is defined. Based on the analysis of a circuit replacing the double-fed machine, an expression is derived relating the moment, slip, amplitude and phase of additional voltage across the rotor. The conditions maximizing the moment with respect to amplitude and phase of additional voltage in the rotor circuit are also obtained, the phase surface of function of machine electromagnetic moment is constructed. The analysis of basic equation of electric drive motion in relation to electric drive of mine hoisting installations and the conclusion about the necessity of work in all four quadrants of coordinate plane “moment-slip” are made. Family of mechanical characteristics is constructed for a double-fed machine and its achievable speed control range in asynchronous mode is determined. Based on the type of mechanical characteristics and the calculated range of speed control, the conclusion is made about the suitability of using a dual-fed asynchronous machine for driving mine mechanisms with a small required speed control range and the need for organizing a combined operating mode for driving mine hoisting installations and other mechanisms with a large speed control range.


    Directory of Open Access Journals (Sweden)

    Serban Vlad


    Full Text Available The asynchronous systems are the non-deterministic real timebinarymodels of the asynchronous circuits from electrical engineering.Autonomy means that the circuits and their models have no input.Regularity means analogies with the dynamical systems, thus such systems may be considered to be real time dynamical systems with a’vector field’, Universality refers to the case when the state space of the system is the greatest possible in the sense of theinclusion. The purpose of this paper is that of defining, by analogy with the dynamical systems theory, the omega-limit sets, the invariance and the basins of attraction of the universal regular autonomous asynchronous systems.

  2. Modeling and Analysis of Asynchronous Systems Using SAL and Hybrid SAL (United States)

    Tiwari, Ashish; Dutertre, Bruno


    We present formal models and results of formal analysis of two different asynchronous systems. We first examine a mid-value select module that merges the signals coming from three different sensors that are each asynchronously sampling the same input signal. We then consider the phase locking protocol proposed by Daly, Hopkins, and McKenna. This protocol is designed to keep a set of non-faulty (asynchronous) clocks phase locked even in the presence of Byzantine-faulty clocks on the network. All models and verifications have been developed using the SAL model checking tools and the Hybrid SAL abstractor.

  3. Asynchronous Video Interviewing as a New Technology in Personnel Selection: The Applicant's Point of View. (United States)

    Brenner, Falko S; Ortner, Tuulia M; Fay, Doris


    The present study aimed to integrate findings from technology acceptance research with research on applicant reactions to new technology for the emerging selection procedure of asynchronous video interviewing. One hundred six volunteers experienced asynchronous video interviewing and filled out several questionnaires including one on the applicants' personalities. In line with previous technology acceptance research, the data revealed that perceived usefulness and perceived ease of use predicted attitudes toward asynchronous video interviewing. Furthermore, openness revealed to moderate the relation between perceived usefulness and attitudes toward this particular selection technology. No significant effects emerged for computer self-efficacy, job interview self-efficacy, extraversion, neuroticism, and conscientiousness. Theoretical and practical implications are discussed.

  4. Asynchronous response of tropical forest leaf phenology to seasonal and el Niño-driven drought.

    Directory of Open Access Journals (Sweden)

    Stephanie Pau

    Full Text Available The Hawaiian Islands are an ideal location to study the response of tropical forests to climate variability because of their extreme isolation in the middle of the Pacific, which makes them especially sensitive to El Niño-Southern Oscillation (ENSO. Most research examining the response of tropical forests to drought or El Niño have focused on rainforests, however, tropical dry forests cover a large area of the tropics and may respond very differently than rainforests. We use satellite-derived Normalized Difference Vegetation Index (NDVI from February 2000-February 2009 to show that rainforests and dry forests in the Hawaiian Islands exhibit asynchronous responses in leaf phenology to seasonal and El Niño-driven drought. Dry forest NDVI was more tightly coupled with precipitation compared to rainforest NDVI. Rainforest cloud frequency was negatively correlated with the degree of asynchronicity (Delta(NDVI between forest types, most strongly at a 1-month lag. Rainforest green-up and dry forest brown-down was particularly apparent during the 2002-003 El Niño. The spatial pattern of NDVI response to the NINO 3.4 Sea Surface Temperature (SST index during 2002-2003 showed that the leeward side exhibited significant negative correlations to increased SSTs, whereas the windward side exhibited significant positive correlations to increased SSTs, most evident at an 8 to 9-month lag. This study demonstrates that different tropical forest types exhibit asynchronous responses to seasonal and El Niño-driven drought, and suggests that mechanisms controlling dry forest leaf phenology are related to water-limitation, whereas rainforests are more light-limited.

  5. N-CANDA data integration: anatomy of an asynchronous infrastructure for multi-site, multi-instrument longitudinal data capture. (United States)

    Rohlfing, Torsten; Cummins, Kevin; Henthorn, Trevor; Chu, Weiwei; Nichols, B Nolan


    The infrastructure for data collection implemented by the National Consortium on Alcohol and NeuroDevelopment in Adolescence (N-CANDA) for data collection comprises several innovative features: (a) secure, asynchronous transfer and persistent storage of collected data via a revision control system; (b) two-stage import into a longitudinal database; and (c) use of a script-controlled web browser for data retrieval from a third-party, web-based neuropsychological test battery. The asynchronous operation of data transmission and import is of particular benefit, as it has allowed the consortium sites to begin data collection before the receiving database infrastructure had been deployed. Records were collected within 86 days of funding, 35 days after finalizing the collected instruments. Final instruments were added to the database import 225 days after instrument selection, with up to 173 records already collected at that time. Thus, the concepts implemented in N-CANDA's data collection system helped reduce project start-up time by several months. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to

  6. High frame rate ultrasound monitoring of high intensity focused ultrasound-induced temperature changes: a novel asynchronous approach. (United States)

    Liu, Hao-Li; Huang, Sheng-Min; Li, Meng-Lin


    When applying diagnostic ultrasound to guide focused ultrasound (FUS) thermal therapy, high frame rate ultrasonic temperature monitoring is valuable in better treatment control and dose monitoring. However, one of the potential problems encountered when performing ultrasonic temperature monitoring of a FUS procedure is interference between the FUS and imaging systems. Potential means of overcoming this problem include the switch between the FUS system and the imaging system (limited by a reduced frame rate of thermal imaging) or the development of complex synchronization protocols between the FUS therapeutic system and the ultrasonic imaging apparatus (limited by implementation efforts both for software and hardware designs, and low potential for widespread diffusion). In this paper, we apply an asynchronous idea to retrieving high frame rate and FUS-interference-free thermal imaging during FUS thermal therapy. Tone-burst delivery mode of the FUS energy is employed in our method, and the imaging and FUS systems are purposely operated in an asynchronous manner. Such asynchronous operation causes FUS interference to saturate sequential image frames at different A-lines; thus clean A-lines from several image frames can be extracted by a total energy-thresholding technique and then combined to reconstruct interference-free B-mode images at a high frame rate for temperature estimation. The performance of the proposed method is demonstrated by phantom experiments. Relationships of the FUS duty-cycle with the maximum reconstructed frame rate of thermal imaging and the corresponding maximum temperature increase are also studied. Its performance was also evaluated and compared with the existing manually synchronous and synchronous approaches. By proper selection of the FUS duty-cycle, using our method, the frame rate of thermal imaging can be increased up to tenfold compared with that provided by the manually synchronous approach. Our method is capable of pushing the frame

  7. Asynchronous Free-Space Optical CDMA Communications System for Last-mile Access Network

    DEFF Research Database (Denmark)

    Jurado-Navas, Antonio; Raddo, Thiago R.; Sanches, Anderson L.


    We propose a new hybrid asynchronous OCDMA-FSO communications system for access network solutions. New ABER expressions are derived under gamma-gamma scintillation channels, where all users can surprisingly achieve error-free transmissions when FEC is employed....

  8. Asynchronous abdomino-parasacral resection of a giant pelvic lipoma protruding to the left buttock

    Directory of Open Access Journals (Sweden)

    Masanori Sato


    CONCLUSION: The asynchronous abdomino-parasacral approach with several turnings of the patient's body and plastic bag packing of the tumor were advantageous to manage en bloc resection of the giant pelvic lipoma presented in this case study.

  9. Determining sociability, social space, and social presence in (A)synchronous collaborative groups

    NARCIS (Netherlands)

    Kreijns, K.; Kirschner, P.A.; Jochems, W.; Buuren, H. van


    The effectiveness of group learning in asynchronous distributed learning groups depends on the social interaction that takes place. This social interaction affects both cognitive and socioemotional processes that take place during learning, group forming, establishment of group structures, and group

  10. Asynchronous Sensor fuSion for Improved Safety of air Traffic (ASSIST) Project (United States)

    National Aeronautics and Space Administration — SSCI proposes to develop, implement and test a collision detection system for unmanned aerial vehicles (UAV), referred to as the Asynchronous Sensor fuSion for...

  11. Students experiences with collaborative learning in asynchronous computer-supported collaborative learning environments.

    NARCIS (Netherlands)

    Dewiyanti, Silvia; Brand-Gruwel, Saskia; Jochems, Wim; Broers, Nick


    Dewiyanti, S., Brand-Gruwel, S., Jochems, W., & Broers, N. (2007). Students experiences with collaborative learning in asynchronous computer-supported collaborative learning environments. Computers in Human Behavior, 23, 496-514.

  12. Low-power Implementation of an Encryption/Decryption System with Asynchronous Techniques

    Directory of Open Access Journals (Sweden)

    Nikos Sklavos


    Full Text Available An asynchronous VLSI implementation of the International Data Encryption Algorithm (IDEA is presented in this paper. In order to evaluate the asynchronous design a synchronous version of the algorithm was also designed. VHDL hardware description language was used in order to describe the algorithm. By using Synopsys commercial available tools the VHDL code was synthesized. After placing and routing both designs were fabricated with 0.6 μm CMOS technology. With a system clock of up to 8 MHz and a power supply of 5 V the two chips were tested and evaluated comparing with the software implementation of the IDEA algorithm. This new approach proves efficiently the lowest power consumption of the asynchronous implementation compared to the existing synchronous. Therefore, the asynchronous chip performs efficiently in Wireless Encryption Protocols and high speed networks.

  13. 106-17 Telemetry Standards. Annex A.4. Asynchronous Recorder Multiplexer Output Re-Constructor (ARMOR) (United States)


    Telemetry Standards, RCC Standard 106-17 Annex A .4, July 2017 ANNEX A .4 Asynchronous Recorder Multiplexer Output Re-Constructor (ARMOR...Acronyms ............................................................................................................................... A .4-iii 1...General ........................................................................................................................ A .4-1 1.1. Setup on Tape

  14. AP-IO: Asynchronous Pipeline I/O for Hiding Periodic Output Cost in CFD Simulation


    Xiaoguang, Ren; Xinhai, Xu


    Computational fluid dynamics (CFD) simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO) optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. In AP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pip...

  15. Violation of the equivalence principle for stressed bodies in asynchronous relativity

    Energy Technology Data Exchange (ETDEWEB)

    Andrade Martins, R. de (Centro de Logica, Epistemologia e Historia da Ciencia, Campinas (Brazil))


    In the recently developed asynchronous formulation of the relativistic theory of extended bodies, the inertial mass of a body does not explicitly depend on its pressure or stress. The detailed analysis of the weight of a box filled with a gas and placed in a weak gravitational field shows that this feature of asynchronous relativity implies a breakdown of the equivalence between inertial and passive gravitational mass for stressed systems.

  16. An Evaluation of Parallel Synchronous and Conservative Asynchronous Logic-Level Simulations

    Directory of Open Access Journals (Sweden)

    Ausif Mahmood


    a circuit remain fixed during the entire simulation. We remove this limitation and, by extending the analyses to multi-input, multi-output circuits with an arbitrary number of input events, show that the conservative asynchronous simulation extracts more parallelism and executes faster than synchronous simulation in general. Our conclusions are supported by a comparison of the idealized execution times of synchronous and conservative asynchronous algorithms on ISCAS combinational and sequential benchmark circuits.

  17. Comparing face-to-face, synchronous, and asynchronous learning: postgraduate dental resident preferences. (United States)

    Kunin, Marc; Julliard, Kell N; Rodriguez, Tobias E


    The Department of Dental Medicine of Lutheran Medical Center has developed an asynchronous online curriculum consisting of prerecorded PowerPoint presentations with audio explanations. The focus of this study was to evaluate if the new asynchronous format satisfied the educational needs of the residents compared to traditional lecture (face-to-face) and synchronous (distance learning) formats. Lectures were delivered to 219 dental residents employing face-to-face and synchronous formats, as well as the new asynchronous format; 169 (77 percent) participated in the study. Outcomes were assessed with pretests, posttests, and individual lecture surveys. Results found the residents preferred face-to-face and asynchronous formats to the synchronous format in terms of effectiveness and clarity of presentations. This preference was directly related to the residents' perception of how well the technology worked in each format. The residents also rated the quality of student-instructor and student-student interactions in the synchronous and asynchronous formats significantly higher after taking the lecture series than they did before taking it. However, they rated the face-to-face format as significantly more conducive to student-instructor and student-student interaction. While the study found technology had a major impact on the efficacy of this curricular model, the results suggest that the asynchronous format can be an effective way to teach a postgraduate course.

  18. Asynchronous web-based patient-centered home telemedicine system. (United States)

    Lau, Christopher; Churchill, R Sean; Kim, Janice; Matsen, Frederick A; Kim, Yongmin


    A web-based system for asynchronous multimedia messaging between shoulder replacement surgery patients at home and their surgeons was developed and tested. A web browser plug-in simplifies the process of capturing video and transferring it to a web site for novice computer users. The design of the video capture plug-in can be reused to acquire and securely transfer any type of data over the web. For example, readings from home biosensor instruments (e.g., glucometers and spirometers) that can be connected to a personal computer can be transferred to a home telemedicine web site. Both patients and doctors can access this web site to monitor health status longitudinally. Six patients, whose familiarity with computers ranged from no experience to expert users, used the system. All of the subjects were able to use the system to check treatment reminders and to send at least one message with video to their surgeons. The surgeons monitored the system regularly and always responded to messages within 24 h during the six-month trial period.

  19. Microwave Diplexer Purely Based on Direct Synchronous and Asynchronous Coupling

    Directory of Open Access Journals (Sweden)

    A. O. Nwajana


    Full Text Available A diplexer realized purely based on direct coupling is presented. No cross-coupling is involved in the design process. The microwave diplexer is achieved by coupling a dual-band bandpass filter onto two individual channel filters. This design eliminates the need for employing external junctions in diplexer design, as opposed to the conventional design approach which requires separate junctions for energy distribution. A 10-pole (10th order diplexer has been successfully designed, simulated, fabricated and measured. The diplexer is composed of 2 poles from the dual-band filter, 4 poles from the Tx bandpass filter, and the remaining 4 poles from the Rx bandpass filter. The design was implemented using synchronously and asynchronously tuned microstrip square open-loop resonators. The simulation and measurement results show that an isolation of 50 dB is achieved between the diplexer Tx and Rx bands. The minimum insertion loss is 2.88 dB for the transmit band, and 2.95 dB for the receive band.

  20. Photonic analog-to-digital converter via asynchronous oversampling (United States)

    Carver, Spencer; Reeves, Erin; Siahmakoun, Azad; Granieri, Sergio


    This paper presents a hybrid opto-electronic asynchronous delta-sigma modulator, implemented in the form of a fiber-optic Analog-to-Digital converter (ADC). This architecture was chosen for its independence of an external clock and ease of demodulation through a single low-pass filter stage. The fiber-optic prototype consists of an input laser (wavelength λ1) which is modulated with an input RF signal, a high-speed comparator circuit working as bi-stable quantizer, and a fiber-optic loop that includes a SOA and a band-pass filter that act as a leaky integrator. The fiber-optic loop acts as a fiber-ring resonator (FRR), and defines the resonance wavelength λ2 of the system. The gain within this loop is modified through cross-gain modulation (XGM) by the input wavelength λ1, and thus achieves the desired modulation effect. The proposed architecture has been constructed and characterized at a sampling rate of 15.4 MS/s processing input analog signals in the range of dc-3 MHz with a signal-to-noise ratio of 36 dB and an effective number of bits of 5.7.

  1. Asynchronous interpretation of manual and automated audiometry: Agreement and reliability. (United States)

    Brennan-Jones, Christopher G; Eikelboom, Robert H; Bennett, Rebecca J; Tao, Karina Fm; Swanepoel, De Wet


    Introduction Remote interpretation of automated audiometry offers the potential to enable asynchronous tele-audiology assessment and diagnosis in areas where synchronous tele-audiometry may not be possible or practical. The aim of this study was to compare remote interpretation of manual and automated audiometry. Methods Five audiologists each interpreted manual and automated audiograms obtained from 42 patients. The main outcome variable was the audiologist's recommendation for patient management (which included treatment recommendations, referral or discharge) between the manual and automated audiometry test. Cohen's Kappa and Krippendorff's Alpha were used to calculate and quantify the intra- and inter-observer agreement, respectively, and McNemar's test was used to assess the audiologist-rated accuracy of audiograms. Audiograms were randomised and audiologists were blinded as to whether they were interpreting a manual or automated audiogram. Results Intra-observer agreement was substantial for management outcomes when comparing interpretations for manual and automated audiograms. Inter-observer agreement was moderate between clinicians for determining management decisions when interpreting both manual and automated audiograms. Audiologists were 2.8 times more likely to question the accuracy of an automated audiogram compared to a manual audiogram. Discussion There is a lack of agreement between audiologists when interpreting audiograms, whether recorded with automated or manual audiometry. The main variability in remote audiogram interpretation is likely to be individual clinician variation, rather than automation.

  2. Sparse asynchronous cortical generators can produce measurable scalp EEG signals. (United States)

    von Ellenrieder, Nicolás; Dan, Jonathan; Frauscher, Birgit; Gotman, Jean


    We investigate to what degree the synchronous activation of a smooth patch of cortex is necessary for observing EEG scalp activity. We perform extensive simulations to compare the activity generated on the scalp by different models of cortical activation, based on intracranial EEG findings reported in the literature. The spatial activation is modeled as a cortical patch of constant activation or as random sets of small generators (0.1 to 3cm(2) each) concentrated in a cortical region. Temporal activation models for the generation of oscillatory activity are either equal phase or random phase across the cortical patches. The results show that smooth or random spatial activation profiles produce scalp electric potential distributions with the same shape. Also, in the generation of oscillatory activity, multiple cortical generators with random phase produce scalp activity attenuated on average only 2 to 4 times compared to generators with equal phase. Sparse asynchronous cortical generators can produce measurable scalp EEG. This is a possible explanation for seemingly paradoxical observations of simultaneous disorganized intracranial activity and scalp EEG signals. Thus, the standard interpretation of scalp EEG might constitute an oversimplification of the underlying brain activity. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Obstacle avoidance in social groups: new insights from asynchronous models. (United States)

    Croft, Simon; Budgey, Richard; Pitchford, Jonathan W; Wood, A Jamie


    For moving animals, the successful avoidance of hazardous obstacles is an important capability. Despite this, few models of collective motion have addressed the relationship between behavioural and social features and obstacle avoidance. We develop an asynchronous individual-based model for social movement which allows social structure within groups to be included. We assess the dynamics of group navigation and resulting collision risk in the context of information transfer through the system. In agreement with previous work, we find that group size has a nonlinear effect on collision risk. We implement examples of possible network structures to explore the impact social preferences have on collision risk. We show that any social heterogeneity induces greater obstacle avoidance with further improvements corresponding to groups containing fewer influential individuals. The model provides a platform for both further theoretical investigation and practical application. In particular, we argue that the role of social structures within bird flocks may have an important role to play in assessing the risk of collisions with wind turbines, but that new methods of data analysis are needed to identify these social structures. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  4. FACT. Normalized and asynchronous mirror alignment for Cherenkov telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Sebastian Achim [ETH Zurich (Switzerland); Buss, Jens [TU Dortmund (Germany)


    Imaging Atmospheric Cherenkov Telescopes (IACTs) need fast and large imaging optics to map the faint Cherenkov light emitted in cosmic ray air showers onto their image sensors. Segmented reflectors are inexpensive, lightweight and offer good image quality. However, alignment of the mirror facets remains a challenge. A good alignment is crucial in IACT observations to separate gamma rays from hadronic cosmic rays. We present a star tracking alignment method which is not restricted to clear nights. It normalizes the mirror facet reflections to be independent of the reference star or the cloud coverage. It records asynchronously of the telescope drive which makes the method easy to integrate in existing telescopes. It can be combined with remote facet actuation, but it does not need one to work. Furthermore, it can reconstruct all individual mirror facet point spread functions. We present the method and alignment results on the First Geiger-mode Photo Diode Avalanche Cherenkov Telescope (FACT) on the Canary Island of La Palma, Spain.

  5. [System of telesonography with synchronous teleconsultations and asynchronous telediagnoses (Togo)]. (United States)

    Adambounou, K; Farin, F; Boucher, A; Adjenou, K V; Gbeassor, M; N'dakena, K; Vincent, N; Arbeille, P


    Ultrasonography is an important nonirradiating diagnostic medical imaging procedure, frequently used, especially in urgent circumstances. This relatively inexpensive noninvasive examination makes it possible to diagnose disorders in various parts of the human body, by examining, for example, the abdomen and pelvis, the cardiovascular system, and the muscles and joints. Ultrasound is also an operator-dependent examination, in that the quality of the result depends on precision in the manipulation of the probe. Unfortunately, many small medical centers and isolated sites do not have an appropriate well-trained sonographer to perform initial evaluations, and an untrained operator cannot capture the appropriate echographic views required for a safe diagnosis of current patients, even with realtime vocal guidance (personal data). The lack of experienced physicians or qualified technicians means that diagnostic ultrasound is not always accessible to patients for rapid examination worldwide, especially in Africa, Amazonia or near the North or South Poles. This situation has led to the development of a new concept of telemedicine: telesonography, with a remote ultrasound diagnosis either in real time (synchronous) or delayed (asynchronous; store-and-forward). These systems of real-time telesonography and data transmission require expensive and complex technology with sophisticated equipment not available in many developing countries. The purpose of this study is to design a low-cost real-time system of telesonography for teleconsultations with experts and a delayed telediagnostic mode between isolated peripheral hospitals and a University Hospital center (UHC). An IP camera and an internet video server were installed in a geographically isolated site equipped with an ultrasound machine and an operator with basic training in its use. Synchronous teleconsultation (second-opinion diagnosis) is possible via internet with a UHC expert. If no ultrasound operator is available at

  6. Performance Studies for Protection Against Asynchronous Dumps in the LHC

    CERN Document Server

    Kramer, T; Bracco, C; Goddard, B; Meddahi, M


    The LHC beam dump system has to safely dispose all beams in a wide energy range of 450 GeV to 7 TeV. A 3 ms abort gap in the beam structure for the switch-on of the extraction kicker field ideally allows a loss-free extraction under normal operating conditions. However, a low number of asynchronous beam aborts is to be expected from reliability calculations and from the first year's operational experience with the beam dump kickers. For such cases, MAD-X simulations including all optics and alignment errors have been performed to determine loss patterns around the LHC as a function of the position of the main protection elements in interaction region six. Special attention was paid to the beam load on the tungsten collimators which protect the triplets in the LHC experimental insertions, and the tracking results compared with semi-analytical numerical estimates. The simulations are also compared to the results of beam commissioning of these protection devices.

  7. Tracking Transition: Issues in Asynchronous E-Mail Interviewing

    Directory of Open Access Journals (Sweden)

    Muir Houston


    Full Text Available The purpose and focus of this paper is twofold. The first concerns the methodological issues involved with tracking a mobile population, namely students graduating from university; whose patterns of residence may for some time be transitory in nature. The second is to provide some details from a small sample of graduates on the issues raised in the transition from undergraduate study. The paper will tackle the two issues in order. First, an examination of recent methods of qualitative data collection which the development of information technology, in the form of Computer Mediated Communication (CMC, has allowed is undertaken. Second, the results of using one of these techniques (asynchronous e-mail to gather information on the transition from undergraduate study are reported. In addition, advantages and disadvantages that can arise in the use of these new techniques are reported. This paper engages with the overall theme of transition in a number of ways. First, the students are in a process of transition in status; from undergraduate to graduate. Second, in many cases, they may well be in transition in terms of location; from the university location either back home, or away to a new location. Third, they are in transition in terms of activity; either seeking or into employment or engaging in further study at a higher level. Finally, they may be in transition in relation to developing new social networks. URN: urn:nbn:de:0114-fqs0802116

  8. ACK filling void first algorithm and performance for asynchronous OPS (United States)

    Liu, Huanlin; Shi, Yonghe; Chen, Qianbin; Pan, Yingjun


    OPS with feedback shared FDL buffer produce large voids due to FDL buffers only supplying discrete step delay and causing FDL queue virtually occupation. By analyzing the TCP traffic and ACK packets feature, the ACK packet void filling first scheduling is presented to decrease packet loss rate and to reduce the FDL voids. When the FDL buffer void size is fit for the ACK packet, the ACK packet is scheduled to FDL immediately. An ACK and non-ACK packets difference and process flow is designed according the TCP packet frame structure. Compared with the conventional FIFO scheduling and smallest FDL void first scheduling, the algorithm reduces greatly the number of ACK occupying the FDL buffer and eliminates large numbers of ACK's bad influence on efficiency of IP data transmission under different FDL buffer depth and traffic load. The results of simulation show that the proposed scheduling makes use of ACK packets first void filling scheduling mechanism to reduce FDL excess load, increases output utilization and reduce packet loss ratio for asynchronous optical network. This approach is shown to minimize the FDL numbers with the feature of high stabilization and photonic integration and to improve real time TCP traffic performance for Internet network.

  9. Enhancing Critical Thinking in Graduate Nursing Online Asynchronous Discussions. (United States)

    Novotny, Nancy L; Stapleton, Stephen J; Hardy, Elaine C


    Graduate nursing students in online courses often have limited success in developing the critical thinking (CT) skills essential for advanced roles. This study describes the use of complementary strategies in a graduate-level nursing course to enhance CT in online discussions. Using Paul and Elder's framework for understanding the components of CT, the authors designed an asynchronous online course using multiple strategies to promote CT. We used mixed methods to collect descriptive and numerical data and content and repeated measures analyses to identify changes in CT skills and student perceptions across the semester. CT scores increased significantly and aligned with students' perceived improvements in CT. Evidence of CT in online discussions increased significantly across the semester with the use of multiple instructional strategies and substantial student and faculty efforts. The findings are a useful benchmark for future studies comparing combinations of strategies to identify those most effective and least arduous. [J Nurs Educ. 2016;55(9):514-521.]. Copyright 2016, SLACK Incorporated.

  10. Model checking methodology for large systems, faults and asynchronous behaviour. SARANA 2011 work report

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, J. [VTT Technical Research Centre of Finland, Espoo (Finland); Launiainen, T.; Heljanko, K.; Ropponen, J. [Aalto Univ., Espoo (Finland). Dept. of Information and Computer Science


    Digital instrumentation and control (I and C) systems are challenging to verify. They enable complicated control functions, and the state spaces of the models easily become too large for comprehensive verification through traditional methods. Model checking is a formal method that can be used for system verification. A number of efficient model checking systems are available that provide analysis tools to determine automatically whether a given state machine model satisfies the desired safety properties. This report reviews the work performed in the Safety Evaluation and Reliability Analysis of Nuclear Automation (SARANA) project in 2011 regarding model checking. We have developed new, more exact modelling methods that are able to capture the behaviour of a system more realistically. In particular, we have developed more detailed fault models depicting the hardware configuration of a system, and methodology to model function-block-based systems asynchronously. In order to improve the usability of our model checking methods, we have developed an algorithm for model checking large modular systems. The algorithm can be used to verify properties of a model that could otherwise not be verified in a straightforward manner. (orig.)

  11. Asynchronous neuro-osseous growth in adolescent idiopathic scoliosis - MRI-based research

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Winnie C.W.; Rasalkar, Darshana D. [The Chinese University of Hong Kong, Department of Diagnostic Radiology and Organ Imaging, Hong Kong, SAR (China); Cheng, Jack C.Y. [The Chinese University of Hong Kong, Department of Orthopaedics and Traumatology, Hong Kong, SAR (China)


    Adolescent idiopathic scoliosis (AIS) is a common worldwide problem and has been treated for many decades; however, there still remain uncertain areas about this disorder. Its involvement and impact on different parts of the human body remain underestimated due to lack of technology in imaging for objective assessment in the past. The advances in imaging technique and image analysis technology have provided a novel approach for the understanding of the phenotypic presentation of neuro-osseous changes in AIS patients as compared with normal controls. This review is the summary of morphological assessment of the skeletal and nervous systems in girls with AIS based on MRI. Girls with AIS are found to have morphological differences in multiple areas including the vertebral column, spinal cord, skull and brain when compared with age- and sex-matched normal controls. Taken together, the abnormalities in the skeletal system and nervous system of AIS are likely to be inter-related and reflect a systemic process of asynchronous neuro-osseous growth. The current knowledge about the anatomical changes in AIS has important implications with respect to the understanding of fundamental pathomechanical processes involved in the evolution of the scoliotic deformity. (orig.)

  12. Asynchronous vs didactic education: it's too early to throw in the towel on tradition. (United States)

    Jordan, Jaime; Jalali, Azadeh; Clarke, Samuel; Dyne, Pamela; Spector, Tahlia; Coates, Wendy


    Asynchronous, computer based instruction is cost effective, allows self-directed pacing and review, and addresses preferences of millennial learners. Current research suggests there is no significant difference in learning compared to traditional classroom instruction. Data are limited for novice learners in emergency medicine. The objective of this study was to compare asynchronous, computer-based instruction with traditional didactics for senior medical students during a week-long intensive course in acute care. We hypothesized both modalities would be equivalent. This was a prospective observational quasi-experimental study of 4th year medical students who were novice learners with minimal prior exposure to curricular elements. We assessed baseline knowledge with an objective pre-test. The curriculum was delivered in either traditional lecture format (shock, acute abdomen, dyspnea, field trauma) or via asynchronous, computer-based modules (chest pain, EKG interpretation, pain management, trauma). An interactive review covering all topics was followed by a post-test. Knowledge retention was measured after 10 weeks. Pre and post-test items were written by a panel of medical educators and validated with a reference group of learners. Mean scores were analyzed using dependent t-test and attitudes were assessed by a 5-point Likert scale. 44 of 48 students completed the protocol. Students initially acquired more knowledge from didactic education as demonstrated by mean gain scores (didactic: 28.39% ± 18.06; asynchronous 9.93% ± 23.22). Mean difference between didactic and asynchronous = 18.45% with 95% CI [10.40 to 26.50]; p = 0.0001. Retention testing demonstrated similar knowledge attrition: mean gain scores -14.94% (didactic); -17.61% (asynchronous), which was not significantly different: 2.68% ± 20.85, 95% CI [-3.66 to 9.02], p = 0.399. The attitudinal survey revealed that 60.4% of students believed the asynchronous modules were educational and 95


    Directory of Open Access Journals (Sweden)

    H. K. Hetman


    Full Text Available Purpose. Parameters of the nominal mode are related to the most important performance indicators of traction means, therefore, the problems of choosing their optimal values always inevitably arise when forming technical requirements for a new rolling stock. The paper describes the features of solving the above-mentioned problems for electric trains with an asynchronous traction drive in the case of two-zone and three-zone frequency control of power. Methodology. Power of nominal mode of the rolling stock should be chosen in such a way that it would be possible to realize a predetermined travel time along in the section or the movement speed. On that basis, and also taking into account the fact that the important operational characteristics of electric trains include the acceleration value during the start-up and acceleration at the design speed, we will formulate the problem of determining the nominal power. In the task for a given range of traction, it is necessary to find such a value of the nominal mode power and the corresponding force value to ensure the ability to carry out transportations with the given level of average speed with minimal energy consumption for traction. At the same time, it is necessary to fulfill the following conditions: a the speed of the electric train on the section does not exceed the established limits; b it is possible to realize the given values of accelerations. A more detailed consideration of the problem shows that in real conditions, when the starting acceleration and the mass of the train are given, the problem of determining electric train power is practically reduced to determining the optimal value of the nominal mode speed. Findings. The task of choosing the optimal values of the nominal mode speed is solved by determining the electric power consumption with the variation of the possible values of starting speed. Therefore, only those values that ensure the implementation of the given starting and

  14. Contrôle d'une machine asynchrone par estimation robuste de la vitesse (United States)

    Roboam, X.; Hapiot, J. C.; de Fornel, B.; Andrieux, C.


    This paper describes the study and the implementation of a variable speed drive for induction motor with no mechanical sensor. Power is supplied by a current-controlled voltage-source inverter. The lack of information (only two line-current sensors) requires an accurate and reliable reconstitution of the main quantities not sensed (flux, speed, torque). The results obtained show the excellent quality of the estimated speed, whatever the operating condition and despite the perturbations applied to the system. This study finally leads to the construction of a prototype. Cet article décrit l'étude et la mise en oeuvre d'un variateur de vitesse pour machine asynchrone sans capteur mécanique et alimentée par un onduleur de tension cotrôlé en courant. Le manque d'information (2 capteurs de courants de ligne uniquement) nécessite la reconstitution fiable et précise des grandeurs fondamentales non mesurées (flux, vitesse, couple). Les résultats obtenus montrent notamment l'excellente qualité de l'estimation de vitesse, quel que soit le point de fonctionnement et en dépit des perturbations auxquelles le système est soumis. Cette étude donne lieu à la réalisation d'un variateur prototype.

  15. An asynchronous writing method for restart files in the gysela code in prevision of exascale systems*

    Directory of Open Access Journals (Sweden)

    Thomine O.


    Full Text Available The present work deals with an optimization procedure developed in the full-f global GYrokinetic SEmi-LAgrangian code (GYSELA. Optimizing the writing of the restart files is necessary to reduce the computing impact of crashes. These files require a very large memory space, and particularly so for very large mesh sizes. The limited bandwidth of the data pipe between the comput- ing nodes and the storage system induces a non-scalable part in the GYSELA code, which increases with the mesh size. Indeed the transfer time of RAM to data depends linearly on the files size. The necessity of non synchronized writing-in-file procedure is therefore crucial. A new GYSELA module has been developed. This asynchronous procedure allows the frequent writ- ing of the restart files, whilst preventing a severe slowing down due to the limited writing bandwidth. This method has been improved to generate a checksum control of the restart files, and automatically rerun the code in case of a crash for any cause.

  16. iHadoop: Asynchronous Iterations Support for MapReduce

    KAUST Repository

    Elnikety, Eslam


    MapReduce is a distributed programming framework designed to ease the development of scalable data-intensive applications for large clusters of commodity machines. Most machine learning and data mining applications involve iterative computations over large datasets, such as the Web hyperlink structures and social network graphs. Yet, the MapReduce model does not efficiently support this important class of applications. The architecture of MapReduce, most critically its dataflow techniques and task scheduling, is completely unaware of the nature of iterative applications; tasks are scheduled according to a policy that optimizes the execution for a single iteration which wastes bandwidth, I/O, and CPU cycles when compared with an optimal execution for a consecutive set of iterations. This work presents iHadoop, a modified MapReduce model, and an associated implementation, optimized for iterative computations. The iHadoop model schedules iterations asynchronously. It connects the output of one iteration to the next, allowing both to process their data concurrently. iHadoop\\'s task scheduler exploits inter- iteration data locality by scheduling tasks that exhibit a producer/consumer relation on the same physical machine allowing a fast local data transfer. For those iterative applications that require satisfying certain criteria before termination, iHadoop runs the check concurrently during the execution of the subsequent iteration to further reduce the application\\'s latency. This thesis also describes our implementation of the iHadoop model, and evaluates its performance against Hadoop, the widely used open source implementation of MapReduce. Experiments using different data analysis applications over real-world and synthetic datasets show that iHadoop performs better than Hadoop for iterative algorithms, reducing execution time of iterative applications by 25% on average. Furthermore, integrating iHadoop with HaLoop, a variant Hadoop implementation that caches

  17. Magnetoencephalography demonstrates multiple asynchronous generators during human sleep spindles. (United States)

    Dehghani, Nima; Cash, Sydney S; Rossetti, Andrea O; Chen, Chih Chuan; Halgren, Eric


    Sleep spindles are approximately 1 s bursts of 10-16 Hz activity that occur during stage 2 sleep. Spindles are highly synchronous across the cortex and thalamus in animals, and across the scalp in humans, implying correspondingly widespread and synchronized cortical generators. However, prior studies have noted occasional dissociations of the magnetoencephalogram (MEG) from the EEG during spindles, although detailed studies of this phenomenon have been lacking. We systematically compared high-density MEG and EEG recordings during naturally occurring spindles in healthy humans. As expected, EEG was highly coherent across the scalp, with consistent topography across spindles. In contrast, the simultaneously recorded MEG was not synchronous, but varied strongly in amplitude and phase across locations and spindles. Overall, average coherence between pairs of EEG sensors was approximately 0.7, whereas MEG coherence was approximately 0.3 during spindles. Whereas 2 principle components explained approximately 50% of EEG spindle variance, >15 were required for MEG. Each PCA component for MEG typically involved several widely distributed locations, which were relatively coherent with each other. These results show that, in contrast to current models based on animal experiments, multiple asynchronous neural generators are active during normal human sleep spindles and are visible to MEG. It is possible that these multiple sources may overlap sufficiently in different EEG sensors to appear synchronous. Alternatively, EEG recordings may reflect diffusely distributed synchronous generators that are less visible to MEG. An intriguing possibility is that MEG preferentially records from the focal core thalamocortical system during spindles, and EEG from the distributed matrix system.

  18. Asynchronous Task-Based Parallelization of Algebraic Multigrid

    KAUST Repository

    AlOnazi, Amani A.


    As processor clock rates become more dynamic and workloads become more adaptive, the vulnerability to global synchronization that already complicates programming for performance in today\\'s petascale environment will be exacerbated. Algebraic multigrid (AMG), the solver of choice in many large-scale PDE-based simulations, scales well in the weak sense, with fixed problem size per node, on tightly coupled systems when loads are well balanced and core performance is reliable. However, its strong scaling to many cores within a node is challenging. Reducing synchronization and increasing concurrency are vital adaptations of AMG to hybrid architectures. Recent communication-reducing improvements to classical additive AMG by Vassilevski and Yang improve concurrency and increase communication-computation overlap, while retaining convergence properties close to those of standard multiplicative AMG, but remain bulk synchronous.We extend the Vassilevski and Yang additive AMG to asynchronous task-based parallelism using a hybrid MPI+OmpSs (from the Barcelona Supercomputer Center) within a node, along with MPI for internode communications. We implement a tiling approach to decompose the grid hierarchy into parallel units within task containers. We compare against the MPI-only BoomerAMG and the Auxiliary-space Maxwell Solver (AMS) in the hypre library for the 3D Laplacian operator and the electromagnetic diffusion, respectively. In time to solution for a full solve an MPI-OmpSs hybrid improves over an all-MPI approach in strong scaling at full core count (32 threads per single Haswell node of the Cray XC40) and maintains this per node advantage as both weak scale to thousands of cores, with MPI between nodes.

  19. Features of the Asynchronous Correlation between the China Coal Price Index and Coal Mining Accidental Deaths.

    Directory of Open Access Journals (Sweden)

    Yuecheng Huang

    Full Text Available The features of the asynchronous correlation between accident indices and the factors that influence accidents can provide an effective reference for warnings of coal mining accidents. However, what are the features of this correlation? To answer this question, data from the China coal price index and the number of deaths from coal mining accidents were selected as the sample data. The fluctuation modes of the asynchronous correlation between the two data sets were defined according to the asynchronous correlation coefficients, symbolization, and sliding windows. We then built several directed and weighted network models, within which the fluctuation modes and the transformations between modes were represented by nodes and edges. Then, the features of the asynchronous correlation between these two variables could be studied from a perspective of network topology. We found that the correlation between the price index and the accidental deaths was asynchronous and fluctuating. Certain aspects, such as the key fluctuation modes, the subgroups characteristics, the transmission medium, the periodicity and transmission path length in the network, were analyzed by using complex network theory, analytical methods and spectral analysis method. These results provide a scientific reference for generating warnings for coal mining accidents based on economic indices.

  20. Asynchronous video streaming vs. synchronous videoconferencing for teaching a pharmacogenetic pharmacotherapy course. (United States)

    Moridani, Majid


    To compare students' performance and course evaluations for a pharmacogenetic pharmacotherapy course taught by synchronous videoconferencing method via the Internet and for the same course taught via asynchronous video streaming via the Internet. In spring 2005, a pharmacogenetic therapy course was taught to 73 students located on Amarillo, Lubbock, and Dallas campuses using synchronous videoconferencing, and in spring 2006, to 78 students located on the same 3 campuses using asynchronous video streaming. A course evaluation was administered to each group at the end of the courses. Students in the asynchronous setting had final course grades of 89% +/- 7% compared to the mean final course grade of 87% +/- 7% in the synchronous group (p = 0.05). Regardless of which technology was used, average course grades did not differ significantly among the 3 campus sites. Significantly more of the students in the asynchronous setting agreed (57%) with the statement that they could read the lecture notes and absorb the content on their own without attending the class than students in the synchronous class (23%; chi-square test; p videos over delivery of content using the synchronous or asynchronous method alone.

  1. Synchronous and asynchronous modes of synaptic transmission utilize different calcium sources. (United States)

    Wen, Hua; Hubbard, Jeffrey M; Rakela, Benjamin; Linhoff, Michael W; Mandel, Gail; Brehm, Paul


    Asynchronous transmission plays a prominent role at certain synapses but lacks the mechanistic insights of its synchronous counterpart. The current view posits that triggering of asynchronous release during repetitive stimulation involves expansion of the same calcium domains underlying synchronous transmission. In this study, live imaging and paired patch clamp recording at the zebrafish neuromuscular synapse reveal contributions by spatially distinct calcium sources. Synchronous release is tied to calcium entry into synaptic boutons via P/Q type calcium channels, whereas asynchronous release is boosted by a propagating intracellular calcium source initiated at off-synaptic locations in the axon and axonal branch points. This secondary calcium source fully accounts for the persistence following termination of the stimulus and sensitivity to slow calcium buffers reported for asynchronous release. The neuromuscular junction and CNS neurons share these features, raising the possibility that secondary calcium sources are common among synapses with prominent asynchronous release. DOI:

  2. Neurochemical and neuropharmacological aspects of circadian disruptions: an introduction to asynchronization. (United States)

    Kohyama, Jun


    Circadian disruptions are common in modern society, and there is an urgent need for effective treatment strategies. According to standard diagnostic criteria, most adolescents showing both insomnia and daytime sleepiness are diagnosed as having behavioral-induced sleep efficiency syndrome resulting from insomnia due to inadequate sleep hygiene. However, a simple intervention of adequate sleep hygiene often fails to treat them. As a solution to this clinical problem, the present review first overviews the basic neurochemical and neuropharmachological aspects of sleep and circadian rhythm regulation, then explains several circadian disruptions from similar viewpoints, and finally introduces the clinical notion of asynchronization. Asynchronization is designated to explain the pathophysiology/pathogenesis of exhibition of both insomnia and hypersomnia in adolescents, which comprises disturbances in various aspects of biological rhythms. The major triggers for asynchronization are considered to be a combination of light exposure during the night, which disturbs the biological clock and decreases melatonin secretion, as well as a lack of light exposure in the morning, which prohibits normal synchronization of the biological clock to the 24-hour cycle of the earth and decreases the activity of serotonin. In the chronic phase of asynchronization, involvement of both wake- and sleep-promoting systems is suggested. Both conventional and alternative therapeutic approaches for potential treatment of asynchronization are suggested.

  3. The Controlled Electric Drive of the Automatic Cooling System of the Engine Room on a Vessel

    Directory of Open Access Journals (Sweden)

    Bevz Dennis V.


    Full Text Available Development of an automatic cooling system control by the Zelio Logic controller. Development of the simulation model of the open-loop system “frequency inverter – asynchronous motor with IR-compensation” in Matlab Simulink. Analysis of the transient characteristics ω = f(t, M = f(t at the start of the asynchronous motor.

  4. An Asynchronous Time-Division-Multiplexed Network-on-Chip for Real-Time Systems

    DEFF Research Database (Denmark)

    Kasapaki, Evangelia

    Multi-processor architectures using networks-on-chip (NOCs) for communication are becoming the standard approach in the development of embedded systems and general purpose platforms. Typically, multi-processor platforms follow a globally asynchronous locally synchronous (GALS) timing organization...... more flexible timing within its structure, to address signal distribution issues, using a network of synchronous routers. NOCs consist of a switching structure of routers connected by links, with network interfaces (NIs) that connect the processors to the switching structure. Argo uses a novel NI...... design that supports time-predictability, and asynchronous routers that form a time-elastic network. The NI design integrates the DMA functionality and the TDM schedule, and uses dual-ported local memories. The routers combine the router functionality and asynchronous elastic behavior. They also use...

  5. Beyond an Institutionalized Learning Environment: Fostering Interactions and Learning Using Synchronous and Asynchronous Messaging Systems

    Directory of Open Access Journals (Sweden)

    Nikki Philline C. DE LA ROSA


    Full Text Available Beyond an Institutionalized Learning Environment: Fostering Interactions and Learning Using Synchronous and Asynchronous Messaging Systems Ma. Luisa D. MARIANO Nikki Philline C. DE LA ROSA University of the Philippines Open University-PHILIPPINE ABSTRACT This paper seeks to examine the use of synchronous and asynchronous messaging systems with distance education students and the implications for student interaction and learning in the institutionalized Integrated Virtual Learning Environment (IVLE of the University of the Philippines Open University (UPOU. It will present, as a case in point, the learning experiences of UPOU students in obtaining tutorial support and using the IVLE and alternative synchronous and asynchronous messaging systems to maximize and facilitate online activities involving the Faculty-in-Charge, Tutor, UPOU support staff and the students.


    Directory of Open Access Journals (Sweden)

    Keiko Kitade


    Full Text Available In order to demonstrate how learners utilize the text-based asynchronous attributes of the Bulletin Board System, this study explored Japanese-as-a-second-language learners' metalanguage episodes (Swain & Lapkin, 1995, 1998 in offline verbal peer speech and online asynchronous discussions with their Japanese key pals. The findings suggest the crucial role of offline collaborative dialogue, the interactional modes in which the episodes occur, and the unique discourse structure of metalanguage episodes concerning online and offline interactions. A high score on the posttest also suggests the high retention of linguistic knowledge constructed through offline peer dialogue. In the offline mode, the learners were able to collaboratively construct knowledge with peers in the stipulated time, while simultaneously focusing on task content in the online interaction. The retrospective interviews and questionnaires reveal the factors that could affect the benefits of the asynchronous computer-mediated communication medium for language learning.

  7. GPU-Accelerated Asynchronous Error Correction for Mixed Precision Iterative Refinement

    Energy Technology Data Exchange (ETDEWEB)

    Antz, Hartwig [Karlsruhe Inst. of Technology (KIT) (Germany); Luszczek, Piotr [Univ. of Tennessee, Knoxville, TN (United States); Dongarra, Jack [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Manchester (United Kingdom); Heuveline, Vinent [Karlsruhe Inst. of Technology (KIT) (Germany)


    In hardware-aware high performance computing, block- asynchronous iteration and mixed precision iterative refinement are two techniques that are applied to leverage the computing power of SIMD accelerators like GPUs. Although they use a very different approach for this purpose, they share the basic idea of compensating the convergence behaviour of an inferior numerical algorithm by a more efficient usage of the provided computing power. In this paper, we want to analyze the potential of combining both techniques. Therefore, we implement a mixed precision iterative refinement algorithm using a block-asynchronous iteration as an error correction solver, and compare its performance with a pure implementation of a block-asynchronous iteration and an iterative refinement method using double precision for the error correction solver. For matrices from theUniversity of FloridaMatrix collection,we report the convergence behaviour and provide the total solver runtime using different GPU architectures.

  8. Synaptotagmin-7 Is an Asynchronous Calcium Sensor for Synaptic Transmission in Neurons Expressing SNAP-23

    DEFF Research Database (Denmark)

    Weber, Jens P; Toft-Bertelsen, Trine L; Mohrmann, Ralf


    stimulation, and can even play a dominant role in some synapses. Here, we show that substitution of SNAP-23 for SNAP-25 in mouse autaptic glutamatergic hippocampal neurons results in asynchronous release and a higher frequency of spontaneous release events (mEPSCs). Use of neurons from double-knock-out (SNAP......-25, synaptotagmin-7) mice in combination with viral transduction showed that SNAP-23-driven release is triggered by endogenous synaptotagmin-7. In the absence of synaptotagmin-7 release became even more asynchronous, and the spontaneous release rate increased even more, indicating that synaptotagmin......-7 acts to synchronize release and suppress spontaneous release. However, compared to synaptotagmin-1, synaptotagmin-7 is a both leaky and asynchronous calcium sensor. In the presence of SNAP-25, consequences of the elimination of synaptotagmin-7 were small or absent, indicating that the protein...

  9. Asynchronous Cholinergic Drive Correlates with Excitation-Inhibition Imbalance via a Neuronal Ca2+ Sensor Protein

    Directory of Open Access Journals (Sweden)

    Keming Zhou


    Full Text Available Excitation-inhibition imbalance in neural networks is widely linked to neurological and neuropsychiatric disorders. However, how genetic factors alter neuronal activity, leading to excitation-inhibition imbalance, remains unclear. Here, using the C. elegans locomotor circuit, we examine how altering neuronal activity for varying time periods affects synaptic release pattern and animal behavior. We show that while short-duration activation of excitatory cholinergic neurons elicits a reversible enhancement of presynaptic strength, persistent activation results to asynchronous and reduced cholinergic drive, inducing imbalance between endogenous excitation and inhibition. We find that the neuronal calcium sensor protein NCS-2 is required for asynchronous cholinergic release in an activity-dependent manner and dampens excitability of inhibitory neurons non-cell autonomously. The function of NCS-2 requires its Ca2+ binding and membrane association domains. These results reveal a synaptic mechanism implicating asynchronous release in regulation of excitation-inhibition balance.

  10. Dual stator winding variable speed asynchronous generator: magnetic equivalent circuit with saturation, FEM analysis and experiments (United States)

    Tutelea, L. N.; Muntean, N.; Deaconu, S. I.; Cunţan, C. D.


    The authors carried out a theoretical and experimental study of dual stator winding squirrel cage asynchronous generator (DSWA) behaviour in the presence of saturation regime (non-sinusoidal) due to the variable speed operation. The main aims are the determination of the relations of calculating the equivalent parameters of the machine windings, FEM validation of parameters and characteristics with free FEMM 4.2 computing software and the practice experimental tests for verifying them. Issue is limited to three phase range of double stator winding cage-asynchronous generator of small sized powers, the most currently used in the small adjustable speed wind or hydro power plants. The tests were carried out using three-phase asynchronous generator having rated power of 6 [kVA].

  11. Concerted and asynchronous mechanism of ground state proton transfer in alcohol mediated 7-hydroxyquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Baotao [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jang, Du-Jeon [Department of Chemistry, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, Jin Yong, E-mail: [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)


    Highlights: • Reaction rate constants obtained by DFT agree with experimental ones quite well. • Experimental postulate of concerted and asynchronous GSPT was confirmed. • The GSPT reaction can be decomposed into three asynchronous steps. - Abstract: Alcohols mediated 7-hydroxyquinoline (7-HQ) complex has received enormous attractions on the issue of proton transfer reaction in the ground and excited states. In the present paper, concentrating on the ground state proton transfer (GSPT), density functional theory (DFT) calculations were carried out to investigate the intrinsic insight into the reaction mechanism. We found that the GSPT is concerted and asynchronous process and can be accelerated by more acidic alcohol. Such GSPT was initiated by the proton transfer from alcohol to keto group of 7-HQ and finished by the proton transfer from nitrogen to alcohol. Our findings were in agreement with experimental conclusions quite well. Our results would be helpful to understand the proton transfer reaction for 7-HQ and related systems.

  12. Methodological Reflections on the Use of Asynchronous Online Focus Groups in Health Research

    Directory of Open Access Journals (Sweden)

    Sarah Williams PhD


    Full Text Available The Internet is increasingly used as a tool in qualitative research. In particular, asynchronous online focus groups are used when factors such as cost, time, or access to participants can make conducting face-to-face research difficult. In this article we consider key methodological issues involved in using asynchronous online focus groups to explore experiences of health and illness. The written nature of Internet communication, the lack of physical presence, and the asynchronous, longitudinal aspects enable participants who might not normally contribute to research studies to reflect on their personal stories before disclosing them to the researcher. Implications for study design, recruitment strategies, and ethics should be considered when deciding whether to use this method.

  13. Increased Mass Loss and Asynchronous Behavior of Marine-Terminating Outlet Glaciers at Upernavik Isstrøm, NW Greenland

    DEFF Research Database (Denmark)

    Larsen, Signe Hillerup; Khan, Shfaqat Abbas; Ahlstrøm, Andreas Peter


    on UI glaciers is found to be related to increased surface melt. Our investigations suggest that three out of the four main glaciers in the UI are likely to be in unstable positions and may have the potential to rapidly thin and accelerate and increase their contribution to sea level in the future.......In order to model and predict future behavior of marine terminating glaciers, it is essential to understand the different factors that control a glaciers response to climate change. Here we present a detailed study of the asynchronous changes in dynamic behavior of four adjacent marine......-terminating glaciers at Upernavik Isstrøm (UI), Northwest Greenland, between 1992 and 2013. Velocities were stable for all outlets at UI between 1992 and 2005. The northernmost glacier started to accelerate and thin in 2006 and continued to do so into 2011 after which time the velocities stabilized. The second most...

  14. Differences in Electronic Exchanges in Synchronous and Asynchronous Computer-Mediated Communication: The Effect of Culture as a Mediating Variable (United States)

    Angeli, Charoula; Schwartz, Neil H.


    Two hundred and eighty undergraduates from universities in two countries were asked to read didactic material, and then think and write about potential solutions to an ill-defined problem. The writing was conducted within a synchronous or asynchronous computer-mediated communication (CMC) environment. Asynchronous CMC took the form of email…

  15. Enhancing Discussions in the Asynchronous Online Classroom: The Lack of Face-to-Face Interaction Does Not Lessen the Lesson (United States)

    Comer, Debra R.; Lenaghan, Janet A.


    This article addresses educators' concerns about using asynchronous online discussions in lieu of face-to-face discussions. Drawing from research on asynchronous online education and Bloom's taxonomy, the authors introduce the system of "original examples" and "value-added comments" that they have developed to promote engaging and meaningful…

  16. Asynchronous and synchronous distance learning in stem education, using the example of the online master program wind energy systems (United States)

    Gleim, Daniela; Kuhl, Detlef


    This paper describes the 100% online teaching concepts of the degree program Online M.Sc. Wind Energy Systems. These are the synchronous teaching concept, the asynchronous learning concept and a combination of synchronous and asynchronous learning concept. The challenges that students and teachers have to face in the implementation of these teaching concepts are described here.

  17. Heating calculation features at self-start of large asynchronous motor (United States)

    Shevchenko, A. A.; Temlyakova, Z. S.; Grechkin, V. V.; Vilberger, M. E.


    The article proposes a method for optimizing the incremental heating calculation in the active volume of a large asynchronous motor for certain kinds of load characteristics. The incremental heating calculation is conditioned by the need to determine the aging level of the insulation and to predict a decrease in the electric machine service life. The method for optimizing the incremental heating calculation of asynchronous motor active volume is based on the automation of calculating the heating when simulating the self-starting process of the motor after eliminating an AC drop.

  18. Numerical modeling of a pulsed asynchronous generator with iron-free cylindrical solid rotor (United States)

    Guettafi, A.; Delmas, A.; Quichaud, G.


    This article presents the numerical simulation with finite element method of the transient regime of an asynchronous generator with iron-free cylindrical solid rotor. During this operation kinetic energy of the rotor is transferred through the ideal rectifier bridge to a load-inductance in order to create a high magnetic field pulse. The interest of this device is the less value of capacitors battery for self-oscillations of the asynchronous generator compared to this one necessary for direct transfer of its energy to the load-inductance.

  19. Asynchronous updates can promote the evolution of cooperation on multiplex networks (United States)

    Allen, James M.; Hoyle, Rebecca B.


    We study the importance to the frequency of cooperation of the choice of updating strategies in a game played asynchronously or synchronously across layers in a multiplex network. Updating asynchronously in the public goods game leads to higher frequencies of cooperation compared to synchronous updates. How large this effect is depends on the sensitivity of the game dynamics to changes in the number of cooperators surrounding a player, with the largest effect observed when players payoffs are small. The discovery of this effect enhances understanding of cooperation on multiplex networks, and demonstrates a new way to maintain cooperation in these systems.

  20. Asynchronous teaching of psychomotor skills through VR annotations: evaluation in digital rectal examination. (United States)

    Rissanen, Mikko J; Kume, Naoto; Kuroda, Yoshihiro; Kuroda, Tomohiro; Yoshimura, Koji; Yoshihara, Hiroyuki


    Many VR technology based training systems use expert's motion data as the training aid, but would not provide any short-cut to teaching medical skills that do not depend on exact motions. Earlier we presented Annotated Simulation Records (ASRs), which can be used to encapsulate experts' insight on psychomotor skills. Annotations made to behavioural parameters in training simulators enable asynchronous teaching instead of just motion training in a proactive way to the learner. We evaluated ASRs for asynchronous teaching of Digital Rectal Examination (DRE) with 3 urologists and 8 medical students. The ASRs were found more effective than motion-based training with verbal feedback.

  1. State assignment for asynchronous FSMs with the use of the incompatibility and complement graph (United States)

    Kulisz, Józef


    The paper presents an application of a novel concept of graph - the Incompatibility and Complement Graph - to state assignment for asynchronous FSMs. A specific feature of the graph is that it contains two kinds of edges: connecting mutually incompatible nodes, and connecting mutually complementing nodes. The graph can be useful in certain class of optimization problems, in which compatibility of bit patterns both in the true, and in the complemented form has to be analyzed. An example of such a problem is covering analysis in state assignment for asynchronous FSMs. The paper presents a simple example explaining the method. Appropriate algorithms for the graph building and coloring are also presented.

  2. Numerical modeling of a pulsed asynchronous generator with iron-free cylindrical solid rotor

    Energy Technology Data Exchange (ETDEWEB)

    Guettafi, A. [Inst. d' Electrotechnique, Univ. de Batna, Batna (Algeria); Delmas, A.; Quichaud, G. [Lab. de Physique des Gaz et des Plasmas, Univ. Paris Sud, Orsay (France)


    This article presents the numerical simulation with finite element method of the transient regime of an asynchronous generator with iron-free cylindrical solid rotor. During this operation kinetic energy of the rotor is transferred through the ideal rectifier bridge to a load-inductance in order to create a high magnetic field pulse. The interest of this device is the less value of capacitors battery for self-oscillations of the asynchronous generator compared to this one necessary for direct transfer of its energy to the load-inductance. (orig.)


    Directory of Open Access Journals (Sweden)

    M. I. Kotsur


    Full Text Available The article discusses the issue of increasing the energy efficiency of electric drive systems by determining the optimum value of the adjusting parameter converter, providing maximum efficiency of the drive system on the example of a frequency-current asynchronous gate cascade. The aim work is to develop easy to implement methods for determining the optimum switching frequency of the power switches of the converter in the form of analytical expressions with which the condition of minimization of losses in the drive. The object of investigation is the process of converting electromagnetic energy in the motor-converter system. The subject of this investigation is frequency-current asynchronous-gate cascade drive system. The methods of calculation of the losses in the AC motor and the power converter elements are considered. The objective function of total losses in the electric drive system, depending on the switching frequency of the power switches and the total harmonic distortion of the stator and rotor currents AC motor are determined. As a result, the objective function of total losses in the electric drive system has been converted into the form of a single variable, depending only on the frequency switching keys of the power converter. With the help of the simulation of the losses in the drive control system, which based peculiarities of electromagnetic and energetic processes in this class drive system are calculated. The adequacy of the calculation of the proposed simplified method to determine the effective frequency of power switches in the converter are confirmed. The proposed method of the determining the optimal frequency switching of the power switchers can be applied to engineering design and commissioning of the converter depending on the class and modes of operation of the drive control system.

  4. Long-term asynchronous decoding of arm motion using electrocorticographic signals in monkey

    Directory of Open Access Journals (Sweden)

    Zenas C Chao


    Full Text Available Brain–machine interfaces (BMIs employ the electrical activity generated by cortical neurons directly for controlling external devices and have been conceived as a means for restoring human cognitive or sensory-motor functions. The dominant approach in BMI research has been to decode motor variables based on single-unit activity (SUA. Unfortunately, this approach suffers from poor long-term stability and daily recalibration is normally required to maintain reliable performance. A possible alternative is BMIs based on electrocorticograms (ECoGs, which measure population activity and can provide more durable and stable recording. However, the level of long-term stability that ECoG-based decoding can offer remains unclear. Here we propose a novel ECoG-based decoding paradigm and show that we have successfully decoded hand positions and arm joint angles during an asynchronous food-reaching task in monkeys when explicit cues prompting the onset of movement were not required. Performance using our ECoG-based decoder was comparable to existing SUA-based systems while evincing far superior stability and durability. In addition, the same decoder could be used for months without any drift in accuracy or recalibration. These results were achieved by incorporating the spatio-spectro-temporal integration of activity across multiple cortical areas to compensate for the lower fidelity of ECoG signals. These results show the feasibility of high-performance, chronic and versatile ECoG-based neuroprosthetic devices for real-life applications. This new method provides a stable platform for investigating cortical correlates for understanding motor control, sensory perception, and high-level cognitive processes.

  5. High-performance image communication network with asynchronous transfer mode technology (United States)

    Wong, Albert W. K.; Huang, H. K.; Lee, Joseph K.; Bazzill, Todd M.; Zhu, Xiaoming


    Asynchronous transfer mode (ATM) technology has been implemented within our radiology department's hospital-wide PACS as well as in a wide area network (WAN) connecting affiliated hospitals. This paper describes our implementation strategies and the network performance observed in a clinical setting. The image communication network for our PACS is composed of two network interfaces: ATM (OC-3, 155 Mbps) and Ethernet (10 Mbps). This communication network connects four major campus buildings and two remote hospitals, providing intra- and interbuilding communication for radiologic images including CT, MR, CR, US, and digitized screen-film images. The network links these modalities via their acquisition computers to the PACS controller and to display workstations. The ATM serves as the primary network for transmission of radiologic images and relevant data within the entire PACS. The standard Ethernet is used as a backup network for ATM. It interconnects all PACS components including radiologic imaging systems, acquisition computers, display workstations, the PACS controller, the database servers, and the RIS and HIS. Our communication network operates on a 24 hrs/day, 7 days/week basis. Performance of the ATM network was evaluated in terms of disk-to-disk, disk-to-memory, and memory-to- memory transmission rates. The average memory-to-memory transmission rate over the wide area ATM network was 8.3 MByte/s, which corresponds to transferring a 40-slice (or, 20- MByte) CT examination to a remote site in less than 3 seconds. With the emerging ATM technology, we believe that ATM-based digital communication network is a suitable choice for large-scale PACS involving both LAN and WAN.

  6. Study of the asynchronous traction drive's operating modes by computer simulation. Part 1: Problem formulation and computer model

    Directory of Open Access Journals (Sweden)



    Full Text Available In this paper, the problems arising from the design of electric locomotives with asynchronous traction drive (with three-phase AC induction motors are considered as including the debugging of control algorithms. The electrical circuit provides the individual (by axle control of traction motors. This allows realizing the operational disconnection/connection of one or more axles in the automatic mode, with account of actual load. In perspective, the evaluation of locomotive's energy efficiency at the realization of various control algorithms must be obtained. Another objective is to research the dynamic processes in various modes of the electric locomotive operation (start and acceleration, traction regime, coasting movement, wheel-slide protection, etc. To solve these problems, a complex computer model based on the representation of AC traction drive as controlled electromechanical system, is developed in Part 1. The description of methods applied in modeling of traction drive elements (traction motors, power converters, control systems, as well as of mechanical part and of "wheel-rail" contact, is given. The control system provides the individual control of the traction motors. Part 2 of the paper focuses on the results of dynamic processes modeling in various modes of electric locomotive operation.

  7. Using Reflective Peer Assessment to Promote Students' Conceptual Understanding through Asynchronous Discussions (United States)

    Lin, Huann-shyang; Hong, Zuway-R; Wang, Hsin-Hui; Lee, Sung-Tao


    This study explores the impact of using assessment items with competing theories to encourage students to practice evaluative reflection and collaborative argumentation in asynchronous discussions. Thirty undergraduate students from various departments worked in small groups and took turns collaboratively discussing the given item's answer,…

  8. Router Designs for an Asynchronous Time-Division-Multiplexed Network-on-Chip

    DEFF Research Database (Denmark)

    Kasapaki, Evangelia; Sparsø, Jens; Sørensen, Rasmus Bo


    In this paper we explore the design of an asynchronous router for a time-division-multiplexed (TDM) network-on-chip (NOC) that is being developed for a multi-processor platform for hard real-time systems. TDM inherently requires a common time reference, and existing TDM-based NOC designs are either...

  9. Synthesis and Layout of an Asynchronous Network-on-Chip using Standard EDA Tools

    DEFF Research Database (Denmark)

    Müller, Christoph; Kasapaki, Evangelia; Sørensen, Rasmus Bo


    is the key role that clock signals play in specifying time-constraints for the synthesis. In this paper explain how we handled the synthesis and layout of an asynchronous network-on-chip for a multi-core platform. Focus is on the design process while the actual NOC-design and its performance are presented...

  10. Participation in Asynchronous Online Discussion Forums Does Improve Student Learning of Gross Anatomy (United States)

    Green, Rodney A.; Farchione, Davide; Hughes, Diane L.; Chan, Siew-Pang


    Asynchronous online discussion forums are common in blended learning models and are popular with students. A previous report has suggested that participation in these forums may assist student learning in a gross anatomy subject but it was unclear as to whether more academically able students post more often or whether participation led to…

  11. A Study of Asynchronous and Synchronous Discussion on Cognitive Maps in a Distributed Learning Environment. (United States)

    Bhattacharya, Madhumita

    This paper reports on a comparative study of the use of asynchronous (bulletin board) and synchronous (chat) discussion on three learning units based on the cognitive maps developed by the learners. Cognitive maps have been found to be an effective tool for learners for discussion in a distributed learning environment. Cognitive maps provided…

  12. Effects of Asynchronous Music on Students' Lesson Satisfaction and Motivation at the Situational Level (United States)

    Digelidis, Nikolaos; Karageorghis, Costas I.; Papapavlou, Anastasia; Papaioannou, Athanasios G.


    The aim of this study was to examine the effects of asynchronous (background) music on senior students' motivation and lesson satisfaction at the situational level. A counterbalanced mixed-model design was employed with two factors comprising condition (three levels) and gender (two levels). Two hundred students (82 boys, 118 girls; M [subscript…

  13. Credit Hours with No Set Time: A Study of Credit Policies in Asynchronous Online Education (United States)

    Prasuhn, Frederick Carl


    U.S. public university system policies were examined to learn how credit hours were determined for asynchronous online education. Findings indicated that (a) credit hour meaning and use are not consistent, (b) primary responsibility for credit hour decisions was at the local level, and (c) no policies exist to guide credit hour application for…

  14. Three Interaction Patterns on Asynchronous Online Discussion Behaviours: A Methodological Comparison (United States)

    Jo, I.; Park, Y.; Lee, H.


    An asynchronous online discussion (AOD) is one format of instructional methods that facilitate student-centered learning. In the wealth of AOD research, this study evaluated how students' behavior on AOD influences their academic outcomes. This case study compared the differential analytic methods including web log mining, social network analysis…

  15. Beyond Social Presence: Facelessness and the Ethics of Asynchronous Online Education (United States)

    Rose, Ellen


    In this position paper, I argue that a focus on achieving and increasing social presence in online courses tends to derail a consideration of the ethical implications and dimensions of the essential facelessness of asynchronous education. Drawing upon the work of Emmanuel Levinas and Nel Noddings, who contended that the face is the basis of…

  16. Thematic Analysis of the "Games" Students Play in Asynchronous Learning Environments (United States)

    MacMillan, Thalia; Forte, Michele; Grant, Cynthia


    The dynamics of the student-student relationship within the asynchronous online classroom, as evidenced by conversations in an online discussion board, is a balancing act potentially more complex than those occurring in real-time. In order for learning to truly be considered effective, a collaborative, safe environment needs to exist among…

  17. Factors Related to Cognitive, Emotional, and Behavioral Engagement in the Online Asynchronous Classroom (United States)

    Pilotti, Maura; Anderson, Stephanie; Hardy, Pamela; Murphy, Pamela; Vincent, Pamela


    The purpose of this investigation was to examine the relationships among measures of student engagement, instructor engagement, student performance, and properties of the online classroom. The authors assessed behavioral, cognitive, and emotional engagement of students and instructors in asynchronous discussion forums and collected measures of…

  18. A Coding Scheme to Analyse the Online Asynchronous Discussion Forums of University Students (United States)

    Biasutti, Michele


    The current study describes the development of a content analysis coding scheme to examine transcripts of online asynchronous discussion groups in higher education. The theoretical framework comprises the theories regarding knowledge construction in computer-supported collaborative learning (CSCL) based on a sociocultural perspective. The coding…

  19. Digging beneath the Surface: Analyzing the Complexity of Instructors' Participation in Asynchronous Discussion (United States)

    Clarke, Lane Whitney; Bartholomew, Audrey


    The purpose of this study was to investigate instructor participation in asynchronous discussions through an in-depth content analysis of instructors' postings and comments through the Community of Inquiry (COI) framework (Garrison et. al, 2001). We developed an analytical tool based on this framework in order to better understand what instructors…

  20. Trajectory exploration within asynchronous binary asteroid systems using refined Lagrangian coherent structures (United States)

    Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan


    Ground observations have found that asynchronous systems constitute most of the population of the near-Earth binary asteroids. This paper concerns the trajectory of a particle in the asynchronous system which is systematically described using periodic ellipsoidal and spherical body models. Due to the non-autonomous characteristics of the asynchronous system, Lagrangian coherent structures (LCS) are employed to identify the various dynamical behaviors. To enhance the accuracy of LCS, a robust LCS finding algorithm is developed incorporating hierarchical grid refinement, one-dimensional search and variational theory verification. In this way, the intricate dynamical transport boundaries are detected efficiently. These boundaries indicate that a total of 15 types of trajectories exist near asynchronous binary asteroids. According to their Kepler energy variations, these trajectories can be grouped into four basic categories, i.e., transitory, escape, impact and flyby trajectories. Furthermore, the influence of the ellipsoid's spin period on the dynamical behavior is discussed in the context of the change of dynamical regions. We found that the transitory and impact motions occur easily in the synchronous-like binary systems, in which the rotation period of the ellipsoid is nearly equal to that of the mutual orbit. Meanwhile, the results confirm a positive correlation between the spinning rate of the ellipsoid and the probability of the escape and flyby trajectories. The LCS also reveal a marked increase in trajectory diversity after a larger initial energy is selected.

  1. Using the Community of Inquiry Model to Investigate Students' Knowledge Construction in Asynchronous Online Discussions (United States)

    Liu, Chien-Jen; Yang, Shu Ching


    This study used the Community of Inquiry (CoI) model proposed by Garrison to investigate students' level of knowledge construction in asynchronous discussions. The participants included 36 senior students (27 males) majoring in information management. The students attended 18 weeks of an online information ethics course. In this study, four types…

  2. Questions as Indicators of Ocean Literacy: Students' Online Asynchronous Discussion with a Marine Scientist (United States)

    Fauville, Géraldine


    In this article, 61 high-school students learned about ocean acidification through a virtual laboratory followed by a virtual lecture and an asynchronous discussion with a marine scientist on an online platform: VoiceThread. This study focuses on the students' development of ocean literacy when prompted to ask questions to the scientist. The…

  3. The Role of Beliefs and Motivation in Asynchronous Online Learning in College-Level Classes (United States)

    Xie, Kui; Huang, Kun


    Epistemic and learning beliefs were found to affect college students' cognitive engagement and study strategies, as well as motivation in classroom settings. However, the relationships between epistemic and learning beliefs, motivation, learning perception, and students' actual learning participation in asynchronous online settings have been…

  4. Collaborative Learning Processes in an Asynchronous Environment: An Analysis through Discourse and Social Networks (United States)

    Tirado, Ramon; Aguaded, Ignacio; Hernando, Angel


    This article analyses an experience in collaborative learning in an asynchronous writing environment through discussion forums on a WebCt platform of the University of Huelva's virtual campus, and was part of an innovative teaching project in 2007-08. The main objectives are to describe the processes of collaborative knowledge construction and the…

  5. Asynchronous Web Discussions in Teacher Training Courses: Promoting Collaborative Learning--Or Not? (United States)

    Biesenbach-Lucas, Sigrun


    Over the past few years, asynchronous web-based technologies have been examined for their usefulness in promoting collaborative learning among university students. Variations in implementation of this technology will determine to what extent students' learning is actually collaborative. This article discusses curricular adaptations made in the…

  6. An Examination of Computer Engineering Students' Perceptions about Asynchronous Discussion Forums (United States)

    Ozyurt, Ozcan; Ozyurt, Hacer


    This study was conducted in order to reveal the usage profiles and perceptions of Asynchronous Discussion Forums (ADFs) of 126 computer engineering students from the Computer Engineering Department in a university in Turkey. By using a mixed methods research design both quantitative and qualitative data were collected and analyzed. Research…

  7. Multithreaded Asynchronous Graph Traversal for In-Memory and Semi-External Memory

    KAUST Repository

    Pearce, Roger


    Processing large graphs is becoming increasingly important for many domains such as social networks, bioinformatics, etc. Unfortunately, many algorithms and implementations do not scale with increasing graph sizes. As a result, researchers have attempted to meet the growing data demands using parallel and external memory techniques. We present a novel asynchronous approach to compute Breadth-First-Search (BFS), Single-Source-Shortest-Paths, and Connected Components for large graphs in shared memory. Our highly parallel asynchronous approach hides data latency due to both poor locality and delays in the underlying graph data storage. We present an experimental study applying our technique to both In-Memory and Semi-External Memory graphs utilizing multi-core processors and solid-state memory devices. Our experiments using synthetic and real-world datasets show that our asynchronous approach is able to overcome data latencies and provide significant speedup over alternative approaches. For example, on billion vertex graphs our asynchronous BFS scales up to 14x on 16-cores. © 2010 IEEE.

  8. Defining the Symmetry of the Universal Semi-Regular Autonomous Asynchronous Systems

    Directory of Open Access Journals (Sweden)

    Serban E. Vlad


    Full Text Available The regular autonomous asynchronous systems are the non-deterministic Boolean dynamical systems and universality means the greatest in the sense of the inclusion. The paper gives four definitions of symmetry of these systems in a slightly more general framework, called semi-regularity, and also many examples.

  9. The Effects of Self-Generated Synchronous and Asynchronous Visual Speech Feedback on Overt Stuttering Frequency (United States)

    Snyder, Gregory J.; Hough, Monica Strauss; Blanchet, Paul; Ivy, Lennette J.; Waddell, Dwight


    Purpose: Relatively recent research documents that visual choral speech, which represents an externally generated form of synchronous visual speech feedback, significantly enhanced fluency in those who stutter. As a consequence, it was hypothesized that self-generated synchronous and asynchronous visual speech feedback would likewise enhance…

  10. An efficient algorithm for computing attractors of synchronous and asynchronous Boolean networks. (United States)

    Zheng, Desheng; Yang, Guowu; Li, Xiaoyu; Wang, Zhicai; Liu, Feng; He, Lei


    Biological networks, such as genetic regulatory networks, often contain positive and negative feedback loops that settle down to dynamically stable patterns. Identifying these patterns, the so-called attractors, can provide important insights for biologists to understand the molecular mechanisms underlying many coordinated cellular processes such as cellular division, differentiation, and homeostasis. Both synchronous and asynchronous Boolean networks have been used to simulate genetic regulatory networks and identify their attractors. The common methods of computing attractors are that start with a randomly selected initial state and finish with exhaustive search of the state space of a network. However, the time complexity of these methods grows exponentially with respect to the number and length of attractors. Here, we build two algorithms to achieve the computation of attractors in synchronous and asynchronous Boolean networks. For the synchronous scenario, combing with iterative methods and reduced order binary decision diagrams (ROBDD), we propose an improved algorithm to compute attractors. For another algorithm, the attractors of synchronous Boolean networks are utilized in asynchronous Boolean translation functions to derive attractors of asynchronous scenario. The proposed algorithms are implemented in a procedure called geneFAtt. Compared to existing tools such as genYsis, geneFAtt is significantly [Formula: see text] faster in computing attractors for empirical experimental systems. The software package is available at

  11. Using Asynchronous Learning Technology To Make the Connections among Faculty, Students, and Teachers. (United States)

    McMullen, David W.; Goldbaum, Howard; Wolffe, Robert J.; Sattler, Joan L.

    This paper traces the evolution and application of asynchronous teaching and learning tools at Bradley University (Illinois), emphasizing their use in teacher education. The paper details the utilization of e-mail, the World Wide Web, and CyberProf, highlighting collaborative projects that emphasize mentoring and professional development. In the…

  12. Synchronous and Asynchronous E-Language Learning: A Case Study of Virtual University of Pakistan (United States)

    Perveen, Ayesha


    This case study evaluated the impact of synchronous and asynchronous E-Language Learning activities (ELL-ivities) in an E-Language Learning Environment (ELLE) at Virtual University of Pakistan. The purpose of the study was to assess e-language learning analytics based on the constructivist approach of collaborative construction of knowledge. The…

  13. Pedagogical dimensions of effective online asynchronous teacher communication in higher education

    NARCIS (Netherlands)

    Smits, A.; Voogt, J.; Rutledge, D.; Slykhuis, D.


    In this research teacher behaviour in online asynchronous discussions is studied. To this end teachers’ online messages were analyzed and correlated to measures of student satisfaction. Findings show a positive relation between student satisfaction and the presence of content knowledge, multiple

  14. Ecological Affordance and Anxiety in an Oral Asynchronous Computer-Mediated Environment (United States)

    McNeil, Levi


    Previous research suggests that the affordances (van Lier, 2000) of asynchronous computer-mediated communication (ACMC) environments help reduce foreign language anxiety (FLA). However, FLA is rarely the focus of these studies and research has not adequately addressed the relationship between FLA and the affordances that students use. This study…

  15. Flipping the Online Classroom with Web 2.0: The Asynchronous Workshop (United States)

    Cummings, Lance


    This article examines how Web 2.0 technologies can be used to "flip" the online classroom by creating asynchronous workshops in social environments where immediacy and social presence can be maximized. Using experience teaching several communication and writing classes in Google Apps (Google+, Google Hangouts, Google Drive, etc.), I…

  16. Comparing Face-To-Face and Asynchronous Online Communication as Mechanisms for Critical Reflective Dialogue (United States)

    Salter, Susan; Douglas, Tracy; Kember, David


    Two mechanisms for engaging in critical reflective dialogue are discussed and compared: face-to-face meetings and asynchronous online discussion. The context is an umbrella action research project, with over 20 participants, which aimed to improve practices in online teaching and contribute to the development of graduate attributes. The article…

  17. Type of Positive Interdependence and Affiliation Motive in an Asynchronous, Collaborative Learning Environment (United States)

    Brewer, Susan; Klein, James D.


    In this study, we investigated the effect of type of positive interdependence (roles, rewards, roles-plus-rewards, or no structure) and affiliation motives (high vs. low) in an asynchronous, collaborative learning environment. College reentry students worked together in small, fully online discussion groups that lasted for seven days. Results…


    Directory of Open Access Journals (Sweden)

    I. V. Tokmakov


    Full Text Available The article is dedicated to development of numerical method of electromechanical transient processes calculation in asynchronous motors. Electromechanical transient processes might be quite continuous that causes the calculation time increase and accumulation of errors due to use of modern software solutions. The aim of this work is to design more accelerated method of calculation of electromechanical transient processes in asynchronous motors and to create the convenient and practical model scheme of method. The method is based on approximation of state equations solution with the help of expansion of the solution with orthogonal Chebyshev’s polynomials. The scheme interpretation of this method is presented; it considers the rotor rotation frequency as some current. The given method allows to substitute operations with momentary values of currents by operations with currents images, which are interpreted as constant currents at equivalent circuit. As the result the initial integro-differential equations of state are substituted by the algebraic equations of current images. Also there is method of calculation of production image of the currents which are present at electrical machine. CPU time is decreased more than twice compared to common methods due to calculation of transient process in asynchronous motor according to the given method. Considered method is convenient for calculations of transient processes in complex circuits that include not only asynchronous motors but other electrical machines

  19. Introducing group-based asynchronous learning to business education : Reflections on effective course design and delivery

    NARCIS (Netherlands)

    Arnold, I.J.M.; Walker, R.


    This paper explores the contribution of virtual tools to student learning within full-time management programmes. More specifically, the paper focuses on asynchronous communication tools, considering the scope they offer for group-based collaborative learning outside the classroom. We report on the

  20. Exploring Change in Graduate Students' Perceptions of Web-Based Education throughout an Asynchronous Course (United States)

    Timotheou, Maria Mama


    This paper presents the main findings of a UK study exploring graduate students' perceptions of web-based education, with a specific focus on their change over time, throughout an asynchronous course. Data were collected through online messages and interviews, and analyzed qualitatively, following content and thematic analyses. Participant pre-…

  1. Exploring Singapore Primary School Students' Perceptions of Chinese Asynchronous Online Discussions (United States)

    Chin, Wong Wan; Sum, Cheung Wing; Foon, Hew Khe


    Background: Asynchronous online discussion (AOD) has found widespread use in tertiary education and adult learning environment; however, there has been little research on its use in elementary school, especially in the context of the teaching of the Chinese Language. This study explores the use of AOD in a Chinese Language class in a primary…

  2. The Effect of Instructor Information Provision on Critical Thinking in Students Using Asynchronous Online Discussion (United States)

    Klisc, Chris; McGill, Tanya; Hobbs, Valerie


    The facilitation of critical thinking is one of the most frequently discussed potential benefits of the asynchronous online discussion environment, but many studies have reported that it does not occur to any great extent. This study investigated the effect of information provided to students on the facilitation of their critical thinking outcomes…

  3. Efficient operation of asynchronous motors - Final report; Effizienter Betrieb von Asynchronmotoren - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Beeli, N.; Jenni, F.


    Research has shown that the reduction of energy losses in electrical machines offers an enormous saving potential. The largest share of these losses is represented by induction motors in the medium power range. A significant fraction of these losses could be minimized by using modern frequency converters instead of traditional drive systems. However, even when operated with converters, the efficiency of these machines is still not optimal: By implementing an intelligent control scheme which involves a reduction in the magnetizing current, a significant improvement in efficiency can be achieved. Theoretical studies of the economical potential were conducted with and without the iron saturation taken into account. The behavior of the machines in the two cases of operation was described by numerical simulation. Two control algorithms that could be used in a converter have been developed: One utilizing a typical control methodology (constant flux in the machine as a reference) and another designed for optimal performance. The results show that an economical potential of up to 643 GWh per year is possible in Switzerland for all asynchronous machines, which corresponds to 4% of the total power consumption of these machines in Switzerland. With a price of 0.15 CHF/kWh, this represents a saving of approximately 95 million CHF. At this stage, it should be emphasized that this potential can be exploited provided that each machine is already equipped with a frequency converter. Converters with optimized performance are available from some manufacturers. Further investigation was required to determine if the measured savings correspond to the theoretical results. Thus, three converters have been measured in the laboratory using a controlled experiment. It was found that these saving options are effective only for non-dynamic regimes and that the algorithms are not yet ideal for torques below 10% of nominal. The reason for these results are unclear, as the algorithms used are

  4. The Interplay of Content and Community in Synchronous and Asynchronous Communication: Virtual Communication in a Graduate Seminar

    Directory of Open Access Journals (Sweden)

    Richard A. Schwier


    Full Text Available A group of graduate students and an instructor at the University of Saskatchewan experimented with the use of synchronous communication (chat and asynchronous communication (bulletin board in a theory course in Educational Communications and Technology for an eight-month period. Synchronous communication contributed dramatically to the continuity and convenience of the class, and promoted a strong sense of community. At the same time, it was viewed as less effective than asynchronous communication for dealing with content and issues deeply, and it introduced a number of pedagogical and intellectual limitations. We concluded that synchronous and asynchronous strategies were suitable for different types of learning, and what we experienced was a balancing act between content and community in our group. A combination of synchronous and asynchronous experiences seems to be necessary to promote the kind of engagement and depth required in a graduate seminar.

  5. SEU/SEL Resistant Ultra-Low Power Asynchronous Processor Design for Low-Temperature Applications Project (United States)

    National Aeronautics and Space Administration — This Phase I SBIR proposal seeks funding to develop a radiation-hardened circuit architecture to achieve SEU and SEL immunity by using delay-insensitive asynchronous...

  6. Synchronization, retiming and OTDM of an asynchronous 10 Gigabit Ethernet NRZ packet using a time lens for Terabit Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Laguardia Areal, Janaina; Mulvad, Hans Christian Hansen


    An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal.......An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal....

  7. Realistic modelling of the effects of asynchronous motion at the base of bridge piers

    CERN Document Server

    Romanelli, F; Vaccari, F


    Frequently long-span bridges provide deep valley crossings, which require special consideration due to the possibility of local amplification of the ground motion as a consequence of topographical irregularities and local soil conditions. This does in fact cause locally enhanced seismic input with the possibility for the bridge piers to respond asynchronously. This introduces special design requirements so that possible out-of-phase ground displacements and the associated large relative displacements of adjacent piers can be accommodated without excessive damage. Assessment of the local variability of the ground motion due to local lateral heterogeneities and to attenuation properties is thus crucial toward the realistic definition of the asynchronous motion at the base of the bridge piers. We illustrate the work done in the framework of a large international cooperation to assess the importance of non-synchronous seismic excitation of long structures. To accomplish this task we compute complete synthetic acc...

  8. Bayesian operational modal analysis with asynchronous data, part I: Most probable value (United States)

    Zhu, Yi-Chen; Au, Siu-Kui


    In vibration tests, multiple sensors are used to obtain detailed mode shape information about the tested structure. Time synchronisation among data channels is required in conventional modal identification approaches. Modal identification can be more flexibly conducted if this is not required. Motivated by the potential gain in feasibility and economy, this work proposes a Bayesian frequency domain method for modal identification using asynchronous 'output-only' ambient data, i.e. 'operational modal analysis'. It provides a rigorous means for identifying the global mode shape taking into account the quality of the measured data and their asynchronous nature. This paper (Part I) proposes an efficient algorithm for determining the most probable values of modal properties. The method is validated using synthetic and laboratory data. The companion paper (Part II) investigates identification uncertainty and challenges in applications to field vibration data.

  9. Quorum system and random based asynchronous rendezvous protocol for cognitive radio ad hoc networks

    Directory of Open Access Journals (Sweden)

    Sylwia Romaszko


    Full Text Available This paper proposes a rendezvous protocol for cognitive radio ad hoc networks, RAC2E-gQS, which utilizes (1 the asynchronous and randomness properties of the RAC2E protocol, and (2 channel mapping protocol, based on a grid Quorum System (gQS, and taking into account channel heterogeneity and asymmetric channel views. We show that the combination of the RAC2E protocol with the grid-quorum based channel mapping can yield a powerful RAC2E-gQS rendezvous protocol for asynchronous operation in a distributed environment assuring a rapid rendezvous between the cognitive radio nodes having available both symmetric and asymmetric channel views. We also propose an enhancement of the protocol, which uses a torus QS for a slot allocation, dealing with the worst case scenario, a large number of channels with opposite ranking lists.

  10. CABARET scheme with conservation-flux asynchronous time-stepping for nonlinear aeroacoustics problems (United States)

    Semiletov, V. A.; Karabasov, S. A.


    Explicit time stepping renders many high-resolution computational schemes to become less efficient when dealing with non-uniform grids typical of many aeroacoustic applications. Asynchronous time stepping, i.e., updating the solution in different cell sizes according to their local rates, is known to be a promising way to improve the efficiency of explicit time-stepping methods without compromise in accuracy. In the present paper, a new asynchronous time-stepping algorithm is developed for the Compact Accurately Boundary-Adjusting high-REsolution Technique (CABARET) Euler method. This allows to significantly speedup the original single-step CABARET method with non-uniform grids and improves its accuracy at the same time. Numerical examples are provided and issues associated with the method performance on various grid resolutions are discussed.

  11. Intercultural Communication Online: Conversation Analysis and the Investigation of Asynchronous Written Discourse

    Directory of Open Access Journals (Sweden)

    Will Gibson


    Full Text Available This paper works through the methodological issues involved in treating "culture" and "interculturality" as interactionally demonstrable and observable phenomena in written online asynchronous discourse. In particular, the paper explores the ways that conversation analysis (CA and its focus on sequentiality and membership categorization analysis might aid the analysis of culture as a textural interactional achievement. The paper argues that, while there are some clear differences between sequential talk and written asynchronous discourse, there are still interesting ways in which CA's analytic foci may be worked through in relation to online discourse. Both the concern with sequentiality and with membership categories may well help us to see how the construction of visible and recognizable intercultural discourse practices are accomplished through written modes in online forums. URN: urn:nbn:de:0114-fqs0901493

  12. An asynchronous spacetime discontinuous Galerkin finite element method for time domain electromagnetics (United States)

    Abedi, Reza; Mudaliar, Saba


    We present an asynchronous spacetime discontinuous Galerkin (aSDG) method for time domain electromagnetics in which space and time are directly discretized. By using differential forms we express Maxwell's equations and consequently their discontinuous Galerkin discretization for arbitrary domains in spacetime. The elements are discretized with electric and magnetic basis functions that are discontinuous across all inter-element boundaries and can have arbitrary high and per element spacetime orders. When restricted to unstructured grids that satisfy a specific causality constraint, the method has a local and asynchronous solution procedure with linear solution complexity in terms of the number of elements. We numerically investigate the convergence properties of the method for 1D to 3D uniform grids for energy dissipation, an error relative to the exact solution, and von Neumann dissipation and dispersion errors. Two dimensional simulations demonstrate the effectiveness of the method in resolving sharp wave fronts.

  13. A low-power asynchronous data-path for a FIR filter bank

    DEFF Research Database (Denmark)

    Nielsen, Lars Skovby; Sparsø, Jens


    ways: by reducing the switching activity in the circuit, and by applying adaptive scaling of the supply voltage, in order to exploit the fact that the average case latency as 2-3 times better than the worst case. The paper reports on a study of properties of real life data, and discusses......This paper describes a number of design issues relating to the implementation of low-power asynchronous signal processing circuits. Specifically, the paper addresses the design of a dedicated processor structure that implements an audio FIR filter bank which is part of an industrial application....... The algorithm requires a fixed number of steps and the moderate speed requirement allows a sequential implementation. The latter, in combination with a huge predominance of numerically small data values in the input data stream, is the key to a low-power asynchronous implementation. Power is minimized in two...

  14. Fluka studies of the Asynchronous Beam Dump Effects on LHC Point 6

    CERN Document Server

    Versaci, R; Goddard, B; Mereghetti, A; Schmidt, R; Vlachoudis, V; CERN. Geneva. ATS Department


    The LHC is a record-breaking machine for beam energy and intensity. An intense effort has therefore been deployed in simulating critical operational scenarios of energy deposition. Using FLUKA Monte Carlo simulations, we have investigated the effects of an asynchronous beam dump at the LHC Point 6 where beams, with a stored energy of 360 MJ, can instantaneously release up to a few J cm^-3 in the cryogenic magnets which have a quench limit of the order of the mJ cm^-3. In the present paper we will describe the simulation approach, and discuss the evaluated maximum energy release onto the superconducting magnets during an asynchronous beam dump. We will then analyze the shielding provided by collimators installed in the area and discuss safety limits for the operation of the LHC.

  15. Sum rates of asynchronous GFDMA and SC-FDMA for 5G uplink

    Directory of Open Access Journals (Sweden)

    Woojin Park


    Full Text Available The fifth generation (5G of mobile communication envisions ultralow latency less than 1 ms for radio interface. To this end, frameless asynchronous multiple access may be needed to allow users to transmit instantly without waiting for the next frame start. In this paper, generalized frequency division multiple-access (GFDMA, one of the promising multiple-access candidates for 5G mobile, is compared with the conventional single-carrier FDMA (SC-FDMA in terms of the uplink sum rate when both techniques are adapted for the asynchronous scenario. In particular, a waveform windowing technique is applied to both schemes to mitigate the inter-user interference due to non-zero out-of-band emission.

  16. Surface-distributed low-frequency asynchronous stimulation delays fatigue of stimulated muscles. (United States)

    Maneski, Lana Z Popović; Malešević, Nebojša M; Savić, Andrej M; Keller, Thierry; Popović, Dejan B


    One important reason why functional electrical stimulation (FES) has not gained widespread clinical use is the limitation imposed by rapid muscle fatigue due to non-physiological activation of the stimulated muscles. We aimed to show that asynchronous low-pulse-rate (LPR) electrical stimulation applied by multipad surface electrodes greatly postpones the occurrence of muscle fatigue compared with conventional stimulation (high pulse rate, HPR). We compared the produced force vs. time of the forearm muscles responsible for finger flexion in 2 stimulation protocols, LPR (fL = 10 Hz) and HPR (fH = 40 Hz). Surface-distributed low-frequency asynchronous stimulation (sDLFAS) doubles the time interval before the onset of fatigue (104 ± 80%) compared with conventional synchronous stimulation. Combining the performance of multipad electrodes (increased selectivity and facilitated positioning) with sDLFAS (decreased fatigue) can improve many FES applications in both the lower and upper extremities. Copyright © 2013 Wiley Periodicals, Inc.

  17. Asynchronous Magnetic Bead Rotation (AMBR Microviscometer for Label-Free DNA Analysis

    Directory of Open Access Journals (Sweden)

    Yunzi Li


    Full Text Available We have developed a label-free viscosity-based DNA detection system, using paramagnetic beads as an asynchronous magnetic bead rotation (AMBR microviscometer. We have demonstrated experimentally that the bead rotation period is linearly proportional to the viscosity of a DNA solution surrounding the paramagnetic bead, as expected theoretically. Simple optical measurement of asynchronous microbead motion determines solution viscosity precisely in microscale volumes, thus allowing an estimate of DNA concentration or average fragment length. The response of the AMBR microviscometer yields reproducible measurement of DNA solutions, enzymatic digestion reactions, and PCR systems at template concentrations across a 5000-fold range. The results demonstrate the feasibility of viscosity-based DNA detection using AMBR in microscale aqueous volumes.

  18. Synchronous and asynchronous detection of ultra-law light levels using CMOS-compatible semiconductor technologies


    Lotto, Christian; Seitz, Peter; Charbon, Edoardo; Enz, Christian; Farine, Pierre-André


    This work presents significant improvements of noise performance in synchronous CMOS image sensors and in asynchronous energy-sensitive singlephoton X-ray imaging systems. A detailed analysis of synchronous CMOS low-noise image sensors using conventional architectures reveals room for potential noise performance improvements, namely noise in switched-capacitor column-parallel amplifiers as well as imperfections in the low-pass filtering properties provided by such switched-capacitor amplifier...

  19. Determining sociability, social space, and social presence in (A)synchronous collaborative groups


    Kreijns, K.; Kirschner, P.A.; Jochems, W.; Buuren, H. van


    The effectiveness of group learning in asynchronous distributed learning groups depends on the social interaction that takes place. This social interaction affects both cognitive and socioemotional processes that take place during learning, group forming, establishment of group structures, and group dynamics. Though now known to be important, this aspect is often ignored, denied or forgotten by educators and researchers who tend to concentrate on cognitive processes and on-task contexts. This...

  20. Effects of asynchronous music on flow states and shooting performance among netball players


    Pates, J; Karageorghis, CI; Fryer, R; Maynard, I


    Objectives: To examine the effects of self-selected asynchronous (background) music on flow and netball shooting performance in three netball players. Based on the research of it was hypothesized that music would promote flow and would therefore have a positive impact on netball shooting performance.Design: An idiographic single-subject multiple baselines across-subjects design was employed (). The rationale centred upon the work of who indicated that single-subject designs were the most appr...

  1. Commande multivariable du moteur asynchrone triphasé à cage par ...

    African Journals Online (AJOL)

    La commande du moteur asynchrone triphasé à cage alimenté par des convertisseurs est traitée comme celle d'un système multivariable. L'étude du comportement du moteur a été réalisée en simulation, avec différentes valeurs de la fréquence d'alimentation, pour justifier le choix de l'onduleur. Le programme de ...

  2. Differential effects of synchronous and asynchronous multifinger coactivation on human tactile performance

    Directory of Open Access Journals (Sweden)

    Dinse Hubert R


    Full Text Available Abstract Background Repeated execution of a tactile task enhances task performance. In the present study we sought to improve tactile performance with unattended activation-based learning processes (i.e., focused stimulation of dermal receptors evoking neural coactivation (CA. Previous studies show that the application of CA to a single finger reduced the stationary two-point discrimination threshold and significantly increased tactile acuity. These changes were accompanied by an expansion of the cortical finger representation in primary somatosensory cortex (SI. Here we investigated the effect of different types of multifinger CA on the tactile performance of each finger of the right hand. Results Synchronous and asynchronous CA was applied to all fingers of a subject's dominant hand. We evaluated changes in absolute touch thresholds, static two-point discrimination thresholds, and mislocalization of tactile stimuli to the fingertips. After synchronous CA, tactile acuity improved (i.e., discrimination thresholds decreased and the frequency of mislocalization of tactile stimuli changed from directly neighboring fingers to more distant fingers. On the other hand, asynchronous CA did not significant improve tactile acuity. In fact, there was evidence of impaired tactile acuity. Multifinger CA with synchronous or asynchronous stimulation did not significantly alter absolute touch thresholds. Conclusion Our results demonstrate that it is possible to extend tactile CA to all fingers of a hand. The observed changes in mislocalization of tactile stimuli after synchronous CA indicate changes in the topography of the cortical hand representation. Although single-finger CA has been shown to improve tactile acuity, asynchronous CA of all fingers of the hand had the opposite effect, suggesting the need for synchrony in multifinger CA for improving tactile acuity.

  3. Synaptotagmin-7 is an asynchronous calcium sensor for synaptic transmission in neurons expressing SNAP-23. (United States)

    Weber, Jens P; Toft-Bertelsen, Trine L; Mohrmann, Ralf; Delgado-Martinez, Ignacio; Sørensen, Jakob B


    Synchronization of neurotransmitter release with the presynaptic action potential is essential for maintaining fidelity of information transfer in the central nervous system. However, synchronous release is frequently accompanied by an asynchronous release component that builds up during repetitive stimulation, and can even play a dominant role in some synapses. Here, we show that substitution of SNAP-23 for SNAP-25 in mouse autaptic glutamatergic hippocampal neurons results in asynchronous release and a higher frequency of spontaneous release events (mEPSCs). Use of neurons from double-knock-out (SNAP-25, synaptotagmin-7) mice in combination with viral transduction showed that SNAP-23-driven release is triggered by endogenous synaptotagmin-7. In the absence of synaptotagmin-7 release became even more asynchronous, and the spontaneous release rate increased even more, indicating that synaptotagmin-7 acts to synchronize release and suppress spontaneous release. However, compared to synaptotagmin-1, synaptotagmin-7 is a both leaky and asynchronous calcium sensor. In the presence of SNAP-25, consequences of the elimination of synaptotagmin-7 were small or absent, indicating that the protein pairs SNAP-25/synaptotagmin-1 and SNAP-23/synaptotagmin-7 might act as mutually exclusive calcium sensors. Expression of fusion proteins between pHluorin (pH-sensitive GFP) and synaptotagmin-1 or -7 showed that vesicles that fuse using the SNAP-23/synaptotagmin-7 combination contained synaptotagmin-1, while synaptotagmin-7 barely displayed activity-dependent trafficking between vesicle and plasma membrane, implying that it acts as a plasma membrane calcium sensor. Overall, these findings support the idea of alternative syt∶SNARE combinations driving release with different kinetics and fidelity.

  4. The design of high performance asynchronous circuits for the Caltech MiniMIPS processor


    Pénzes, Paul I.


    The purpose of this report is to describe the design and implementation of an asynchronous Fetch unit used in the high-performance Caltech MiniMIPS microprocesors. The Caltech MiniMIPS microprocesors was designed based on the Martin synthesis techniques. The main goals of this project were to investigate new architectural issues in asyncronous processor design and to develop new techniques and tools that can meet high throughput requirements.

  5. A Coordinate Descent Primal-Dual Algorithm and Application to Distributed Asynchronous Optimization


    Bianchi, Pascal; Hachem, Walid; Iutzeler, Franck


    10 pages; International audience; Based on the idea of randomized coordinate descent of $\\alpha$-averaged operators, a randomized primal-dual optimization algorithm is introduced, where a random subset of coordinates is updated at each iteration. The algorithm builds upon a variant of a recent (deterministic) algorithm proposed by Vũ and Condat that includes the well known ADMM as a particular case. The obtained algorithm is used to solve asynchronously a distributed optimization problem. A n...

  6. AP-IO: Asynchronous Pipeline I/O for Hiding Periodic Output Cost in CFD Simulation

    Directory of Open Access Journals (Sweden)

    Ren Xiaoguang


    Full Text Available Computational fluid dynamics (CFD simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. In AP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pipeline mode, therefore the write overhead can be hidden with more calculation than classic asynchronous I/O. We design the framework of AP-IO and implement it in OpenFOAM, providing CFD users with a user-friendly interface. Experimental results on the Tianhe-2 supercomputer demonstrate that AP-IO can achieve a good optimization effect for the periodical snapshot output in CFD application, and the effect is especially better for massively parallel CFD simulations, which can reduce the total execution time up to about 40%.

  7. Asynchronous replication and autosome-pair non-equivalence in human embryonic stem cells.

    Directory of Open Access Journals (Sweden)

    Devkanya Dutta

    Full Text Available A number of mammalian genes exhibit the unusual properties of random monoallelic expression and random asynchronous replication. Such exceptional genes include genes subject to X inactivation and autosomal genes including odorant receptors, immunoglobulins, interleukins, pheromone receptors, and p120 catenin. In differentiated cells, random asynchronous replication of interspersed autosomal genes is coordinated at the whole chromosome level, indicative of chromosome-pair non-equivalence. Here we have investigated the replication pattern of the random asynchronously replicating genes in undifferentiated human embryonic stem cells, using fluorescence in situ hybridization based assay. We show that allele-specific replication of X-linked genes and random monoallelic autosomal genes occur in human embryonic stem cells. The direction of replication is coordinated at the whole chromosome level and can cross the centromere, indicating the existence of autosome-pair non-equivalence in human embryonic stem cells. These results suggest that epigenetic mechanism(s that randomly distinguish between two parental alleles are emerging in the cells of the inner cell mass, the source of human embryonic stem cells.

  8. Two-Particle Asynchronous Quantum Correlation: Wavefunction Collapse Acting as a Beamsplitter (United States)

    Kowalski, F. V.; Browne, R. S.


    A two-body quantum correlation is calculated for a particle reflecting from a moving mirror. Correlated interference results when the incident and reflected particle substates and their associated mirror substates overlap. Using the Copenhagen interpretation of measurement, an asynchronous joint probability density (PDF), which is a function both of the different positions and different times at which the particle and mirror are measured, is derived assuming that no interaction occurs between each measurement. Measurement of the particle first, in the correlated interference region, results in a splitting of the mirror substate into ones which have and have not reflected the particle. An analog of the interference from the Doppler effect for only measurements of the particle (a marginal PDF), in this two-body system, is shown to be a consequence of the asynchronous measurement. The simplification obtained for a microscopic particle reflecting from a mesoscopic or macroscopic mirror is used to illustrate asynchronous correlation interferometry. In this case, the small displacement between these mirror states can yield negligible environmental decoherence times. In addition, interference of these mirror states does not vanish in the limit of large mirror mass due to the small momentum exchange in reflecting a microscopic particle.

  9. A Methodology for the Design and Verification of Globally Asynchronous/Locally Synchronous Architectures (United States)

    Miller, Steven P.; Whalen, Mike W.; O'Brien, Dan; Heimdahl, Mats P.; Joshi, Anjali


    Recent advanced in model-checking have made it practical to formally verify the correctness of many complex synchronous systems (i.e., systems driven by a single clock). However, many computer systems are implemented by asynchronously composing several synchronous components, where each component has its own clock and these clocks are not synchronized. Formal verification of such Globally Asynchronous/Locally Synchronous (GA/LS) architectures is a much more difficult task. In this report, we describe a methodology for developing and reasoning about such systems. This approach allows a developer to start from an ideal system specification and refine it along two axes. Along one axis, the system can be refined one component at a time towards an implementation. Along the other axis, the behavior of the system can be relaxed to produce a more cost effective but still acceptable solution. We illustrate this process by applying it to the synchronization logic of a Dual Fight Guidance System, evolving the system from an ideal case in which the components do not fail and communicate synchronously to one in which the components can fail and communicate asynchronously. For each step, we show how the system requirements have to change if the system is to be implemented and prove that each implementation meets the revised system requirements through modelchecking.

  10. Diagnosis of hearing loss using automated audiometry in an asynchronous telehealth model: A pilot accuracy study. (United States)

    Brennan-Jones, Christopher G; Eikelboom, Robert H; Swanepoel, De Wet


    Introduction Standard criteria exist for diagnosing different types of hearing loss, yet audiologists interpret audiograms manually. This pilot study examined the feasibility of standardised interpretations of audiometry in a telehealth model of care. The aim of this study was to examine diagnostic accuracy of automated audiometry in adults with hearing loss in an asynchronous telehealth model using pre-defined diagnostic protocols. Materials and methods We recruited 42 study participants from a public audiology and otolaryngology clinic in Perth, Western Australia. Manual audiometry was performed by an audiologist either before or after automated audiometry. Diagnostic protocols were applied asynchronously for normal hearing, disabling hearing loss, conductive hearing loss and unilateral hearing loss. Sensitivity and specificity analyses were conducted using a two-by-two matrix and Cohen's kappa was used to measure agreement. Results The overall sensitivity for the diagnostic criteria was 0.88 (range: 0.86-1) and overall specificity was 0.93 (range: 0.86-0.97). Overall kappa ( k) agreement was 'substantial' k = 0.80 (95% confidence interval (CI) 0.70-0.89) and significant at p audiometry provide accurate identification of disabling, conductive and unilateral hearing loss. This method has the potential to improve synchronous and asynchronous tele-audiology service delivery.

  11. A Scalable Multicore Architecture With Heterogeneous Memory Structures for Dynamic Neuromorphic Asynchronous Processors (DYNAPs). (United States)

    Moradi, Saber; Qiao, Ning; Stefanini, Fabio; Indiveri, Giacomo


    Neuromorphic computing systems comprise networks of neurons that use asynchronous events for both computation and communication. This type of representation offers several advantages in terms of bandwidth and power consumption in neuromorphic electronic systems. However, managing the traffic of asynchronous events in large scale systems is a daunting task, both in terms of circuit complexity and memory requirements. Here, we present a novel routing methodology that employs both hierarchical and mesh routing strategies and combines heterogeneous memory structures for minimizing both memory requirements and latency, while maximizing programming flexibility to support a wide range of event-based neural network architectures, through parameter configuration. We validated the proposed scheme in a prototype multicore neuromorphic processor chip that employs hybrid analog/digital circuits for emulating synapse and neuron dynamics together with asynchronous digital circuits for managing the address-event traffic. We present a theoretical analysis of the proposed connectivity scheme, describe the methods and circuits used to implement such scheme, and characterize the prototype chip. Finally, we demonstrate the use of the neuromorphic processor with a convolutional neural network for the real-time classification of visual symbols being flashed to a dynamic vision sensor (DVS) at high speed.

  12. Synchronous and Asynchronous E-Language Learning: A Case Study of Virtual University of Pakistan

    Directory of Open Access Journals (Sweden)

    Ayesha Perveen


    Full Text Available This case study evaluated the impact of synchronous and asynchronous E-Language Learning activities (ELL-tivities in an E-Language Learning Environment (ELLE at Virtual University of Pakistan. The purpose of the study was to assess e-language learning analytics based on the constructivist approach of collaborative construction of knowledge. The courses selected for random sampling were English Comprehension (Eng101, Business & Technical English (Eng201 and Business Communication (Eng301. Three methods were employed to collect the data: observation of the communication and performance on given channels, students’ opinions on Graded Discussion Board (GDB, and a survey questionnaire. Out of a total population of 9919, 1025 responses were received for the survey questionnaire. The findings revealed that asynchronous e-language learning was quite beneficial for second language (L2 learners, but with some limitations which could be scaffolded by synchronous sessions. Based on the findings, the researcher suggested a blend of both synchronous and asynchronous paradigms to create an ideal environment for e-language learning in Pakistan.

  13. Learning Management System Development with Application of Asynchronous Learning Method in STMIK IBBI Medan

    Directory of Open Access Journals (Sweden)

    Marwa Halim


    Full Text Available This article will explain asynchronous learn- ing system using attractive discussion forums and video teaching materials features for user so that the devel- opment of both features will increase e-learning system usage by students and lecturers which can eventually im- prove the students’ absorption on the provided teaching materials, increase the active participation of students, improve self-learning ability, and to improve the quality of learning materials. The method used in this study by distributing questionnaires in online form to stakeholders users consisting of lecturers and students with the num- ber of respondents is 225 people and author use model ADDIE which focuses on Analysis, Design, Development, Implementation and Evaluation as development design. Results of this study is an application of web-based asynchronous learning which can be used by students and lecturers with the results of the application evaluation is based on a survey to students and lecturers. From this study, can be concluded that to support online learning with asynchronous method using the video learning feature in online lecture needs to be developed in order to support the science transformation process from lecturers to students. Attractive video teaching  materials  model for students has characteristics such as screen shots and presentation models.

  14. Asynchronous event driven distributed energy management using profile steering

    NARCIS (Netherlands)

    Hoogsteen, G.; Molderink, A.; Hurink, J. L.; Smit, G. J. M.


    Distributed Energy Management methodologies with a scheduling approach based on predictions require means to avoid problems related to prediction errors. Various approaches deal with such prediction errors by applying a different online control mechanism, such as a double-sided auction. However,

  15. Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications

    Energy Technology Data Exchange (ETDEWEB)

    Di Pendina, G., E-mail:, E-mail:, E-mail:; Zianbetov, E., E-mail:, E-mail:, E-mail: [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France); Beigne, E., E-mail:, E-mail:, E-mail: [Univ. Grenoble Alpes, CEA, LETI, F-38000 Grenoble (France)


    Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes.

  16. Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications (United States)

    Di Pendina, G.; Zianbetov, E.; Beigne, E.


    Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes.

  17. To the Problem of Electromechanical Interaction in Elevators with Controlled Electric Drive and Fuzzy Speed Controller

    Directory of Open Access Journals (Sweden)

    A. S. Koval


    Full Text Available The paper considers problems concerning electromechanical interaction in elevators with an adjustable asynchronous electric drive equipped with the vector control systems under direct torque control and direct torque control with pulse-width modulator. A mathematical description of electromechanical elevator system with due account of nonlinearity of the worm gear is given in the paper. The paper presents a simplified circuit design of a control system with a fuzzy speed controller. It has been established that the factor of electromechanical interaction in electromechanical system with the adjustable asynchronous electric drive and an fuzzy speed controller is within the range which corresponds to existence of the essential electromechanical interaction.

  18. An Asynchronous Low Power and High Performance VLSI Architecture for Viterbi Decoder Implemented with Quasi Delay Insensitive Templates. (United States)

    Devi, T Kalavathi; Palaniappan, Sakthivel


    Convolutional codes are comprehensively used as Forward Error Correction (FEC) codes in digital communication systems. For decoding of convolutional codes at the receiver end, Viterbi decoder is often used to have high priority. This decoder meets the demand of high speed and low power. At present, the design of a competent system in Very Large Scale Integration (VLSI) technology requires these VLSI parameters to be finely defined. The proposed asynchronous method focuses on reducing the power consumption of Viterbi decoder for various constraint lengths using asynchronous modules. The asynchronous designs are based on commonly used Quasi Delay Insensitive (QDI) templates, namely, Precharge Half Buffer (PCHB) and Weak Conditioned Half Buffer (WCHB). The functionality of the proposed asynchronous design is simulated and verified using Tanner Spice (TSPICE) in 0.25 µm, 65 nm, and 180 nm technologies of Taiwan Semiconductor Manufacture Company (TSMC). The simulation result illustrates that the asynchronous design techniques have 25.21% of power reduction compared to synchronous design and work at a speed of 475 MHz.

  19. An Asynchronous Low Power and High Performance VLSI Architecture for Viterbi Decoder Implemented with Quasi Delay Insensitive Templates

    Directory of Open Access Journals (Sweden)

    T. Kalavathi Devi


    Full Text Available Convolutional codes are comprehensively used as Forward Error Correction (FEC codes in digital communication systems. For decoding of convolutional codes at the receiver end, Viterbi decoder is often used to have high priority. This decoder meets the demand of high speed and low power. At present, the design of a competent system in Very Large Scale Integration (VLSI technology requires these VLSI parameters to be finely defined. The proposed asynchronous method focuses on reducing the power consumption of Viterbi decoder for various constraint lengths using asynchronous modules. The asynchronous designs are based on commonly used Quasi Delay Insensitive (QDI templates, namely, Precharge Half Buffer (PCHB and Weak Conditioned Half Buffer (WCHB. The functionality of the proposed asynchronous design is simulated and verified using Tanner Spice (TSPICE in 0.25 µm, 65 nm, and 180 nm technologies of Taiwan Semiconductor Manufacture Company (TSMC. The simulation result illustrates that the asynchronous design techniques have 25.21% of power reduction compared to synchronous design and work at a speed of 475 MHz.



    D. S. Biluhin


    The possibility of application of the modern power semiconductor keys is considered for realization of asynchronous method of control of voltage level for circuits of on-board feeding of electric locomotives.


    Directory of Open Access Journals (Sweden)

    D. S. Biluhin


    Full Text Available The possibility of application of the modern power semiconductor keys is considered for realization of asynchronous method of control of voltage level for circuits of on-board feeding of electric locomotives.

  2. Effects of synchronous versus asynchronous mode of propulsion on wheelchair basketball sprinting. (United States)

    Faupin, Arnaud; Borel, Benoit; Meyer, Christophe; Gorce, Philippe; Watelain, Eric


    This study aimed to first investigate synchronous (SYN) versus asynchronous (ASY) mode of propulsion and, second, investigate the wheel camber effects on sprinting performance as well as temporal parameters. Seven wheelchair basketball players performed four maximal eight-second sprints on a wheelchair ergometer. They repeated the test according to two modes of propulsion (SYN and ASY) and two wheel cambers (9° and 15°). The mean maximal velocity and push power output was greater in the synchronous mode compared to the asynchronous mode for both camber angles. However, the fluctuation in the velocity profile is inferior for ASY versus SYN mode for both camber angles. Greater push time/cycle time (Pt/Ct) and arm frequency (AF) for synchronous mode versus asynchronous mode and inversely, lesser Ct and rest time (Rt) values for the synchronous mode, for which greater velocity were observed. SYN mode leads to better performance than ASY mode in terms of maximal propulsion velocity. However, ASY propulsion allows greater continuity of the hand-rim force application, reducing fluctuations in the velocity profile. The camber angle had no effect on ASY and SYN mean maximal velocity and push power output. The study of wheelchair propulsion strategies is important for better understanding physiological and biomechanical impacts of wheelchair propulsion for individuals with disabilities. From a kinematical point of view, this study highlights synchronous mode of propulsion to be more efficient, with regards to mean maximal velocity reaching during maximal sprinting exercises. Even if this study focuses on well-trained wheelchair athletes, results from this study could complement the knowledge on the physiological and biomechanical adaptations to wheelchair propulsion and therefore, might be interesting for wheelchair modifications for purposes of rehabilitation.

  3. Asynchronous spread spectrum communication paradigm for use in low-power applications: description and simulation results (United States)

    Welch, E. B.; Holmes, David R., III; Coker, Jonathan D.; Schaefer, Timothy M.; Gilbert, Barry K.; Daniel, Erik S.


    Contemporary wireless communication strategies focus on efficient use of bandwidth in order to allow more users to exploit the RF spectrum through techniques like Frequency-hopping spread spectrum (SS) and Direct-sequence SS. In many real-world applications, these methods are implemented for synchronous communication systems. To achieve synchronous communication, two-way handshaking that requires overhead circuitry is performed between the sender and receiver. In order to use spread spectrum methods for certain unconstrained and low-power applications, such as implantable and remote monitoring devices, it is necessary to refine these methods to support asynchronous communication. We have designed and modeled a SS system, which could be integrated with a custom integrated circuit that would provide elementary multi-user communication. The SS logic generates a gold-code based on address and data bits that is then modulated with a carrier to transmit the information. Because the system is asynchronous, we treat each transmitted code as an independent piece of information. The receiver decodes the information using a full correlation with the ideal known gold-codes. For efficiency purposes, the filter is applied in the frequency domain. A threshold is applied to the output of the filter to determine if a particular code is transmitted as well as the point in time/space from which the signal was sent. The method was simulated and evaluated under several scenarios including different carrier frequencies, multiple targets, and various positions relative to the receiver from the simulated receiver. The results demonstrate the utility of asynchronous SS under many different conditions.

  4. Participation in asynchronous online discussion forums does improve student learning of gross anatomy. (United States)

    Green, Rodney A; Farchione, Davide; Hughes, Diane L; Chan, Siew-Pang


    Asynchronous online discussion forums are common in blended learning models and are popular with students. A previous report has suggested that participation in these forums may assist student learning in a gross anatomy subject but it was unclear as to whether more academically able students post more often or whether participation led to improved learning outcomes. This study used a path model to analyze the contribution of forum participation, previous academic ability, and student campus of enrolment to final marks in a multicampus gross anatomy course for physiotherapy students. The course has a substantial online learning management system (LMS) that incorporates asynchronous forums as a learning tool, particularly to answer learning objectives. Students were encouraged to post new threads and answer queries in threads started by others. The forums were moderated weekly by staff. Discussion forums were the most used feature of the LMS site with 31,920 hits. Forty-eight percent of the students posted at least once with 186 threads initiated by students and a total of 608 posts. The total number of posts made a significant direct contribution to final mark (P = 0.008) as did previous academic ability (P = 0.002). Although campus did not contribute to final mark, there was a trend for students at the campus where the course coordinator was situated to post more often than those at the other campus (P = 0.073). These results indicate that asynchronous online discussion forums can be an effective tool for improving student learning outcomes as evidenced by final marks in gross anatomy teaching. Copyright © 2013 American Association of Anatomists.

  5. The Pacific Asynchronous TeleHealth (PATH) system: review of 1,000 pediatric teleconsultations. (United States)

    Mahnke, Christopher Becket; Jordan, Christopher P; Bergvall, Ethan; Person, Donald A; Pinsker, Jordan E


    The aim of this study was to evaluate the impact on pediatric care of the Pacific Asynchronous TeleHealth (PATH) system, a provider-to-provider teleconsultation platform utilized by military medical facilities throughout the Pacific Region. This review focuses on access to care, quality of care, and cost savings for the Department of Defense as a result of ongoing development of the PATH system from 2006 to 2009. This is a retrospective review of 1,000 consecutive teleconsultations occurring from January 2006 to March 2009. Three pediatric subspecialists reviewed the characteristics of each teleconsultation and the ultimate outcome. The PATH system processed > 300 pediatric teleconsultations in 2009 from 20 hospitals and clinics throughout the Pacific Region. The number of teleconsultations has grown significantly since 2006. Median teleconsultation response time was 14.5 h with 97% of teleconsultations answered within 1 week. The majority (75%) of teleconsultations came from areas without host nation pediatric subspecialty resources. Most teleconsultations (72%) involved diagnostic questions, whereas 21% were primarily for treatment issues. Teleconsultations originated predominantly from outpatient clinics (90%), with question resolution in 60% of cases without a face-to-face subspecialty evaluation. Fifteen percent of teleconsultations resulted in patient transfer to our center for definitive diagnosis and treatment. The diagnostic and/or treatment plan was modified in 74% of teleconsultations. PATH precluded patient transfer in 12%-43% of teleconsultations (annual savings: $208,283-$746,348 per year) and generated an average of 1.7 relative value units per teleconsultation. PATH provided patient access to pediatric subspecialty expertise via provider-to-provider asynchronous teleconsultation. Internet-based pediatric subspecialty teleconsultation provides fast, convenient, cost-effective, quality pediatric care to populations of patients who might otherwise

  6. Development and implementation of an asynchronous emergency medicine residency curriculum using a web-based platform. (United States)

    Kornegay, Joshua G; Leone, Katrina A; Wallner, Clare; Hansen, Matthew; Yarris, Lalena M


    The Residency Review Committee in Emergency Medicine requires residency programs to deliver at least 5 hours of weekly didactics. Achieving at least a 70 % average attendance rate per resident is required for residency program accreditation, and is used as a benchmark for residency graduation in our program. We developed a web-based, asynchronous curriculum to replace 1 hour of synchronous didactics, and hypothesized that the curriculum would be feasible to implement, well received by learners, and improve conference participation. This paper describes the feasibility and learner acceptability of a longitudinal asynchronous curriculum, and describes its impact on postgraduate year-1(PGY-1) resident conference participation and annual in-training examination scores. Using formal curriculum design methods, we developed modules and paired assessment exercises to replace 1 hour of weekly didactics. We measured feasibility (development and implementation time and costs) and learner acceptability (measured on an anonymous survey). We compared pre- and post-intervention conference participation and in-service training examination scores using a two sample t test. The asynchronous curriculum proved feasible to develop and implement. PGY-1 resident conference participation improved compared to the pre-intervention year (85.6 vs. 62 %; 95 % CI 0.295-0.177; p curriculum changes. Strengths of the curriculum included clarity and timeliness of assignments. Weaknesses included technical difficulties with the online platform. Our curriculum is feasible to develop and implement. Despite technical difficulties, residents report high satisfaction with this new curriculum. Among PGY-1 residents there is improved conference participation compared to the prior year.

  7. Fast Simulation of Mechanical Heterogeneity in the Electrically Asynchronous Heart Using the MultiPatch Module.

    Directory of Open Access Journals (Sweden)

    John Walmsley


    Full Text Available Cardiac electrical asynchrony occurs as a result of cardiac pacing or conduction disorders such as left bundle-branch block (LBBB. Electrically asynchronous activation causes myocardial contraction heterogeneity that can be detrimental for cardiac function. Computational models provide a tool for understanding pathological consequences of dyssynchronous contraction. Simulations of mechanical dyssynchrony within the heart are typically performed using the finite element method, whose computational intensity may present an obstacle to clinical deployment of patient-specific models. We present an alternative based on the CircAdapt lumped-parameter model of the heart and circulatory system, called the MultiPatch module. Cardiac walls are subdivided into an arbitrary number of patches of homogeneous tissue. Tissue properties and activation time can differ between patches. All patches within a wall share a common wall tension and curvature. Consequently, spatial location within the wall is not required to calculate deformation in a patch. We test the hypothesis that activation time is more important than tissue location for determining mechanical deformation in asynchronous hearts. We perform simulations representing an experimental study of myocardial deformation induced by ventricular pacing, and a patient with LBBB and heart failure using endocardial recordings of electrical activation, wall volumes, and end-diastolic volumes. Direct comparison between simulated and experimental strain patterns shows both qualitative and quantitative agreement between model fibre strain and experimental circumferential strain in terms of shortening and rebound stretch during ejection. Local myofibre strain in the patient simulation shows qualitative agreement with circumferential strain patterns observed in the patient using tagged MRI. We conclude that the MultiPatch module produces realistic regional deformation patterns in the asynchronous heart and that

  8. Renewal Approach to the Analysis of the Asynchronous State for Coupled Noisy Oscillators

    CERN Document Server

    Farkhooi, Farzad


    We develop a framework in which the activity of nonlinear pulse-coupled oscillators is posed within the renewal theory. In this approach, the evolution of inter-event density allows for a self-consistent calculation that determines the asynchronous state and its stability. This framework, can readily be extended to the analysis of systems with more state variables. To exhibit this, we study a nonlinear pulse-coupled system, where couplings are dynamic and activity dependent. We investigate stability of this system and we show it undergoes a super-critical Hopf bifurcation to collective synchronization.

  9. Bayesian operational modal analysis with asynchronous data, Part II: Posterior uncertainty (United States)

    Zhu, Yi-Chen; Au, Siu-Kui


    A Bayesian modal identification method has been proposed in the companion paper that allows the most probable values of modal parameters to be determined using asynchronous ambient vibration data. This paper investigates the identification uncertainty of modal parameters in terms of their posterior covariance matrix. Computational issues are addressed. Analytical expressions are derived to allow the posterior covariance matrix to be evaluated accurately and efficiently. Synthetic, laboratory and field data examples are presented to verify the consistency, investigate potential modelling error and demonstrate practical applications.

  10. Quantum-limited timing jitter characterization of mode-locked lasers by asynchronous optical sampling. (United States)

    Shi, Haosen; Song, Youjian; Yu, JiaHe; Li, Runmin; Hu, Minglie; Wang, Chingyue


    We demonstrate a novel time domain timing jitter characterization method for ultra-low noise mode-locked lasers. An asynchronous optical sampling (ASOPS) technique is employed, allowing timing jitter statistics on a magnified timescale. As a result, sub femtosecond period jitter of an optical pulse train can be readily accessible to slow detectors and electronics (~100 MHz). The concept is applied to determine the quantum-limited timing jitter for a passively mode-locked Er-fiber laser. Period jitter histogram is acquired following an eye diagram analysis routinely used in electronics. The identified diffusion constant for pulse timing agrees well with analytical solution of perturbed master equation.

  11. Asynchronous BCI and local neural classifiers: an overview of the Adaptive Brain Interface project. (United States)

    Millán, José del R; Mouriño, Josep


    In this communication, we give an overview of our work on an asynchronous brain-computer interface (where the subject makes self-paced decisions on when to switch from one mental task to the next) that responds every 0.5 s. A local neural classifier tries to recognize three different mental tasks; it may also respond "unknown" for uncertain samples as the classifier has incorporated statistical rejection criteria. We report our experience with 15 subjects. We also briefly describe two brain-actuated applications we have developed: a virtual keyboard and a mobile robot (emulating a motorized wheelchair).

  12. Exploring effectiveness of team communication: Balancing synchronous and asynchronous communication in design teams

    DEFF Research Database (Denmark)

    den Otter, Ad; Emmitt, Stephen


    Effective teams use a balance of synchronous and asynchronous communication. Team communication is dependent on the communication acts of team members and the ability of managers to facilitate, stimulate and motivate them. Team members from organizations using different information systems tend...... to have different understanding, opinions, and rates of adoption and skills levels regarding specific IT tools. The purpose of this paper is to explore the effective use of tools for communication in design teams and the strategies for the use of specific tools....

  13. The use of Facebook for virtual asynchronous focus groups in qualitative research. (United States)

    Biedermann, Narelle


    The Internet and the development of more user-engaging applications have opened a whole new world for researchers as a means of recruitment and data collection source. This paper describes the methodological approach of a research study that explored the experiences of Australian military spouses who packed up their family and home to accompany their spouse on an overseas posting. The study used Facebook as a recruitment tool and then as a data source through the conduct of an asynchronous virtual focus group. This paper outlines the advantages and disadvantages of this unique data source as a means of capturing the voices of a hard-to-reach population.

  14. Survey is based on Synchronized and Asynchronized Approach of MAC Protocols in WSN

    Directory of Open Access Journals (Sweden)

    Soni Chaurasia


    Full Text Available A wireless network is made of spatially distributed autonomous devices. These devices are called sensors. The sensor is used for monitoring physical or environmental conditions. The potential application of wireless sensor network is environmental monitoring, healthcare applications and tactical systems. In this paper focus is on the MAC protocol for WSN. Wireless sensor network is deployed for wide range to send and receive data with the help of medium. Here literature survey of MAC protocol based on the synchronized and asynchronized approach is described which is used to meet different objective like access a medium, statistical channel allocation, spectrum utilization

  15. The analysis of an operating mode of the asynchronous generator with capacitor excitation

    Directory of Open Access Journals (Sweden)

    Postoronca S.


    Full Text Available On the basis of a symbolical method of calculation of electric circuits the analysis of features of work of the three-phase asynchronous generator with two windings on статоре and capacitor excitation is executed. Results of the analysis of influence on a phase corner of a current and voltage of a windings of excitation of the generator are submitted at change of its loading from a mode of idling up to a mode of short circuit. Recommendations on stabilization of a target voltage of the generator are formulated at change of its loading.

  16. Simulation of Dynamic Regimes in Asynchronous Traction Electric Drives of Locomotives

    Directory of Open Access Journals (Sweden)

    P. O. Seyidov


    Full Text Available The paper considers a dynamic model for locomotive electric drive with four asynchronous traction motors and their stator windings are serially connected. A mathematical model for motors being fed by one autonomous inverter has been developed in the paper. Serial connection makes it possible to increase a value of the total supply voltage. An analysis of the developed model shows that currents consumed by motors with their serial connection are lower in case of their parallel operation.  Direct and frequency start-up curves are given on the basis of the developed model.

  17. Tiling and Asynchronous Communication Optimizations for Stencil Computations

    KAUST Repository

    Malas, Tareq


    The importance of stencil-based algorithms in computational science has focused attention on optimized parallel implementations for multilevel cache-based processors. Temporal blocking schemes leverage the large bandwidth and low latency of caches to accelerate stencil updates and approach theoretical peak performance. A key ingredient is the reduction of data traffic across slow data paths, especially the main memory interface. Most of the established work concentrates on updating separate cache blocks per thread, which works on all types of shared memory systems, regardless of whether there is a shared cache among the cores. This approach is memory-bandwidth limited in several situations, where the cache space for each thread can be too small to provide sufficient in-cache data reuse. We introduce a generalized multi-dimensional intra-tile parallelization scheme for shared-cache multicore processors that results in a significant reduction of cache size requirements and shows a large saving in memory bandwidth usage compared to existing approaches. It also provides data access patterns that allow efficient hardware prefetching. Our parameterized thread groups concept provides a controllable trade-off between concurrency and memory usage, shifting the pressure between the memory interface and the Central Processing Unit (CPU).We also introduce efficient diamond tiling structure for both shared memory cache blocking and distributed memory relaxed-synchronization communication, demonstrated using one-dimensional domain decomposition. We describe the approach and our open-source testbed implementation details (called Girih), present performance results on contemporary Intel processors, and apply advanced performance modeling techniques to reconcile the observed performance with hardware capabilities. Furthermore, we conduct a comparison with the state-of-the-art stencil frameworks PLUTO and Pochoir in shared memory, using corner-case stencil operators. We study the

  18. Comparaison entre les différentes commandes d'un moteur asynchrone pour un véhicule électrique en vue de minimiser les pertes de l'onduleur (United States)

    Papazian, J.-C.; Rognon, J.-P.; Roye, D.; Delbosc, Ph.


    The losses of an inverter supplying an induction motor are compared for different vector control and pulse width modulation strategies. The study is carried out in simulation. As a conclusion, an optimal control in terms of losses is determined. Les pertes par conduction et par commutation d'un onduleur alimentant un moteur asynchrone sont comparées pour différentes solutions de contrôle vectoriel et de modulation de largeur d'impulsions. L'étude est réalisée en simulation. En conclusion, une commande optimale au niveau des pertes est déterminée.

  19. Asynchronous Video Interviewing as a New Technology in Personnel Selection: The Applicant’s Point of View (United States)

    Brenner, Falko S.; Ortner, Tuulia M.; Fay, Doris


    The present study aimed to integrate findings from technology acceptance research with research on applicant reactions to new technology for the emerging selection procedure of asynchronous video interviewing. One hundred six volunteers experienced asynchronous video interviewing and filled out several questionnaires including one on the applicants’ personalities. In line with previous technology acceptance research, the data revealed that perceived usefulness and perceived ease of use predicted attitudes toward asynchronous video interviewing. Furthermore, openness revealed to moderate the relation between perceived usefulness and attitudes toward this particular selection technology. No significant effects emerged for computer self-efficacy, job interview self-efficacy, extraversion, neuroticism, and conscientiousness. Theoretical and practical implications are discussed. PMID:27378969

  20. Merging the Forces of Asynchronous Tutoring and Synchronous Conferencing: A Qualitative Study of Arab ESL Academic Writers Using E-Tutoring (United States)

    Alqadoumi, Omar Mohamed


    Previous studies in the field of e-tutoring dealt either with asynchronous tutoring or synchronous conferencing as modes for providing e-tutoring services to English learners. This qualitative research study reports the experiences of Arab ESL tutees with both asynchronous tutoring and synchronous conferencing. It also reports the experiences of…

  1. Accelerator physics studies on the effects from an asynchronous beam dump onto the LHC experimental region collimators

    CERN Document Server

    Lari, L; Boccone, V; Bruce, R; Cerutti, F; Rossi, A; Vlachoudis, V; Mereghetti, A; Faus-Golfe, A


    Asynchronous beam aborts at the LHC are estimated to occur on average once per year. Accelerator physics studies of asynchronous dumps have been performed at different beam energies and beta-stars. The loss patterns are analyzed in order to identify the losses in particular on the Phase 1 Tertiary Collimators (TCT), since their tungsten-based active jaw insert has a lower damage threshold than the carbon-based other LHC collimators. Settings of the tilt angle of the TCTs are discussed with the aim of reducing the thermal loads on the TCT themselves.

  2. "Conversations réflexives" dans la classe de langues virtuelle par conférence asynchrone "Reflective conversations" in asynchronous conferencing for distance language learnersning

    Directory of Open Access Journals (Sweden)

    Robin Goodfellow


    Full Text Available A l’Open University, université britannique de télé-enseignement, les concepteurs de matériaux utilisent depuis longtemps des pédagogies qui amènent l’apprenant à réfléchir sur son apprentissage et à expliciter cette réflexion. Or aujourd’hui les Technologies de l’Information et de la Communication (TIC leur permettent de faire interagir apprenants, professeurs et locuteurs natifs. Ainsi l’apprenant participe à la communication et reçoit en retour des messages en langue cible, dont il se sert pour améliorer sa compétence communicative. Qu’en est-il, dès lors, du rôle de la réflexion consciente dans le processus d’apprentissage ? Vu les importantes possibilités d’interactivité offertes par les TIC, doit-on encore prôner la réflexion consciente dans le télé-enseignement ? Nous répondons par l’affirmative, considérant que les concepteurs d’environnements virtuels doivent faciliter et la réflexion consciente et l’interactivité spontanée. Nous soutenons que la conférence télématique asynchrone est un outil qui permet d’atteindre cet objectif. Nous cherchons à voir dans quelle mesure la réflexivité et l’interactivité interviennent dans ce type de conférence, et à préciser la valeur pédagogique de ces échanges. Nous étudions une conférence organisée pour des étudiants de français langue étrangère (FLE et nous proposons une pédagogie visant à promouvoir ce que nous appelons des "conversations réflexives", c’est-à-dire des échanges privilégiant des thèmes langagiers ou portant sur l’apprentissage même des langues.In the UK Open University the principle that distance language learners should be encouraged to reflect on their own learning has traditionally been central to the design of conventional (i.e. print , audio and video course materials. However, since Computer-Mediated-Communication (CMC technologies have created the possibility for learners to interact with each

  3. Asynchronous Task-Based Polar Decomposition on Single Node Manycore Architectures

    KAUST Repository

    Sukkari, Dalal E.


    This paper introduces the first asynchronous, task-based formulation of the polar decomposition and its corresponding implementation on manycore architectures. Based on a formulation of the iterative QR dynamically-weighted Halley algorithm (QDWH) for the calculation of the polar decomposition, the proposed implementation replaces the original LU factorization for the condition number estimator by the more adequate QR factorization to enable software portability across various architectures. Relying on fine-grained computations, the novel task-based implementation is capable of taking advantage of the identity structure of the matrix involved during the QDWH iterations, which decreases the overall algorithmic complexity. Furthermore, the artifactual synchronization points have been weakened compared to previous implementations, unveiling look-ahead opportunities for better hardware occupancy. The overall QDWH-based polar decomposition can then be represented as a directed acyclic graph (DAG), where nodes represent computational tasks and edges define the inter-task data dependencies. The StarPU dynamic runtime system is employed to traverse the DAG, to track the various data dependencies and to asynchronously schedule the computational tasks on the underlying hardware resources, resulting in an out-of-order task scheduling. Benchmarking experiments show significant improvements against existing state-of-the-art high performance implementations for the polar decomposition on latest shared-memory vendors\\' systems, while maintaining numerical accuracy.

  4. Visual and Auditory Components in the Perception of Asynchronous Audiovisual Speech. (United States)

    García-Pérez, Miguel A; Alcalá-Quintana, Rocío


    Research on asynchronous audiovisual speech perception manipulates experimental conditions to observe their effects on synchrony judgments. Probabilistic models establish a link between the sensory and decisional processes underlying such judgments and the observed data, via interpretable parameters that allow testing hypotheses and making inferences about how experimental manipulations affect such processes. Two models of this type have recently been proposed, one based on independent channels and the other using a Bayesian approach. Both models are fitted here to a common data set, with a subsequent analysis of the interpretation they provide about how experimental manipulations affected the processes underlying perceived synchrony. The data consist of synchrony judgments as a function of audiovisual offset in a speech stimulus, under four within-subjects manipulations of the quality of the visual component. The Bayesian model could not accommodate asymmetric data, was rejected by goodness-of-fit statistics for 8/16 observers, and was found to be nonidentifiable, which renders uninterpretable parameter estimates. The independent-channels model captured asymmetric data, was rejected for only 1/16 observers, and identified how sensory and decisional processes mediating asynchronous audiovisual speech perception are affected by manipulations that only alter the quality of the visual component of the speech signal.

  5. Scalability of Several Asynchronous Many-Task Models for In Situ Statistical Analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Pebay, Philippe Pierre [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bennett, Janine Camille [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Kolla, Hemanth [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Borghesi, Giulio [Sandia National Lab. (SNL-CA), Livermore, CA (United States)


    This report is a sequel to [PB16], in which we provided a first progress report on research and development towards a scalable, asynchronous many-task, in situ statistical analysis engine using the Legion runtime system. This earlier work included a prototype implementation of a proposed solution, using a proxy mini-application as a surrogate for a full-scale scientific simulation code. The first scalability studies were conducted with the above on modestly-sized experimental clusters. In contrast, in the current work we have integrated our in situ analysis engines with a full-size scientific application (S3D, using the Legion-SPMD model), and have conducted nu- merical tests on the largest computational platform currently available for DOE science ap- plications. We also provide details regarding the design and development of a light-weight asynchronous collectives library. We describe how this library is utilized within our SPMD- Legion S3D workflow, and compare the data aggregation technique deployed herein to the approach taken within our previous work.

  6. Website creation and resource management: developing collaborative strategies for asynchronous interaction with library users. (United States)

    Hopkins, Mark E; Summers-Ables, Joy E; Clifton, Shari C; Coffman, Michael A


    To make electronic resources available to library users while effectively harnessing intellectual capital within the library, ultimately fostering the library's use of technology to interact asynchronously with its patrons (users). The methods used in the project included: (1) developing a new library website to facilitate the creation, management, accessibility, maintenance and dissemination of library resources; and (2) establishing ownership by those who participated in the project, while creating effective work allocation strategies through the implementation of a content management system that allowed the library to manage cost, complexity and interoperability. Preliminary results indicate that contributors to the system benefit from an increased understanding of the library's resources and add content valuable to library patrons. These strategies have helped promote the manageable creation and maintenance of electronic content in accomplishing the library's goal of interacting with its patrons. Establishment of a contributive system for adding to the library's electronic resources and electronic content has been successful. Further work will look at improving asynchronous interaction, particularly highlighting accessibility of electronic content and resources. © 2010 The authors. Health Information and Libraries Journal © 2010 Health Libraries Group.

  7. A 10-bit 110 MHz SAR ADC with asynchronous trimming in 65-nm CMOS (United States)

    Xu, Daiguo; Xu, Shiliu; Li, Xi; Pu, Jie


    A 10-bit 110 MHz SAR ADC with asynchronous trimming is presented. In this paper, a high linearity sampling switch is used to produce a constant parasitical barrier capacitance which would not change with the range of input signals. As a result, the linearity of the SAR ADC will increase with high linearity sampled signals. Farther more, a high-speed and low-power dynamic comparator is proposed which would reduce the comparison time and save power consumption at the same time compared to existing technology. Additionally, the proposed comparator provides a better performance with the decreasing of power supply. Moreover, a highspeed successive approximation register is exhibited to speed up the conversion time and will reduce about 50% register delay. Lastly, an asynchronous trimming method is provided to make the capacitive-DAC settle up completely instead of using the redundant cycle which would prolong the whole conversion period. This SAR ADC is implemented in 65-nm CMOS technology the core occupies an active area of only 0.025 mm{}2 and consumes 1.8 mW. The SAR ADC achieves SFDR > 68 dB and SNDR > 57 dB, resulting in the FOM of 28 fJ/conversion-step. From the test results, the presented SAR ADC provides a better FOM compared to previous research and is suitable for a kind of ADC IP in the design SOC. Project supported by the Science and Technology on Analog Integrated Circuit Laboratory (No. 9140C090105140C09041).

  8. The theory of asynchronous relative motion II: universal and regular solutions (United States)

    Roa, Javier; Peláez, Jesús


    Two fully regular and universal solutions to the problem of spacecraft relative motion are derived from the Sperling-Burdet (SB) and the Kustaanheimo-Stiefel (KS) regularizations. There are no singularities in the resulting solutions, and their form is not affected by the type of reference orbit (circular, elliptic, parabolic, or hyperbolic). In addition, the solutions to the problem are given in compact tensorial expressions and directly referred to the initial state vector of the leader spacecraft. The SB and KS formulations introduce a fictitious time by means of the Sundman transformation. Because of using an alternative independent variable, the solutions are built based on the theory of asynchronous relative motion. This technique simplifies the required derivations. Closed-form expressions of the partial derivatives of orbital motion with respect to the initial state are provided explicitly. Numerical experiments show that the performance of a given representation of the dynamics depends strongly on the time transformation, whereas it is virtually independent from the choice of variables to parameterize orbital motion. In the circular and elliptic cases, the linear solutions coincide exactly with the results obtained with the Clohessy-Wiltshire and Yamanaka-Ankersen state-transition matrices. Examples of relative orbits about parabolic and hyperbolic reference orbits are also presented. Finally, the theory of asynchronous relative motion provides a simple mechanism to introduce nonlinearities in the solution, improving its accuracy.

  9. Data-Aware Retrodiction for Asynchronous Harmonic Measurement in a Cyber-Physical Energy System

    Directory of Open Access Journals (Sweden)

    Youda Liu


    Full Text Available Cyber-physical energy systems provide a networked solution for safety, reliability and efficiency problems in smart grids. On the demand side, the secure and trustworthy energy supply requires real-time supervising and online power quality assessing. Harmonics measurement is necessary in power quality evaluation. However, under the large-scale distributed metering architecture, harmonic measurement faces the out-of-sequence measurement (OOSM problem, which is the result of latencies in sensing or the communication process and brings deviations in data fusion. This paper depicts a distributed measurement network for large-scale asynchronous harmonic analysis and exploits a nonlinear autoregressive model with exogenous inputs (NARX network to reorder the out-of-sequence measuring data. The NARX network gets the characteristics of the electrical harmonics from practical data rather than the kinematic equations. Thus, the data-aware network approximates the behavior of the practical electrical parameter with real-time data and improves the retrodiction accuracy. Theoretical analysis demonstrates that the data-aware method maintains a reasonable consumption of computing resources. Experiments on a practical testbed of a cyber-physical system are implemented, and harmonic measurement and analysis accuracy are adopted to evaluate the measuring mechanism under a distributed metering network. Results demonstrate an improvement of the harmonics analysis precision and validate the asynchronous measuring method in cyber-physical energy systems.

  10. An Autonomous Wireless Sensor Node With Asynchronous ECG Monitoring in 0.18 μ m CMOS. (United States)

    Mansano, Andre L; Li, Yongjia; Bagga, Sumit; Serdijn, Wouter A


    The design of a 13.56 MHz/402 MHz autonomous wireless sensor node with asynchronous ECG monitoring for near field communication is presented. The sensor node consists of an RF energy harvester (RFEH), a power management unit, an ECG readout, a data encoder and an RF backscattering transmitter. The energy harvester supplies the system with 1.25 V and offers a power conversion efficiency of 19% from a -13 dBm RF source at 13.56 MHz. The power management unit regulates the output voltage of the RFEH to supply the ECG readout with VECG = 0.95 V and the data encoder with VDE = 0.65 V . The ECG readout comprises an analog front-end (low noise amplifier and programmable voltage to current converter) and an asynchronous level crossing ADC with 8 bits resolution. The ADC output is encoded by a pulse generator that drives a backscattering transmitter at 402 MHz. The total power consumption of the sensor node circuitry is 9.7 μ W for a data rate of 90 kb/s and a heart rate of 70 bpm. The chip has been designed in a 0.18 μm CMOS process and shows superior RF input power sensitivity and lower power consumption when compared to previous works.

  11. Asynchronous detection of kinesthetic attention during mobilization of lower limbs using EEG measurements. (United States)

    Melinscak, Filip; Montesano, Luis; Minguez, Javier


    Attention is known to modulate the plasticity of the motor cortex, and plasticity is crucial for recovery in motor rehabilitation. This study addresses the possibility of using an EEG-based brain-computer interface (BCI) to detect kinesthetic attention to movement. A novel experiment emulating physical rehabilitation was designed to study kinesthetic attention. The protocol involved continuous mobilization of lower limbs during which participants reported levels of attention to movement-from focused kinesthetic attention to mind wandering. For this protocol an asynchronous BCI detector of kinesthetic attention and deliberate mind wandering was designed. EEG analysis showed significant differences in theta, alpha, and beta bands, related to the attentional state. These changes were further pinpointed to bands relative to the frequency of the individual alpha peak. The accuracy of the designed BCI ranged between 60.8% and 68.4% (significantly above chance level), depending on the used analysis window length, i.e. acceptable detection delay. This study shows it is possible to use self-reporting to study attention-related changes in EEG during continuous mobilization. Such a protocol is used to develop an asynchronous BCI detector of kinesthetic attention, with potential applications to motor rehabilitation.

  12. FLUKA Studies of the Asynchronous Beam Dump Effects on LHC Point 6

    CERN Document Server

    Versaci, R; Goddard, B; Schmidt, R; Vlachoudis, V; Mereghetti, A


    The LHC is a record-breaking machine for beam energy and intensity. An intense effort has therefore been deployed in simulating critical operational scenarios of energy deposition. FLUKA is the most widely used code for this kind of simulations at CERN because of the high reliability of its results and the ease to custom detailed simulations all along hundreds of meters of beam line. We have investigated the effects of an asynchronous beam dump on the LHC Point 6 where, beams with a stored energy of 360 MJ, can instantaneously release up to a few J cm−3 in the cryogenic magnets which have a quench limit of the order of the mJ cm−3. In the present paper we will describe the simulation approach, and discuss the evaluated maximum energy release onto the superconducting magnets during an asynchronous beam dump. We will then analyse the shielding provided by collimators installed in the area and discuss safety limits for the operation of the LHC.

  13. An implantable closedloop asynchronous drug delivery system for the treatment of refractory epilepsy. (United States)

    Salam, Muhammad Tariqus; Mirzaei, Marjan; Ly, My Sandra; Nguyen, Dang Khoa; Sawan, Mohamad


    In this paper, we present an implantable device for intra-cerebral electroencephalography (icEEG) data acquisition and real-time epileptic seizure detection with simultaneous focal antiepileptic drug injection feedback. This implantable device includes a neural signal amplifier, an asynchronous seizure detector, a drug delivery system (DDS) including a micropump, and a hybrid subdural electrode (HSE). The asynchronous detection algorithm is based on data-dependent analysis and validated with Matlab tools. The detector and DDS have a power saving mode. The HSE contacts are made of Platinum (Pt) encapsulated with polydimethylsiloxane (PDMS). Given the heterogeneity of electrographic seizure signals and seizure suppression threshold, the implantable device provides tunable parameters facility through an external transmitter to adapt to each individual's neurophysiology prior to clinical deployment. The proposed detector and DDS were assembled in Ø 50 mm and Ø 30 mm circular printed circuit boards, respectively. The detector was validated using icEEG recordings of seven patients who had previously undergone an intracranial investigation for epilepsy surgery. The triggering of the DDS was tested and a predefined seizure suppression dose was delivered ~16 s after electrographical seizure onsets. The device's power consumption was reduced by 12% in active mode and 49% in power saving mode compared to similar seizure detection algorithms implemented with synchronous architecture.

  14. Learner Perceptions of Asynchronous Oral Computer-mediated Communication: Proficiency and Second Langauge Selves

    Directory of Open Access Journals (Sweden)

    Jesse Gleason


    Full Text Available Abstract The present study addresses the perceptions of international teaching assistants regarding the role of language learning tasks using Wimba Voice (WV in aiding the improvement of their second language (L2 oral skills. It specifically examines how this asynchronous computer-mediated communication (CMC technology can foster the development of these learners’ L2 selves. According to Dörnyei (2009, the more clearly learners can envision their future L2 selves, the more motivated they will be to achieve their L2 goals. With increased planning of oral production, access to instructor and peer feedback, and additional opportunities for self-reflection, asynchronous CMC technologies have been found to enable L2 learners to express their thoughts at their own pace and feel more relaxed and confident than in more threatening face-to-face situations (Sun, 2009. The findings suggest that learners have a variety of opinions regarding the role of asynchronous WV tasks in motivating them to develop their L2 oral proficiency. Also, many may prefer oral CMC environments that facilitate interaction and meaning negotiation. Results were inconclusive concerning the effect of WV-based tasks on students' perceptions of their future L2 selves; however, this may have been due to the short time frame in which these activities were employed. Résumé Nous étudions ici les perceptions d’un groupe d’assistants internationaux sur le rôle des tâches d’apprentissage linguistique à l’aide de Wimba Voice (WV. Le projet avait pour but d’améliorer les compétences orales des participants dans leur langue seconde. La présente étude examine en particulier la voie par laquelle cette technologie de la communication asynchrone par ordinateur peut favoriser l’évolution de la langue seconde des apprenants. Selon Dörnyei (2009, plus les apprenants peuvent envisager clairement un futur emploi de leur langue seconde, plus ils seront motivés à atteindre

  15. Electrical engineering unit for the reactive power control of the load bus at the voltage instability (United States)

    Kotenev, A. V.; Kotenev, V. I.; Kochetkov, V. V.; Elkin, D. A.


    For the purpose of reactive power control error reduction and decrease of the voltage sags in the electric power system caused by the asynchronous motors started the mathematical model of the load bus was developed. The model was built up of the sub-models of the following elements: a transformer, a transmission line, a synchronous and an asynchronous loads and a capacitor bank load, and represents the automatic reactive power control system taking into account electromagnetic processes of the asynchronous motors started and reactive power changing of the electric power system elements caused by the voltage fluctuation. The active power/time and reactive power/time characteristics based on the recommended procedure of the equivalent electric circuit parameters calculation were obtained. The derived automatic reactive power control system was shown to eliminate the voltage sags in the electric power system caused by the asynchronous motors started.

  16. Asynchronous readers and asynchronous writers

    NARCIS (Netherlands)

    Boode, Antoon Hendrik; Broenink, Johannes F.


    Abstract. Reading and writing is modelled in CSP using actions containing the symbols ? and !. These reading actions and writing actions are synchronous, and there is a one-to-one relationship between occurrences of pairs of these actions. In the CPA conference 2016, we introduced the

  17. Analysis of an Asynchronous Online Discussion as a Supportive Model for Peer Collaboration and Reflection in Teacher Education (United States)

    Plešec Gasparic, Romina; Pecar, Mojca


    Professional development of future teachers is based on connecting theory and practice with the aim of supporting and developing critical, independent, responsible decision-making and active teaching. With this aim we designed a blended learning environment with an asynchronous online discussion, enabling collaboration and reflection even when…

  18. Missed Opportunities for Science Learning: Unacknowledged Unscientific Arguments in Asynchronous Online and Face-To-Face Discussions (United States)

    Callis-Duehl, Kristine; Idsardi, Robert; Humphrey, Eve A.; Gougis, Rebekka Darner


    We explored the scientific argumentation that occurs among university biology students during an argumentation task implemented in two environments: face-to-face in a classroom and online in an asynchronous discussion. We observed 10 student groups, each composed of three students. Our analysis focused on how students respond to their peers'…

  19. Effects of Synchronous and Asynchronous Computer-Mediated Communication (CMC) Oral Conversations on English Language Learners' Discourse Functions (United States)

    AbuSeileek, Ali Farhan; Qatawneh, Khaleel


    This study aimed to explore the effects of synchronous and asynchronous computer mediated communication (CMC) oral discussions on question types and strategies used by English as a Foreign Language (EFL) learners. The participants were randomly assigned to two treatment conditions/groups; the first group used synchronous CMC, while the second…

  20. Analysis Of Functional Stability Of The Triphased Asynchronous Generator Used In Conversion Systems Of A Eolian Energy Into Electric Energy

    Directory of Open Access Journals (Sweden)



    Full Text Available This paper presents a study of the influence of the main perturbation agent over the functional stability of the triphased asynchronous generator (for the two alternative: with coiled and short circuit rotor, used for the conversion systems from a eolian energy into electric energy.

  1. Applying reflection and moderation in an asynchronous computer-supported collaborative learning environment in campus-based higher education.

    NARCIS (Netherlands)

    Dewiyanti, Silvia; Brand-Gruwel, Saskia; Jochems, Wim


    Working together while accomplishing a task is a characteristic of a powerful learning environment that aims at active knowledge construction. Studies have demonstrated that collaborative learning by using asynchronous communication tools can have advantages over collaboration in a face-to-face

  2. Instructional Design and Facilitation Approaches That Promote Critical Thinking in Asynchronous Online Discussions: A Review of the Literature (United States)

    Schindler, Laura A.; Burkholder, Gary J.


    Asynchronous online discussions (AODs) are often used to promote critical thinking in online courses; however, recent research suggests that levels of critical thinking in discussions remain low. Furthermore, there is a lack of consensus in the literature about the definition of critical thinking and many of the existing studies focus on one…

  3. The Effectiveness of Synchronous and Asynchronous Written Corrective Feedback on Grammatical Accuracy in a Computer-Mediated Environment (United States)

    Shintani, Natsuko; Aubrey, Scott


    This study extends research on written corrective feedback (CF) by investigating how timing of CF affects grammar acquisition. Specifically, it examined the relative effects of synchronous and asynchronous CF on the accurate use of the hypothetical conditional structure. Participants were 68 intermediate-level students of English at a university…

  4. Online-BSEE (Online Bachelor of Science in Electrical Engineering): An Asynchronous Online Electrical Engineering Degree Program with Laboratory (United States)

    Tang, Wendy; Westgate, Charles; Liu, Pao-Lo; Gouzman, Michael


    The Online Bachelor of Science in Electrical Engineering is a collaborative effort among three University Centers at SUNY (State University of New York), namely Stony Brook, Binghamton, and Buffalo. The program delivers the complete electrical engineering curriculum at the bachelor level to students online and asynchronously. Students, however,…

  5. Arguing as an Academic Purpose: The Role of Asynchronous Conferencing in Supporting Argumentative Dialogue in School and University (United States)

    Coffin, Caroline; Hewings, Ann; North, Sarah


    Learning to argue is a key academic purpose for both first and second language students. It has been claimed that computer mediated asynchronous text-based conferencing is a useful medium for developing argumentation skills (Andriessen, Baker, & Suthers, 2003). This paper reports on two research studies which explore this claim. One study focused…

  6. Torque harmonics of an asynchronous motor supplied by a voltage- or current-sourced inverter quasi-square operation

    Energy Technology Data Exchange (ETDEWEB)

    Kyyrae, J. [Helsinki University of Technology, Institute of Intelligent Power Electronics, Espoo (Finland)


    Voltage- and current-sourced dc-ac converters operating in quasi-square area are compared. Their characteristics are calculated with switching vector, which is space-vector of switching functions. When the load is an asynchronous motor various analytical equations, including torque, are calculated efficiently. Motor current and torque approximations are compared with the simulated ones. (orig.) 6 refs.

  7. How People Learn in an Asynchronous Online Learning Environment: The Relationships between Graduate Students' Learning Strategies and Learning Satisfaction (United States)

    Choi, Beomkyu


    The purpose of this study was to examine the relationships between learners' learning strategies and learning satisfaction in an asynchronous online learning environment. In an attempt to shed some light on how people learn in an online learning environment, one hundred and sixteen graduate students who were taking online learning courses…


    Directory of Open Access Journals (Sweden)

    Valeriy G. Apalkov


    Full Text Available The article covers the key problems of forming cross cultural competence by means of asynchronic Internet-communication techniques. A concise overview of main studies in using e-mail group in forming cross cultural competence. An algorithm of forming cross cultural competence of high school students is described. 

  9. Asynchronous Group Key Distribution on top of the CC2420 Security Mechanisms for Sensor Networks

    DEFF Research Database (Denmark)

    Hansen, Morten Tranberg


    scheme with no time synchronization requirements. The scheme decreases the number of key updates by providing them on an as needed basis according to the amount of network traffic. We evaluate the CC2420 radio security mechanism and show how to use it as a basis to implement secure group communication......A sensor network is a network consisting of small, inexpensive, low-powered sensor nodes that communicate to complete a common task. Sensor nodes are characterized by having limited communication and computation capabilities, energy, and storage. They often are deployed in hostile environments...... creating a demand for encryption and authentication of the messages sent between them. Due to severe resource constraints on the sensor nodes, efficient key distribution schemes and secure communication protocols with low overhead are desired. In this paper we present an asynchronous group key distribution...

  10. Renewal Approach to the Analysis of the Asynchronous State for Coupled Noisy Oscillators. (United States)

    Farkhooi, Farzad; van Vreeswijk, Carl


    We develop a framework in which the activity of nonlinear pulse-coupled oscillators is posed within the renewal theory. In this approach, the evolution of the interevent density allows for a self-consistent calculation that determines the asynchronous state and its stability. This framework can readily be extended to the analysis of systems with more state variables and provides a population density treatment to evolve them in their thermodynamical limits. To demonstrate this we study a nonlinear pulse-coupled system, where couplings are dynamic and activity dependent. We investigate its stability and numerically study the nonequilibrium behavior of the system after the bifurcation. We show that this system undergoes a supercritical Hopf bifurcation to collective synchronization.

  11. Application of a simple asynchronous mechanical light chopper to multielectron coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kenji; Suzuki, Isao H. [Photon Factory, IMSS, KEK, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Penent, Francis; Lablanquie, Pascal [Universite Pierre et Marie Curie (UPMC), 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); CNRS, LCPMR(UMR 7614), 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Hikosaka, Yasumasa; Shigemasa, Eiji [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Eland, John H. D. [PTCL, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom)


    A simple asynchronous mechanical light chopper, based on modification of a turbo-molecular pump, has been developed to extend the interval between light pulses in single bunch operation at the Photon Factory storage ring. A pulse repetition rate of 80 kHz was achieved using a cylinder rotating at 48000 rpm, with 100 slits of 80 {mu}m width. This allows absolute timing of particles up to 12.48 {mu}s instead of the single-bunch period of 624 ns. We have applied the chopper together with a light pulse monitor to measure multielectron coincidence spectra using a magnetic bottle time-of-flight electron spectrometer. With such a system, the electron energies are determined without any ambiguity, the folding of coincidence spectra disappears and the effect of false coincidences is drastically reduced.

  12. High power-efficient asynchronous SAR ADC for IoT devices (United States)

    Zhang, Beichen; Yao, Bingbing; Liu, Liyuan; Liu, Jian; Wu, Nanjian


    This paper presents a power-efficient 100-MS/s, 10-bit asynchronous successive approximation register (SAR) ADC. It includes an on-chip reference buffer and the total power dissipation is 6.8 mW. To achieve high performance with high power-efficiency in the proposed ADC, bootstrapped switch, redundancy, set-and-down switching approach, dynamic comparator and dynamic logic techniques are employed. The prototype was fabricated using 65 nm standard CMOS technology. At a 1.2-V supply and 100 MS/s, the ADC achieves an SNDR of 56.2 dB and a SFDR of 65.1 dB. The ADC core consumes only 3.1 mW, resulting in a figure of merit (FOM) of 30.27 fJ/conversionstep and occupies an active area of only 0.009 mm2.

  13. Concerted and asynchronous mechanism of ground state proton transfer in alcohol mediated 7-hydroxyquinoline (United States)

    Kang, Baotao; Jang, Du-Jeon; Lee, Jin Yong


    Alcohols mediated 7-hydroxyquinoline (7-HQ) complex has received enormous attractions on the issue of proton transfer reaction in the ground and excited states. In the present paper, concentrating on the ground state proton transfer (GSPT), density functional theory (DFT) calculations were carried out to investigate the intrinsic insight into the reaction mechanism. We found that the GSPT is concerted and asynchronous process and can be accelerated by more acidic alcohol. Such GSPT was initiated by the proton transfer from alcohol to keto group of 7-HQ and finished by the proton transfer from nitrogen to alcohol. Our findings were in agreement with experimental conclusions quite well. Our results would be helpful to understand the proton transfer reaction for 7-HQ and related systems.

  14. Computationally Efficient Chaotic Spreading Sequence Selection for Asynchronous DS-CDMA

    Directory of Open Access Journals (Sweden)

    Litviņenko Anna


    Full Text Available The choice of the spreading sequence for asynchronous direct-sequence code-division multiple-access (DS-CDMA systems plays a crucial role for the mitigation of multiple-access interference. Considering the rich dynamics of chaotic sequences, their use for spreading allows overcoming the limitations of the classical spreading sequences. However, to ensure low cross-correlation between the sequences, careful selection must be performed. This paper presents a novel exhaustive search algorithm, which allows finding sets of chaotic spreading sequences of required length with a particularly low mutual cross-correlation. The efficiency of the search is verified by simulations, which show a significant advantage compared to non-selected chaotic sequences. Moreover, the impact of sequence length on the efficiency of the selection is studied.

  15. Middleware for Processing Message Queues with Elasticity Support and Sequential Integrity of Asynchronous Message Processing (United States)

    Henrique Teixeira, Eduardo; Patrícia Favacho de Araújo, Aletéia


    Elasticity in computing refers to dynamically adjusting the amount of allocated resources to process a distributed application. In order to achieve this, mechanisms are needed to avoid the phenomenon of the elasticity threshold detection moving constantly up or down. The existing work fails to deliver sequential integrity of asynchronous messages processing and the asymmetries of data distribution to achieve parallel consumption. This paper fills this gaps and proposes a middleware solution to dynamically analyze the flow of message queue, and a mechanism to increase the parallelized consumption based on the output behavior. An architecture for IOD (Increase On Demand) middleware is presented, with support for the increase and decrease of thread's to cope with the growth of message queues, using the technique of limit-based heuristics over a given period of time and grouping messages into sub-queues based on classification criteria.

  16. Formal Specification and Verification of Fully Asynchronous Implementations of the Data Encryption Standard

    Directory of Open Access Journals (Sweden)

    Wendelin Serwe


    Full Text Available This paper presents two formal models of the Data Encryption Standard (DES, a first using the international standard LOTOS, and a second using the more recent process calculus LNT. Both models encode the DES in the style of asynchronous circuits, i.e., the data-flow blocks of the DES algorithm are represented by processes communicating via rendezvous. To ensure correctness of the models, several techniques have been applied, including model checking, equivalence checking, and comparing the results produced by a prototype automatically generated from the formal model with those of existing implementations of the DES. The complete code of the models is provided as appendices and also available on the website of the CADP verification toolbox.

  17. Analysis of Single-Locus Replication Timing in Asynchronous Cycling Cells. (United States)

    Federica, Lo Sardo


    In higher eucaryotes, not all the genome is replicated simultaneously: there are parts of the genome that replicate at the beginning of S-phase (early S-phase), others that are replicated later. In each cell, early replicating genomic regions are alternated to late-replicating regions. In general, eucaryotic genomes are organized into structural domains where genes showing the same epigenetic state replicate at the same time.Here, we will describe the protocol that we routinely used for the analysis of replication timing of specific loci in Drosophila embryonic cell lines (S2 and S3) based on BrdU labeling and FACS sorting of different S-phase fractions (early, mid, late) of asynchronous cycling cells.

  18. Argo: A Time-Elastic Time-Division-Multiplexed NOC using Asynchronous Routers

    DEFF Research Database (Denmark)

    Kasapaki, Evangelia; Sparsø, Jens


    In this paper we explore the use of asynchronous routers in a time-division-multiplexed (TDM) network-on-chip (NOC), Argo, that is being developed for a multi-processor platform for hard real-time systems. TDM inherently requires a common time reference, and existing TDM-based NOC designs....... Argo has interesting elastic timing properties that allow it to tolerate skew between the network interfaces (NIs). The paper presents Argo NOC-architecture and provides a quantitative analysis of its ability of absorb skew between the NIs. Using a signal transition graph model and realistic component...... delays derived from a 65nm CMOS implementation, a worstcase analysis shows that a typical design can tolerate a skew of 1-5 cycles (depending on FIFO depths and NI clock frequency). Simulation results of a 2 x 2 NOC confirm this....

  19. Decomposition approach to the stability of recurrent neural networks with asynchronous time delays in quaternion field. (United States)

    Zhang, Dandan; Kou, Kit Ian; Liu, Yang; Cao, Jinde


    In this paper, the global exponential stability for recurrent neural networks (QVNNs) with asynchronous time delays is investigated in quaternion field. Due to the non-commutativity of quaternion multiplication resulting from Hamilton rules: ij=-ji=k, jk=-kj=i, ki=-ik=j, ijk=i(2)=j(2)=k(2)=-1, the QVNN is decomposed into four real-valued systems, which are studied separately. The exponential convergence is proved directly accompanied with the existence and uniqueness of the equilibrium point to the consider systems. Combining with the generalized ∞-norm and Cauchy convergence property in the quaternion field, some sufficient conditions to guarantee the stability are established without using any Lyapunov-Krasovskii functional and linear matrix inequality. Finally, a numerical example is given to demonstrate the effectiveness of the results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. International service learning in the Dominican Republic: An asynchronous pilot in interprofessional education. (United States)

    Foster, Jennifer; Pullen, Sara


    Despite the logistical barriers of asynchronous academic calendars, university students in nursing and physical therapy in one academic health centre piloted an international, interprofessional, service learning project in the Dominican Republic. Although the nursing students and physical therapy students were not able to be in-country at the same time, they provided care to a common caseload of traumatic injury patients and those with chronic, debilitating conditions. Interprofessional communication occurred with the development of SBAR (Situation, Background, Assessment, Recommendation) reports from the Team Training curriculum of the Agency for Healthcare Research and Quality. Students learned the depth of physical therapy and the breadth of nursing. The pilot led to a more refined design to pair nursing and PT students, requiring them to communicate via mobile phone regarding results of examinations, and suggestions for follow-up by the nursing students, to ensure continuity of care and a more comprehensive approach to services.

  1. Distributed Constrained Stochastic Subgradient Algorithms Based on Random Projection and Asynchronous Broadcast over Networks

    Directory of Open Access Journals (Sweden)

    Junlong Zhu


    Full Text Available We consider a distributed constrained optimization problem over a time-varying network, where each agent only knows its own cost functions and its constraint set. However, the local constraint set may not be known in advance or consists of huge number of components in some applications. To deal with such cases, we propose a distributed stochastic subgradient algorithm over time-varying networks, where the estimate of each agent projects onto its constraint set by using random projection technique and the implement of information exchange between agents by employing asynchronous broadcast communication protocol. We show that our proposed algorithm is convergent with probability 1 by choosing suitable learning rate. For constant learning rate, we obtain an error bound, which is defined as the expected distance between the estimates of agent and the optimal solution. We also establish an asymptotic upper bound between the global objective function value at the average of the estimates and the optimal value.

  2. Time encoding and reconstruction of multichannel data by brain implants using asynchronous sigma delta modulators. (United States)

    Senay, Seda; Chaparro, Luis F; Sclabassi, Robert J; Sun, Mingui


    Recently, information technology and microelectronics have enabled implanting miniature and highly intelligent devices within the brain for in-vitro diagnostic and therapeutic functions. Power and physical size constraints of these devices necessitate novel signal processing methods. In this paper we investigate an effective data acquisition and reconstruction method for brain implants based on Asynchronous Sigma Delta Modulators (ASDMs). The ASDMs are analog non-linear feedback systems capable of time coding signals. The proposed reconstruction algorithm is based on the Prolate Spheroidal Wave Function (PSWF) expansion of the sinc functions and the order of expansion is given by the input signal being coded. Multiplexing and transmission of the different channels of data are accomplished by chirp orthogonal frequency division multiplexing. Computer simulations using multi channel electroencephalographic data are performed for wireless transmission by brain implants for monitoring abnormal brain activities of epilepsy patients.

  3. An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs)

    CERN Document Server

    Huang, W; Berry, J; Maolinbay, M; Martelli, C; Mody, P; Nassif, S; Yeakey, M


    The development of a full-custom electronic acquisition system designed for readout of large-area active matrix flat-panel imaging arrays is reported. The arrays, which comprise two-dimensional matrices of pixels utilizing amorphous silicon thin-film transistors, are themselves under development for a wide variety of X-ray imaging applications. The acquisition system was specifically designed to facilitate detailed, quantitative investigations of the properties of these novel imaging arrays and contains significant enhancements compared to a previously developed acquisition system. These enhancements include pipelined preamplifier circuits to allow faster readout speed, expanded addressing capabilities allowing a maximum of 4096 array data lines, and on-board summing of image frames. The values of many acquisition system parameters, including timings and voltages, may be specified and downloaded from a host computer. Once acquisition is enabled, the system operates asynchronously of its host computer. The sys...

  4. Temperature, paternity and asynchronous hatching influence early developmental characteristics of larval Atlantic cod, Gadus morhua

    DEFF Research Database (Denmark)

    Politis, Sebastian Nikitas; Dahlke, Flemming T.; Butts, Ian A.E.


    or if they hatched at the end of the hatching period at a specific temperature. Differences in larval morphometrics among temperatures for early hatching larvae decreased or even reversed for later hatching larvae. In light of anticipated global climate change, the present study on cod provides further insight...... (LN), yolk-sac area (AY), and deformities. Larvae hatching on a given day were incubated at the same temperature and sampled at 4days post-hatch (DPH) for growth, yolk utilization rate (YUR) and efficiency (YUE). The mean±SE duration of the hatching window decreased with increasing temperature in both......Offspring, especially during early development, are influenced by both intrinsic properties endowed to them by their parents, extrinsic environmental factors as well as the interplay between genes and the environment. We investigated the effects of paternity (P), temperature (T), and asynchronous...

  5. Asynchronous Distance Education Forum - Brainstorming vs. Snowballing: A Case Study for Teaching in Programming Didactics (United States)

    Patriarcheas, Kiriakos; Xenos, Michalis

    Asynchronous discussion fora all the more become part of the educational process of distance education. The goal of this research is the study of the educational techniques of Brainstorming and Snowballing to their utilisation in the frame of a distance education forum, both as far as participation and creation of learning environment and also educational effectiveness are concerned. This research refers to computer teachers’ training on didactics of programming within the framework of educational micro-worlds. As it is deduced from the data analysis and the study of the messages higher participation and improvement of critical thinking are noted when Brainstorming technique is used, while fairly less time is spent and less off-topic interventions are made when Snowballing technique is used. Meanwhile, Brainstorming is found to be more advantageous than Snowballing concerning the effectiveness both in primary level (trained teachers) and in secondary level of adaptation and knowledge impartment to the students (results of their students).

  6. Asynchronous Two-Way Relaying Networks Using Distributed Differential Space-Time Coding

    Directory of Open Access Journals (Sweden)

    Minjie Qian


    Full Text Available A signal detection scheme is proposed for two-way relaying network (TWRN using distributed differential space-time coding (DDSTC under imperfect synchronization. Unlike most of existing work, which assumed perfect synchronization and channel state information (CSI at all nodes, a more realistic scenario is investigated here by considering the signals transmitted from the two source nodes arriving at the relay not exactly at the same time due to the distributed nature of the nodes, and no CSI is available at any node. The proposed signal detection scheme is then demonstrated to remove the imperfect synchronization effect significantly through simulation results. Furthermore, pairwise error probability (PEP of the asynchronous TWRN is analyzed and derived for both source nodes. Based on the simplified PEP expression, an optimum power allocation (OPA scheme is then determined to further improve the whole system performance, when neither the source nor the relay has any knowledge of the CSI.

  7. Approximating Frequent Items in Asynchronous Data Stream over a Sliding Window

    DEFF Research Database (Denmark)

    Ting, Hing-Fung; Lee, Lap Kei; Chan, Ho-Leung


    with sufficient accuracy. Prior to our work, the best solution is given by Cormode et al. [1], who gave an O (1/ε log W log (εB/ log W) min {log W, 1/ε} log |U|)- space data structure that can approximate the frequent items within an ε error bound, where W and B are parameters of the sliding window, and U......In an asynchronous data stream, the data items may be out of order with respect to their original timestamps. This paper studies the space complexity required by a data structure to maintain such a data stream so that it can approximate the set of frequent items over a sliding time window...... is the set of all possible item names. We gave a more space-efficient data structure that only requires O (1/ε log W log (εB/ logW) log log W) space....

  8. Fiber-coupled high-speed asynchronous optical sampling with sub-50 fs time resolution. (United States)

    Krauss, N; Nast, A; Heinecke, D C; Kölbl, C; Barros, H G; Dekorsy, T


    We present a fiber-coupled pump-probe system with a sub-50 fs time resolution and a nanosecond time window, based on high-speed asynchronous optical sampling. By use of a transmission grism pulse compressor, we achieve pump pulses with a pulse duration of 42 fs, an average power of 300 mW and a peak power exceeding 5 kW at a pulse repetition rate of 1 GHz after 6 m of optical fiber. With this system we demonstrate thickness mapping of soft X-ray mirrors at a sub-nm thickness resolution on a cm(2) scan area. In addition, terahertz field generation with resolved spectral components of up to 3.5 THz at a GHz frequency resolution is demonstrated.

  9. [Asynchronous Bilateral Testicular Infarction with Suspected Polyarteritis Nodosa : A Case Report]. (United States)

    Kurokawa, Masayuki; Naito, Sei; Ichiyanagi, Osamu; Suto, Aya; Kurota, Yuta; Sakurai, Toshihiko; Nishida, Hayato; Kawazoe, Hisashi; Kato, Tomoyuki; Nagaoka, Akira; Ito, Hiromi; Yamakawa, Mitsunori; Tsuchiya, Norihiko


    This report documents a case of asynchronous bilateral testicular infarction. The patient was a 42- year-old man who presented with left testicular pain and swelling. He had a past history of right idiopathic testicular infarction and underwent a right orchiectomy 6 years ago. He also had received treatment for 5 years for suspected polyarteritis nodosa (PAN). The left scrotal pain persisted for a week and left orchiectomy was performed. Pathological evaluations demonstrated a benign testis with testicular hemorrhage and chronic vasculopathy. There was no fibrinoid necrosis of medium-size vessel walls which characterizes PAN. In this report, we review the pathogenesis, risk of contralateral testicular infarction, and management of testicular infarction.

  10. Highly Scalable Asynchronous Computing Method for Partial Differential Equations: A Path Towards Exascale (United States)

    Konduri, Aditya

    Many natural and engineering systems are governed by nonlinear partial differential equations (PDEs) which result in a multiscale phenomena, e.g. turbulent flows. Numerical simulations of these problems are computationally very expensive and demand for extreme levels of parallelism. At realistic conditions, simulations are being carried out on massively parallel computers with hundreds of thousands of processing elements (PEs). It has been observed that communication between PEs as well as their synchronization at these extreme scales take up a significant portion of the total simulation time and result in poor scalability of codes. This issue is likely to pose a bottleneck in scalability of codes on future Exascale systems. In this work, we propose an asynchronous computing algorithm based on widely used finite difference methods to solve PDEs in which synchronization between PEs due to communication is relaxed at a mathematical level. We show that while stability is conserved when schemes are used asynchronously, accuracy is greatly degraded. Since message arrivals at PEs are random processes, so is the behavior of the error. We propose a new statistical framework in which we show that average errors drop always to first-order regardless of the original scheme. We propose new asynchrony-tolerant schemes that maintain accuracy when synchronization is relaxed. The quality of the solution is shown to depend, not only on the physical phenomena and numerical schemes, but also on the characteristics of the computing machine. A novel algorithm using remote memory access communications has been developed to demonstrate excellent scalability of the method for large-scale computing. Finally, we present a path to extend this method in solving complex multi-scale problems on Exascale machines.

  11. The flipped classroom: a modality for mixed asynchronous and synchronous learning in a residency program. (United States)

    Young, Timothy P; Bailey, Caleb J; Guptill, Mindi; Thorp, Andrea W; Thomas, Tamara L


    A "flipped classroom" educational model exchanges the traditional format of a classroom lecture and homework problem set. We piloted two flipped classroom sessions in our emergency medicine (EM) residency didactic schedule. We aimed to learn about resident and faculty impressions of the sessions, in order to develop them as a regular component of our residency curriculum. We evaluated residents' impression of the asynchronous video component and synchronous classroom component using four Likert items. We used open-ended questions to inquire about resident and faculty impressions of the advantages and disadvantages of the format. For the Likert items evaluating the video lectures, 33/35 residents (94%, 95% CI 80%-99%) responded that the video lecture added to their knowledge about the topic, and 33/35 residents felt that watching the video was a valuable use of their time. For items evaluating the flipped classroom format, 36/38 residents (95%, 95% CI 82%-99%) preferred the format to a traditional lecture on the topic, and 38/38 residents (100%, 95% CI 89%-100%) felt that the small group session was effective in helping them learn about the topic. Most residents preferred to see the format monthly in our curriculum and chose an ideal group size of 5.5 (first session) and 7 (second session). Residents cited the interactivity of the sessions and access to experts as advantages of the format. Faculty felt the ability to assess residents' understanding of concepts and provide feedback were advantages. Our flipped classroom model was positively received by EM residents. Residents preferred a small group size and favored frequent use of the format in our curriculum. The flipped classroom represents one modality that programs may use to incorporate a mixture of asynchronous and interactive synchronous learning and provide additional opportunities to evaluate residents.

  12. The Flipped Classroom: A Modality for Mixed Asynchronous and Synchronous Learning in a Residency Program

    Directory of Open Access Journals (Sweden)

    Timothy P. Young


    Full Text Available Introduction: A “flipped classroom” educational model exchanges the traditional format of a classroom lecture and homework problem set. We piloted two flipped classroom sessions in our emergency medicine (EM residency didactic schedule. We aimed to learn about resident and faculty impressions of the sessions, in order to develop them as a regular component of our residency curriculum. Methods: We evaluated residents’ impression of the asynchronous video component and synchronous classroom component using four Likert items. We used open-ended questions to inquire about resident and faculty impressions of the advantages and disadvantages of the format. Results: For the Likert items evaluating the video lectures, 33/35 residents (94%, 95% CI 80%-99% responded that the video lecture added to their knowledge about the topic, and 33/35 residents felt that watching the video was a valuable use of their time. For items evaluating the flipped classroom format, 36/38 residents (95%, 95% CI 82%-99% preferred the format to a traditional lecture on the topic, and 38/38 residents (100%, 95% CI 89%-100% felt that the small group session was effective in helping them learn about the topic. Most residents preferred to see the format monthly in our curriculum and chose an ideal group size of 5.5 (first session and 7 (second session. Residents cited the interactivity of the sessions and access to experts as advantages of the format. Faculty felt the ability to assess residents’ understanding of concepts and provide feedback were advantages. Conclusion: Our flipped classroom model was positively received by EM residents. Residents preferred a small group size and favored frequent use of the format in our curriculum. The flipped classroom represents one modality that programs may use to incorporate a mixture of asynchronous and interactive synchronous learning and provide additional opportunities to evaluate residents. [West J Emerg Med. 2014;15(7:-0.

  13. A new asynchronous parallel algorithm for inferring large-scale gene regulatory networks.

    Directory of Open Access Journals (Sweden)

    Xiangyun Xiao

    Full Text Available The reconstruction of gene regulatory networks (GRNs from high-throughput experimental data has been considered one of the most important issues in systems biology research. With the development of high-throughput technology and the complexity of biological problems, we need to reconstruct GRNs that contain thousands of genes. However, when many existing algorithms are used to handle these large-scale problems, they will encounter two important issues: low accuracy and high computational cost. To overcome these difficulties, the main goal of this study is to design an effective parallel algorithm to infer large-scale GRNs based on high-performance parallel computing environments. In this study, we proposed a novel asynchronous parallel framework to improve the accuracy and lower the time complexity of large-scale GRN inference by combining splitting technology and ordinary differential equation (ODE-based optimization. The presented algorithm uses the sparsity and modularity of GRNs to split whole large-scale GRNs into many small-scale modular subnetworks. Through the ODE-based optimization of all subnetworks in parallel and their asynchronous communications, we can easily obtain the parameters of the whole network. To test the performance of the proposed approach, we used well-known benchmark datasets from Dialogue for Reverse Engineering Assessments and Methods challenge (DREAM, experimentally determined GRN of Escherichia coli and one published dataset that contains more than 10 thousand genes to compare the proposed approach with several popular algorithms on the same high-performance computing environments in terms of both accuracy and time complexity. The numerical results demonstrate that our parallel algorithm exhibits obvious superiority in inferring large-scale GRNs.

  14. Determining sociability, social space, and social presence in (a)synchronous collaborative groups. (United States)

    Kreijns, Karel; Kirschner, Paul A; Jochems, Wim; Van Buuren, Hans


    The effectiveness of group learning in asynchronous distributed learning groups depends on the social interaction that takes place. This social interaction affects both cognitive and socioemotional processes that take place during learning, group forming, establishment of group structures, and group dynamics. Though now known to be important, this aspect is often ignored, denied or forgotten by educators and researchers who tend to concentrate on cognitive processes and on-task contexts. This "one-sided" educational focus largely determines the set of requirements in the design of computer-supported collaborative learning (CSCL) environments resulting in functional CSCL environments. In contrast, our research is aimed at the design and implementation of sociable CSCL environments which may increase the likelihood that a sound social space will emerge. We use a theoretical framework that is based upon an ecological approach to social interaction, centering on the concept of social affordances, the concept of the sociability of CSCL environments, and social presence theory. The hypothesis is that the higher the sociability, the more likely that social interaction will take place or will increase, and the more likely that this will result in an emerging sound social space. In the present research, the variables of interest are sociability, social space, and social presence. This study deals with the construction and validation of three instruments to determine sociability, social space, and social presence in (a)synchronous collaborating groups. The findings suggest that the instruments have potential to be useful as measures for the respective variables. However, it must be realized that these measures are "first steps."

  15. Identification of imprinted genes using a novel screening method based on asynchronous DNA replication

    Energy Technology Data Exchange (ETDEWEB)

    Kawame, H.; Hansen, R.S.; Gartler, S.M. [Univ. of Washington, Seattle, WA (United States)


    Genomic imprinting refers to the process of epigenetic change that occurs during germ cell development that results in either maternal- or paternal-specific gene expression. Identification of imprinted genes is of primary importance to the understanding of imprinting mechanisms and the role of specific imprinted genes in human disease. Recently, it has been established that chromosomal regions known to contain imprinted genes replicate asynchronously. We propose a novel screening method to identify imprinted genes based on replication asynchrony as a marker for imprinted domains. Dividing human cells were pulse-labeled with BrdU and separated into different fractions of S-phase by flow cytometry. A library of late-replicating inter-Alu sequences should be enriched in gene-associated sequences that replicate early on one chromosome and late on the other homologue. Clones were analyzed for replication timing by hybridization to inter-Alu replication profiles. Candidates for replication asynchrony exhibited broad or biphasic replication timing, and these were analyzed for chromosomal location by hybridizations to inter-Alu products from a hybrid mapping panel. Initial screening of 123 clones resulted in 3 asynchronously-replicating clones that localized to single chromosomes. Chromosome 17 and chromosome 19 candidates might be located in regions thought to be imprinted by synteny with mouse chromosomes. A chromosome 15 clone was further characterized because of its possible localization to the Prader-Willi/Angelman locus. This sequence was localized outside the region deleted in Prader-Willi patients, and was found to be expressed in human cell lines. Replication asynchrony for this sequence appears to be polymorphic because cells derived from some individuals indicated synchronous replication. This appears to be the first example of a polymorphism in replication asynchrony.

  16. Venom regeneration in the centipede Scolopendra polymorpha: evidence for asynchronous venom component synthesis. (United States)

    Cooper, Allen M; Kelln, Wayne J; Hayes, William K


    Venom regeneration comprises a vital process in animals that rely on venom for prey capture and defense. Venom regeneration in scolopendromorph centipedes likely influences their ability to subdue prey and defend themselves, and may influence the quantity and quality of venom extracted by researchers investigating the venom's biochemistry. We investigated venom volume and total protein regeneration during the 14-day period subsequent to venom extraction in the North American centipede Scolopendra polymorpha. We further tested the hypothesis that venom protein components, separated by reversed-phase fast protein liquid chromatography (RP-FPLC), undergo asynchronous (non-parallel) synthesis. During the first 48 h, volume and protein mass increased linearly. Protein regeneration lagged behind volume regeneration, with 65–86% of venom volume and 29–47% of protein mass regenerated during the first 2 days. No additional regeneration occurred over the subsequent 12 days, and neither volume nor protein mass reached initial levels 7 months later (93% and 76%, respectively). Centipede body length was negatively associated with rate of venom regeneration. Analysis of chromatograms of individual venom samples revealed that 5 of 10 chromatographic regions and 12 of 28 peaks demonstrated changes in percent of total peak area (i.e., percent of total protein) among milking intervals, indicating that venom proteins are regenerated asynchronously. Moreover, specimens from Arizona and California differed in relative amounts of some venom components. The considerable regeneration of venom occurring within the first 48 h, despite the reduced protein content, suggests that predatory and defensive capacities are minimally constrained by the timing of venom replacement.

  17. Time Students Spend Reading Threaded Discussions in Online Graduate Courses Requiring Asynchronous Participation

    Directory of Open Access Journals (Sweden)

    Abbie H. Brown


    Full Text Available The authors report the results of a study that provides bases for comparison between the time necessary to participate in courses delivered asynchronously online and courses delivered in a traditional classroom setting. Weekly discussion threads from 21 sections of six courses offered as part of online, degree-granting, accredited, graduate programs were examined. The purpose of this research is to determine whether students are spending more or less time participating in an online course than in a traditional classroom.The discussion size (i.e., the number of words per discussion was determined using the automatic word count function in MS Word. Once the word counts for each course section were determined, the average words per discussion were calculated. The authors used 180 words per minute to calculate the average reading time, based on the work of Ziefle (1998 and Carver (1985, 1990, in order to determine the average minutes per week a student spent reading the discussions.The study indicates that a typical, graduate-level, online, asynchronous discussion requires about one hour a week of reading time, and the time commitment for participatory activity is similar to that of traditional, face-to-face courses, given that it takes under two hours to compose initial messages and responses to the discussion prompt.Although these findings are informative, further research is recommended in the area of time spent on online course activities in terms of student hours earned to enable a direct focus on various student characteristics, such as English language competency and student level.

  18. Computationally Efficient Blind Code Synchronization for Asynchronous DS-CDMA Systems with Adaptive Antenna Arrays

    Directory of Open Access Journals (Sweden)

    Chia-Chang Hu


    Full Text Available A novel space-time adaptive near-far robust code-synchronization array detector for asynchronous DS-CDMA systems is developed in this paper. There are the same basic requirements that are needed by the conventional matched filter of an asynchronous DS-CDMA system. For the real-time applicability, a computationally efficient architecture of the proposed detector is developed that is based on the concept of the multistage Wiener filter (MWF of Goldstein and Reed. This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigendecomposition of a covariance matrix. As a consequence, this detector achieves a complexity that is only a linear function of the size of antenna array (J, the rank of the MWF (M, the system processing gain (N, and the number of samples in a chip interval (S, that is, 𝒪(JMNS. The complexity of the equivalent detector based on the minimum mean-squared error (MMSE or the subspace-based eigenstructure analysis is a function of 𝒪((JNS3. Moreover, this multistage scheme provides a rapid adaptive convergence under limited observation-data support. Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the J-element antenna array, the amount of the L-sample support, and the rank of the M-stage MWF. The performance advantage of the proposed detector over other DS-CDMA detectors is investigated as well.

  19. Aide à l'apprentissage du discours oral dans un contexte de communication asynchrone Help with the learning of spoken discourse in an asynchronous context

    Directory of Open Access Journals (Sweden)

    John Fynn


    Full Text Available Nous avons développé VoiceForum pour résoudre un problème concernant l'aide à apporter aux apprenants engagés dans un travail d'interaction orale en L2. Dans le cadre d'une approche par tâches, facilitée par la tendance actuelle à développer des outils de type collecticiel, nous abordons la problématique de la rétroaction à chaud. Les formateurs sont confrontés au dilemme de savoir s'ils doivent privilégier le sens ou la forme. Nous constatons que privilégier la forme conduit à inhiber fortement les échanges. Pour contourner cet obstacle, VoiceForum fonctionne en mode asynchrone. Il permet à des apprenants de converser à l'oral en laissant des messages oraux sur un forum. Une autre fonction du logiciel est d'autoriser le tuteur à créer des aides personnalisées sous forme de rétroactions positives ou négatives liées aux messages envoyés. L'intérêt de ces aides, c'est qu'elles sont contextualisées et donc plus pertinentes pour les apprenants. Ces aides demeurent accessibles au sein du forum qui comporte un outil de recherche pour en faciliter la consultation. Nous faisons l'hypothèse que les aides créées constituent ainsi une nouvelle ressource évolutive qui sera plus efficace que la pratique courante de fournir aux participants une liste de rétroactions à la fin d'une séance de discussion.We have developed our VoiceForum software solution to solve a basic problem regarding how to help learners in L2 spoken interaction activities. In a task-based approach, which is facilitated by the present trend towards groupware solutions, we discuss the problem of giving learners immediate feedback on their oral work. At the centre of this problem, trainers are faced with the dilemma of knowing whether to focus on meaning or on form. We have observed that focusing on form greatly inhibits interaction.To get round this problem, VoiceForum works asynchronously. It enables learners to talk together by posting spoken messages

  20. Refining an Asynchronous Telerehabilitation Platform for Speech-Language Pathology: Engaging End-Users in the Process. (United States)

    Hill, Annie J; Breslin, Hugh M


    Asynchronous telerehabilitation in which computer-based interventions are remotely monitored and adapted offline is an emerging service delivery model in the rehabilitation of communication disorders. The asynchronous nature of this model may hold a benefit over its synchronous counterpart by eliminating scheduling issues and thus improving efficiency in a healthcare landscape of constrained resource allocation. The design of asynchronous telerehabilitation platforms should therefore ensure efficiency and flexibility. The authors have been engaged in a program of research to develop and evaluate an asynchronous telerehabilitation platform for use in speech-language pathology. eSALT is a novel asynchronous telerehabilitation platform in which clinicians design and individualize therapy tasks for transfer to a client's mobile device. An inbuilt telerehabilitation module allows for remote monitoring and updating of tasks. This paper introduces eSALT and reports outcomes from an usability study that considered the needs of two end-user groups, people with aphasia and clinicians, in the on-going refinement of eSALT. In the study participants with aphasia were paired with clinicians who used eSALT to design and customize therapy tasks. After training on the mobile device the participants engaged in therapy at home for a period of 3 weeks, while clinicians remotely monitored and updated tasks. Following the home trial, participants, and clinicians engaged in semi-structured interviews and completed surveys on the usability of eSALT and their satisfaction with the platform. Content analysis of data involving five participants and three clinicians revealed a number of usability themes including ease of use, user support, satisfaction, limitations, and potential improvements. These findings were translated into a number of refinements of the eSALT platform including the development of a client interface for use on the Apple iPad®, greater variety in feedback options to both

  1. Clonal expansion and linear genome evolution through breast cancer progression from pre-invasive stages to asynchronous metastasis

    DEFF Research Database (Denmark)

    Krøigård, Anne Bruun; Larsen, Martin Jakob; Lænkholm, Anne-Vibeke


    Evolution of the breast cancer genome from pre-invasive stages to asynchronous metastasis is complex and mostly unexplored, but highly demanded as it may provide novel markers for and mechanistic insights in cancer progression. The increasing use of personalized therapy of breast cancer...... necessitates knowledge of the degree of genomic concordance between different steps of malignant progression as primary tumors often are used as surrogates of systemic disease. Based on exome sequencing we performed copy number profiling and point mutation detection on successive steps of breast cancer...... progression from one breast cancer patient, including two different regions of Ductal Carcinoma In Situ (DCIS), primary tumor and an asynchronous metastasis. We identify a remarkable landscape of somatic mutations, retained throughout breast cancer progression and with new mutational events emerging at each...

  2. Investigation on intermolecular interaction between berberine and β-cyclodextrin by 2D UV-Vis asynchronous spectra. (United States)

    He, Anqi; Kang, Xiaoyan; Xu, Yizhuang; Noda, Isao; Ozaki, Yukihiro; Wu, Jinguang


    The interaction between berberine chloride and β-cyclodextrin (β-CyD) is investigated via 2D asynchronous UV-Vis spectrum. The occurrence of cross peaks around (420nm, 420nm) in 2D asynchronous spectrum reveals that specific intermolecular interaction indeed exists between berberine chloride and β-CyD. In spite of the difficulty caused by overlapping of cross peaks, we manage to confirm that the 420nm band of berberine undergoes a red-shift, and its bandwidth decreases under the interaction with β-CyD. The red-shift of the 420nm band that can be assigned to n-π* transition indicates the environment of berberine becomes more hydrophobic. The above spectral behavior is helpful in understanding why the solubility of berberine is enhanced by β-CyD. Copyright © 2017. Published by Elsevier B.V.

  3. Asynchronous Geiger-mode APD cameras with free-running InGaAsP pixels (Conference Presentation) (United States)

    Itzler, Mark; Salzano, Gennaro; Entwistle, Mark; Jiang, Xudong; Owens, Mark; Piccione, Brian; Wilton, Sam; Slomkowski, Krystyna; Roszko, Scott C.; Wei, Esther


    We describe Geiger-mode avalanche photodiode (GmAPD) cameras designed with asynchronous free-running operation that supports single-photon direct detection and coherent detection 3D LiDAR imaging as well as free-running applications such as free-space optical communications and target acquisition and tracking. Each free-running pixel in the 32x32 focal plane array performs independent time-of-flight measurements with a selectable reset time between 0.1 and 10 μs. Asynchronous reporting of time-of-flight and pixel location data allows continuous operation for arbitrarily long periods of time at sampling rates exceeding 0.7 Gsample/s. We report results for cameras optimized for operation using either 1.0 or 1.5 μm LiDAR sources.

  4. The probability estimate of the defects of the asynchronous motors based on the complex method of diagnostics (United States)

    Zhukovskiy, Yu L.; Korolev, N. A.; Babanova, I. S.; Boikov, A. V.


    This article is devoted to the development of a method for probability estimate of failure of an asynchronous motor as a part of electric drive with a frequency converter. The proposed method is based on a comprehensive method of diagnostics of vibration and electrical characteristics that take into account the quality of the supply network and the operating conditions. The developed diagnostic system allows to increase the accuracy and quality of diagnoses by determining the probability of failure-free operation of the electromechanical equipment, when the parameters deviate from the norm. This system uses an artificial neural networks (ANNs). The results of the system for estimator the technical condition are probability diagrams of the technical state and quantitative evaluation of the defects of the asynchronous motor and its components.

  5. Exoplanet dynamics. Asynchronous rotation of Earth-mass planets in the habitable zone of lower-mass stars. (United States)

    Leconte, Jérémy; Wu, Hanbo; Menou, Kristen; Murray, Norman


    Planets in the habitable zone of lower-mass stars are often assumed to be in a state of tidally synchronized rotation, which would considerably affect their putative habitability. Although thermal tides cause Venus to rotate retrogradely, simple scaling arguments tend to attribute this peculiarity to the massive Venusian atmosphere. Using a global climate model, we show that even a relatively thin atmosphere can drive terrestrial planets' rotation away from synchronicity. We derive a more realistic atmospheric tide model that predicts four asynchronous equilibrium spin states, two being stable, when the amplitude of the thermal tide exceeds a threshold that is met for habitable Earth-like planets with a 1-bar atmosphere around stars more massive than ~0.5 to 0.7 solar mass. Thus, many recently discovered terrestrial planets could exhibit asynchronous spin-orbit rotation, even with a thin atmosphere. Copyright © 2015, American Association for the Advancement of Science.

  6. Fluka Studies of the Asynchronous Beam Dump Effects on LHC Point 6 for a 7 TeV beam

    CERN Document Server



    The LHC is a record-breaking machine for beam energy and intensity. An intense effort has therefore been deployed in simulating critical operational scenarios of energy deposition. Using FLUKA Monte Carlo simulations, we have investigated the effects of an asynchronous beam dump at the LHC Point 6 where beams, with a stored energy of 360 MJ, can instantaneously release up to a few J cm^{-3} in the cryogenic magnets which have a quench limit of the order of the mJ cm^{-3}. In the present paper we will describe the simulation approach, and discuss the evaluated maximum energy release onto the superconducting magnets during an asynchronous beam dump of a 7 TeV beam. We will then analyze the shielding provided by collimators installed in the area and discuss safety limits for the operation of the LHC.

  7. The Nature of Elementary Science Teachers' Experiences with Synchronous Online, Asynchronous Online and Face-to-Face Coaching (United States)

    Gilbert, Amanda M.

    This study investigated the nature of instructional coaching interactions in three formats: online synchronous, online asynchronous, and face-to-face. Knight's (2007) Seven Partnership Principles of Instructional Coaching were used as a framework to analyze and compare the coaching interactions between coach and teacher to determine whether online coaching may be a viable option to provide support for the teachers unprepared to teach the new science standards. Some previous research has suggested that online communication can result in deeper personal interactions (Walther, 1996), while other studies suggest that interactions are more natural and easier in formats that are more similar to face-to-face interactions (Kock, 2005). The findings of this study support the media naturalness theory (Kock, 2005) and suggest that collaboration may be especially difficult in asynchronous online communication. Although differences were noted in the actual interactions, teacher perception remained fairly consistently positive across the three formats. Research beyond this exploratory study is needed to make findings generalizable.

  8. Evaluation of an Asynchronous Physician Voice Mail Sign-out for Emergency Department Admissions (United States)

    Horwitz, Leora I.; Parwani, Vivek; Shah, Nidhi R.; Schuur, Jeremiah D.; Meredith, Thom; Jenq, Grace Y.; Kulkarni, Raghavendra G.


    Background Communication failures contribute to errors in the transfer of patients from the emergency department (ED) to inpatient medicine units. Oral (synchronous) communication has numerous benefits but is costly and time-consuming. Taped (asynchronous) communication may be more reliable and efficient, but lacks interaction. We evaluated a new asynchronous physician-physician sign-out compared to the traditional synchronous sign-out. Methods A voicemail-based, semi-structured sign-out for routine ED admissions to internal medicine was implemented in October, 2007 at an urban, academic medical center. Outcomes were obtained by pre- and post-intervention surveys of ED and IM housestaff, physician assistants and hospitalist attendings; and by examination of access logs and administrative data. Outcome measures included utilization; physician perceptions of ease, accuracy, content, interaction and errors; and rate of transfers to intensive care from the floor within 24 hours of ED admission. Results were analyzed both quantitatively, and qualitatively using standard qualitative analytic techniques. Results During September-October, 2008 (one year post-intervention), voicemails were recorded regarding 90.5% of medicine admissions; 69.7% of these were accessed at least once by admitting physicians. The median length of each sign-out was 2.6 minutes (IQR 1.9 to 3.5). We received 117/197 responses (59%) to the pre-intervention survey and 113/206 responses (55%) to the post-intervention survey. A total of 73/101 (72%) respondents reported dictated sign-out was easier than oral sign-out and 43/101 (43%) reported it was more accurate. However, 70/101 (69%) reported interaction among participants was worse. There was no change in the rate of ICU transfer within 24 hours of admission from the ED in April-June, 2007 (65/6,147; 1.1%) versus April-June 2008 (70/6,263; 1.1%); difference of 0%, 95% CI, −0.4% to 0.3%. The proportion of internists reporting at least one perceived

  9. Sustainable project of microgeneration systems based on asynchronous generator; Projeto sustentavel de sistemas de microgeracao baseados em gerador assincrono

    Energy Technology Data Exchange (ETDEWEB)

    Salazar Herrera, Victoria Alejandra; Romero, Jesus Franklin Andrade [Universidade Federal do ABC (CECS/UFABC), Santo Andre, SP (Brazil). Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas. Programa de Pos-Graduacao em Energia], emails:,


    Recently, the interest in decentralized generation systems has increased considering a multidisciplinary and sustainable approach. In this sense, this work proposes the evaluation of isolated microgeneration systems, focusing the life cycle of the asynchronous generator, considering the technological, economic and environmental dimensions. By means of the generator efficiency, the unbalanced voltage percentage and the emissions factor, the work point out the relevance of health diagnosis of isolated microgeneration systems objectifying minimize the impacts caused by faulty operation of the generator. (author)

  10. An Asynchronous Low Power and High Performance VLSI Architecture for Viterbi Decoder Implemented with Quasi Delay Insensitive Templates


    T. Kalavathi Devi; Sakthivel Palaniappan


    Convolutional codes are comprehensively used as Forward Error Correction (FEC) codes in digital communication systems. For decoding of convolutional codes at the receiver end, Viterbi decoder is often used to have high priority. This decoder meets the demand of high speed and low power. At present, the design of a competent system in Very Large Scale Integration (VLSI) technology requires these VLSI parameters to be finely defined. The proposed asynchronous method focuses on reducing the powe...

  11. Clonal expansion and linear genome evolution through breast cancer progression from pre-invasive stages to asynchronous metastasis

    DEFF Research Database (Denmark)

    Krøigård, Anne Bruun; Larsen, Martin Jakob; Lænkholm, Anne Vibeke


    Evolution of the breast cancer genome from pre-invasive stages to asynchronous metastasis is complex and mostly unexplored, but highly demanded as it may provide novel markers for and mechanistic insights in cancer progression. The increasing use of personalized therapy of breast cancer...... the different stages of tumor evolution in this patient emphasizes the importance of molecular profiling of metastatic tissue directing molecularly targeted therapy at recurrence....

  12. Asynchronous single-shot characterization of high-repetition-rate ultrafast waveforms using a time-lens-based temporal magnifier. (United States)

    Okawachi, Yoshitomo; Salem, Reza; Johnson, Adrea R; Saha, Kasturi; Levy, Jacob S; Lipson, Michal; Gaeta, Alexander L


    We demonstrate asynchronous, single-shot characterization of an ultrafast, high-repetition-rate pulse source using a time-lens-based temporal magnifier. We measure a 225 GHz repetition-rate pulse train from a microresonator-based frequency comb. In addition, we show that such a system can be used as a frequency compressor for real-time, high-speed RF spectral characterization.

  13. New Optimal Solutions for Real-Time Reconfigurable Periodic Asynchronous Operating System Tasks with Minimizations of Response Time


    Hamza Gharsellaoui; Mohamed Khalgui; Samir Ben Ahmed


    Scheduling tasks is an essential requirement in most real-time and embedded systems, but leads to unwanted central processing unit (CPU) overheads. The authors present a real-time schedulability algorithm for preemptable, asynchronous and periodic reconfigurable task systems with arbitrary relative deadlines, scheduled on a uniprocessor by an optimal scheduling algorithm based on the earliest deadline first (EDF) principles and on the dynamic reconfiguration. A reconfiguration scenario is ass...

  14. Synchronization, retiming and time-division multiplexing of an asynchronous 10 gigabit NRZ Ethernet packet to Terabit Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Laguardia Areal, Janaina; Mulvad, Hans Christian Hansen


    An asynchronous 10 Gb/s Ethernet packet with maximum packet size of 1518 bytes is synchronized and retimed to a master clock with 200 kHz frequency offset using a time lens. The NRZ packet is simultaneously converted into an RZ packet, then further pulse compressed to a FWHM of 400 fs and finally....../s of the Ethernet packet is achieved. © 2011 Optical Society of America....

  15. The impact of asynchronous online course design for professional development on science-teacher self-efficacy (United States)

    Long, Caryn L. Smith

    This dissertation examines how various designs of asynchronous online courses for teacher professional development may impact science-teacher self-efficacy. Mayer's studies, providing the cognitive theory of multimedia learning, targeted designs of asynchronous online learning and the point where contributions of written, auditory, and visual information on these sites could cause cognitive overload (Mayer, 2005). With increasing usage of online resources for educators to gain teaching credits, understanding how to construct these professional development offerings is critical. Teacher self-efficacy can affect how well information from these courses relays to students in their classroom. This research explored the connection between online asynchronous professional development design and teacher self-efficacy through analysis of a physics-based course in three distinct course-design offerings, while collecting content-acquisition data and self-efficacy effects before and after participation. Results from this research showed teacher self-efficacy had improved in all online treatments which included a text-only, text and audio and text, audio and animation version of the same physics content. Content knowledge was most effected by the text-only and text and audio treatments with significan growth occurring in the remember, apply, and analyze levels of bloom's taxonomy. Due to the small number of participants, it cannot be said that these results are conclusive.

  16. Breaking The Millisecond Barrier On SpiNNaker: Implementing Asynchronous Event-Based Plastic Models With Microsecond Resolution

    Directory of Open Access Journals (Sweden)

    Xavier eLagorce


    Full Text Available Spike-based neuromorphic sensors such as retinas and cochleas, change the way in which the world is sampled. Instead of producing data sampled at a constant rate, these sensors output spikes that are asynchronous and event driven. The event-based nature of neuromorphic sensors implies a complete paradigm shift in current perception algorithms towards those that emphasize the importance of precise timing. The spikes produced by these sensors usually have a time resolution in the order of microseconds. This high temporal resolution is a crucial factor in learning tasks. It is also widely used in the field of biological neural networks. Sound localization for instance relies on detecting time lags between the two ears which, in the barn owl, reaches a temporal resolution of 5 microseconds. Current available neuromorphic computation platforms such as SpiNNaker often limit their users to a time resolution in the order of milliseconds that is not compatible with the asynchronous outputs of neuromorphic sensors. To overcome these limitations and allow for the exploration of new types of neuromorphic computing architectures, we introduce a novel software framework on the SpiNNaker platform. This framework allows for simulations of spiking networks and plasticity mechanisms using a completely asynchronous and event-based scheme running with a microsecond time resolution. Results on two example networks using this new implementation are presented.

  17. Research on navigation of satellite constellation based on an asynchronous observation model using X-ray pulsar (United States)

    Guo, Pengbin; Sun, Jian; Hu, Shuling; Xue, Ju


    Pulsar navigation is a promising navigation method for high-altitude orbit space tasks or deep space exploration. At present, an important reason for restricting the development of pulsar navigation is that navigation accuracy is not high due to the slow update of the measurements. In order to improve the accuracy of pulsar navigation, an asynchronous observation model which can improve the update rate of the measurements is proposed on the basis of satellite constellation which has a broad space for development because of its visibility and reliability. The simulation results show that the asynchronous observation model improves the positioning accuracy by 31.48% and velocity accuracy by 24.75% than that of the synchronous observation model. With the new Doppler effects compensation method in the asynchronous observation model proposed in this paper, the positioning accuracy is improved by 32.27%, and the velocity accuracy is improved by 34.07% than that of the traditional method. The simulation results show that without considering the clock error will result in a filtering divergence.

  18. IGR J19552+0044: A new asynchronous short period polar. Filling the gap between intermediate and ordinary polars (United States)

    Tovmassian, G.; González-Buitrago, D.; Thorstensen, J.; Kotze, E.; Breytenbach, H.; Schwope, A.; Bernardini, F.; Zharikov, S. V.; Hernandez, M. S.; Buckley, D. A. H.; de Miguel, E.; Hambsch, F.-J.; Myers, G.; Goff, W.; Cejudo, D.; Starkey, D.; Campbell, T.; Ulowetz, J.; Stein, W.; Nelson, P.; Reichart, D. E.; Haislip, J. B.; Ivarsen, K. M.; LaCluyze, A. P.; Moore, J. P.; Miroshnichenko, A. S.


    Context. Based on XMM-Newton X-ray observations IGR J19552+0044 appears to be either a pre-polar or an asynchronous polar. Aims: We conducted follow-up optical observations to identify the sources and periods of variability precisely and to classify this X-ray source correctly. Methods: Extensive multicolor photometric and medium- to high-resolution spectroscopy observations were performed and period search codes were applied to sort out the complex variability of the object. Results: We found firm evidence of discording spectroscopic (81.29 ± 0.01 m) and photometric (83.599 ± 0.002 m) periods that we ascribe to the white dwarf (WD) spin period and binary orbital period, respectively. This confirms that IGR J19552+0044 is an asynchronous polar. Wavelength dependent variability and its continuously changing shape point at a cyclotron emission from a magnetic WD with a relatively low magnetic field below 20 MG. Conclusions: The difference between the WD spin period and the binary orbital period proves that IGR J19552+0044 is a polar with the largest known degree of asynchronism (0.97 or 3%). Photometric and spectroscopic observational data are only available at the CDS via anonymous ftp to ( or via

  19. Evaluation of an Asynchronous Online Interprofessional Clinical Experience for DNP Students. (United States)

    Manning, Mary Lou; Pogorzelska-Maziarz, Monika


    Little evidence exists guiding interprofessional experiences in Doctor of Nursing Practice (DNP) programs, especially in online learning environments. The primary aim of this study was to evaluate a DNP program interprofessional clinical experience. Students enrolled in an online asynchronous DNP 15-week course used direct observation and individual and group reflection to evaluate team interprofessional collaboration. Observations were measured using the Jefferson Teamwork Observation Guide (JTOG). Eleven students conducted 84 interprofessional observations. The overall mean score across all JTOG observations was 3.44 (SD ± .48). No statistically significant differences exist in the overall or domain-specific scores by observer participation in the team or by type of setting. Corresponding reflections tended to support JTOG scores. Findings suggest that this experience increased students' own personal awareness of interprofessional practice and helped them connect new learning to existing knowledge. How this translates into actual clinical or leadership practice is unknown and provides an important area for future investigation. [J Nurs Educ. 2017;56(10):618-622.]. Copyright 2017, SLACK Incorporated.

  20. VASA: Interactive Computational Steering of Large Asynchronous Simulation Pipelines for Societal Infrastructure. (United States)

    Ko, Sungahn; Zhao, Jieqiong; Xia, Jing; Afzal, Shehzad; Wang, Xiaoyu; Abram, Greg; Elmqvist, Niklas; Kne, Len; Van Riper, David; Gaither, Kelly; Kennedy, Shaun; Tolone, William; Ribarsky, William; Ebert, David S


    We present VASA, a visual analytics platform consisting of a desktop application, a component model, and a suite of distributed simulation components for modeling the impact of societal threats such as weather, food contamination, and traffic on critical infrastructure such as supply chains, road networks, and power grids. Each component encapsulates a high-fidelity simulation model that together form an asynchronous simulation pipeline: a system of systems of individual simulations with a common data and parameter exchange format. At the heart of VASA is the Workbench, a visual analytics application providing three distinct features: (1) low-fidelity approximations of the distributed simulation components using local simulation proxies to enable analysts to interactively configure a simulation run; (2) computational steering mechanisms to manage the execution of individual simulation components; and (3) spatiotemporal and interactive methods to explore the combined results of a simulation run. We showcase the utility of the platform using examples involving supply chains during a hurricane as well as food contamination in a fast food restaurant chain.

  1. Student outcomes associated with use of asynchronous online discussion forums in gross anatomy teaching. (United States)

    Green, Rodney A; Hughes, Diane L


    Asynchronous online discussion forums are increasingly common in blended learning environments but the relationship to student learning outcomes has not been reported for anatomy teaching. Forums were monitored in two multicampus anatomy courses; an introductory first year course and a second year physiotherapy-specific course. The forums are structured with a separate site for each course module and moderated weekly by staff. Students are encouraged to post to new threads (initial post) and answer queries in threads started by others (reply post). Analysis of forums was conducted separately for each course and included overall activity (posts and views) for a full semester and a detailed analysis for one week in the middle of semester. Students were classified as zero, moderate, or high contributors to the forums based on the number of posts. Final mark for the course was related to level of forum contribution using nonparametric tests. Forum threads were characterized as task-focused, administrative, or other. A higher proportion of second year (36%) than first-year (17%) students posted on the forums and the postings were more likely to be task-focused and student initiated. Second-year students that posted frequently to the forum gained a higher final mark for the course than those that did not post or only posted a moderate number of times (P higher proportion of administrative threads. Forums in anatomy courses can be powerful learning tools encouraging deeper learning and improved learning outcomes. Copyright © 2012 American Association of Anatomists.

  2. Blind Synchronization in Asynchronous UWB Networks Based on the Transmit-Reference Scheme

    Directory of Open Access Journals (Sweden)

    Leus Geert


    Full Text Available Ultra-wideband (UWB wireless communication systems are based on the transmission of extremely narrow pulses, with a duration inferior to a nanosecond. The application of transmit reference (TR to UWB systems allows to side-step channel estimation at the receiver, with a tradeoff of the effective transmission bandwidth, which is reduced by the usage of a reference pulse. Similar to CDMA systems, different users can share the same available bandwidth by means of different spreading codes. This allows the receiver to separate users, and to recover the timing information of the transmitted data packets. The nature of UWB transmissions—short, burst-like packets—requires a fast synchronization algorithm, that can accommodate several asynchronous users. Exploiting the fact that a shift in time corresponds to a phase rotation in the frequency domain, a blind and computationally effcient synchronization algorithm that takes advantage of the shift invariance structure in the frequency domain is proposed in this paper. Integer and fractional delay estimations are considered, along with a subsequent symbol estimation step. This results in a collision-avoiding multiuser algorithm, readily applicable to a fast acquisition procedure in a UWB ad hoc network.

  3. Asynchronous development of stigmatic receptivity in the pear (Pyrus communis; Rosaceae) flower. (United States)

    Sanzol, Javier; Rallo, Pilar; Herrero, María


    While stigma anatomy is well documented for a good number of species, little information is available on the acquisition and cessation of stigmatic receptivity. The aim of this work is to characterize the development of stigma receptivity, from anthesis to stigma degeneration, in the pentacarpellar pear (Pyrus communis) flower. Stigma development and stigmatic receptivity were monitored over two consecutive years, as the capacity of the stigmas to offer support for pollen germination and pollen tube growth. In an experiment where hand pollinations were delayed for specified times after anthesis, three different stigmatic developmental stages could be observed: (1) immature stigmas, which allow pollen adhesion but not hydration; (2) receptive stigmas, which allow proper pollen hydration and germination; and (3) degenerated stigmas, in which pollen hydrates and germinates properly, but pollen tube growth is impaired soon after germination. This developmental characterization showed that stigmas in different developmental stages coexist within a flower and that the acquisition and cessation of stigmatic receptivity by each carpel occur in a sequential manner. In this way, while the duration of stigmatic receptivity for each carpel is rather short, the flower has an expanded receptive period. This asynchronous period of receptivity for the different stigmas of a single flower is discussed as a strategy that could serve to maximize pollination resources under unreliable pollination conditions.

  4. Application of high performance asynchronous socket communication in power distribution automation (United States)

    Wang, Ziyu


    With the development of information technology and Internet technology, and the growing demand for electricity, the stability and the reliable operation of power system have been the goal of power grid workers. With the advent of the era of big data, the power data will gradually become an important breakthrough to guarantee the safe and reliable operation of the power grid. So, in the electric power industry, how to efficiently and robustly receive the data transmitted by the data acquisition device, make the power distribution automation system be able to execute scientific decision quickly, which is the pursuit direction in power grid. In this paper, some existing problems in the power system communication are analysed, and with the help of the network technology, a set of solutions called Asynchronous Socket Technology to the problem in network communication which meets the high concurrency and the high throughput is proposed. Besides, the paper also looks forward to the development direction of power distribution automation in the era of big data and artificial intelligence.

  5. Traffic Multiresolution Modeling and Consistency Analysis of Urban Expressway Based on Asynchronous Integration Strategy

    Directory of Open Access Journals (Sweden)

    Liyan Zhang


    Full Text Available The paper studies multiresolution traffic flow simulation model of urban expressway. Firstly, compared with two-level hybrid model, three-level multiresolution hybrid model has been chosen. Then, multiresolution simulation framework and integration strategies are introduced. Thirdly, the paper proposes an urban expressway multiresolution traffic simulation model by asynchronous integration strategy based on Set Theory, which includes three submodels: macromodel, mesomodel, and micromodel. After that, the applicable conditions and derivation process of the three submodels are discussed in detail. In addition, in order to simulate and evaluate the multiresolution model, “simple simulation scenario” of North-South Elevated Expressway in Shanghai has been established. The simulation results showed the following. (1 Volume-density relationships of three submodels are unanimous with detector data. (2 When traffic density is high, macromodel has a high precision and smaller error and the dispersion of results is smaller. Compared with macromodel, simulation accuracies of micromodel and mesomodel are lower but errors are bigger. (3 Multiresolution model can simulate characteristics of traffic flow, capture traffic wave, and keep the consistency of traffic state transition. Finally, the results showed that the novel multiresolution model can have higher simulation accuracy and it is feasible and effective in the real traffic simulation scenario.

  6. Operation Characteristics Optimization of Low Power Three-Phase Asynchronous Motors

    Directory of Open Access Journals (Sweden)

    VLAD, I.


    Full Text Available Most published papers on low power asynchronous motors were aimed to achieve better operational performances in different operating conditions. The optimal design of the general-purpose motors requires searching and selecting an electric machine to meet minimum operating costs criterion and certain customer imposed restrictive conditions. In this paper, there are many significant simulations providing qualitative and quantitative information on reducing active and reactive energy losses in motors, and on parameters and constructive solution. The optimization study applied the minimal operating costs criterion, and it took into account the starting restrictive conditions. Thirteen variables regarding electromagnetic stresses and main constructive dimensions were considered. The operating costs of the optimized motor decreased with 25.6%, as compared to the existing solution. This paper can be a practical and theoretical support for the development and implementation of modern design methods, based on theoretical and experimental study of stationary and transient processes in low power motors, to increase efficiency and power factor.

  7. Diagnostics and protection of the winding insulation of asynchronous motors operating in aggressive environments

    Directory of Open Access Journals (Sweden)

    Валерій Єгорович Кривоносов


    Full Text Available Asynchronous motors work under drastic dusty conditions at industrial enterprises. As a consequence dust and moisture work into the winding. The location where the winding gets out of the groove is subject to dynamic forces, it resulting in microcracks. As a result, conducting bridges are formed on the frontal end of the winding. The amount of current flowing through the dust layer depends on the material and its thickness. Studies of this issue have not been conducted in modern literature. The task of timely detection and diagnosis of the natural aging of insulation, its becoming dusty and wet is relevant. As a result of physical phenomena simulation the relationship curves of the surface resistance dependence on different materials and thicknesses of the dust layers have been obtained. An expression that makes it possible to define the current flowing through the layer of dust has been derived. The effect of moisture on the insulation resistance and the dust material has been defined. The corresponding curves have been obtained. The change in rate of surface conductance that makes it possible to diagnose the covering of the insulation surface with non-conductive dust has been defined. Based on the analysis and experimental modeling a method of timely detection of the winding becoming dusty and moist has been developed. This method is implemented in a device consisting of a low voltage source, an insulation resistance measuring unit, a surface state sensor, a signalling and switching unit, a microprocessor unit and a power supply unit

  8. An asynchronous data-driven readout prototype for CEPC vertex detector (United States)

    Yang, Ping; Sun, Xiangming; Huang, Guangming; Xiao, Le; Gao, Chaosong; Huang, Xing; Zhou, Wei; Ren, Weiping; Li, Yashu; Liu, Jianchao; You, Bihui; Zhang, Li


    The Circular Electron Positron Collider (CEPC) is proposed as a Higgs boson and/or Z boson factory for high-precision measurements on the Higgs boson. The precision of secondary vertex impact parameter plays an important role in such measurements which typically rely on flavor-tagging. Thus silicon CMOS Pixel Sensors (CPS) are the most promising technology candidate for a CEPC vertex detector, which can most likely feature a high position resolution, a low power consumption and a fast readout simultaneously. For the R&D of the CEPC vertex detector, we have developed a prototype MIC4 in the Towerjazz 180 nm CMOS Image Sensor (CIS) process. We have proposed and implemented a new architecture of asynchronous zero-suppression data-driven readout inside the matrix combined with a binary front-end inside the pixel. The matrix contains 128 rows and 64 columns with a small pixel pitch of 25 μm. The readout architecture has implemented the traditional OR-gate chain inside a super pixel combined with a priority arbiter tree between the super pixels, only reading out relevant pixels. The MIC4 architecture will be introduced in more detail in this paper. It will be taped out in May and will be characterized when the chip comes back.

  9. Hybrid EEG-fNIRS Asynchronous Brain-Computer Interface for Multiple Motor Tasks. (United States)

    Buccino, Alessio Paolo; Keles, Hasan Onur; Omurtag, Ahmet


    Non-invasive Brain-Computer Interfaces (BCI) have demonstrated great promise for neuroprosthetics and assistive devices. Here we aim to investigate methods to combine Electroencephalography (EEG) and functional Near-Infrared Spectroscopy (fNIRS) in an asynchronous Sensory Motor rhythm (SMR)-based BCI. We attempted to classify 4 different executed movements, namely, Right-Arm-Left-Arm-Right-Hand-Left-Hand tasks. Previous studies demonstrated the benefit of EEG-fNIRS combination. However, since normally fNIRS hemodynamic response shows a long delay, we investigated new features, involving slope indicators, in order to immediately detect changes in the signals. Moreover, Common Spatial Patterns (CSPs) have been applied to both EEG and fNIRS signals. 15 healthy subjects took part in the experiments and since 25 trials per class were available, CSPs have been regularized with information from the entire population of participants and optimized using genetic algorithms. The different features have been compared in terms of performance and the dynamic accuracy over trials shows that the introduced methods diminish the fNIRS delay in the detection of changes.

  10. Asynchronous onset of eutrophication among shallow prairie lakes of the Northern Great Plains, Alberta, Canada. (United States)

    Maheaux, Heather; Leavitt, Peter R; Jackson, Leland J


    Coherent timing of agricultural expansion, fertilizer application, atmospheric nutrient deposition, and accelerated global warming is expected to promote synchronous fertilization of regional surface waters and coherent development of algal blooms and lake eutrophication. While broad-scale cyanobacterial expansion is evident in global meta-analyses, little is known of whether lakes in discrete catchments within a common lake district also exhibit coherent water quality degradation through anthropogenic forcing. Consequently, the primary goal of this study was to determine whether agricultural development since ca. 1900, accelerated use of fertilizer since 1960, atmospheric deposition of reactive N, or regional climate warming has resulted in coherent patterns of eutrophication of surface waters in southern Alberta, Canada. Unexpectedly, analysis of sedimentary pigments as an index of changes in total algal abundance since ca. 1850 revealed that while total algal abundance (as β-carotene, pheophytin a) increased in nine of 10 lakes over 150 years, the onset of eutrophication varied by a century and was asynchronous across basins. Similarly, analysis of temporal sequences with least-squares regression revealed that the relative abundance of cyanobacteria (echinenone) either decreased or did not change significantly in eight of the lakes since ca. 1850, whereas purple sulfur bacteria (as okenone) increased significantly in seven study sites. These patterns are consistent with the catchment filter hypothesis, which posits that lakes exhibit unique responses to common forcing associated with the influx of mass as water, nutrients, or particles. © 2015 John Wiley & Sons Ltd.

  11. Monitoring the growth and drug susceptibility of individual bacteria using asynchronous magnetic bead rotation sensors. (United States)

    Kinnunen, Paivo; Sinn, Irene; McNaughton, Brandon H; Newton, Duane W; Burns, Mark A; Kopelman, Raoul


    Continuous growth of individual bacteria has been previously studied by direct observation using optical imaging. However, optical microscopy studies are inherently diffraction limited and limited in the number of individual cells that can be continuously monitored. Here we report on the use of the asynchronous magnetic bead rotation (AMBR) sensor, which is not diffraction limited. The AMBR sensor allows for the measurement of nanoscale growth dynamics of individual bacterial cells, over multiple generations. This torque-based magnetic bead sensor monitors variations in drag caused by the attachment and growth of a single bacterial cell. In this manner, we observed the growth and division of individual Escherichia coli, with 80-nm sensitivity to the cell length. Over the life cycle of a cell, we observed up to a 300% increase in the rotational period of the biosensor due to increased cell volume. In addition, we observed single bacterial cell growth response to antibiotics. This work demonstrates the non-microscopy limited AMBR biosensor for monitoring individual cell growth dynamics, including cell elongation, generation time, lag time, and division, as well as their sensitivity to antibiotics. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. Analysis of an unconfined aquifer subject to asynchronous dual-tide propagation (United States)

    Rotzoll, K.; El-Kadi, A. I.; Gingerich, S.B.


    Most published solutions for aquifer responses to ocean tides focus on the one-sided attenuation of the signal as it propagates inland. However, island aquifers experience periodic forcing from the entire coast, which can lead to integrated effects of different tidal signals, especially on narrow high-permeability islands. In general, studies disregard a potential time lag as the tidal wave sweeps around the island. We present a one-dimensional analytical solution to the ground water flow equation subject to asynchronous and asymmetric oscillating head conditions on opposite boundaries and test it on data from an unconfined volcanic aquifer in Maui. The solution considers sediment-damping effects at the coastline. The response of Maui Aquifers indicate that water table elevations near the center of the aquifer are influenced by a combination of tides from opposite coasts. A better match between the observed ground water head and the theoretical response can be obtained with the proposed dual-tide solution than with single-sided solutions. Hydraulic diffusivity was estimated to be 2.3 ?? 107 m 2/d. This translates into a hydraulic conductivity of 500 m/d, assuming a specific yield of 0.04 and an aquifer thickness of 1.8 km. A numerical experiment confirmed the hydraulic diffusivity value and showed that the y-intercepts of the modal attenuation and phase differences estimated by regression can approximate damping factors caused by low-permeability units at the boundary.

  13. The recalibration patterns of perceptual synchrony and multisensory integration after exposure to asynchronous speech. (United States)

    Yuan, Xiangyong; Bi, Cuihua; Yin, Huazhan; Li, Baolin; Huang, Xiting


    Perceptual synchrony and multisensory integration both vary as a function of stimulus onset asynchrony, but evidences from behavioral, patient, and lesion studies all support some dissociation between these two processes. Although it has been found that both perceptual synchrony and multisensory integration are recalibrated after exposure to asynchronous multisensory stimuli, no studies have directly compared these two recalibration patterns. We addressed this by using McGurk speech and requiring participants to perform simultaneity judgments and a syllable identification task in separate sessions. The results revealed that after exposure to asynchrony, both perceptual synchrony and McGurk fusion shifted toward the temporal lag. The recalibration aftereffects (i.e., the magnitude of shifts) of these two processes have no significant difference and correlation. In addition, McGurk fusion increased strongly at the direction of the temporal lag, which could not be fully explained by fusion shifts. Thus, the present research implies that recalibration patterns of explicit and implicit timing represented by perceptual synchrony and multisensory integration have both similarity and difference. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. An investigation of assessment and feedback practices in fully asynchronous online undergraduate mathematics courses (United States)

    Trenholm, Sven; Alcock, Lara; Robinson, Carol


    Research suggests it is difficult to learn mathematics in the fully asynchronous online (FAO) instructional modality, yet little is known about associated teaching and assessment practices. In this study, we investigate FAO mathematics assessment and feedback practices in particular consideration of both claims and findings that these practices have a powerful influence on learning. A survey questionnaire was constructed and completed by 70 FAO undergraduate mathematics instructors, mostly from the USA, who were each asked to detail their assessment and feedback practices in a single FAO mathematics course. Alongside these questions, participants also answered the 16-item version of the Approaches to Teaching Inventory. In addition, a novel feedback framework was also created and used to examine how feedback practices may be related to participants' approaches to teaching. Results show that assessment and feedback practices are varied and complex: in particular, we found there was not a simple emphasis on summative assessment instruments, nor a concomitant expectation these would always be invigilated. Though richer assessment feedback appears to be emphasized, evidence suggests this feedback may not be primarily directed at advancing student learning. Moreover, we found evidence of a reliance on computer--human interactions (e.g. via computer-assisted assessment systems) and further evidence of a decline in human interactions, suggesting a dynamic that is both consistent with current online learning theory and claims FAO mathematics courses are becoming commodified. Several avenues for further research are suggested.

  15. Conceptualising and measuring collaborative critical thinking on asynchronous discussion forums: Challenges and possible solutions

    Directory of Open Access Journals (Sweden)

    Nazanin Ghodrati


    Full Text Available The use of asynchronous discussion forums (ADFs is thought to assist in enhancing students’ collaborative learning and critical thinking throughout higher education. However, previous research has mainly focused on individual critical thinking while the investigation of critical thinking during group work has been generally overlooked. Furthermore, few studies have investigated critical thinking processes of the individual and of the group in a single study to present a comprehensive picture of collaborative critical thinking (CCT. To address these gaps, I examined the demonstration of CCT on ADFs in a graduate subject at an Australian university over two academic semesters as students discussed topics online. In this paper, I discuss the ontological and methodological challenges in conducting the above research and present possible solutions to these challenges. At the ontological level, I discuss challenges in conceptualising and defining CCT. At the methodological level, I present challenges in constructing a coding scheme to measure the demonstration of CCT on ADFs. I then discuss ways to tackle the above challenges, propose an operational definition of CCT and present a synthetic coding scheme for measuring CCT in computer-supported collaborative learning contexts such as on ADFs.

  16. Mutual and asynchronous anticipation and action in sports as globally competitive and locally coordinative dynamics (United States)

    Fujii, Keisuke; Isaka, Tadao; Kouzaki, Motoki; Yamamoto, Yuji


    Humans interact by changing their actions, perceiving other’s actions and executing solutions in conflicting situations. Using oscillator models, nonlinear dynamics have been considered for describing these complex human movements as an emergence of self-organisation. However, these frameworks cannot explain the hierarchical structures of complex behaviours between conflicting inter-agent and adapting intra-agent systems, especially in sport competitions wherein mutually quick decision making and execution are required. Here we adopt a hybrid multiscale approach to model an attack-and-defend game during which both players predict the opponent’s movement and move with a delay. From both simulated and measured data, one synchronous outcome between two-agent (i.e. successful defence) can be described as one attractor. In contrast, the other coordination-breaking outcome (i.e. successful attack) cannot be explained using gradient dynamics because the asymmetric interaction cannot always assume a conserved physical quantity. Instead, we provide the asymmetric and asynchronous hierarchical dynamical models to discuss two-agent competition. Our framework suggests that possessing information about an opponent and oneself in local-coordinative and global-competitive scale enables us to gain a deeper understanding of sports competitions. We anticipate developments in the scientific fields of complex movement adapting to such uncontrolled environments.

  17. How do general practice residents use social networking sites in asynchronous distance learning? (United States)

    Maisonneuve, Hubert; Chambe, Juliette; Lorenzo, Mathieu; Pelaccia, Thierry


    Blended learning environments - involving both face-to-face and remote interactions - make it easier to adapt learning programs to constraints such as residents' location and low teacher-student ratio. Social networking sites (SNS) such as Facebook®, while not originally intended to be used as learning environments, may be adapted for the distance-learning part of training programs. The purpose of our study was to explore the use of SNS for asynchronous distance learning in a blended learning environment as well as its influence on learners' face-to-face interactions. We conducted a qualitative study and carried out semi-structured interviews. We performed purposeful sampling for maximal variation to include eight general practice residents in 2(nd) and 3(rd) year training. A thematic analysis was performed. The social integration of SNS facilitates the engagement of users in their learning tasks. This may also stimulate students' interactions and group cohesion when members meet up in person. Most of the general practice residents who work in the blended learning environment we studied had a positive appraisal on their use of SNS. In particular, we report a positive impact on their engagement in learning and their participation in discussions during face-to-face instruction. Further studies are needed in order to evaluate the effectiveness of SNS in blended learning environments and the appropriation of SNS by teachers.

  18. Enhancement of asynchronous release from fast-spiking interneuron in human and rat epileptic neocortex.

    Directory of Open Access Journals (Sweden)

    Man Jiang

    Full Text Available Down-regulation of GABAergic inhibition may result in the generation of epileptiform activities. Besides spike-triggered synchronous GABA release, changes in asynchronous release (AR following high-frequency discharges may further regulate epileptiform activities. In brain slices obtained from surgically removed human neocortical tissues of patients with intractable epilepsy and brain tumor, we found that AR occurred at GABAergic output synapses of fast-spiking (FS neurons and its strength depended on the type of connections, with FS autapses showing the strongest AR. In addition, we found that AR depended on residual Ca²⁺ at presynaptic terminals but was independent of postsynaptic firing. Furthermore, AR at FS autapses was markedly elevated in human epileptic tissue as compared to non-epileptic tissue. In a rat model of epilepsy, we found similar elevation of AR at both FS autapses and synapses onto excitatory neurons. Further experiments and analysis showed that AR elevation in epileptic tissue may result from an increase in action potential amplitude in the FS neurons and elevation of residual Ca²⁺ concentration. Together, these results revealed that GABAergic AR occurred at both human and rat neocortex, and its elevation in epileptic tissue may contribute to the regulation of epileptiform activities.

  19. The influence of rhythm and personality in the endurance response to motivational asynchronous music. (United States)

    Crust, Lee; Clough, Peter J


    In this study, we examined participants' responses to motivational asynchronous music by isolating rhythmical properties and exploring personality correlates. Fifty-eight physically active participants (41 men and 17 women) aged 22.3 +/- 6.4 years performed an isometric weight-holding task on three occasions while being randomly exposed to no music, rhythm and motivational music. The rhythm and music conditions were edited portions of the same musical selection and had identical fast tempi, although the rhythm condition contained no melody, harmonies or lyrics. Participants each completed a copy of Cattell's 16PF following the third and final trial. A repeated-measures analysis of variance found the participants held the weight suspended for significantly longer when listening to motivational music in comparison to rhythm or no music. When listening to rhythm, participants endured the task for significantly longer than when listening to no music. The response to music was found to be significantly related to liveliness, while sensitivity correlated with responses to music factors (harmony, melody, lyrics, etc.) not present in the rhythm condition. These results suggest that responses to motivational music are subtle in nature and are determined by both musical factors and individual characteristics, and potentially an interaction between the two.

  20. SocialRAD: an infrastructure for a secure, cooperative, asynchronous teleradiology system. (United States)

    Figueiredo, João Filho Matos; Motta, Gustavo Henrique Matos Bezerra


    The popularity of teleradiology services has enabled a major advance in the provision of health services to areas with difficult geographical access. However, this potential has also brought with it a number of challenges: the large volume of data, characteristic of imaging tests, and security requirements designed to ensure confidentiality and integrity. Moreover, there is also a number of ethical questions involving the dominant model on the market, whereby this service is outsourced to private companies, and is not directly undertaken by professional radiologists. Therefore, the present paper proposes a cooperative model of teleradiology, where health professionals interact directly with the hospitals providing patient care. This has involved the integration of a wide range of technologies, such as the interconnection models Peer-to-Peer, Cloud Computing, Dynamic DNS, RESTful Web Services, as well as security and interoperability standards, with the aim of promoting a secure, collaborative asynchronous environment. The developed model is currently being used on an experimental basis, providing teleradiology support to cities in the north-eastern hinterland of Brazil, and is fulfilling all expectations.

  1. An Asynchronous Many-Task Implementation of In-Situ Statistical Analysis using Legion.

    Energy Technology Data Exchange (ETDEWEB)

    Pebay, Philippe Pierre [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bennett, Janine Camille [Sandia National Lab. (SNL-CA), Livermore, CA (United States)


    In this report, we propose a framework for the design and implementation of in-situ analy- ses using an asynchronous many-task (AMT) model, using the Legion programming model together with the MiniAero mini-application as a surrogate for full-scale parallel scientific computing applications. The bulk of this work consists of converting the Learn/Derive/Assess model which we had initially developed for parallel statistical analysis using MPI [PTBM11], from a SPMD to an AMT model. In this goal, we propose an original use of the concept of Legion logical regions as a replacement for the parallel communication schemes used for the only operation of the statistics engines that require explicit communication. We then evaluate this proposed scheme in a shared memory environment, using the Legion port of MiniAero as a proxy for a full-scale scientific application, as a means to provide input data sets of variable size for the in-situ statistical analyses in an AMT context. We demonstrate in particular that the approach has merit, and warrants further investigation, in collaboration with ongoing efforts to improve the overall parallel performance of the Legion system.

  2. Hybrid EEG-fNIRS Asynchronous Brain-Computer Interface for Multiple Motor Tasks.

    Directory of Open Access Journals (Sweden)

    Alessio Paolo Buccino

    Full Text Available Non-invasive Brain-Computer Interfaces (BCI have demonstrated great promise for neuroprosthetics and assistive devices. Here we aim to investigate methods to combine Electroencephalography (EEG and functional Near-Infrared Spectroscopy (fNIRS in an asynchronous Sensory Motor rhythm (SMR-based BCI. We attempted to classify 4 different executed movements, namely, Right-Arm-Left-Arm-Right-Hand-Left-Hand tasks. Previous studies demonstrated the benefit of EEG-fNIRS combination. However, since normally fNIRS hemodynamic response shows a long delay, we investigated new features, involving slope indicators, in order to immediately detect changes in the signals. Moreover, Common Spatial Patterns (CSPs have been applied to both EEG and fNIRS signals. 15 healthy subjects took part in the experiments and since 25 trials per class were available, CSPs have been regularized with information from the entire population of participants and optimized using genetic algorithms. The different features have been compared in terms of performance and the dynamic accuracy over trials shows that the introduced methods diminish the fNIRS delay in the detection of changes.

  3. A high level implementation and performance evaluation of level-I asynchronous cache on FPGA

    Directory of Open Access Journals (Sweden)

    Mansi Jhamb


    Full Text Available To bridge the ever-increasing performance gap between the processor and the main memory in a cost-effective manner, novel cache designs and implementations are indispensable. Cache is responsible for a major part of energy consumption (approx. 50% of processors. This paper presents a high level implementation of a micropipelined asynchronous architecture of L1 cache. Due to the fact that each cache memory implementation is time consuming and error-prone process, a synthesizable and a configurable model proves out to be of immense help as it aids in generating a range of caches in a reproducible and quick fashion. The micropipelined cache, implemented using C-Elements acts as a distributed message-passing system. The RTL cache model implemented in this paper, comprising of data and instruction caches has a wide array of configurable parameters. In addition to timing robustness our implementation has high average cache throughput and low latency. The implemented architecture comprises of two direct-mapped, write-through caches for data and instruction. The architecture is implemented in a Field Programmable Gate Array (FPGA chip using Very High Speed Integrated Circuit Hardware Description Language (VHSIC HDL along with advanced synthesis and place-and-route tools.


    Directory of Open Access Journals (Sweden)

    D. S. Yarymbash


    Full Text Available Purpose. Development of new effective approach for the realization of three-dimensional mathematical model of transient electrical and magnetic fields in induction motors, which based on their design features, the nonlinearity of the electrical and magnetic properties of the active and structural materials, which provides adequacy or high simulation accuracy. Research methods. Numerical simulation of the conjugate spatial transient electrical and magnetic fields of the induction motor in the mode of short-circuit, with the help of methods of the theory of electromagnetic fields, finite element, theory of electrical machines and electrical circuits. The obtained results. Theoretical researches and simulation results, which based on numerical realization of the finite element method of three-dimensional mathematical model of the induction motor are obtained. Theoretical researches indicate the features of electrical and magnetic processes of AC power conversion in a short circuit mode. In the area of the coil ends of the low power asynchronous motor it is allocated to 12,5% of the total energy of its magnetic field, which is mainly localized in the active part of the stator, the rotor and the air gap. In the central area of the active part of the induction motor, the length is up to 60% of the total length of the stator and rotor core, the magnetic field has plane-parallel form, but is transformed into zones of coil ends of the stator windings, and near of its core end. The features of the magnetic field and energy distribution, which have a significant effect on the parameters of a short-circuit of small power induction motor and its operating modes are defined. Scientific novelty. The regularities of the distribution of the induction and magnetic field energy in the short-circuit mode and their quantitative relation for active zone and the area of the coil ends of the stator windings of the low-power asynchronous motors are defined. Practical

  5. Babies know bad dancing when they see it: Older but not younger infants discriminate between synchronous and asynchronous audiovisual musical displays. (United States)

    Hannon, Erin E; Schachner, Adena; Nave-Blodgett, Jessica E


    Movement to music is a universal human behavior, yet little is known about how observers perceive audiovisual synchrony in complex musical displays such as a person dancing to music, particularly during infancy and childhood. In the current study, we investigated how perception of musical audiovisual synchrony develops over the first year of life. We habituated infants to a video of a person dancing to music and subsequently presented videos in which the visual track was matched (synchronous) or mismatched (asynchronous) with the audio track. In a visual-only control condition, we presented the same visual stimuli with no sound. In Experiment 1, we found that older infants (8-12months) exhibited a novelty preference for the mismatched movie when both auditory information and visual information were available and showed no preference when only visual information was available. By contrast, younger infants (5-8months) in Experiment 2 did not discriminate matching stimuli from mismatching stimuli. This suggests that the ability to perceive musical audiovisual synchrony may develop during the second half of the first year of infancy. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Modélisation et commande vectorielle d'un moteur asynchrone saturé avec contrôle dynamique du flux (United States)

    Lemaire-Semail, B.; Bouillault, F.; Razek, A.


    A numerical computation of squirrel cage induction machine parameters is presented, using the finite element method. The effects of main field saturation are studied, and the different parameters can be calculated for any magnetic condition. To take into account magnetic state variations, a dynamic mutual inductance is introduced in the saturated machine model. All these parameters values are used in modelling a field oriented controlled machine; the system realization is described and several experimental results are given. Interesting simulation results are also presented, especially in the field weakening range. Une méthode de calcul par éléments finis des paramètres électriques d'une machine asynchrone à cage rotorique est présentée, permettant en particulier d'étudier l'influence de la saturation magnétique sur le modèle de la machine. A cet effet, une inductance mutuelle dynamique est introduite. Ces paramètres sont ensuite utilisés dans une commande vectorielle de la machine dont la mise en place est décrite, accompagnée de résultats expérimentaux. Des résultats de simulation sont également joints, notamment concernant les fonctionnements en désexcitation.

  7. Asynchronous brain-computer interface for cognitive assessment in people with cerebral palsy (United States)

    Alcaide-Aguirre, R. E.; Warschausky, S. A.; Brown, D.; Aref, A.; Huggins, J. E.


    Objective. Typically, clinical measures of cognition require motor or speech responses. Thus, a significant percentage of people with disabilities are not able to complete standardized assessments. This situation could be resolved by employing a more accessible test administration method, such as a brain-computer interface (BCI). A BCI can circumvent motor and speech requirements by translating brain activity to identify a subject’s response. By eliminating the need for motor or speech input, one could use a BCI to assess an individual who previously did not have access to clinical tests. Approach. We developed an asynchronous, event-related potential BCI-facilitated administration procedure for the peabody picture vocabulary test (PPVT-IV). We then tested our system in typically developing individuals (N  =  11), as well as people with cerebral palsy (N  =  19) to compare results to the standardized PPVT-IV format and administration. Main results. Standard scores on the BCI-facilitated PPVT-IV, and the standard PPVT-IV were highly correlated (r  =  0.95, p  <  0.001), with a mean difference of 2.0  ±  6.4 points, which is within the standard error of the PPVT-IV. Significance. Thus, our BCI-facilitated PPVT-IV provided comparable results to the standard PPVT-IV, suggesting that populations for whom standardized cognitive tests are not accessible could benefit from our BCI-facilitated approach.

  8. Amplification of asynchronous inhibition-mediated synchronization by feedback in recurrent networks.

    Directory of Open Access Journals (Sweden)

    Sashi Marella


    Full Text Available Synchronization of 30-80 Hz oscillatory activity of the principle neurons in the olfactory bulb (mitral cells is believed to be important for odor discrimination. Previous theoretical studies of these fast rhythms in other brain areas have proposed that principle neuron synchrony can be mediated by short-latency, rapidly decaying inhibition. This phasic inhibition provides a narrow time window for the principle neurons to fire, thus promoting synchrony. However, in the olfactory bulb, the inhibitory granule cells produce long lasting, small amplitude, asynchronous and aperiodic inhibitory input and thus the narrow time window that is required to synchronize spiking does not exist. Instead, it has been suggested that correlated output of the granule cells could serve to synchronize uncoupled mitral cells through a mechanism called "stochastic synchronization", wherein the synchronization arises through correlation of inputs to two neural oscillators. Almost all work on synchrony due to correlations presumes that the correlation is imposed and fixed. Building on theory and experiments that we and others have developed, we show that increased synchrony in the mitral cells could produce an increase in granule cell activity for those granule cells that share a synchronous group of mitral cells. Common granule cell input increases the input correlation to the mitral cells and hence their synchrony by providing a positive feedback loop in correlation. Thus we demonstrate the emergence and temporal evolution of input correlation in recurrent networks with feedback. We explore several theoretical models of this idea, ranging from spiking models to an analytically tractable model.

  9. The theory of asynchronous relative motion I: time transformations and nonlinear corrections (United States)

    Roa, Javier; Peláez, Jesús


    Using alternative independent variables in lieu of time has important advantages when propagating the partial derivatives of the trajectory. This paper focuses on spacecraft relative motion, but the concepts presented here can be extended to any problem involving the variational equations of orbital motion. A usual approach for modeling the relative dynamics is to evaluate how the reference orbit changes when modifying the initial conditions slightly. But when the time is a mere dependent variable, changes in the initial conditions will result in changes in time as well: a time delay between the reference and the neighbor solution will appear. The theory of asynchronous relative motion shows how the time delay can be corrected to recover the physical sense of the solution and, more importantly, how this correction can be used to improve significantly the accuracy of the linear solutions to relative motion found in the literature. As an example, an improved version of the Clohessy-Wiltshire (CW) solution is presented explicitly. The correcting terms are extremely compact, and the solution proves more accurate than the second and even third order CW equations for long propagations. The application to the elliptic case is also discussed. The theory is not restricted to Keplerian orbits, as it holds under any perturbation. To prove this statement, two examples of realistic trajectories are presented: a pair of spacecraft orbiting the Earth and perturbed by a realistic force model; and two probes describing a quasi-periodic orbit in the Jupiter-Europa system subject to third-body perturbations. The numerical examples show that the new theory yields reductions in the propagation error of several orders of magnitude, both in position and velocity, when compared to the linear approach.

  10. Multi-Threshold NULL Convention Logic (MTNCL: An Ultra-Low Power Asynchronous Circuit Design Methodology

    Directory of Open Access Journals (Sweden)

    Liang Zhou


    Full Text Available This paper develops an ultra-low power asynchronous circuit design methodology, called Multi-Threshold NULL Convention Logic (MTNCL, also known as Sleep Convention Logic (SCL, which combines Multi-Threshold CMOS (MTCMOS with NULL Convention Logic (NCL, to yield significant power reduction without any of the drawbacks of applying MTCMOS to synchronous circuits. In contrast to other power reduction techniques that usually result in large area overhead, MTNCL circuits are actually smaller than their original NCL versions. MTNCL utilizes high-Vt transistors to gate power and ground of a low-Vt logic block to provide for both fast switching and very low leakage power when idle. To demonstrate the advantages of MTNCL, a number of 32-bit IEEE single-precision floating-point co-processors were designed for comparison using the 1.2 V IBM 8RF-LM 130 nm CMOS process: original NCL, MTNCL with just combinational logic (C/L slept, Bit-Wise MTNCL (BWMTNCL, MTNCL with C/L and completion logic slept, MTNCL with C/L, completion logic, and registers slept, MTNCL with Safe Sleep architecture, and synchronous MTCMOS. These designs are compared in terms of throughput, area, dynamic energy, and idle power, showing the tradeoffs between the various MTNCL architectures, and that the best MTNCL design is much better than the original NCL design in all aspects, and much better than the synchronous MTCMOS design in terms of area, energy per operation, and idle power, although the synchronous design can operate faster.

  11. Transcultural psychiatry made simple--asynchronous telepsychiatry as an approach to providing culturally relevant care. (United States)

    Yellowlees, Peter M; Odor, Alberto; Iosif, Ana-Maria; Parish, Michelle Burke; Nafiz, Najia; Patrice, Kesha; Xiong, Glen; McCaron, Robert; Sanchez, Richard; Ochoa, Enrique; Hilty, Donald


    To examine the feasibility and diagnostic reliability of asynchronous telepsychiatry (ATP) consultations in Spanish and ATP consultation with Spanish-to-English translation. Twenty-four interviews of Spanish-speaking patients were videorecorded by a bilingual clinician who also collected patient history data and gave the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) to each patient. The ATP data (video of the interview and patient history) were forwarded for psychiatric consultation and a diagnostic assessment by the investigators. The ATP data were then examined separately by two Spanish-speaking psychiatrists, before being translated into English and then re-examined by two English-speaking psychiatrists. Agreement between the expert diagnoses of the investigators and the diagnoses from the Spanish consultations, the Spanish-to-English translated consultations, and the SCID-I results was assessed using kappa statistics. We found acceptable levels of agreement for major diagnostic groupings among the Spanish- and English-speaking psychiatrists. Kappa values for diagnostic agreement between the expert and the translated consultations, the original language consultations, and the SCID-I were at least 0.52 (percentage agreement, 79%) and higher. ATP consultations in Spanish, and those translated from Spanish to English, are feasible, and broad diagnostic reliability was achieved. The ATP process allows for rapid language translation. This approach could be useful across national boundaries and in numerous ethnic groups. Cross-language ATP may also offer significant benefits over the use of real-time interpreting services and has the potential to improve the quality of care by allowing for the addition of culturally relevant information.

  12. A bio-inspired asynchronous skin system for crack detection applications (United States)

    Sharp, Nathan; Kuntz, Alan; Brubaker, Cole; Amos, Stephanie; Gao, Wei; Gupta, Gautum; Mohite, Aditya; Farrar, Charles; Mascareñas, David


    In many applications of structural health monitoring (SHM) it is imperative or advantageous to have large sensor arrays in order to properly sense the state of health of the structure. Typically these sensor networks are implemented by placing a large number of sensors over a structure and running individual cables from each sensor back to a central measurement station. Data is then collected from each sensor on the network at a constant sampling rate regardless of the current timescales at which events are acting on the structure. These conventional SHM sensor networks have a number of shortfalls. They tend to have a large number of cables that can represent a single point of failure for each sensor as well as add significant weight and installation costs. The constant sampling rate associated with each sensor very quickly leads to large amounts of data that must be analyzed, stored, and possibly transmitted to a remote user. This leads to increased demands on power consumption, bandwidth, and size. It also taxes our current techniques for managing large amounts of data. For the last decade the goal of the SHM community has been to endow structures with the functionality of a biological nervous system. Despite this goal the community has predominantly ignored the biological nervous system as inspiration for building structural nervous systems, choosing instead to focus on experimental mechanics and simulation techniques. In this work we explore the use of a novel, bio-inspired, SHM skin. This skin makes use of distributed computing and asynchronous communication techniques to alleviate the scale of the data management challenge as well as reduce power. The system also periodically sends a ‘heat beat’ signal to provide state-of-health updates. This conductive skin was implemented using conductive ink resistors as well as with graphene-oxide capacitors.

  13. Asynchronous spread spectrum communication for a micro-miniature transponder: implementation and test results (United States)

    Holmes, David R., III; Welch, E. B.; Philpott, Rick A.; Coker, Jonathan D.; Schaefer, Timothy M.; Gilbert, Barry K.; Daniel, Erik S.


    While the field of wireless communication has developed dramatically over the past several decades, there are several notable applications of wireless technologies which impose constraints on power-consumption and form-factor that are not compatible with commercial technologies such as 802.11a,b,g or Bluetooth. These applications include implantable devices and remote monitoring devices. Such devices are better suited to transponder technology which is more power-efficient and can sustain data rates acceptable for these applications. Using a well-defined set of functional needs and system restrictions, we have developed an ultra-compact and ultra-low-powered transponder which contains spread spectrum (SS) logic for wireless communications. The transponder chip was designed and built in the Jazz BiCMOS SiGe technology. The device is activated via a pure tone and emits a SS response which is modulated over the carrier with binary phase shift keying (BPSK). The SS signal is a Gold Code generated from two 9-bit m-sequence generators. One of the m-sequences is seeded with a fixed value while the other 9-bit register is pinned out and can be a fixed ID or a bus to transmit data from a microcontroller. The data is received and decoded by a standard PC with a high-speed acquisition board. In order to support multiple devices at various distances, asynchronous decoding is applied. When active, the device draws less than 35 mW of power (@ 3.0V). Assuming a duty cycle of less than 1%, the device can be powered for several days using a very small coin battery. The device has been tested in the laboratory; natural environment testing is underway.

  14. Asynchronous spread spectrum communication for a microminiature transponder: implementation and test results (United States)

    Holmes, David R., III; Welch, E. B.; Philpott, Rick A.; Coker, Jonathan D.; Schaefer, Timothy M.; Gilbert, Barry K.; Daniel, Erik S.


    While the field of wireless communication has developed dramatically over the past several decades, there are several notable applications of wireless technologies which impose constraints on power-consumption and form-factor that are not compatible with cutting edge technologies. These applications include implantable devices and remote monitoring devices. Using a well-defined set of functional needs and system restrictions, we have developed an ultra-compact and ultra-low-powered transponder which contains spread spectrum (SS) logic for wireless communications. The transponder chip was designed and built in the Jazz BiCMOS SiGe technology. The device is activated via a pure tone and emits a SS response which is modulated over the carrier with binary phase shift keying (BPSK). The SS signal is a gold-code generated from two 9-bit m-sequence generators. One of the m-sequences is seeded with a fixed value while the other 9-bit register is pinned out and can be a fixed ID or a bus to transmit data from a microcontroller. The data is received and decoded by a standard PC with a high-speed acquisition board. In order to support multiple devices at various distances, asynchronous decoding is applied. When active, the device draws less than 35 mA of current. Because the duty cycle of this device is likely less than 1%, the device can be powered for several hours using a very small coin battery. The device has been tested both in the lab and natural environment testing is underway. Future work will combine the device with a microcontroller in the field to achieve specific monitoring goals.

  15. Simultaneous and independent optical impairments monitoring using singular spectrum analysis of asynchronously sampled signal amplitudes (United States)

    Guesmi, Latifa; Menif, Mourad


    Optical performance monitoring (OPM) becomes an inviting topic in high speed optical communication networks. In this paper, a novel technique of OPM based on a new elaborated computation approach of singular spectrum analysis (SSA) for time series prediction is presented. Indeed, various optical impairments among chromatic dispersion (CD), polarization mode dispersion (PMD) and amplified spontaneous emission (ASE) noise are a major factors limiting quality of transmission data in the systems with data rates lager than 40 Gbit/s. This technique proposed an independent and simultaneous multi-impairments monitoring, where we used SSA of time series analysis and forecasting. It has proven their usefulness in the temporal analysis of short and noisy time series in several fields, that it is based on the singular value decomposition (SVD). Also, advanced optical modulation formats (100 Gbit/s non-return-to zero dual-polarization quadrature phase shift keying (NRZ-DP-QPSK) and 160 Gbit/s DP-16 quadrature amplitude modulation (DP-16QAM)) offering high spectral efficiencies have been successfully employed by analyzing their asynchronously sampled amplitude. The simulated results proved that our method is efficient on CD, first-order PMD, Q-factor and OSNR monitoring, which enabled large monitoring ranges, the CD in the range of 170-1700 ps/nm.Km and 170-1110 ps/nm.Km for 100 Gbit/s NRZ-DP-QPSK and 160 Gbit/s DP-16QAM respectively, and also the DGD up to 20 ps is monitored. We could accurately monitor the OSNR in the range of 10-40 dB with monitoring error remains less than 1 dB in the presence of large accumulated CD.

  16. Fault Detection based on MCSA for a 400Hz Asynchronous Motor for Airborne Applications

    Directory of Open Access Journals (Sweden)

    Steffen Haus


    Full Text Available Future health monitoring concepts in different fields of engineering require reliable fault detection to avoid unscheduled machine downtime. Diagnosis of electrical induction machines for industrial applications is widely discussed in literature. In aviation industry, this topic is still only rarely discussed.A common approach to health monitoring for electrical induction machines is to use Motor Current Signature Analysis (MCSA based on a Fast Fourier Transform (FFT. Research results on this topic are available for comparatively large motors, where the power supply is typically based on 50Hz alternating current, which is the general power supply frequency for industrial applications.In this paper, transferability to airborne applications, where the power supply is 400Hz, is assessed. Three phase asynchronous motors are used to analyse detectability of different motor faults. The possibility to transfer fault detection results from 50Hz to 400Hz induction machines is the main question answered in this research work. 400Hz power supply frequency requires adjusted motor design, causing increased motor speed compared to 50Hz supply frequency. The motor used for experiments in this work is a 800W motor with 200V phase to phase power supply, powering an avionic fan. The fault cases to be examined are a bearing fault, a rotor unbalance, a stator winding fault, a broken rotor bar and a static air gap eccentricity. These are the most common faults in electrical induction machines which can cause machine downtime. The focus of the research work is the feasibility of the application of MCSA for small scale, high speed motor design, using the Fourier spectra of the current signal.Detectability is given for all but the bearing fault, although rotor unbalance can only be detected in case of severe damage level. Results obtained in the experiments are interpreted with respect to the motor design. Physical interpretation are given in case the results differ

  17. Contradictory indications from terrestrial archives for the asynchronous LGM glaciation in the Central Spanish Pyrenees (United States)

    Hirsch, Florian; Raab, Thomas


    Studies from several Mediterranean sites suggest a nonuniform glaciation during the last glacial cycle. For the Pyrenees an asynchronous maximum ice extent compared to the global last glacial maximum (LGM) is controversially discussed. Our study sites are located in the Central Spanish Pyrenees, namely the Aragon and Gallego Valley. Both valleys are type locations for the Pleistocene glaciations and the early maximum ice extent for the Pyrenees was dated amongst other sites in the Gallego Valley to about 36 ka. Due to the potential time span since the earlier deglaciation compared to LGM sites from Central Europe we used a pedological and sedimentological approach to reconstruct the Late Quaternary landscape development. Our results indicate a considerable reshaping of the LGM landscape prior to the onset of the Holocene. The LGM tills are covered by a deposit with high content of fine sand and coarse silt. On the slopes the clasts in these fine-grained sediments are aligned parallel to the slope direction, whereas in the underlaying tills the clasts are aligned rectangular to the slope direction and therefore representing the direction of the Pleistocene glacier movement. We attribute the alignment of the clasts in the sediment covering the tills to solifluction induced by periglacial conditions. The high contents of coarse silt and fine sand are also characteristic for the eolian component in periglacial slope deposits. OSL datings suggest an age of about 14 ka for these sediments. Soil micromorphology shows that the periglacial deposits were not subject to intensive pedogenic processes prior to the sedimentation but that profiles are strongly affected by lessivation after deposition. Soil erosion is only evident during the Holocene and we associate these phases of soil erosion with the human impact. We found no indications for geomorphologic and pedogenic processes between the reported deposition of the LGM till around 36 ka and the periglacial conditions dated


    Directory of Open Access Journals (Sweden)

    V. S. Malyar


    Full Text Available A mathematical model is developed to study the operation of three-phase asynchronous motor with squirrel-cage rotor when the stator winding is powered from a single phase network. To create a rotating magnetic field one of the phases is fed through the capacitor. Due to the asymmetry of power feed not only transients, but the steady-state regimes are dynamic, so they are described by differential equations in any coordinate system. Their study cannot be carried out with sufficient adequacy on the basis of known equivalent circuits and require the use of dynamic parameters. In the mathematical model the state equations of the circuits of the stator and rotor are composed in the stationary three phase coordinate system. Calculation of the established mode is performed by solving the boundary problem that makes it possible to obtain the coordinate dependences over the period, without calculation of the transient process. In order to perform it, the original nonlinear differential equations are algebraized by approximating the variables with the use of cubic splines. The resulting nonlinear system of algebraic equations is a discrete analogue of the initial system of differential equations. It is solved by parameter continuation method. To calculate the static characteristics as a function of a certain variable, the system is analytically differentiated, and then numerically integrated over this variable. In the process of integration, Newton's refinement is performed at each step or at every few steps, making it possible to implement the integration in just a few steps using Euler's method. Jacobi matrices in both cases are the same. To account for the current displacement in the rods of the squirrel-cage rotor, each of them, along with the squirrel-cage rings, is divided in height into several elements. This results in several squirrel-cage rotor windings which are represented by three-phase windings with magnetic coupling between them.

  19. A multi-threaded approach to using asynchronous C libraries with Java (United States)

    Gates, John; Deich, William


    It is very common to write device drivers and code that access low level operation system functions in C or C+ +. There are also many powerful C and C++ libraries available for a variety of tasks. Java is a programming language that is meant to be system independent and is arguably much simpler to code than C/C++. However, Java has minimal support for talking to native libraries, which results in interesting challenges when using C/C++ libraries with Java code. Part of the problem is that Java's standard mechanism for communicating with C libraries, Java Native Interface, requires a significant amount of effort to do fairly simple things, such as copy structure data from C to a class in Java. This is largely solved by using the Java Native Access Library, which provides a reasonable way of transferring data between C structures and Java classes and calling C functions from Java. A more serious issue is that there is no mechanism for a C/C++ library loaded by a Java program to call a Java function in the Java program, as this is a major issue with any library that uses callback functions. A solution to this problem was found using a moderate amount of C code and multiple threads in Java. The Keck Task Language API (KTL) is used as a primary means of inter-process communication at Keck and Lick Observatory. KTL is implemented in a series or C libraries and uses callback functions for asynchronous communication. It is a good demonstration of how to use a C library within a Java program.

  20. Asynchronous dentofacial development and dental crowding: a cross-sectional study in a contemporary sample of children in France. (United States)

    Yan-Vergnes, Wei; Vergnes, Jean-Noel; Dumoncel, Jean; Baron, Pascal; Marchal-Sixou, Christine; Braga, José


    The causes of dental crowding are not fully understood, but it may result from an evolutionary trend towards reduced facial volume, without a proportional reduction in tooth sizes. Most previous studies conducted among modern humans have revealed a very low or non-existent correlation between tooth size and jaw size. Cross-comparison between dental age and facial skeletal age could help to provide better knowledge of the dynamic process of dental crowding. The primary objective of this research was to study the synchronism of dental maturation and skeletal facial growth in a sample of modern children living in France. The secondary objective was to assess the link between dentofacial asynchronism and dental crowding. The random sample comprised 28 subjects (16 girls, 12 boys). Mean chronological age was 13.5 years (± 2.1; range 9.2-17.6). Mean dental age was 14.2 years (± 2.8; range 7.5-17) and mean facial skeletal age was 12.8 years (± 2.6, range 7-22). In the estimations of dental age and facial skeletal age, there was no evidence of systematic bias. There were 10 subjects (9 girls, 1 boy) with asynchronous dentofacial development. Finally, there were 13 subjects (8 girls, 5 boys) with dental crowding. A significant association was found between delayed facial skeletal growth/advanced dental maturation and dental crowding (P = 0.01). Dental maturation and facial growth are not necessarily synchronous. Further understanding of the interactions between dental maturation and facial growth could have crucial implications in biological anthropology, as well as for the clinical practice of orthodontists. From an anthropological perspective, this study suggests that asynchronous dentofacial development could, at least partially, explain the frequency of dental crowding in modern populations.

  1. A geometric approach for fault detection and isolation of stator short circuit failure in a single asynchronous machine

    KAUST Repository

    Khelouat, Samir


    This paper deals with the problem of detection and isolation of stator short-circuit failure in a single asynchronous machine using a geometric approach. After recalling the basis of the geometric approach for fault detection and isolation in nonlinear systems, we will study some structural properties which are fault detectability and isolation fault filter existence. We will then design filters for residual generation. We will consider two approaches: a two-filters structure and a single filter structure, both aiming at generating residuals which are sensitive to one fault and insensitive to the other faults. Some numerical tests will be presented to illustrate the efficiency of the method.

  2. Student participation and interactivity using asynchronous computer-mediated communication for resolution of an undergraduate capstone management case study. (United States)

    Miller, Paulette J


    Online discussion activities are designed for computer-mediated learning activities in face-to-face, hybrid, and totally online courses. The use of asynchronous computer-mediated communication (A-CMC) coupled with authentic workplace case studies provides students in the protected learning environment with opportunities to practice workplace decision making and communication. In this study, communication behaviors of transmitter and receiver were analyzed to determine participation and interactivity in communication among small-group participants in a health information management capstone management course.

  3. Introducing a downsized, open computer system with asynchronous transfer mode in PACS and its effect on image data transfer. (United States)

    Inoue, T; Koyama, Y; Suzuki, H; Oriuchi, N; Aoyagi, K; Tomaru, Y; Ookoshi, A; Yamamoto, S; Nakajima, T; Aoki, J; Endo, K


    To assess the effectiveness of the introduction of a downsized, open computer system and asynchronous transfer mode (ATM) as a network in a medium-sized picture archiving and communication system (PACS), we conducted experiments on image data transmission. The speed of image transfer, including registration in the computers in the new PACS, was four to eleven times faster than that in our first PACS. However, the introduction of ATM did not contribute significantly to the improvement of speed of image transfer because of the use of Ethernet branches between the gateway and display workstation computers. A star architecture without Ethernet branches may be suitable for PACS using an ATM network.

  4. Asynchronous telemedicine applications in rehabilitation of acquired speech-language disorders in neurologic patients

    Directory of Open Access Journals (Sweden)

    Beijer L


    outcome measures for efficacy and effectiveness testing partially account for this. From the perspective of scientific evidence, the benefits of asynchronous SL telemedicine applications concern data storage and data analyses. To facilitate implementation of telemedicine, there is a call for development of information and communication technology infrastructures that allow feasible applications which meet requirements with regard to licensure and medical privacy laws. For applications with evidence for beneficial effects, we are challenged to develop new business models that apply to a new health care environment. Keywords: telemedicine, speech, language, disorders, rehabilitation 

  5. Severity of Asynchronous Slipped Capital Femoral Epiphyses in Skeletally Immature Versus More Skeletally Mature Patients. (United States)

    Nowicki, Philip D; Silva, Selina; Toelle, Lisa; Strohmeyer, Greg; Wahlquist, Trevor; Li, Ying; Farley, Frances A; Caird, Michelle S


    Routine prophylactic screw fixation for skeletally immature patients with slipped capital femoral epiphysis (SCFE) continues to be debated. The purpose of this study was to assess the slip severity of a second SCFE in skeletally immature versus more mature patients and determine necessity of contralateral hip prophylactic screw fixation. All patients treated for SCFE at 3 pediatric hospitals over a 10-year time period (January 1, 2002 to December 31, 2011) were evaluated. Patients were included if they had a unilateral SCFE and a contralateral asynchronous SCFE, and were divided into immature (Oxford triradiate score 1) versus more mature (Oxford triradiate score 2 and 3) groups. Data evaluation included age, time between slips, body mass index, Southwick angles of first then second SCFEs, and follow-up duration. There were a total of 45 patients: 16 patients in the skeletally immature and 29 patients in the more mature group. Average age at first SCFE in immature patients was 10.9 years and in more mature patients 12.1 years (P=0.70). Age at second SCFE in immature patients was 11.5 years and in more mature patients 13.0 years (P=0.023). Average time between SCFEs was 6.6 months for immature and 11.4 months for more mature patients (P=0.093). Southwick angles for immature patient first and second SCFEs were 25 and 12.9 degrees, respectively, and for more mature patient first and second SCFEs were 31 and 21 degrees, respectively. Southwick angles were higher at first and second slips in the more mature group, significant only at the second slip (P=0.032). SCFE severity at initial event was predictive of severity of second SCFE regardless of maturity (P=0.043). Regression analysis of slip severity against multiple patient factors demonstrated triradiate score was not a factor assessing subsequent SCFE magnitude (P=0.099). There was no significant difference between first and second SCFEs regardless of skeletal maturity but severity of initial SCFE did correlate with

  6. The effects on health behavior and health outcomes of Internet-based asynchronous communication between health providers and patients with a chronic condition: a systematic review. (United States)

    de Jong, Catharina Carolina; Ros, Wynand Jg; Schrijvers, Guus


    In support of professional practice, asynchronous communication between the patient and the provider is implemented separately or in combination with Internet-based self-management interventions. This interaction occurs primarily through electronic messaging or discussion boards. There is little evidence as to whether it is a useful tool for chronically ill patients to support their self-management and increase the effectiveness of interventions. The aim of our study was to review the use and usability of patient-provider asynchronous communication for chronically ill patients and the effects of such communication on health behavior, health outcomes, and patient satisfaction. A literature search was performed using PubMed and Embase. The quality of the articles was appraised according to the National Institute for Health and Clinical Excellence (NICE) criteria. The use and usability of the asynchronous communication was analyzed by examining the frequency of use and the number of users of the interventions with asynchronous communication, as well as of separate electronic messaging. The effectiveness of asynchronous communication was analyzed by examining effects on health behavior, health outcomes, and patient satisfaction. Patients' knowledge concerning their chronic condition increased and they seemed to appreciate being able to communicate asynchronously with their providers. They not only had specific questions but also wanted to communicate about feeling ill. A decrease in visits to the physician was shown in two studies (P=.07, P=.07). Increases in self-management/self-efficacy for patients with back pain, dyspnea, and heart failure were found. Positive health outcomes were shown in 12 studies, where the clinical outcomes for diabetic patients (HbA1c level) and for asthmatic patients (forced expiratory volume [FEV]) improved. Physical symptoms improved in five studies. Five studies generated a variety of positive psychosocial outcomes. The effect of

  7. Invertebrate muscles: thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle. (United States)

    Hooper, Scott L; Hobbs, Kevin H; Thuma, Jeffrey B


    This is the second in a series of canonical reviews on invertebrate muscle. We cover here thin and thick filament structure, the molecular basis of force generation and its regulation, and two special properties of some invertebrate muscle, catch and asynchronous muscle. Invertebrate thin filaments resemble vertebrate thin filaments, although helix structure and tropomyosin arrangement show small differences. Invertebrate thick filaments, alternatively, are very different from vertebrate striated thick filaments and show great variation within invertebrates. Part of this diversity stems from variation in paramyosin content, which is greatly increased in very large diameter invertebrate thick filaments. Other of it arises from relatively small changes in filament backbone structure, which results in filaments with grossly similar myosin head placements (rotating crowns of heads every 14.5 nm) but large changes in detail (distances between heads in azimuthal registration varying from three to thousands of crowns). The lever arm basis of force generation is common to both vertebrates and invertebrates, and in some invertebrates this process is understood on the near atomic level. Invertebrate actomyosin is both thin (tropomyosin:troponin) and thick (primarily via direct Ca(++) binding to myosin) filament regulated, and most invertebrate muscles are dually regulated. These mechanisms are well understood on the molecular level, but the behavioral utility of dual regulation is less so. The phosphorylation state of the thick filament associated giant protein, twitchin, has been recently shown to be the molecular basis of catch. The molecular basis of the stretch activation underlying asynchronous muscle activity, however, remains unresolved.

  8. User satisfaction with asynchronous telemedicine: a study of users of Santa Catarina's system of telemedicine and telehealth. (United States)

    von Wangenheim, Aldo; de Souza Nobre, Luiz Felipe; Tognoli, Heitor; Nassar, Silvia Modesto; Ho, Kendall


    User satisfaction analyses in synchronous telemedicine and teleconsultation environments have been widely performed and generally show satisfied users. In the field of asynchronous telemedicine, however, satisfaction studies were performed only in one single location or with a restricted set of users. With the aim of offering an exemplar evaluation of the impact of the statewide use of a large-scale asynchronous telemedicine network on the satisfaction of the involved users, this study presents the results obtained from a survey of the perceived quality of the service by both patients and healthcare staff. For this purpose, a survey with satisfaction questionnaires was performed with 564 patients from seven upstate municipalities and 56 healthcare professionals from 46 municipalities, using a methodology from the process improvement field. The collected data were quantified and underwent statistical analysis, which showed a clear perception of the improvement in the quality of service by both patients and healthcare professionals. The present findings also showed that both patients and healthcare professionals felt that introducing these new technologies was a positive step, even in upstate areas and when they involved great changes in the usual processes of primary care.

  9. An asynchronous learning approach for the instructional component of a dual-campus pharmacy resident teaching program. (United States)

    Garrison, Gina Daubney; Baia, Patricia; Canning, Jacquelyn E; Strang, Aimee F


    To describe the shift to an asynchronous online approach for pedagogy instruction within a pharmacy resident teaching program offered by a dual-campus college. The pedagogy instruction component of the teaching program (Part I) was redesigned with a focus on the content, delivery, and coordination of the learning environment. Asynchronous online learning replaced distance technology or lecture capture. Using a pedagogical content knowledge framework, residents participated in self-paced online learning using faculty recordings, readings, and discussion board activities. A learning management system was used to assess achievement of learning objectives and participation prior to progressing to the teaching experiences component of the teaching program (Part II). Evaluation of resident pedagogical knowledge development and participation in Part I of the teaching program was achieved through the learning management system. Participant surveys and written reflections showed general satisfaction with the online learning environment. Future considerations include addition of a live orientation session and increased faculty presence in the online learning environment. An online approach framed by educational theory can be an effective way to provide pedagogy instruction within a teaching program.

  10. Commande Vectorielle Sans Capteur d’un Moteur Asynchrone Associée à un Observateur de Kubota

    Directory of Open Access Journals (Sweden)

    Karim Negadi


    Full Text Available Cette étude concerne l'observation et la commande du moteur asynchrone sans capteur mécanique. L'objectif est de proposer une loi de commande sans capteur mécanique utilisant un observateur adaptatif estimant la vitesse, sur la base d’un mécanisme d’adaptation de Kubota. Le but principal est de parvenir à un contrôle simple, adaptatif et performant, ce qui va nous permettre de tester et d'évaluer les performances de l’observateur proposé, associé à la commande sans capteur du moteur asynchrone, en ayant comme informations disponibles les courants et les tensions statoriques. L’algorithme proposé consiste en un observateur reconstruisant les composantes du flux rotorique et un mécanisme basé sur un l’algorithme de Kubota, et générant la loi d’adaptation pour l’estimation de la vitesse. Des tests sont effectués et validés par voie expérimentale, les résultats obtenus illustrent de bonnes performances en terme de robustesse, vis-à-vis des variations des paramètres du moteur et montrent l’excellente qualité de la loi de commande associée à l'observateur, malgré les problèmes d'observabilité lorsque le moteur fonctionne à basse vitesse.

  11. Parallel tempering simulation of the three-dimensional Edwards-Anderson model with compact asynchronous multispin coding on GPU (United States)

    Fang, Ye; Feng, Sheng; Tam, Ka-Ming; Yun, Zhifeng; Moreno, Juana; Ramanujam, J.; Jarrell, Mark


    Monte Carlo simulations of the Ising model play an important role in the field of computational statistical physics, and they have revealed many properties of the model over the past few decades. However, the effect of frustration due to random disorder, in particular the possible spin glass phase, remains a crucial but poorly understood problem. One of the obstacles in the Monte Carlo simulation of random frustrated systems is their long relaxation time making an efficient parallel implementation on state-of-the-art computation platforms highly desirable. The Graphics Processing Unit (GPU) is such a platform that provides an opportunity to significantly enhance the computational performance and thus gain new insight into this problem. In this paper, we present optimization and tuning approaches for the CUDA implementation of the spin glass simulation on GPUs. We discuss the integration of various design alternatives, such as GPU kernel construction with minimal communication, memory tiling, and look-up tables. We present a binary data format, Compact Asynchronous Multispin Coding (CAMSC), which provides an additional 28.4% speedup compared with the traditionally used Asynchronous Multispin Coding (AMSC). Our overall design sustains a performance of 33.5 ps per spin flip attempt for simulating the three-dimensional Edwards-Anderson model with parallel tempering, which significantly improves the performance over existing GPU implementations.

  12. Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve. (United States)

    Dean, Jesse C; Clair-Auger, Joanna M; Lagerquist, Olle; Collins, David F


    Motoneurons receive a barrage of inputs from descending and reflex pathways. Much of our understanding about how these inputs are transformed into motor output in humans has come from recordings of single motor units during voluntary contractions. This approach, however, is limited because the input is ill-defined. Herein, we quantify the discharge of soleus motor units in response to well-defined trains of afferent input delivered at physiologically-relevant frequencies. Constant frequency stimulation of the tibial nerve (10-100 Hz for 30 s), below threshold for eliciting M-waves or H-reflexes with a single pulse, recruited motor units in 7/9 subjects. All 25 motor units recruited during stimulation were also recruited during weak (stimulation at 20 Hz (7.8 Hz) was lower than during 30 Hz (8.6 Hz) and 40 Hz (8.4 Hz) stimulation. Discharge was largely asynchronous from the stimulus pulses with "time-locked" discharge occurring at an H-reflex latency with only a 24% probability. Motor units continued to discharge after cessation of the stimulation in 89% of trials, although at a lower rate (5.8 Hz) than during the stimulation (7.9 Hz). This work supports the idea that the afferent volley evoked by repetitive stimulation recruits motor units through the integration of synaptic drive and intrinsic properties of motoneurons, resulting in "physiological" recruitment which adheres to Henneman's size principle and results in relatively low discharge rates and asynchronous firing.

  13. Technologies That Assist in Online Group Work: A Comparison of Synchronous and Asynchronous Computer Mediated Communication Technologies on Students' Learning and Community (United States)

    Rockinson-Szapkiw, Amanda; Wendt, Jillian


    While the benefits of online group work completed using asynchronous CMC technology is documented, researchers have identified a number of challenges that result in ineffective and unsuccessful online group work. Fewer channels of communication and lack of immediacy when compared to face-to-face group work are a few of the noted limitations. Thus,…

  14. Asynchronous Interaction, Online Technologies Self-Efficacy and Self-Regulated Learning as Predictors of Academic Achievement in an Online Class (United States)

    McGhee, Rosie M. Hector


    This research is a correlational study of the relationship among the independent variables: asynchronous interaction, online technologies self-efficacy, and self-regulated learning, and the dependent variable; academic achievement. This study involves an online computer literacy course at a local community college. Very little research exists on…

  15. A Comparison of Classroom and Online Asynchronous Problem-Based Learning for Students Undertaking Statistics Training as Part of a Public Health Masters Degree (United States)

    de Jong, N.; Verstegen, D. M. L.; Tan, F. E. S.; O'Connor, S. J.


    This case-study compared traditional, face-to-face classroom-based teaching with asynchronous online learning and teaching methods in two sets of students undertaking a problem-based learning module in the multilevel and exploratory factor analysis of longitudinal data as part of a Masters degree in Public Health at Maastricht University. Students…

  16. Teaching Writing within the Common European Framework of Reference (CEFR): A Supplement Asynchronous Blended Learning Approach in an EFL Undergraduate Course in Egypt (United States)

    Shaarawy, Hanaa Youssef; Lotfy, Nohayer Esmat


    Based on the Common European Framework of Reference (CEFR) and following a blended learning approach (a supplement model), this article reports on a quasi-experiment where writing was taught evenly with other language skills in everyday language contexts and where asynchronous online activities were required from students to extend learning beyond…

  17. Intercultural Communication Strategies: Discursive Strategies between Americans and Thais in an English Language Asynchronous Argumentative Online Forum and Their Impact for Language Education (United States)

    Sagaravasi, Varasiri


    This dissertation aims at investigating the speech act of disagreement as it is carried out linguistically in an English-language asynchronous online forum between unacquainted Americans and Thais (TEFL and TESL). The analysis and interpretation of the data are based on both "emic" and "etic" perspectives, in the framework of…

  18. Self-sustained asynchronous irregular states and Up-Down states in thalamic, cortical and thalamocortical networks of nonlinear integrate-and-fire neurons. (United States)

    Destexhe, Alain


    Randomly-connected networks of integrate-and-fire (IF) neurons are known to display asynchronous irregular (AI) activity states, which resemble the discharge activity recorded in the cerebral cortex of awake animals. However, it is not clear whether such activity states are specific to simple IF models, or if they also exist in networks where neurons are endowed with complex intrinsic properties similar to electrophysiological measurements. Here, we investigate the occurrence of AI states in networks of nonlinear IF neurons, such as the adaptive exponential IF (Brette-Gerstner-Izhikevich) model. This model can display intrinsic properties such as low-threshold spike (LTS), regular spiking (RS) or fast-spiking (FS). We successively investigate the oscillatory and AI dynamics of thalamic, cortical and thalamocortical networks using such models. AI states can be found in each case, sometimes with surprisingly small network size of the order of a few tens of neurons. We show that the presence of LTS neurons in cortex or in thalamus, explains the robust emergence of AI states for relatively small network sizes. Finally, we investigate the role of spike-frequency adaptation (SFA). In cortical networks with strong SFA in RS cells, the AI state is transient, but when SFA is reduced, AI states can be self-sustained for long times. In thalamocortical networks, AI states are found when the cortex is itself in an AI state, but with strong SFA, the thalamocortical network displays Up and Down state transitions, similar to intracellular recordings during slow-wave sleep or anesthesia. Self-sustained Up and Down states could also be generated by two-layer cortical networks with LTS cells. These models suggest that intrinsic properties such as adaptation and low-threshold bursting activity are crucial for the genesis and control of AI states in thalamocortical networks.

  19. Relative shortening and functional tethering of spinal cord in adolescent scoliosis – Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE

    Directory of Open Access Journals (Sweden)

    Burwell R Geoffrey


    Full Text Available Abstract There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS. As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE introduced the electronic focus group (EFG as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine the spinal cord to vertebral growth interaction during adolescence in scoliosis. Using the multi-planar reconstruction technique of magnetic resonance imaging they investigated the relative length of spinal cord to vertebral column including ratios in 28 girls with AIS (mainly thoracic or double major curves and 14 age-matched normal girls. Also evaluated were cerebellar tonsillar position, somatosensory evoked potentials (SSEPs, and clinical neurological examination. In severe AIS compared with normal controls, the vertebral column is significantly longer without detectable spinal cord lengthening. They speculate that anterior spinal column overgrowth relative to a normal length spinal cord exerts a stretching tethering force between the two ends, cranially and caudally leading to the initiation and progression of thoracic AIS. They support and develop the Roth-Porter concept of uncoupled neuro-osseous growth in the pathogenesis of AIS which now they prefer to term 'asynchronous neuro-osseous growth'. Morphological evidence about the curve apex suggests that the spinal cord is also affected, and a 'double pathology' is suggested. AIS is viewed as a disorder with a wide spectrum and a common neuroanatomical abnormality namely, a spinal cord of normal length but short relative to an abnormally lengthened anterior vertebral column. Neuroanatomical changes and/or abnormal neural function may be expressed only in severe cases. This asynchronous neuro-osseous growth

  20. A comparison of classroom and online asynchronous problem-based learning for students undertaking statistics training as part of a Public Health Masters degree. (United States)

    de Jong, N; Verstegen, D M L; Tan, F E S; O'Connor, S J


    This case-study compared traditional, face-to-face classroom-based teaching with asynchronous online learning and teaching methods in two sets of students undertaking a problem-based learning module in the multilevel and exploratory factor analysis of longitudinal data as part of a Masters degree in Public Health at Maastricht University. Students were allocated to one of the two study variants on the basis of their enrolment status as full-time or part-time students. Full-time students (n = 11) followed the classroom-based variant and part-time students (n = 12) followed the online asynchronous variant which included video recorded lectures and a series of asynchronous online group or individual SPSS activities with synchronous tutor feedback. A validated student motivation questionnaire was administered to both groups of students at the start of the study and a second questionnaire was administered at the end of the module. This elicited data about student satisfaction with the module content, teaching and learning methods, and tutor feedback. The module coordinator and problem-based learning tutor were also interviewed about their experience of delivering the experimental online variant and asked to evaluate its success in relation to student attainment of the module's learning outcomes. Student examination results were also compared between the two groups. Asynchronous online teaching and learning methods proved to be an acceptable alternative to classroom-based teaching for both students and staff. Educational outcomes were similar for both groups, but importantly, there was no evidence that the asynchronous online delivery of module content disadvantaged part-time students in comparison to their full-time counterparts.