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Sample records for asynchronous motors

  1. Research on DSP-based Asynchronous Motor Control Technology

    Directory of Open Access Journals (Sweden)

    Jun Yao

    2013-05-01

    Full Text Available The Motor in a variety of electrical transmission and position servo system occupies an extremely important position. After the DSP technology being applied to the motor control, the unification of the hardware and the flexibility of the software can be combined. Take the brushless DC motor for example, studied the mathematical model and the structure of the motor control system, also obtained the design scheme of the DSP-based asynchronous motor control system. With TI's 32 bit fixed point DSPTMS320F2812 as the core design of the hardware system, we wrote the system software, debug the motor control system and the results show that the system achieves the expected effect. The results of the research can be applied to brushless DC motor and other motor control, it will have a wide application prospects.

  2. ON THE ISSUE OF VECTOR CONTROL OF THE ASYNCHRONOUS MOTORS

    Directory of Open Access Journals (Sweden)

    B. I. Firago

    2015-10-01

    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

  3. Ironless asynchronous motors with superconducting auxiliary excitation

    International Nuclear Information System (INIS)

    Describes induction motors having an outer squirrel-cage or slip-ring rotor driving the shaft, and an inner, free-running rotor with the function of compensating the reactive load of the stator. Investigates theoretically the suggestion that a superconducting inner rotor would also produce very high excitation, and enable the iron circuits to be dispensed with. (R.W.S.)

  4. Realization of station for testing asynchronous three-phase motors

    Science.gov (United States)

    Wróbel, A.; Surma, W.

    2016-08-01

    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.

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

    Directory of Open Access Journals (Sweden)

    I.A. Tsodik

    2014-04-01

    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.

  6. Calculation of mechanical characteristic for disk asynchronous motor with free rotor

    OpenAIRE

    Ерошин, Сергей Сергеевич; Мирошник, Сергей Александрович

    2012-01-01

    Taking into account the features of construction of asynchronous motor with free annular rotor analytical formulas for the calculation of its mechanical characteristic have been obtained. New features of machines with annular working tools without mechanical support are revealed

  7. SELECTION OF METHOD FOR REGULATION OF TRACTOR PROPULSION ASYNCHRONOUS ELECTRIC MOTOR AND CONSTRUCTION OF MECHANICAL CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    Ch. I. Zhdanovich

    2015-01-01

    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

  8. Efficiency of three-phase asynchronous motors. Energy loss reduction by means of overdimensioning; Efficientie van driefasen asynchrone motoren. SinuMEC beperkt energieverlies door overdimensionering

    Energy Technology Data Exchange (ETDEWEB)

    Peeters, J.; Van Dorst, C. [Hyteps, Gemert (Netherlands)

    2008-10-15

    The three phase asynchronous motor has been applied in various installations since time immemorial. Although the motor is more efficient at full mechanical load, this is not always applied efficiently. Can the efficiency of low load motors be improved or is this a utopia? The Sinusoidal Motor Controller (SinuMEC) improves efficiency, saves energy and lengthens the life span. [mk]. [Dutch] De driefasen asynchrone motor wordt sinds mensenheugenis in uiteenlopende installaties toegepast. Hoewel de motor met een volle mechanische belasting efficient is, wordt deze niet altijd efficient toegepast. Kan de efficiency van laag belaste motoren worden verbeterd of is dit een utopie? De Sinusoidal Motor efficiency controller (SinuMEC) verbetert de efficiency, bespaart energie en verlengt de levensduur.

  9. Investigation of Closed Vector Control System for Asynchronous Motor Drive of Shipboard Tow Winch

    OpenAIRE

    Н. Mehdiyev; Е. Sultanov

    2014-01-01

    The paper considers a closed vector control system for induction motor rotation speed of a shipboard tow winch. Structural schemes and transfer functions of the system at control and disturbing influences are presented in the paper. The system with asynchronous motor drive parameters of a shipboard tow winch has been investigated in the paper. It has been revealed that transit process duration of the given system is insignificant. The fact is rather important to prevent accidents in case of v...

  10. Zero Dynamics Analysis for Inverse Decoupling Control of Asynchronous Traction Motor

    Directory of Open Access Journals (Sweden)

    Haiying Dong

    2013-07-01

    Full Text Available Considering the problem for inverse system method in EMU AC induction traction motor linear decoupling, the zero dynamics subsystem will be separated from the original dynamic system through coordinate transformation. Firstly, a getting method for zero dynamics of the multiple input multiple output nonlinear system is discussed when γ<n. Second, the zero dynamics analysis for five order nonlinear model of asynchronous traction motor which base on the stationary coordinate system is given by using inverse decoupling method. The analysis results show that if the stability of the zero dynamics can be ensured, then the entire linearization of original nonlinear system is not necessary, need only partial linearization which effect on the external dynamic portion. The inverse decoupling process of asynchronous traction motor can be simplified by this conclusion.

  11. Vector control structure of an asynchronous motor at maximum torque

    Science.gov (United States)

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

    2016-02-01

    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.

  12. MODELING OF SYMMETRIC THREE-PHASE ASYNCHRONOUS ELECTRIC MOTOR IN ASYMMETRIC CONNECTION TO NETWORK

    Directory of Open Access Journals (Sweden)

    V. I. Lukovnikov

    2005-01-01

    Full Text Available The paper shows how to solve the problem concerning reveal of changes in mathematical models and electric parameters of symmetric three-phase short-circuited asynchronous electric motors in case of their connection to single- or two-phase network in comparison with their connection to three-phase network. The uniform methodological approach permitting to generalize the known data and receive new results is offered in the paper.

  13. Torsional stress analysis of the squirrel-cage rotor for three phase asynchronous motors

    Science.gov (United States)

    Axinte, T.; Nutu, C.

    2015-11-01

    The paper aims to determine the torsional stress occurring in the rotor's shaft of the three phase asynchronous motors for a given rotational speed of the rotor. The three phase asynchronous motor is started using the main starting variants, each variant having its own torque characteristic which produces a certain maximum shear stress. The model uses several hypotheses regarding the geometry of the domain, the dynamic behavior, the friction phenomenon and the mass of the shaft which is disregarded in a model and it is considered in a more accurate model. The maximum shear stress is produced by the shock which occurs in the starting process of the motors. This maximum stress may lead to the failure of the rotor either because it breaks, or because of the fatigue of the material produced by frequent starting of the motor. Information resulted from this study are useful for the selection of the appropriate material, of the according geometry of the design and elaboration of the specifications for the in-service use of the motor.This theoretical study will be followed by the development of more accurate models which will also include experimental studies employed to calibrate the theoretical models and to verify their accuracy.

  14. 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)

    1997-12-31

    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.

  15. Frequency control system based on power factor control of asynchronous motor

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-chun; YANG Fei-xia; REN Zhi-ling

    2005-01-01

    Deduced the relationship between the power factor (PF) and the angular frequency according to the simplified equivalent circuit of asynchronous motor, forming a power factor auto-control system. An anti-interference circuit was also introduced in the middle voltage link of inverter to avoid the shift of the optimum PF point caused by the change of the load and the reliable run of the control system was assured. The experiment results show that it has a good self-adaptation in the whole scope of speed adjustment and an obvious economization on energy while it runs under load.

  16. Fault Detection based on MCSA for a 400Hz Asynchronous Motor for Airborne Applications

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    Steffen Haus

    2013-01-01

    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. Relay system for phasing rotating disk selector with drive from asynchronous electric motor

    International Nuclear Information System (INIS)

    Regulating system is described which ensures rotation of a massive disk selector synphaseally with a rotating reactivity modulator in a pulse reactor. Unlike the proportional regulating principle and using d.c. motor commonly utilized in solving similar problems, the given system involves an asynchronous short-circuited electric motor and a relay regulation principle. Thyristor control provides sufficiently simple realization of two selector acceleration modes (strong and weak acceleration) and two retardation modes (strong and weak braking). The mode switch-over moments are due to the regulated magnitude and its product. The given system is simple in maintenance, and has low sensitivity to oscillations in circuit voltage. In an 80-200 mc range of the selector period, the mean-square value of the displacement angle between the selector and reactor is at least +-1 deg

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

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    MARABA, V. A.

    2011-11-01

    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.

  19. Operation Characteristics Optimization of Low Power Three-Phase Asynchronous Motors

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    VLAD, I.

    2014-02-01

    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.

  20. Hybrid EEG-fNIRS Asynchronous Brain-Computer Interface for Multiple Motor Tasks.

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    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Beeli, N.; Jenni, F.

    2010-10-15

    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

  2. Simulation of asynchronous modes of synchronous motors with capacitors in the excitation circuit

    OpenAIRE

    Malyar, V. S.; Malyar, A. V.; I. A. Dobushovska

    2012-01-01

    Розглядається проблема розрахунку асинхронних режимів синхронних двигунів з конденсаторами в обмотці збудження. Задача розв'язується як крайова для нелінійної системи диференціальних рівнянь електричної рівноваги, в яких потокозачеплення контурів обчислюються шляхом розрахунку магнітного поля двигуна на основі теорії магнітних кіл. A problem of calculating asynchronous modes of synchronous motors with capacitors in the excitation circuit is considered. The problem is solved as a boundary o...

  3. Static Parameter Identification of Asynchronous Motor%异步电机参数静态辨识

    Institute of Scientific and Technical Information of China (English)

    崔连香

    2013-01-01

    电机数学模型的参数直接影响无速度传感器矢量控制系统的性能。从异步电机动态数学模型及实际使用情况出发,提出了一种在被控电机静止的状态下借助 FFT及复数运算对电机参数进行辨识的方法。试验结果证明此方法简单可行,能为无速度传感器矢量控制系统提供较高精度的电机参数。%The parameter of motor mathematical model influences the performance no speed sensor vector control system. An identification method in a controlled motor static state by means of FFT and complex operation for identification of the motor parameters under the model of asynchronous motor and the actual application situation were introduced. The test results proved that this method was simple and practical. It could provide a highly precision motor parameters for the vector control system of no speed sensor.

  4. Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve

    Directory of Open Access Journals (Sweden)

    Jesse eDean

    2014-12-01

    Full Text Available 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 (<10% MVC voluntary contractions. Higher frequencies recruited more units (n=3/25 at 10 Hz; n=25/25 at 100 Hz at shorter latencies (19.4±9.4 s at 10 Hz; 4.1±4.0 s at 100 Hz than lower frequencies. When a second unit was recruited, the discharge of the already active unit did not change, suggesting that recruitment was not due to increased synaptic drive. After recruitment, mean discharge rate during 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 discharged after the stimulation ended 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.

  5. On the asynchronously continuous control of mobile robot movement by motor cortical spiking activity.

    Science.gov (United States)

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

    2014-01-01

    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.

  6. Study of frequency-controlled asynchronous motor units temperature versus load and power supply type

    Directory of Open Access Journals (Sweden)

    T.V. Vakaruk

    2014-04-01

    Full Text Available An equivalent thermal circuit is developed to form the basis of a system of heat-balance equations for a frequency-controlled induction motor. With the system of equations, temperatures of АИР 90В2 induction motor stator and rotor windings and cores are calculated and experimentally confirmed. The load dependence of the machine most heated units temperature at different forms of the supply voltage is revealed.

  7. Application of Z-source inverter in the asynchronous motor%Z源逆变器在异步电动机中的应用

    Institute of Scientific and Technical Information of China (English)

    朱红; 祝龙记; 夏若飞

    2014-01-01

    In recent years,the asynchronous motor drive of indirect field-oriented control (IFOC)is widely used in high performance drive systems because of its high efficiency,high stable performance and power factor. In this paper,the IFOC technology is used to control the size of the speed of asynchronous motor,and the Z-source inverter is used,namely putting a pair of LC network in front of the inverter main circuit,to achieve the function of boost or buck the voltage and improve the efficiency of asynchronous motor by controlling the direct duty ratio.%近年来,间接磁场定向控制(IFOC)的异步电机驱动由于其效率高、稳定性能强及功率因数高,被广泛应用在高性能驱动系统中。本文采用IFOC技术来控制异步电机的速度大小,并使用Z源逆变器,即在逆变器主电路前加上一对阻抗(LC)网络,通过控制直通占空比,可以实现升/降压功能、提高异步电机的效率。

  8. THE DEVELOPMENT OF MATHEMATICAL MODEL FOR THE STUDY OF ELECTROMAGNETIC INTERFERENCE FROM THE TRACTION CONVERTERS WITH ASYNCHRONOUS MOTOR

    Directory of Open Access Journals (Sweden)

    V. I. Shcheka

    2010-01-01

    Full Text Available The mathematical modeling and circuit simulation of asynchronous propulsion drive unit with converters on IGBT transistors have been made. The possible noises appearing during drive’s operation have been determined. The spectral composition of phase current of the asynchronous engine has been obtained.

  9. INVESTIGATION ON THE DIAGNOSIS OF SIMPLE AND COMBINES MECHANICAL FAULTS IN ASYNCHRONOUS MOTOR BASED ELECTRIC DRIVES

    Directory of Open Access Journals (Sweden)

    Bouras A. Karim

    2014-01-01

    Full Text Available In this study, the problems of mechanical unbalance, parallel and angular misalignments and their combinations are analyzed experimentally. Such frequent defects in the drives mainly in the major powers are also responsible for the bearings degradation. However, they have not raised the attention of researchers, given the complexity of their modeling. The combination of the phasic current signal analysis and the neutral current by the FFT supplemented by visual interpretation of patterns models these defects resulting from the 3D representation. The results obtained by using the proposed method show the efficiency to provide an accurate diagnosis of the state of the electric drive undergoing to isolated and combined mechanical defaults to a maintenance staff not necessarily expert of mechanical failure. The innovative approach validated experimentally on a 5.37 KW motor, offers an efficiency to provide an accurate diagnosis to a maintenance staff not necessarily composed of experts in this field.

  10. Arguments for the creation of a cost saving high voltage asynchronous motor for mobile sinking winders

    Energy Technology Data Exchange (ETDEWEB)

    Dimashko, A.D.; Tsymbal, V.S.; Volodin, V.V.; Izmailov, G.G.; Ivanenko, S.V.

    1983-07-01

    At various points in shafts and during maintenance and inspection work, the speed of the hoisting buckets must be reduced to below 1 m/s. The current method of speed control by introducing resistance into the wound rotor circuit is inefficient, and research has shown the superiority of varying the supply voltage frequency. A static frequency converter suitable for this purpose on winders of up to 630 kW has been developed using semiconductor technology. The converter's control system is based on Logika-T series transistors. The operating principle of the converter is described, and considerations involved in ensuring the optimum output voltage curve shape are discussed. An experimental model is being tested on a PPM 2 x 1.5 mobile winder. The electric motor of this winder uses the thyristor converter as a low frequency a.c. source and as a controllable d.c. source for deceleration. The range of frequency variation must be kept small because a frequency converter covering the whole range from 0-50 Hz would be complex, unreliable and sensitive to environmental conditions. (In Russian)

  11. 交流异步电动机调速系统控制策略综述%Review of AC asynchronous motor speed control strategy

    Institute of Scientific and Technical Information of China (English)

    丁辉; 胡协和

    2011-01-01

    为了更精确地实现交流异步电动机调速,基于交流异步电动机的数学模型论述异步电动机变压变频(VVVF)调速系统的各种控制策略.总结早期的基于异步电机稳态模型的控制策略,介绍3种较成熟的基于动态模型的控制策略,分析现代控制理论在交流异步电动机调速系统中的应用,展望交流调速控制策略的发展方向.传统的控制策略在工业现场中的应用已经较为成熟,各种现代控制策略和先进控制算法则有广阔的发展前景.%Variable voltage variable frequency (VVVF) speed control strategies were researched based on the mathematical model of alternating current (AC) asynchronous motor in order to achieve more accurate speed control of AC induction motor. The early control methods of induction motor based on the steady-state model were simply summarized. Three mature control schemes based on the dynamic model were introduced. The application of modern control theory in AC asynchronous motor speed control system was analyzed. Finally, the future development direction of AC speed control strategy was given. Traditional strategies were maturely utilized in industrial field, but the modern control theory and advanced control algorithms still have vast potential for future development.

  12. 基于正多面体法的单相异步电机优化设计%The Design Optimization of Single-phase Asynchronous Motor Based on Regular Polyhedron Method

    Institute of Scientific and Technical Information of China (English)

    马吉祥; 孙华

    2011-01-01

    单相异步电机是一种应用极为广泛的电机。电机优化设计是一种复杂的、有约束、非线性、混合离散多变量规划问题。本文选用正多面体优化算法对单相异步电机进行了优化设计。在数学模型的基础上,对正多面体优化算法进行了深入的分析和讨论,并对选定的电机进行优化,对获得的优化结果进行了比较和分析。结果表明,这种算法的性能较为理想,具有一定的实用价值。%Single-phase AC Asynchronous Motor is a very widely-used type electrical motor which has been thoroughly studied. Design optimization of electrical motors is a nonlinear constrained and mixed-discrete multiple variables optimization problem. In this thesis, the fundamental principle of Single-phase AC Asynchronous Motor is introduced and the Regular Polyhedron Method is fully discussed. We study its principle and give the detailed procedure for Single-phase AC Asynchronous Motor optimization. The algorithm is used to optimize selected Single-phase AC Asynchronous Motor and the results are accumulated and analyzed. The results prove that the performance of the algorithms is good and has some practical value.

  13. 石化生产中三相异步电机维护技术的研究%Study of maintenance technique of three-phase asynchronous motor in petrochemical production

    Institute of Scientific and Technical Information of China (English)

    李钢

    2015-01-01

    石化生产中的三相异步电机是最常用的和最重要的电气设备之一,通常情况下,石化生产中三相异步电机的用途是将电机所产生的电能转换形成为所需的机械能。由于三相异步电机结构相对简单、工作实用方便、且耐用坚固易于维修。为了使三相异步电机能够在石化生产中安全稳定的运行工作需要对其进行一定的维护,尽可能的减少三相异步电机的故障。%The three-phase asynchronous motor is the most commonly used in petrochemical production and one of the most important electrical equipment. Under normal circumstances,the use of three-phase asynchronous motor in petrochemical production is to convert motor electrical energy generated by the formation to the desired mechanical energy. Because of the three-phase asynchronous motor is relatively simple in structure,convenient in practical work,strong and durable and easy to maintenance. Certain maintenance is needed for the three-phase asynchronous motor to operate in the petrochemical production safely and stably, and reduce its fault possibly.

  14. Analysis of Asynchronous Motor Phased Optimization of Energy-Saving Control Technology%异步电机相控优化节能控制技术分析

    Institute of Scientific and Technical Information of China (English)

    徐燕; 杨跃农

    2012-01-01

    Phased optimization and energy saving of AC asynchronous motor running problem was analyzed and researched. A comprehensive energy-saving control program of asynchronous motor starting and running was introduced. The program was simple in structure, speed performance, and reliable performance.%对交流异步电动机的相控优化节能运行问题作了全面的分析和研究,提出了异步电动机起动和运行的综合节能控制方案.该综合节能控制方案结构简单,调速性能好,性能可靠.

  15. 利用时间延迟状态反馈实现异步电机的混沌合成%Chaos Synthesis of Asynchronous Motor by Time-Delayed State Feedback

    Institute of Scientific and Technical Information of China (English)

    李卫东; 唐斌

    2012-01-01

    为了在三相交流异步电机的运行过程中实现混沌合成,采用非线性系统的微分几何理论和时间延迟反馈控制的方法,设计了混沌合成控制器.该控制器通过对三相交流异步电机模型的简化分析,并利用非线性控制理论的状态反馈精确线性化方法来设计.应该此控制器即可得到异步电机运行时的混沌合成.应用Matlab软件中Simulink 工具进行仿真分析,仿真结果说明利用时间延迟状态反馈设计的控制器实现异步电机的混沌合成是完全合理可行的,运行结果也是满足要求的.%The chaos synthesis controller is designed using the method of differential geometry theory of nonlinear systems and time-delayed feedback control to realize chaos synthesis in running process of three-phase alternating current (AC) asynchronous motor. The exact linearization approach by state feedback of nonlinear control theory is used for controller design and through simplified analysis on the model of three-phase AC asynchronous motor. Chaos synthesis is got when asynchronous motor running by this controller. Simulink tool in Matlab software is used for Simulation analysis. The simulation results show that the time-delayed state feedback method designed controller implementing chaos synthesis of asynchronous motor is feasible and the control result is satisfied.

  16. 三相异步电动机的杂散损耗研究%Research on Stray Loss of Three-Phase Asynchronous Motor

    Institute of Scientific and Technical Information of China (English)

    宁榕; 李巧莲; 黄坚

    2014-01-01

    Efficiency and temperature rise of motor are affected by stray loss, whose size magnitude is connected with the design parameters of the motor and the quality of the processing technology and so on. Inhibition of stray loss is an effective measure to increase efficiency and reduce cost. The surface loss, tooth pulse vibration, rotor harmonic loss and transverse leakage current loss were analyzed. Based on the selection of design parameters, such as sine winding, slot coordination, air gap length, cast aluminum process, the measures to reduce stray loss was analyzed. The measures were applied to the product development of ultra high efficiency three-phase asynchronous motor. The result shows that the efficiency index has reached new national standard, and achieved IE3 ultra high efficiency standards level, and high frequency stray loss is effectively restrained, and the manufacturing cost is reduced.%杂散损耗影响电机的效率和温升,其大小与电动机的设计参数、加工工艺质量等因素有关。抑制杂散损耗是增效率、降成本的有效措施。分析了表面损耗、齿部脉振损耗、转子谐波损耗、横向泄漏电流损耗,并针对正弦绕组、槽配合、气隙长度、铸铝工艺的设计参数选择,分析了降低杂散损耗的措施。该措施应用到超高效三相异步电动机的产品开发,效率指标达到了新国家标准,达到了IE3超高效率标准等级,有效抑制高频杂散损耗,降低了制造成本。

  17. Simulation research of matrix converter and asynchronous motor control system%矩阵变换器-异步电机矢量控制系统仿真研究

    Institute of Scientific and Technical Information of China (English)

    姜香菊; 刘二林

    2012-01-01

    Space vector pulse width modulation of matrix converter and rotor field oriented vector control of asynchronous motor are combined, and the paper researchs combination strategy for vector control of the matrix converter and rotor field oriented vector control of asynchronous motor. Input voltage and current of matrix converter are simulated by MATLAB, at the same time, no-load starting torque and speed waveform and the electrical load torque waveform of motor are simulated. The simulation results show that the combined control strategy for matrix converter-asynchronous vector control system has good speed performance, and has the advantage of a AC-DC-AC voltage type PWM variable frequency speed regulation system.%研究了将矩阵变换器的空间矢量脉宽调制与异步电机转子磁场定向矢量控制相结合的组合控制策略,并采用MATLAB对矩阵变换器的输入电压波形、输入电流波形、电机空载启动转矩波形、电机空载启动转速波形以及在电机突加负载时的转矩波形等进行仿真.仿真结果表明了采用组合控制策略的矩阵变换器-异步电机矢量控制系统具备良好的调速性能,并且较交-直-交电压型PWM变频调速系统而言具有更多的优势.

  18. Handbook of asynchronous machines with variable speed

    CERN Document Server

    Razik, Hubert

    2013-01-01

    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

  19. REACTIVE POWER COMPENSATION IN ASYNCHRONOUS ELECTRIC DRIVES

    Directory of Open Access Journals (Sweden)

    V.S. Malyar

    2013-10-01

    Full Text Available A problem of calculating capacity of cosine capacitors for individual compensation of reactive power in asynchronous electric drives in stationary and transient operation modes is considered. The algorithm introduced employs a high-adequacy mathematical model of asynchronous motor developed on the theory of representing vectors which takes into account both the magnetic core saturation and the current displacement in the rotor bars.

  20. Characteristics of Three Phase Asynchronous Motor and Analysis of Variable Frequency Speed Regulation%三相异步电动机特性及其变频调速分析

    Institute of Scientific and Technical Information of China (English)

    杨雪林

    2016-01-01

    The motor is currently used the most extensive electrical transmission device, the three-phase asynchronous motor, using electrical theory, in-depth analyzes its equivalent circuit, the rotor circuit, referred to the stator side, forming a complete unity circuit, analyzes the various equations based on equivalent circuit, motor energy transfer process is embodied by the equation, mapped the working characteristic curve according to the equation. All motor control method is different, for three phase asynchronous cage motor, this paper analyzes the modern most popular drive system, variable frequency drive, analyzes the excellent characteristics and attention of frequency converter application.%电动机是目前应用最为广泛的电气传动装置,针对三相异步电动机,利用电工理论,深入分析了其等值电路,将转子回路折算到定子侧,形成一个完整的统一回路,在等值电路的基础上分析了各种方程式,方程式对电动机的能量传递过程有了深刻直观的体现,根据方程式绘制了工作特性曲线。各种电动机控制方法大有不同,针对三相异步鼠笼型电动机,本文分析了现代最流行的驱动系统,即变频驱动,分析了变频器应用时的相关注意事项及变频调速的优良特性。

  1. 异步电机DTC系统脉动最小化研究%Study of Torque Ripple Minimization for Direct Torque Control of Asynchronous Motors

    Institute of Scientific and Technical Information of China (English)

    孙鹏

    2014-01-01

    Direct torque control has been applied widely due to its simple arithmetic, fast transient response and robust stability to parameter changed. As for the conventional direct torque control system for asynchronous motors, there is the effect of voltage space vector on the magnitude of stator flux and flux angle, especially there are large ripples at low speed. Aiming at this issue and based on conventional DTC, a new control strategy is proposed in this paper, this strategy combines flux linkage section subdivision control with synthesizing vectors and can improve the torque response time by introducing Fussy control algorithm, thereby reducing torque ripples effectively. Simulation results show that the strategy can greatly reduce the torque ripples and has a better dynamic and steady performance.%直接转矩控制具有控制简单、动态响应迅速、对参数变化鲁棒性强的特点,因此得到了广泛的应用。在传统的异步电动机直接转矩控制系统中,存在电压空间矢量对定子磁链幅值和磁通角的影响,特别是低速时系统脉动大。针对此问题,文章提出了一种的新的控制方法,该方法将磁链区间细分控制与电压矢量合成结合在一起,并通过引入模糊控制算法进一步提高了转矩响应时间,且减小了转矩脉动。仿真结果表明,本控制方法可以大大减小转矩脉动,具有较好的动静态性能。

  2. Calculation and Analysis on Electro-magnetic Field of the Asynchronous Traction Motor for Freight Locomotive%货运机车异步牵引电机电磁场计算与分析

    Institute of Scientific and Technical Information of China (English)

    阮鸿芳; 于海涛

    2015-01-01

    Taking the AC asynchronous traction mo-tor of the HXD1C high-power locomotive as example, the 2D mathematic model of the electro-magnetic field was established and its solved region was determined either. The finite element method was applied to calculate the electro-magnetic parameters of the traction motor while the calculated result was compared with the actually-test data, and then, came the beneficial conclusion.%以大功率交流传动H X D1C机车用异步牵引电机为例,建立电机二维电磁场数学模型,并确定其求解域.利用有限元方法,计算牵引电机电磁参数,并将计算结果与实测数据进行对比,得出一些有益的结论.

  3. 基于参数回归模型的异步电动机等值电路参数测定%Asynchronous Motor Parameter Determination Using Model Regression Method

    Institute of Scientific and Technical Information of China (English)

    林友杰; 谢卫才

    2011-01-01

    在参数回归模型的基础上,对更接近于实际小转差运行工况的负载运行的实验数据进行参数回归,不仅可以避免常见测定方法的不足,还可以避免测量误差的干扰,得到更为准确的异步电动机等值电路参数.利用1stopt进行实验数据的参数回归处理,可以进行容易地解出异步电动机参数回归模型方程的解.探寻了几种回归模式在获取准确参数方面的可能性,表明基于参数回归模型的异步电动机等值电路参数的1stopt测定方法具有实际的指导意义和应用价值.%The model regression for the parameters of asynchronous motor equivalent circuit based on its parameter regression model and the use of the actual small slip experimental data can avoid the disadvantage of the common method and the measurement error disturbing, and thus the more accurate parameter can be obtained. The parameter regression for the experiment data using 1 stopt can easily resolve the equations of the model regression. Possibility for several model regression mode was studied. The result shows that the asynchronous motor parameter regression model using lstopt for resolving in the equivalent circuit parameter bears actual instruct sense and applied value.

  4. 基于热网络的异步电机过载保护模型及数字算法%Overload Protection Model of Asynchronous Motor Basing on Thermal Network and Digital Algorithm

    Institute of Scientific and Technical Information of China (English)

    李洪涛; 李奎; 倪素娟

    2011-01-01

    According to the different heat sources within the motor, the motor can be divided to five parts,namely, the stator core,the stator slot winding,rotor bar and rotor core, then the lumped parameter method was respectively used to them to establish an five-order thermal network model of asynchronous motor. With ensuring the accuracy of the thermal models,the full-order thermal models could be systematically reduced via pole-zero cancellation. As a result, a low-order thermal network models, which had nearly the major response characteristics in the frequency band of interest and was more simple for estimating the motor temperature, was obtained. In order to make the low-order themal network models could be applied to intelligent motor thermal overload protection relay, an discretization algorithm was proposed.%以试验样机为例,依据电机内部不同的发热源将电机分作五部分,即定子铁心和机壳、定子槽绕组、定子绕组端部、转子导条和转子铁心,分别应用集总参数法建立了五阶的热网络分布模型.在保证模型精度的前提下,利用零极点对消法对五阶热模型进行了降阶简化,从而得到了反应电机温升主要特性、精度高、计算简单的低阶热网络模型.对低阶热模型进行离散化,得到了适用于智能电机过载保护继电器的数字算法.

  5. 三相笼型异步电动机减压起动控制方法综述%Study on Approach of Starting Control by Pressure Reduction of Three-phase Cage-type Asynchronous Motors

    Institute of Scientific and Technical Information of China (English)

    叶新颖

    2015-01-01

    Due to desirable properties of simple structure, solidity and durability, high adaptability and efficient operation, three-phase cage-type asynchronous motor is extensively applied in the fields of industrial and agricultural production, national defense and scientific and technological research. From the perspective of starting control by pressure reduction, the author comprehensively analyzes the quantitative relation of the approaches of the control, respectively illuminates their characteristics and application range and further forecasts the future development trend of approach of motor starting control. The study in this paper is of great significance for the improvement of control circuit performance, motor service life prolongation, utilizing motor performance in energy-efficient manner and remarkable reduction of impact force imposed on power grid.%三相笼型异步电动机由于具有结构简单,坚固耐用,适应性强,运行高效等良好性能,被广泛应用于工农业生产、国防建设、科学技术研究等各个领域。本论文从三相笼型异步电动机的减压起动控制综合分析了减压起动控制方法的控制过程中数量关系并阐述了其各自的特点及适用范围,且对电动机起动控制方法未来的发展趋势做了进一步探讨与展望,对高效利用电动机性能、延长其使用寿命及有效减弱对电网的冲击力等方面的探究具有重要的意义。

  6. Compositional asynchronous membrane systems

    Institute of Scientific and Technical Information of China (English)

    Cosmin Bonchis; Cornel Izbasa; Gabriel Ciobanu

    2007-01-01

    This paper presents an algorithmic way of building complex membrane systems by coupling elementary membranes. Its application seems particularly valuable in the case of asynchronous membrane systems, since the resulting membrane system remains asynchronous. The composition method is based on a handshake mechanism implemented by using antiport rules and promoters.

  7. 基于强跟踪滤波算法的异步电机参数自适应无速度传感器控制%Parameter Adaptation Sensorless Control of Asynchronous Motor Based on Strong Track Filter

    Institute of Scientific and Technical Information of China (English)

    陆可

    2011-01-01

    在异步电机四阶模型的基础上增加机械和转矩方程,并引入负载转矩和转子电阻为状态变量,得到七阶非线性模型.利用强跟踪滤波(STF)算法实现电机状态和转子电阻的同时估计,通过仿真比较了STF和扩展Kalman滤波(EKF)算法的估计性能.结果表明,STF算法能有效估计电机状态及辨识转子电阻,并且具有比EKF算法更理想的估计性能,同时能满足极低速和零速下的估计要求,从而在电机的整个工作范围内实现转子电阻自适应的状态估计.%The equations of machine and torque were added to the fourth-order model of asynchronous motor.A seventh-order nonlinear model was obtained via increasing load torque and rotor resistance as state variables.The motor states and the rotor resistance were estimated simultaneously using strong track filter (STF).Computer simulations were performed to compare the estimation performance between STF and EKF.The results illustrated that STF could estimate the motor states and the rotor resistance effectively, and its performance was more perfect than EKF' s.STF could also satisfy the estimation request running at very low and zero speed, thus it could realize the states estimation with rotor resistance adaptation in the whole operation range.

  8. Speed Sensorless Vector Control of Asynchronous Motor Based on UKF%基于UKF算法的异步电机无速度传感器矢量控制系统

    Institute of Scientific and Technical Information of China (English)

    廖晓文; 陈政石

    2011-01-01

    针对异步电机无速度传感器矢量控制系统的转速、磁链估计问题,提出一种基于无轨迹卡尔曼滤波(UKF)的状态估计算法.为避免常用的对称采样方法仅适用于处理高斯噪声并且sigma点多带来的计算量大问题,依据UT变换理论,采用最小偏度单形采样方法,减少了近1/3的计算量.仿真结果表明,所提出的基于最小偏度采样的UKF估计器能够准确地估计转子磁链、转速.%Concerning the speed and flux estimation problem of speed sensorless vector control of asynchronous motor, a state estimation algorithm based on Unscented Kalman Filter is proposed. Symmetrical sampling strategy is common used but not showed good performance while dealing with non-Gaussian noise, and the large number of sigma points causes reasonable computation load. In the paper, ninimal skew simplex sampling is adopted according to UT transformation theory, as a result, nearly 1/3 computation load is reduced. Simulation results show that the UKF estimator based on the minimal skew simplex sampling can estimate flux and rotor speed precisely.

  9. 微型三相异步电动机设计分析%Design Analysis of Miniature Three-phase Asynchronous Motor

    Institute of Scientific and Technical Information of China (English)

    刘俊利; 邢海龙

    2011-01-01

    This paper introduced the design of a three-phase induction motor of 15 W, presented the demands of this induction motor. The inner diameter and length of the armature and the air gap length were determined firstly. The slots number of the armature and the cage rotor were selected to reduce the additional loss, vibration and noise. The shape of the armature slot and cage slot were chose respectively. The single layer concentrate full pitch winding was employed. The calculation results show the design scheme can meet the demands of the three-phase induction motor of 15W.%介绍了15 W三相异步电动机的电磁设计.针对15 W三相异步电动机的技术指标,分析了其主要尺寸的确定、定转子槽数的配合、定转子槽形的设计及电枢绕组形式的选择.采用磁路法和电磁场仿真对电磁方案进行了性能计算,两种方法的计算结果表明该电磁方案能够满足技术指标要求.

  10. Discussion on the no-load current of three-phase asynchronous motor%浅论三相异步电动机的空载电流

    Institute of Scientific and Technical Information of China (English)

    杨立峰; 郭宗跃; 牛玉敏

    2015-01-01

    该文对以往利用空载电流判断电动机修理质量的方法进行了分析,提出了根据功率因数cosφ和效率η之积的经验值进行经验额定电流计算的方法。并根据长期现场工作经验,针对不同类型的电动机,计算出的经验额定电流和实测的空载电流,给出了鉴定电动机修理质量的具体判断依据。%In this paper, we analysis the conventional method of using the no-load current to judge the quality of motor repairs. Presents mehtod according to the product empirical value of the power factor cosφand efifciencyηto caculate experience rated current.. Based on the long-term ifeld experience, for different types of motor, according to the experience rated current calculated and load current measured, eventually give a speciifc identiifcation basis for motor repair quality.

  11. 异步电动机液体变阻器软启动控制设计%Soft Start Control Design for the Liquid Rheostat of Asynchronous Motor

    Institute of Scientific and Technical Information of China (English)

    徐腊梅; 贺平平; 陈彦龙

    2011-01-01

    The initial firing current of AC asynchronous motor in the starting time is 5 - 7 times of that in normal operation. The oversized start current exerts the disadvantageous impact on the power supply electrical network, and affects normal operation of the equipment. A control method named liquid rheostat resistance "soft start" was proposed to reduce impulse current generated in period of motor starting. The resistance of liquid rheostat which was concatenated in rotor loop was controllable. It reduces with start time increasing;thus starting time and initial firing current are controllable. The high power factor and the best starting torque can be obtained.%交流异步电动机在启动时的启动电流是正常运行电流的5~7倍,过大的启动电流会对供电电网产生不利的冲击,影响设备的正常运行.为减小电动机启动时产生的冲击电流,提出了液体变阻器软启动的控制方法,通过改变串接在转子回路中的液体变阻器的电阻,使其阻值随启动时间的增加而减少,从而调整启动时间和启动电流,并获得较高功率因数和最佳启动转矩.

  12. 基于MATLAB/Simulink的异步电机控制系统建模与仿真%Modeling and simulation of asynchronous motor control system based on MATLAB/Simulink

    Institute of Scientific and Technical Information of China (English)

    孟朝霞; 任一峰

    2012-01-01

    In this paper, based on the means of asynchronous motor' s rotor flux-oriented vector control,and the shortcomings that rotor flux is influenced by motor parameters in magnetic linkage closed loop, this article adopts vector control scheme of magnetic flux opended loop.By modular thought,the functional modules of the opening magnetic flux loop of vector control system is modeled in MATLAB/Simulink. Through the organic integration of each functional modules, a simulation model of vector control system is modeled. The results show that the system has a good dynamic performance and the anti-interference ability,so the feasibility and effectiveness of the modeling method is validated. The results also provides a theoretical foundation for design and debug of actual motor control system.%本文在基于转子磁链定向的异步电机矢量控制理论基础上,针对磁链闭环的矢量控制系统中转子磁链易受电机参数影响的不足,提出了转子磁链开环的矢量控制方案。利用模块化思想,在MATLAB/Simulink建立磁链开环的矢量控制系统的各个功能模块,然后对各个功能模块进行有机的整合,构成矢量控制系统的仿真模型;仿真结果表明该系统具有良好的动态性能和抗干扰能力,进而验证了该控制系统设计的可行性和有效性,为实际电机控制系统的设计和调试奠定了理论基础。

  13. 三相异步电机制动方式瞬态过程仿真分析研究%Simulation study on transient process of 3-phase asynchronous motor braking

    Institute of Scientific and Technical Information of China (English)

    朱春鸯; 周政新

    2013-01-01

    In order to get some constrains and transient process of asynchronous motor braking,by Matlab/Simulink environment,and based on motor simulation model of the mathematic model of d-q coordination and breakers and resistors of Simulink tools,simulation controlling model of motor braking is gotten.The simulation result shows that this method can get the optimization parameters of exhausted-braking,reserve-connection braking,regenerative braking through repeatly modifying voltage and resistors parameters,and so on,what's more,the transient process alteration of rotator and stator current,rotation speed and retarding torque is analyzed.Simulink results can guide us for special project application,at the same time,this method of building simulation model also supply theory into practice for building model of control running of motor and other braking model.%为获取电机制动方式实现的约束条件及制动过程的瞬态特性分析,运用Matlab/Simulink仿真环境平台,应用基于d-q坐标下数学模型建立的电机仿真模型及Simulink工具箱中断路器、阻抗等工具搭建电机制动方式仿真控制模型.通过反复调节模型中模块参数,改变电源电压或负载大小、回路断开闭合的时间等,找到能耗制动、电源反接制动、倒拉反接制动、回馈制动控制回路最优参数,并能直观观察分析比较其制动过程中的定转子瞬态电流、速度及其制动转矩变化的暂态过程,由此确定电机性能为具体的工程案例应用提供实践依据,同时,建立的仿真模型方法也为电机控制运行及其它制动方式建模提供理论指导.

  14. Research on Asynchronous Motor Featured with High Efficiency, High Power Density and Low Noise%高效高功率密度低噪声电机研究

    Institute of Scientific and Technical Information of China (English)

    周玲慧; 向善海; 陈华

    2015-01-01

    Taking the development process of a 3 550 kW 6 kV 6-pole asynchronous motor featured with high efficiency, high power density and low noise as an example, analyzed the approaches and methods to increase the power density and decrease the noise from the aspects of insulation system design, ventilation and heat dissipation design, optimization of electromagnetic design, structure design and manufacturing process, and investigated the influences by related factors on the temperature rise of the motor based on the simulation and test results. Targets were defined for developing this motor of high efficiency, high power density and low noise. Compared with the corresponding parameters of the similar products of the major international electric machines manufactures, test data showed that the defined targets were well achieved of this motor.%以一台3550 kW、6 kV、6极高效高功率密度低噪声电机的研制为例,从绝缘系统和通风散热系统设计、电磁设计、结构设计和加工工艺等方面,分析了提高电机功率密度和降低噪声的途径和方法。结合相关仿真与样机试验,分析了几个相关因素对电机温升的影响。提出了该型号高效高功率密度低噪声电机的研制目标。给出了样机试制与型式试验结果,结合国外先进电机制造企业的相关产品参数,说明了该型号高效高功率密度低噪声电机的研制取得了成功,达到了国际先进水平。

  15. 异步电机三维电磁场及温度场耦合仿真分析∗%Coupling Simulation of 3 D Electromagnetic Field and Thermal Field of Asynchronous Motor

    Institute of Scientific and Technical Information of China (English)

    陈华毅; 杨明发

    2015-01-01

    Deals with 3D temperature estimation for the asynchronous motor Y100L2-4. According to the structure characteristics and electromagnetic parameters, the thermal fields of steady state operation with rated load has been analyzed to extract the heat source of the motor, as the foundation of the steady temperature distribution. The heat dissipation coefficient of each part in motor and the equivalent heat transfer coefficient of air gap between the rotor and stator were analyzed. According to the boundary condition and the equivalent hypothesis and material properties of the motor, the temperature field was derive by One-way coupled simulation of finite element software, based on the simulation results of electromagnetic field. the simulation results have higher accuracy was verify by comparing with the experimental data.%以型号为Y100L2-4的异步电机为对象,建立了三维有限元模型。根据样机的结构特征和电磁参数,仿真计算出了样机额定负载下运行至稳态的电磁场,用以提取较为精确的发热源,进而计算其稳态温度分布。分析了电机各部分散热系数、定转子间气隙的等效传热系数,依据电机的边界条件、等效假设和材料属性,以电磁场仿真结果为基础,利用有限元软件单向耦合出相应的温度场分布图。最后通过与试验数据对比,验证仿真结果有更高的准确性。

  16. VOLTAGE REGULATORS ASYNCHRONOUS GENERATORS

    Directory of Open Access Journals (Sweden)

    Grigorash O. V.

    2015-06-01

    Full Text Available A promising is currently the use of asynchronous generators with capacitive excitation as a source of electricity in stand-alone power systems. Drive asynchronous generators may exercise as a thermal engine and wind wheel wind power plant or turbines of small hydropower plants. The article discusses the structural and schematics of voltage stabilizers and frequency of asynchronous generators with improved operational and technical specifications. Technical novelty of design solutions of the magnetic system and stabilizers asynchronous generator of electricity parameters confirmed by the patents for the invention of the Russian Federation. The proposed technical solution voltage stabilizer asynchronous generators, can reduce the weight of the block capacitors excitation and reactive power compensation, as well as to simplify the control system power circuit which has less power electronic devices. For wind power plants it is an important issue not only to stabilize the voltage of the generator, but also the frequency of the current. Recommend functionality stabilizer schemes parameters of electric power made for direct frequency converters with artificial and natural switching power electronic devices. It is also proposed as part of stabilization systems use single-phase voltage, three-phase transformers with rotating magnetic field, reduce the level of electromagnetic interference generated by power electronic devices for switching, enhance the efficiency and reliability of the stabilizer.

  17. Asynchronized synchronous machines

    CERN Document Server

    Botvinnik, M M

    1964-01-01

    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

  18. Asynchronous P300 BCI

    DEFF Research Database (Denmark)

    Panicker, Rajesh; Puthusserypady, Sadasivan; Sun, Ying

    2010-01-01

    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...

  19. Asynchronous Multiparty Computation

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...

  20. Redundant Asynchronous Microprocessor System

    Science.gov (United States)

    Meyer, G.; Johnston, J. O.; Dunn, W. R.

    1985-01-01

    Fault-tolerant computer structure called RAMPS (for redundant asynchronous microprocessor system) has simplicity of static redundancy but offers intermittent-fault handling ability of complex, dynamically redundant systems. New structure useful wherever several microprocessors are employed for control - in aircraft, industrial processes, robotics, and automatic machining, for example.

  1. 基于FPGA的异步电动机变频调速系统%Variable frequency driver system of asynchronous motor based on FPGA

    Institute of Scientific and Technical Information of China (English)

    吴俊; 邱建琪; 史涔溦; 王莉

    2012-01-01

    Aiming at the slow speed and poor stability of control system designed by traditional micro control unit(MCU)or digital signal processor (DSP) in the way of software, a hardware designed scheme of space vector pulse width modulation (SVPWM) based on field programmable gate array (FPCA) was presented, which based on the background of full digital motor-controller. Combining complished EDA design methodology and Verilog HDL, it was verified and implemented on one-chip FPGA. The "top-down" theme was used to develop core by dividing system according to it's function in the design. It was realized that, at first, design and simulation on single module, secondly, on the whole system, at last verification using FPCA. The algorithm was proved feasible through the simulation and experiment. On the basis of the platform, V/F open loop speed regulation system experiment was completed. The results indicate that the system has excellent stablity characteristic,reasonable chip utility,good reusability,superiority that the MCU and DSP do not have in real time,flexibility etc., and lays the foundation for the design of a special motor-controlling chip.%针对传统的单片机(MCU)或数字信号处理器(DSP)以软件方式实现的控制系统普遍存在速度慢、稳定性差等问题,以实现全数字电机控制器的集成化为背景,提出了一种基于现场可编程门阵列( FPGA)的空间电压矢量脉宽调制(SVPWM)硬件设计方案,并结合EDA模块化的设计方法和Verilog HDL硬件描述语言,在一片FPGA芯片中得到了验证和实现;采用“top-down”设计思想,对系统按功能划分模块进行了设计;首先对各功能模块进行了设计、仿真、验证,然后将整个系统组合起来进行了仿真、验证,最后利用FPGA进行了硬件验证;在此基础上,完成了异步电机SVPWM调制方式的V/F开环变频调速系统的实验.研究结果表明,该系统稳定性高、占用资源少、复用性高,在实

  2. 基于改进LS-SVM的异步电机转子故障诊断%Rotor Fault Diagnosis of Asynchronous Motor Based on Improved LS-SVM

    Institute of Scientific and Technical Information of China (English)

    李伟伟; 王莉; 张琳; 冯丹

    2016-01-01

    In order to improve rotor fault diagnosis accuracy of the asynchronous motor,a multi-class classification algorithm based on improved Least Square Support Vector Machine (LS-SVM)is proposed. First the fault character vectors are collected from the signal spectrum that is acquired from the signals of the motor stator current fault by FFT. Then when the feature vectors are used as the inputs of the improved algorithm for fault diagnosis,the improved algorithm confirms the weight of all faults with analytic hierarchy process,determines the order of the fault diagnosis in accordance with the weight and achieves the fault classification in turn on the basis of the former multi-class algorithm. Experimental results show that the improved algorithm saves time and improves the diagnosis accuracy when it is used for fault diagnosis and it has a bright prospect for generalization.%为了提高异步电动机转子故障的诊断精度,给出了一种基于改进最小二乘支持向量机(LS-SVM)的多故障分类算法。首先运用FFT处理电机的定子电流信号得到信号频谱图,从中提取故障特征向量;然后将特征向量送入改进算法进行故障诊断时,在原有多分类算法的基础上引入层次分析法确定故障类别的权重,根据权重值确定故障的诊断顺序,依次进行故障分类。实验表明,改进算法用于故障诊断节省了诊断时间,提高了诊断精度,具有很好的推广前景。

  3. Reduction of power consumption in motor-driven applications by using PM motors; PM = Permanent Magnet; Reduktion af elforbrug til motordrift ved anvendelse af PM motorer

    Energy Technology Data Exchange (ETDEWEB)

    Hvenegaard, C.M.; Hansen, Mads P.R.; Groenborg Nikolaisen, C. (Teknologisk Institut, Taastrup (Denmark)); Nielsen, Sandie B. (Teknologisk Institut, AArhus (Denmark)); Ritchie, E.; Leban, K. (Aalborg Univ., Aalborg (Denmark))

    2009-12-15

    The traditional asynchronous motor with aluminum rotor is today by far the most widespread and sold electric motor, but a new and more energy efficient type of engine - the permanent magnet motor (PM motor) - is expected in the coming years to win larger and larger market shares. Several engine manufacturers in Europe, USA and Asia are now beginning to market the PM motors, which can replace the traditional asynchronous motor. The project aims to uncover the pros and cons of replacing asynchronous motors including EFF1 engines with PM motors, including the price difference. Furthermore, it is identified how the efficiency of PM motors is affected by low load levels and at various forms of control. Finally, the energy savings potential is analysed, by replacing asynchronous motors with PM motors. The study includes laboratory tests of PM motors, made in a test stand at Danish Technological Institute. (ln)

  4. Permanent magnet motors from ABB eliminate gearboxes%ABB永磁电机在船舶上的应用

    Institute of Scientific and Technical Information of China (English)

    钱丽春

    2004-01-01

    Permanent magnet motor is synchronous and eliminates brushes, rotor windings ABB's permanent magnet motor is an AC synchronous motor. With such a motor, there is no rotor slip, which provides better accuracy than induct asynchronous, motors.

  5. Asynchronous Variational Integrators

    OpenAIRE

    Lew, A.; Marsden, J. E.; Ortiz, M.; West, M

    2003-01-01

    We describe a new class of asynchronous variational integrators (AVI) for nonlinear elastodynamics. The AVIs are distinguished by the following attributes: (i) The algorithms permit the selection of independent time steps in each element, and the local time steps need not bear an integral relation to each other; (ii) the algorithms derive from a spacetime form of a discrete version of Hamilton’s variational principle. As a consequence of this variational structure, the algorith...

  6. Text Mining: (Asynchronous Sequences

    Directory of Open Access Journals (Sweden)

    Sheema Khan

    2014-12-01

    Full Text Available In this paper we tried to correlate text sequences those provides common topics for semantic clues. We propose a two step method for asynchronous text mining. Step one check for the common topics in the sequences and isolates these with their timestamps. Step two takes the topic and tries to give the timestamp of the text document. After multiple repetitions of step two, we could give optimum result.

  7. Finite Element Calculation of Radial Electromagnetic Force Wave in Squirrel-Cage Asynchronous Motors%笼型异步电动机径向电磁力波的有限元计算

    Institute of Scientific and Technical Information of China (English)

    王荀; 邱阿瑞

    2012-01-01

    In this paper, the field-circuit coupled time-stepping finite element model of squirrel-cage asynchronous motor is presented and the validity is verified by means of the comparison between the stator phase current harmonics of the simulating wave and those of the experiment wave. Air gap flux density is calculated by means of this model and radial electromagnetic force is calculated using the classical Maxwell stress tensor method. Air gap flux density and radial electromagnetic force vary in both space domain and time domain and two dimensional Fourier analysis are carried out to calculate harmonics of those. The influence of the tooth and slot and the slip on flux density and radial electromagnetic force are discussed. The relationship of flux density waves and radial electromagnetic force waves are analyzed. Radial electromagnetic force waves and the testing electromagnetic noise spectra are analyzed and compared and the results verify the effectiveness of the calculation of radial electromagnetic force waves. Radial electromagnetic force and its harmonics calculated by the method can be used to electromagnetic noise analysis in the design stage.%建立笼型异步电动机的场路耦合时步有限元模型,通过定子相电流仿真波形和实测波形的谐波比较验证有效性。基于该模型计算气隙磁通密度,进而利用经典的Maxwell应力张量法计算径向电磁力。气隙磁通密度和径向电磁力均随空间和时间变化,利用二维傅里叶分析分别求解它们的谐波;并探讨齿槽和转差率对磁通密度和径向电磁力的影响,以及磁通密度波和径向电磁力波之间的关系。将径向电磁力波和实测电磁噪声频谱进行了分析和对比,结果表明径向电磁力波的计算是合理有效的。利用本文方法计算的径向电磁力及其谐波可应用于在设计阶段对电磁噪声的分析。

  8. 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)

    2006-05-15

    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.)

  9. DESIGN METHODOLOGY OF SELF-EXCITED ASYNCHRONOUS GENERATOR

    Directory of Open Access Journals (Sweden)

    Berzan V.

    2012-04-01

    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.

  10. ASCERTAINMENT OF THE EQUIVALENT CIRCUIT PARAMETERS OF THE ASYNCHRONOUS MACHINE

    Directory of Open Access Journals (Sweden)

    V. S. Safaryan

    2015-01-01

    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

  11. Asynchronous Power Flow Controller

    Directory of Open Access Journals (Sweden)

    Rahul Juneja

    2014-04-01

    Full Text Available In the present system demand of electrical power increases so fast and transfer of electrical power is need of today‟s scenario. . The electrical power is transfer at same frequency through AC transmission line. However, power generation may be at different frequencies such as wind generation, sources at islanding or power generation in different countries. The proposed Asynchronous Power Flow Controller (APFC system essentially consists of two back-to-back voltage source converters as “Shunt Converter” and “Series Converter” which is coupled via a common dc link provided by a dc storage capacitor This paper suggests the power transfer and control between the sources operating at different or same frequencies.

  12. Pro asynchronous programming with .NET

    CERN Document Server

    Blewett, Richard; Ltd, Rock Solid Knowledge

    2014-01-01

    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. THE METHODS AND THE RESULTS OF THE TESTING OF AN ASYNCHRONOUS GENERATOR WITH SIX PHASE ZONES

    Directory of Open Access Journals (Sweden)

    Bogatyrev N. I.

    2016-03-01

    Full Text Available The article contain the peculiarities of testing asynchronous generator with sixzone winding on the basis of the asynchronous motor series 4A100S4 and analysis of obtained characteristics. Circuit parameters of the stator winding can significantly affect the characteristics of the asynchronous generator. Asynchronous generator was tested with a stator winding connected star, autotransformer and sectional winding. Use chastising windings opens the possibility of applying various circuits of capacitors and the load to asynchronous generators, which in turn affect the efficiency and stabilizing properties of the electric machine. Asynchronous generators to test with sectional winding by confirmation of theoretical calculations for determine the most optimal scheme under connect capacitors and load, testing the stator winding. The volume of testing for asynchronous generators standard is not defined, so we proposed testing method, taking into account the design features of the stator winding. Asynchronous generators were tested with the help of special equipment with the use of analyzer of energy power quality. Article contains characteristics of idling, short circuit and others, considered the heat mode. On the basis of the results we have determined the parameters of the circuit, the efficiency and power factor of induction generator

  14. Induction motor control design

    CERN Document Server

    Marino, Riccardo; Verrelli, Cristiano M

    2010-01-01

    ""Nonlinear and Adaptive Control Design for Induction Motors"" is a unified exposition of the most important steps and concerns in the design of estimation and control algorithms for induction motors. A single notation and modern nonlinear control terminology is used to make the book accessible to readers who are not experts in electric motors at the same time as giving a more theoretical control viewpoint to those who are. In order to increase readability, the book concentrates on the induction motor, eschewing the much more complex and less-well-understood control of asynchronous motors. The

  15. ASYNCHRONOUS ELECTRONIC DISCUSSION GROUP:

    Directory of Open Access Journals (Sweden)

    Tina Lim Swee KIM

    2007-01-01

    Full Text Available This paper examines the practice of online discussion in a course specially tailored for in-service teachers who are pursuing their basic degree qualification at a teacher training institute. Analyses of postings to the asynchronous electronic discussion group were made according to the type of postings as proposed by Poole (2000. Four focus areas were looked into, that is, content, technical, procedural, or non-academic. Analyses were done for each quarter of the 12 weeks of interaction. At the end of the learners’ participation in the EDG and before their end-of-course examination, the participants were then given a paper-based questionnaire asking their perceptions on the use of EDG as part of their coursework on the whole. Six aspects of EDG were examined, these are;Ø technical aspects, Ø motivation to use the EDG, Ø quality of interaction, Ø tutor’s response, Ø perceived learning, and Ø attitude towards EDG. Analyses on postings for the EDG showed that the bulk of the postings were made in the last quarter of the online discussions. Further, 97.8% of the postings were on content and the types of content posting registered were predominantly questions (41.19% and those that sought clarification/elaboration (37.48%. Findings from this study suggest that overall the participants were satisfied with the six aspects of EDG examined. The aspect that recorded the highest mean was ‘motivation to read tutor’s responses’ whilst the lowest mean (and the only one with negative perception was for ‘worthiness of time spent on online discussions’.

  16. Behavioral synthesis of asynchronous circuits

    DEFF Research Database (Denmark)

    Nielsen, Sune Fallgaard

    2005-01-01

    domain by introducing a computation model, which resembles the synchronous datapath and control architecture, but which is completely asynchronous. The model contains the possibility for isolating some or all of the functional units by locking their respective inputs and outputs while the functional unit...

  17. Preliminary exploration of fault diagnosis for rotor bar breaking of squirrel cage asynchronous motors based on coil detection%基于线圈探测的笼型异步电机转子断条故障诊断初探

    Institute of Scientific and Technical Information of China (English)

    武玉才; 李永刚; 李和明; 许伯强

    2012-01-01

    笼型异步电机转子断条故障研究是目前国内外关注的热点之一,已经提出的诊断方法在进行故障特征提取时具有一定困难.分析了异步电机参数与导条电气特征间的关系,通过数值仿真得到断条前后转子电流分布规律,结合有限元工具Ansys分析了导条漏磁场在故障前后的变化.研究结果表明探测线圈输出的电压幅值与导条故障的严重程度之间存在对应关系,探测线圈法可以应用于笼型异步电动机转子断条故障的诊断.%Study on the fault diagnosis of rotor broken-bar of cage induction motor is one of the focus of attention worldwide. Diagnostic methods already proposed are difficult to extract the fault feature. The relationship among motor parameters and bar electrical features is analyzed in this paper, and the rotor current distributions before and after the bar breaking fault are obtained by numerical simulation. By combining with the finite element tool Ansys, the change of leakage magnetic field after fault is analyzed. The results show that the voltage amplitude sensed at the detection coil has close correlations with bar fault severity, and search coil method can be used to diagnose of asynchronous motor rotor bar breaking fault.

  18. 电动汽车用异步电机驱动控制系统可靠性分析%Reliability Analysis of Asynchronous Motors Driving and Controlling System in Electric Vehicle

    Institute of Scientific and Technical Information of China (English)

    李强; 王永全; 付瑶琴

    2014-01-01

    电机驱动控制系统是电动汽车的心脏,其可靠性直接影响着电动汽车的安全性。分析了驱动控制系统的主要故障模式,其薄弱环节为电机轴承系统、绝缘系统,及直流母线电容、IGBT等电子元器件。在此基础上建立可靠性模型。采用元器件应力分析法预计电动汽车电机驱动系统的可靠性。%The motor driving and controlling system is the heart of the electric vehicle, whose reliability directly affects the safety of the electric vehicle. The main failure pattern of the motor driving and controlling system was analyzed, in which the motor bearing systems, insulation systems, DC bus capacitors, IGBT and other electronic components are the weak links. On the basis of the analysis, the reliability model was established. Based on the established reliability model, the reliability of motor driving and controlling system in electric vehicles was estimated by the component stress analysis method.

  19. 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.

    2002-11-15

    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)

  20. Asynchronous control for networked systems

    CERN Document Server

    Rubio, Francisco; Bencomo, Sebastián

    2015-01-01

    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 ...

  1. Asynchronous MPI for the Masses

    OpenAIRE

    Wittmann, Markus; Hager, Georg; Zeiser, Thomas; Wellein, Gerhard

    2013-01-01

    We present a simple library which equips MPI implementations with truly asynchronous non-blocking point-to-point operations, and which is independent of the underlying communication infrastructure. It utilizes the MPI profiling interface (PMPI) and the MPI_THREAD_MULTIPLE thread compatibility level, and works with current versions of Intel MPI, Open MPI, MPICH2, MVAPICH2, Cray MPI, and IBM MPI. We show performance comparisons on a commodity InfiniBand cluster and two tier-1 systems in Germany...

  2. Thyristor-based three-phase asynchronous motor soft start research%基于晶闸管软起动的三相异步电动机的研究

    Institute of Scientific and Technical Information of China (English)

    袁帆

    2013-01-01

    This article discusses the use of Thyristor firing angle changed to adjust the voltage across the induction motor stator, thereby changing the motor speed and stator current soft start works. This soft-start mode structure is simple、excellent performance and is easy to be adjusted. For less demanding fan and pump load is very applicable.%文章论述了利用改变晶闸管的触发角来调节异步电动机定子两端电压,进而改变电机的转速和定子电流的软起动的原理。这种软起动方式结构简单,性能好,调试容易,对于要求不高的风机、泵类负载非常适用。

  3. Asynchronous Methods for Deep Reinforcement Learning

    OpenAIRE

    Mnih, Volodymyr; Badia, Adrià Puigdomènech; Mirza, Mehdi; Graves, Alex; Lillicrap, Timothy P.; Harley, Tim; Silver, David; Kavukcuoglu, Koray

    2016-01-01

    We propose a conceptually simple and lightweight framework for deep reinforcement learning that uses asynchronous gradient descent for optimization of deep neural network controllers. We present asynchronous variants of four standard reinforcement learning algorithms and show that parallel actor-learners have a stabilizing effect on training allowing all four methods to successfully train neural network controllers. The best performing method, an asynchronous variant of actor-critic, surpasse...

  4. RBF神经网络在异步电机故障诊断中的应用%The Applications of the RBP Nerve Network in the Fault Diagnosis to the Asynchronous Motor

    Institute of Scientific and Technical Information of China (English)

    穆丽娟; 苏晓娜; 李晓明

    2012-01-01

    This paper applies RBF neural network into the fault diagnosis of motor and constructs the RBF fault diagnosis model of motor. To overcome the limitations of RBF neural network, differential evolutionary algorithm is imported into this paper. The universal search ability of DE algorithm could help us to optimize center, width of basic function and network float weight of RBF neural network, and build the most suitable network model. The experimental result shows that the optimized RBF neural network' s generalization ability and diagnosis accuracy have be substantially improved.%将径向基(RBF)神经网络应用到电机的故障诊断中,建立了异步电机的RBF神经网络诊断模型.为了克服RBF神经网络学习算法的不足,引入了差分进化(DE)算法,并且利用了差分进化(DE)算法的全局搜索能力来优化RBF神经网络基函数的中心、宽度以及网络的连接权值,以获得最优的网络模型.仿真结果表明优化后的RBF神经网络的泛化能力和诊断精度都得到了大幅度提高.

  5. Asynchronous Parallelization of a CFD Solver

    Directory of Open Access Journals (Sweden)

    Daniel S. Abdi

    2015-01-01

    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.

  6. Direct Torque Control of Asynchronism Motor Based on Space Vector Pulse Width Modulation%基于SVPWM的感应电机直接转矩控制方法的研究

    Institute of Scientific and Technical Information of China (English)

    高中臣; 张爱玲; 陈晨

    2009-01-01

    To reduce the low speed torque ripple of induction motor and keep constant switch frequency, this paper proposed a new control strategy on the basis of direct torque control (DTC),which uses Space Vector Pulse Width Modulation instead of switch table.The experiment and simulation results show that it can reduce the torque ripple,and improve the waveform of stator flux and current.%针对传统直接转矩控制开关频率不恒定及低速时的转矩脉动大的缺点,采用了基于SVPWM的直接转矩控制方法.根据转矩和定子磁链的误差确定应该施加的参考电压矢量,然后利用电压空间矢量脉宽调制(SVPWM)的方法合成该矢量.仿真和实验结果表明,基于SVPWM的直接转矩控制(SVPWM-DTC)能够有效减小转矩脉动,改善磁链和电流波形.

  7. Simulation of Indirect Vector Control System of the Asynchronous Motor%异步电动机间接矢量控制系统的仿真研究

    Institute of Scientific and Technical Information of China (English)

    石瑶; 李宏胜

    2015-01-01

    The indirect vector control system of the AC motor with rotor flux open-loop has been widely used because of the simple structure and high control performance. The indirect oriented vector control system was established based on Matlab/simulink. Then it was a research if the changes of the rotor time constant had effect on the rotor flux oriented. The results showed that the real-time adjustment of the rotor time constant had an important role in the system control performance.%异步电动机的转子磁链开环间接矢量控制系统因其结构简单,控制性能高得到广泛的应用。利用Matlab/simulink仿真软件建立了间接定向的矢量控制系统,并根据模型探讨转子时间常数的变化对转子磁链定向的影响。结果表明,转子时间常数的实时调整对系统控制性能有重要作用。

  8. Simulation Study of Asynchronous Motor in Slip Frequency Control Base on Three-level%基于三电平异步电机转差频率矢量控制的仿真研究

    Institute of Scientific and Technical Information of China (English)

    付光杰; 王圣慧; 陈舒; 王建任; 顾宝龙

    2012-01-01

    The direct rotor magnetic field oriented vector control system of Aysnchronous motor is very complex,and the flux feedback signal is not easy to obtain. So this article presents a three-level slip frequency control method with high control precision, control method is simple, high static and dynamic performance characteristics based on slip frequency control method, This method does not need complex coordinate transformation and flux detection. By application of MATLAB/Simulink software to build a simulation model, in the simulation a large number of parameters through the process of debugging and optimization of the ratio adjustment, this system can eliminate the steady-state error and the ability to quickly reduce the deviation. The simulation results show, the three-level inverter slip frequency control system has good control performance.%异步电动机的直接转子磁场定向矢量控制系统极其复杂,而且磁链反馈信号不易获取,鉴于此提出了一种 基于三电平转差频率控制的方法,该方法无需进行复杂的坐标变换和磁通检测,具有控制精度高、控制方法简单、较高的动静态性能等特点.应用MATLAB/Simulink软件搭建了系统的仿真模型,在仿真实验过程中通过大量的参数调试和配比的优化调节,本系统能够消除稳态误差并能够快速减小偏差.仿真结果证明了,三电平转差频率变频调速系统具有良好的控制性能.

  9. Carrying Synchronous Voice Data On Asynchronous Networks

    Science.gov (United States)

    Bergman, Larry A.

    1990-01-01

    Buffers restore synchronism for internal use and permit asynchronism in external transmission. Proposed asynchronous local-area digital communication network (LAN) carries synchronous voice, data, or video signals, or non-real-time asynchronous data signals. Network uses double buffering scheme that reestablishes phase and frequency references at each node in network. Concept demonstrated in token-ring network operating at 80 Mb/s, pending development of equipment operating at planned data rate of 200 Mb/s. Technique generic and used with any LAN as long as protocol offers deterministic (or bonded) access delays and sufficient capacity.

  10. Asynchronous design of Networks-on-Chip

    DEFF Research Database (Denmark)

    Sparsø, Jens

    2007-01-01

    The Network-on-chip concept has evolved as a solution to a broad range of problems related to the design of complex systems-on-chip (SoC) with tenths or hundreds of (heterogeneous) IP-cores. The paper introduces the NoC concept, identifies a range of possible timing organizations (globally......-synchronous, mesochronous, globally-asynchronous locally-synchronous and fully asynchronous), discusses the circuitry needed to implement these timing methodologies, and provides some implementation details for a couple of asynchronous NoCs designed at the Technical University of Denmark (DTU). The paper is written...

  11. Burst-Mode Asynchronous Controllers on FPGA

    Directory of Open Access Journals (Sweden)

    Duarte L. Oliveira

    2008-01-01

    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.

  12. Implementing LOTOS as asynchronously Communicating Processes

    OpenAIRE

    Sjödin, Peter

    1990-01-01

    A technique is presented for translating LOTOS specifications into implementations executing as asynchronously communicating processes. This generation of implementations is described as transformations of LOTOS expressions. A protocol for implementing LOTOS synchronisation is described.

  13. Asynchronous Data Fusion With Parallel Filtering Frame

    OpenAIRE

    Na Li; Junhui Liu

    2011-01-01

    This paper studies the design of data fusion algorithm for asynchronous system with integer times sampling. Firstly, the multisensor asynchronous samplings is mapped to the basic axis, accordingly a sampling sequence of single sensor can be taken. Secondly, aiming at the sensor with the densest sampling points, the modified parallel filtering is given. Afterwards, the sequential filtering fusion method is introduced to deal with the case that there are multiple mapped measurements at some sam...

  14. Asynchronous communication in real space process algebra

    OpenAIRE

    Baeten, JCM Jos; Bergstra, JA Jan

    1992-01-01

    A version of classical real space process algebra is given in which messages travel with constant speed through a three-dimensional medium. It follows that communication is asynchronous and has a broadcasting character. A state operator is used to describe asynchronous message transfer and a priority mechanism allows to express the broadcasting mechanism. As an application, a protocol is specified in which the receiver moves with respect to the sender.

  15. Performance Analysis of Asynchronous Multicarrier Wireless Networks

    OpenAIRE

    Lin, Xingqin; Jiang, Libin; Andrews, Jeffrey G.

    2014-01-01

    This paper develops a novel analytical framework for asynchronous wireless networks deploying multicarrier transmission. Nodes in the network have different notions of timing, so from the viewpoint of a typical receiver, the received signals from different transmitters are asynchronous, leading to a loss of orthogonality between subcarriers. We first develop a detailed link-level analysis based on OFDM, based on which we propose a tractable system-level signal-to-interference-plus-noise ratio...

  16. 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

    2011-01-01

    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

  17. Performance Analysis of Induction Motor of Electric Vehicle Using Vector control

    Institute of Scientific and Technical Information of China (English)

    Liu ping

    2012-01-01

    According to the principle of Vector controlused in an asyn- chronous motor,a simulation model of the asynchronous motor in elec-tric vehicle and Vectorcontrolsystem was established with Matlab/Simu-link software. Simulation analysis of the asynchronous motor driving an electric vehicle was performedunder the classic mode of EV , and the simulation results show the modeland control scheme has better stable and dynamic performance,whichcanbe a good candidate for electric ve- hicle propulsion system

  18. The bond-graph design of a motor used for electrical traction

    Directory of Open Access Journals (Sweden)

    Adriana Grava

    2009-10-01

    Full Text Available In this paper the asynchronous motorwith cage, used for electrical traction is studied andanalyzed. For this motor we realized the associatedbond-graph, we pointed out the equations thatdescribe this motor, and we analyzed the electricaland mechanical features of this motor, by using thesimulation program 20 SIM, in order to improve theperformances of this motor even from the early stageof design.

  19. Asynchronous P300-based brain-computer interface to control a virtual environment: initial tests on end users.

    Science.gov (United States)

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

    2011-10-01

    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.

  20. Asynchronous Complex Pipeline Design Based on ARM Instruction Set

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; WANG Qin; PENG Rui-hua; FU Yu-zhuo

    2008-01-01

    This paper proposes an asynchronous complex pipeline based on ARM-V3 instruction set. Muller pipeline structure is used as prototype, and the factors which may affect pipeline performance are analyzed. To balance the difficulty of asynchronous design and performance analysis, both complete asynchronous and partial asynchronous structures aere designed and compared. Results of comparison with the well-Rnown industrial product ARM922T verify that about 30% and 40% performance improvement of the partial and complete asynchronous complex pipelines can be obtained respectively. The design methodologies can also be used in the design of other asynchronous pipelines.

  1. Energy-saving motor; Energiesparmotor

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M.

    2002-07-01

    This report for the Swiss Federal Office of Energy (SFOE) describes the development and testing of an advanced electrical motor using a permanent-magnet rotor. The aims of the project - to study the technical feasibility and market potential of the Eco-Motor - are discussed and the three phases of the project described. These include the calculation and realisation of a 250-watt prototype operating at 230 V, the measurement of the motor's characteristics as well as those of a comparable asynchronous motor on the test bed at the University of Applied Science in Lucerne, Switzerland, and a market study to establish if the Eco-Motor and its controller can compete against normal asynchronous motors. Also, the results of an analysis of the energy-savings potential is made, should such Eco-Motors be used. Detailed results of the three phases of the project are presented and the prospects of producing such motors in Switzerland for home use as well as for export are examined.

  2. Asynchronous decentralized method for interconnected electricity markets

    International Nuclear Information System (INIS)

    This paper presents an asynchronous decentralized method to solve the optimization problem of interconnected electricity markets. The proposed method decomposes the optimization problem of combined electricity markets into individual optimization problems. The impact of neighboring markets' information is included in the objective function of the individual market optimization problem by the standard Lagrangian relaxation method. Most decentralized optimization methods use synchronous models of communication to exchange updated market information among markets during the iterative process. In this paper, however, the solutions of the individual optimization problems are coordinated through an asynchronous communication model until they converge to the global optimal solution of combined markets. Numerical examples are presented to demonstrate the advantages of the proposed asynchronous method over the existing synchronous methods. (author)

  3. Synchronization of Asynchronous Switched Boolean Network.

    Science.gov (United States)

    Zhang, Hao; Wang, Xingyuan; Lin, Xiaohui

    2015-01-01

    In this paper, the complete synchronizations for asynchronous switched Boolean network with free Boolean sequence controllers and close-loop controllers are studied. First, the basic asynchronous switched Boolean network model is provided. With the method of semi-tensor product, the Boolean dynamics is translated into linear representation. Second, necessary and sufficient conditions for ASBN synchronization with free Boolean sequence control and close-loop control are derived, respectively. Third, some illustrative examples are provided to show the efficiency of the proposed methods.

  4. The non-anticipation of the asynchronous systems

    OpenAIRE

    Vlad, Serban E.

    2008-01-01

    The asynchronous systems are the models of the asynchronous circuits from the digital electrical engineering and non-anticipation is one of the most important properties in systems theory. Our present purpose is to introduce several concepts of non-anticipation of the asynchronous systems.

  5. Acceptability of an Asynchronous Learning Forum on Mobile Devices

    Science.gov (United States)

    Chang, Chih-Kai

    2010-01-01

    Mobile learning has recently become noteworthy because mobile devices have become popular. To construct an asynchronous learning forum on mobile devices is important because an asynchronous learning forum is always an essential part of networked asynchronous distance learning. However, the input interface in handheld learning devices, which is…

  6. Increasing Student Engagement Using Asynchronous Learning

    Science.gov (United States)

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

    2015-01-01

    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…

  7. Asynchronous Rumor Spreading on Random Graphs

    CERN Document Server

    Panagiotou, Konstantinos

    2016-01-01

    We perform a thorough study of various characteristics of the asynchronous push-pull protocol for spreading a rumor on Erd\\H{o}s-R\\'enyi random graphs $G_{n,p}$, for any $p>c\\ln(n)/n$ with $c>1$. In particular, we provide a simple strategy for analyzing the asynchronous push-pull protocol on arbitrary graph topologies and apply this strategy to $G_{n,p}$. We prove tight bounds of logarithmic order for the total time that is needed until the information has spread to all nodes. Surprisingly, the time required by the asynchronous push-pull protocol is asymptotically almost unaffected by the average degree of the graph. Similarly tight bounds for Erd\\H{o}s-R\\'enyi random graphs have previously only been obtained for the synchronous push protocol, where it has been observed that the total running time increases significantly for sparse random graphs. Finally, we quantify the robustness of the protocol with respect to transmission and node failures. Our analysis suggests that the asynchronous protocols are particu...

  8. Duration of asynchronous operations in distributed systems

    OpenAIRE

    Makhaniok, Mikhail; Männer, Reinhard

    1995-01-01

    A distributed asynchronous system is investigated. Its processing elements execute common operations concurrently and distributively. They are implemented as combinatorial circuits and exchange data via open collector bus lines. A method is presented to identify and to minimize the duration of an operation and therefore to increase the performance of the system. No hardware modifications are required.

  9. Inhibition Controls Asynchronous States of Neuronal Networks

    Science.gov (United States)

    Treviño, Mario

    2016-01-01

    Computations in cortical circuits require action potentials from excitatory and inhibitory neurons. In this mini-review, I first provide a quick overview of findings that indicate that GABAergic neurons play a fundamental role in coordinating spikes and generating synchronized network activity. Next, I argue that these observations helped popularize the notion that network oscillations require a high degree of spike correlations among interneurons which, in turn, produce synchronous inhibition of the local microcircuit. The aim of this text is to discuss some recent experimental and computational findings that support a complementary view: one in which interneurons participate actively in producing asynchronous states in cortical networks. This requires a proper mixture of shared excitation and inhibition leading to asynchronous activity between neighboring cells. Such contribution from interneurons would be extremely important because it would tend to reduce the spike correlation between neighboring pyramidal cells, a drop in redundancy that could enhance the information-processing capacity of neural networks. PMID:27274721

  10. Low Latency High Throughout Circular Asynchronous FIFO

    Institute of Scientific and Technical Information of China (English)

    XIAO Yong; ZHOU Runde

    2008-01-01

    This paper describes a circular first in first out (FIFO) and its protocols which have a very low la-tency while still maintaining high throughput. Unlike the existing serial FIFOs based on asynchronous micro-pipelines, this FIFO's cells communicate directly with the input and output ports through a common bus, which effectively eliminates the data movement from the input port to the output port, thereby reducing the latency and the power consumption. Furthermore, the latency does not increase with the number of FIFO stages. Single-track asynchronous protocols are used to simplify the FIFO controller design, with only three C-gates needed in each cell controller, which substantially reduces the area. Simulations with the TSMC 0.25 Ijm CMOS logic process show that the latency of the 4-stage FIFO is less than 581 ps and the throughput is higher than 2.2 GHz.

  11. Existence test for asynchronous interval iterations

    DEFF Research Database (Denmark)

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

    1997-01-01

    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 on...

  12. Multiuser Detection in Asynchronous Multibeam Communications

    CERN Document Server

    Chaouech, Helmi; 10.5121/ijwmn.2012.4102

    2012-01-01

    This paper deals with multi-user detection techniques in asynchronous multibeam satellite communications. The proposed solutions are based on successive interference cancellation architecture (SIC) and channel decoding algorithms. The aim of these detection methods is to reduce the effect of cochannel interference due to co-frequency access, and consequently, improves the capacity of the mulitbeam communications systems, by improving frequency reuse. Channel estimation allows the determination of interference coefficients, which helps their effects compensation. The developed multiuser detections techniques are iterative. Therefore, detection quality is improved from a stage to another. Moreover, a signals combining method, which is integrated into these detection solutions, enhances their capability. The proposed solutions are evaluated through computer simulations, where an asynchronous multibeam satellite link is considered over an AWGN channel. The obtained simulation results showed the robustness of thes...

  13. Inhibition Controls Asynchronous States of Neuronal Networks.

    Science.gov (United States)

    Treviño, Mario

    2016-01-01

    Computations in cortical circuits require action potentials from excitatory and inhibitory neurons. In this mini-review, I first provide a quick overview of findings that indicate that GABAergic neurons play a fundamental role in coordinating spikes and generating synchronized network activity. Next, I argue that these observations helped popularize the notion that network oscillations require a high degree of spike correlations among interneurons which, in turn, produce synchronous inhibition of the local microcircuit. The aim of this text is to discuss some recent experimental and computational findings that support a complementary view: one in which interneurons participate actively in producing asynchronous states in cortical networks. This requires a proper mixture of shared excitation and inhibition leading to asynchronous activity between neighboring cells. Such contribution from interneurons would be extremely important because it would tend to reduce the spike correlation between neighboring pyramidal cells, a drop in redundancy that could enhance the information-processing capacity of neural networks.

  14. Asynchronous Nano-Electronics: Preliminary Investigation

    OpenAIRE

    Martin, Alain J.; Prakash, Piyush

    2008-01-01

    This paper is a preliminary investigation in implementing asynchronous QDI logic in molecular nano-electronics, taking into account the restricted geometry, the lack of control on transistor strengths, the high timing variations. We show that the main building blocks of QDI logic can be successfully implemented; we illustrate the approach with the layout of an adder stage. The proposed techniques to improve the reliability of QDI apply to nano-CMOS as well.

  15. Asynchronous exponential growth of a bacterial population

    Directory of Open Access Journals (Sweden)

    Mohamed Boulanouar

    2014-01-01

    Full Text Available In this work, we complete a study started earlier in [1,2] wherein a model of growing bacterial population has been the matter of a mathematical analysis. We show that the full model is governed by a strongly continuous semigroup. Beside the positivity and the irreducibility of the generated semigroup, we describe its asymptotic behavior in the uniform topology which leads to the asynchronous exponential growth of the bacterial population.

  16. Accurate estimator of correlations between asynchronous signals

    OpenAIRE

    Toth, Bence; Kertesz, Janos

    2008-01-01

    The estimation of the correlation between time series is often hampered by the asynchronicity of the signals. Cumulating data within a time window suppresses this source of noise but weakens the statistics. We present a method to estimate correlations without applying long time windows. We decompose the correlations of data cumulated over a long window using decay of lagged correlations as calculated from short window data. This increases the accuracy of the estimated correlation significantl...

  17. Blending Online Asynchronous and Synchronous Learning

    Directory of Open Access Journals (Sweden)

    Lisa C. Yamagata-Lynch

    2014-04-01

    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.

  18. Prototype energy-saving motor; Prototyp Energiesparmotor

    Energy Technology Data Exchange (ETDEWEB)

    Weingartner, J. [Baechli AG, Kriens-Obernau (Switzerland); Lindegger, M. [Circle Motor AG, Guemligen (Switzerland)

    2004-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) presents the results of investigations made on the development of an energy-efficient electric motor. The aim of the prototype 'Eco-Motor' project was the development of a winding technique and the optimisation of the design of the stator. Various winding techniques (toroid winding, core winding, coil winding) were examined and used in the realisation of prototype 'Eco-Motors' for a nominal voltage of 230 V a.c. The designs were evaluated in both a simulation (FEMM) and as well as in the test facilities at the College of Engineering and Architecture in Lucerne, Switzerland. The measured data of the 'Eco-Motor' were then compared with a standard asynchronous motor. The 'Eco-Motor' with a toroid winding had the best efficiency. At low loads, all 'Eco-Motor' prototypes have a higher efficiency than asynchronous motors. On the other hand, none of the 'Eco-Motors' have yet reached the nominal power of 250 W. The developers state, however, that with a few adjustments this should pose no problems.

  19. Asynchronous detection of kinesthetic attention during mobilization of lower limbs using EEG measurements

    Science.gov (United States)

    Melinscak, Filip; Montesano, Luis; Minguez, Javier

    2016-02-01

    Objective. 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. Approach. 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. Main results. 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. Significance. 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.

  20. SELF CONTROL OF SYNCHRONOUS MOTOR FED BY MATRIX CONVERTER

    OpenAIRE

    CALISKAN, ABUZER; Orhan, Ahmet

    2012-01-01

    In this study self control of synchronous motor fed by matrix converter was examined by developing a Matlab/simulink model. Self control of synchronous motor was performed by fixing frequency of stator voltage to rotor speed. Thus, the probable danger of asynchronism of the motor during transient operation in open loop control is removed. In the developed model, simplified Venturini modulation algorithm was used. This algorithm provides unity fundamental displacement factor at the input regar...

  1. Doubly-fed asynchronous machine with 3-level VSI for variable speed pump storage

    Energy Technology Data Exchange (ETDEWEB)

    Sapin, A.; Hodder, A.; Simond, J.J. [Swiss Federal Institute of Technology, Electromechanics and Electrical Machines Laboratory, Lausanne (Switzerland); Schafer, D. [Alstom Power Generation Ltd, Birr (Switzerland)

    2000-08-01

    This paper deals with a fixed-frequency variable-speed motor/generator with 3-level VSI (Voltage Source Inverter) cascade. The 3-level VSI is applied to a DASM (Doubly-fed ASynchronous Machine) for large pump storage plants. The extension to 3 levels is the original part of this paper. The whole system behavior has been simulated using the 'SIMSEN' simulation software. This paper focuses on the simulation results and also on the comparison with the 12-pulse cycloconverter topology. (orig.)

  2. EPOS for Coordination of Asynchronous Sensor Webs Project

    Data.gov (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...

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

    DEFF Research Database (Denmark)

    Nielsen, Lars Skovby; Sparsø, Jens

    1999-01-01

    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...... by numerically small samples). Apart from the improved RAM design, these measures are only viable in an asynchronous design. The principles and techniques explained in this paper are of a general nature, and they apply to the design of asynchronous low-power digital signal-processing circuits in a broader...

  4. Integrating Asynchronous Digital Design Into the Computer Engineering Curriculum

    Science.gov (United States)

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

    2010-01-01

    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…

  5. Asynchronous Learning Sources in a High-Tech Organization

    Science.gov (United States)

    Bouhnik, Dan; Giat, Yahel; Sanderovitch, Yafit

    2009-01-01

    Purpose: The purpose of this study is to characterize learning from asynchronous sources among research and development (R&D) personnel. It aims to examine four aspects of asynchronous source learning: employee preferences regarding self-learning; extent of source usage; employee satisfaction with these sources and the effect of the sources on the…

  6. Asynchronicity of facial blood perfusion in migraine.

    Directory of Open Access Journals (Sweden)

    Nina Zaproudina

    Full Text Available Asymmetrical changes in blood perfusion and asynchronous blood supply to head tissues likely contribute to migraine pathophysiology. Imaging was widely used in order to understand hemodynamic variations in migraine. However, mapping of blood pulsations in the face of migraineurs has not been performed so far. We used the Blood Pulsation Imaging (BPI technique, which was recently developed in our group, to establish whether 2D-imaging of blood pulsations parameters can reveal new biomarkers of migraine. BPI characteristics were measured in migraineurs during the attack-free interval and compared to healthy subjects with and without a family history of migraine. We found a novel phenomenon of transverse waves of facial blood perfusion in migraineurs in contrast to healthy subjects who showed synchronous blood delivery to both sides of the face. Moreover, the amplitude of blood pulsations was symmetrically distributed over the face of healthy subjects, but asymmetrically in migraineurs and subjects with a family history of migraine. In the migraine patients we found a remarkable correlation between the side of unilateral headache and the direction of the blood perfusion wave. Our data suggest that migraine is associated with lateralization of blood perfusion and asynchronous blood pulsations in the facial area, which could be due to essential dysfunction of the autonomic vascular control in the face. These findings may further enhance our understanding of migraine pathophysiology and suggest new easily available biomarkers of this pathology.

  7. Selective particle capture by asynchronously beating cilia

    Science.gov (United States)

    Ding, Yang; Kanso, Eva

    2015-12-01

    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.

  8. Commande optimale à flux libre des machines asynchrones

    Science.gov (United States)

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

    1992-01-01

    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

  9. Asynchronous Parallel Evolutionary Algorithms for Constrained Optimizations

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Recently Guo Tao proposed a stochastic search algorithm in his PhD thesis for solving function op-timization problems. He combined the subspace search method (a general multi-parent recombination strategy) with the population hill-climbing method. The former keeps a global search for overall situation,and the latter keeps the convergence of the algorithm. Guo's algorithm has many advantages ,such as the sim-plicity of its structure ,the higher accuracy of its results, the wide range of its applications ,and the robustness of its use. In this paper a preliminary theoretical analysis of the algorithm is given and some numerical experiments has been done by using Guo's algorithm for demonstrating the theoretical results. Three asynchronous paral-lel evolutionary algorithms with different granularities for MIMD machines are designed by parallelizing Guo's Algorithm.

  10. Optimum Multiuser Detector for Multipath Slow Fading Asynchronous CDMA Channels

    Institute of Scientific and Technical Information of China (English)

    WangZhaocheng; YangZhixing; 等

    1995-01-01

    A structure of optimum multiuser detector for asynchronous CDMA in multipath slow fading channels is derived and the significant performance gain over the conventional RAKE receiv-er is shown by simulation.

  11. Current Trends in High-Level Synthesis of Asynchronous Circuits

    DEFF Research Database (Denmark)

    Sparsø, Jens

    2009-01-01

    This paper is a survey paper presenting what the author sees as two major and promising trends in the current research in CAD-tools and design-methods for asynchronous circuits. One branch of research builds on top of existing asynchronous CAD-tools that perform syntax directed translation, e.......g. the Haste/TiDE tool from Handshake Solutions or the Balsa tool from the University of Manchester. The aims are to add highlevel synthesis capabilities to these tools and to extend the tools such that a wider range of (higher speed) micro-architectures can be generated. Another branch of research takes...... a conventional synchronous circuit as the starting point, and then adds some form of handshake-based flow-control. One approach keeps the global clock and implements discrete-time asynchronous operation. Another approach substitutes the clocked registers by asynchronous handshake-registers, thus creating truly...

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

    CERN Document Server

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

    2016-01-01

    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.

  13. Asynchronous FSK wireless data traffic interface circuit design

    International Nuclear Information System (INIS)

    This article gives a practical interface circuit, which is able to conduct asynchronous wireless data communication through data transfer broadcasting station. And the circuit's design as well as its applications are introduced. (authors)

  14. Stand-Alone and Hybrid Positioning Using Asynchronous Pseudolites

    Directory of Open Access Journals (Sweden)

    Ciro Gioia

    2014-12-01

    Full Text Available global navigation satellite system (GNSS receivers are usually unable to achieve satisfactory performance in difficult environments, such as open-pit mines, urban canyons and indoors. Pseudolites have the potential to extend GNSS usage and significantly improve receiver performance in such environments by providing additional navigation signals. This also applies to asynchronous pseudolite systems, where different pseudolites operate in an independent way. Asynchronous pseudolite systems require, however, dedicated strategies in order to properly integrate GNSS and pseudolite measurements. In this paper, several asynchronous pseudolite/GNSS integration strategies are considered: loosely- and tightly-coupled approaches are developed and combined with pseudolite proximity and receiver signal strength (RSS-based positioning. The performance of the approaches proposed has been tested in different scenarios, including static and kinematic conditions. The tests performed demonstrate that the methods developed are effective techniques for integrating heterogeneous measurements from different sources, such as asynchronous pseudolites and GNSS.

  15. Solving SAT and Hamiltonian Cycle Problem Using Asynchronous P Systems

    Science.gov (United States)

    Tagawa, Hirofumi; Fujiwara, Akihiro

    In the present paper, we consider fully asynchronous parallelism in membrane computing, and propose two asynchronous P systems for the satisfiability (SAT) and Hamiltonian cycle problem. We first propose an asynchronous P system that solves SAT with n variables and m clauses, and show that the proposed P system computes SAT in O(mn2n) sequential steps or O(mn) parallel steps using O(mn) kinds of objects. We next propose an asynchronous P system that solves the Hamiltonian cycle problem with n nodes, and show that the proposed P system computes the problem in O(n!) sequential steps or O(n2) parallel steps using O(n2) kinds of objects.

  16. A proof system for asynchronously communicating deterministic processes

    NARCIS (Netherlands)

    de Boer, F.S.; van Hulst, M.

    1994-01-01

    We introduce in this paper new communication and synchronization constructs which allow deterministic processes, communicating asynchronously via unbounded FIFO buffers, to cope with an indeterminate environment. We develop for the resulting parallel programming language, which subsumes deterministi

  17. Novel Asynchronous Wrapper and Its Application to GALS Systems

    Institute of Scientific and Technical Information of China (English)

    Zhuang Shengxian; Peng Anjin; Lars Wanhammar

    2006-01-01

    An asynchronous wrapper with novel handshake circuits for data communication in globally asynchronous locally synchronous (GALS) systems is proposed. The handshake circuits include two communication ports and a local clock generator. Two approaches for the implementation of communication ports are presented, one with pure standard cells and the others with Müller-C elements. The detailed design methodology for GALS systems is given and the circuits are validated with VHDL and circuits simulation in standard CMOS technology.

  18. Reasoning on Robot Knowledge from Discrete and Asynchronous Observations

    OpenAIRE

    Ziafati, Pouyan; Elrakaiby, Yehia; Torre, Leon van der; Voos, Holger; dastani, mehdi; Meyer, John-Jules; Van Zee, Marc

    2014-01-01

    Robot knowledge of the world is created from discrete and asynchronous events received from its perception components. Proper representation and maintenance of robot knowledge is crucial to enable the use of robot knowledge for planning, user-interaction, etc. This paper identifies some of the main issues related to the representation, maintenance and querying of robot knowledge based on discrete asynchronous events such as event-history management and synchronization, and introduces a langua...

  19. MODIFIED MICROPIPLINE ARCHITECTURE FOR SYNTHESIZABLE ASYNCHRONOUS FIR FILTER DESIGN

    Directory of Open Access Journals (Sweden)

    Basel Halak

    2016-02-01

    Full Text Available The use of asynchronous design approaches to construct digital signal processing (DSP systems is a rapidly growing research area driven by a wide range of emerging energy constrained applications such as wireless sensor network, portable medical devices and brain implants. The asynchronous design techniques allow the construction of systems which are samples driven, which means they only dissipate dynamic energy when there processing data and idle otherwise. This inherent advantage of asynchronous design over conventional synchronous circuits allows them to be energy efficient. However the implementation flow of asynchronous systems is still difficult due to its lack of compatibility with industrystandard synchronous design tools and modelling languages. This paper devises a novel asynchronous design for a finite impulse response (FIR filter, an essential building block of DSP systems, which is synthesizable and suitable for implementation using conventional synchronous systems design flow and tools. The proposed design is based on a modified version of the micropipline architecture and it is constructed using four phase bundled data protocol. A hardware prototype of the proposed filter has been developed on an FPGA, and systematically verified. The results prove correct functionality of the novel design and a superior performance compared to a synchronous FIR implementation. The findings of this work will allow a wider adoption of asynchronous circuits by DSP designers to harness their energy and performance benefits.

  20. Building asynchronous geospatial processing workflows with web services

    Science.gov (United States)

    Zhao, Peisheng; Di, Liping; Yu, Genong

    2012-02-01

    Geoscience research and applications often involve a geospatial processing workflow. This workflow includes a sequence of operations that use a variety of tools to collect, translate, and analyze distributed heterogeneous geospatial data. Asynchronous mechanisms, by which clients initiate a request and then resume their processing without waiting for a response, are very useful for complicated workflows that take a long time to run. Geospatial contents and capabilities are increasingly becoming available online as interoperable Web services. This online availability significantly enhances the ability to use Web service chains to build distributed geospatial processing workflows. This paper focuses on how to orchestrate Web services for implementing asynchronous geospatial processing workflows. The theoretical bases for asynchronous Web services and workflows, including asynchrony patterns and message transmission, are examined to explore different asynchronous approaches to and architecture of workflow code for the support of asynchronous behavior. A sample geospatial processing workflow, issued by the Open Geospatial Consortium (OGC) Web Service, Phase 6 (OWS-6), is provided to illustrate the implementation of asynchronous geospatial processing workflows and the challenges in using Web Services Business Process Execution Language (WS-BPEL) to develop them.

  1. Ternary Tree Asynchronous Interconnect Network for GALS' SOC

    Directory of Open Access Journals (Sweden)

    Vivek E. Khetade

    2013-03-01

    Full Text Available Interconnect fabric requires easy integration of computational block operating with unrelated clocks.Thispaper presents asynchronous interconnect with ternary tree asynchronous network for GloballyAsynchronous Locally Synchronous (GALS system-on-chip (SOC. Here architecture is proposed forinterconnection with ternary tree asynchronous network where ratio of number NOC design unit andnumber of router is 4:1,6:2, 8:3,10:4 etc .It is scalable for any number of NOC design unit. It offersaneasy integration of different clock domain with lowcommunication overhead .NOC design unit for GALS‘SOC is formulated by wrapping synchronous module with input port along with input port controller,output port along with output port controller and local clock generator. It creates the interface betweensynchronous to asynchronous and asynchronous to synchronous. For this purpose four port asynchronousrouters is designed with routing element and outputarbitration and buffering with micro-pipeline. Thisinterconnect fabric minimizes silicon area, minimize Latency and maximize throughput. Here functionalmodel is made for TTAN and application MPEG4 is mapped on the Network .Desired traffic pattern isgenerated and performance of the network is evaluated. Significant improvement in the networkperformance parameter has been observed.

  2. Managing Asynchronous Data in ATLAS's Concurrent Framework

    CERN Document Server

    Leggett, Charles; The ATLAS collaboration

    2016-01-01

    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...

  3. Asynchronous Rate Chaos in Spiking Neuronal Circuits

    Science.gov (United States)

    Harish, Omri; Hansel, David

    2015-01-01

    The brain exhibits temporally complex patterns of activity with features similar to those of chaotic systems. Theoretical studies over the last twenty years have described various computational advantages for such regimes in neuronal systems. Nevertheless, it still remains unclear whether chaos requires specific cellular properties or network architectures, or whether it is a generic property of neuronal circuits. We investigate the dynamics of networks of excitatory-inhibitory (EI) spiking neurons with random sparse connectivity operating in the regime of balance of excitation and inhibition. Combining Dynamical Mean-Field Theory with numerical simulations, we show that chaotic, asynchronous firing rate fluctuations emerge generically for sufficiently strong synapses. Two different mechanisms can lead to these chaotic fluctuations. One mechanism relies on slow I-I inhibition which gives rise to slow subthreshold voltage and rate fluctuations. The decorrelation time of these fluctuations is proportional to the time constant of the inhibition. The second mechanism relies on the recurrent E-I-E feedback loop. It requires slow excitation but the inhibition can be fast. In the corresponding dynamical regime all neurons exhibit rate fluctuations on the time scale of the excitation. Another feature of this regime is that the population-averaged firing rate is substantially smaller in the excitatory population than in the inhibitory population. This is not necessarily the case in the I-I mechanism. Finally, we discuss the neurophysiological and computational significance of our results. PMID:26230679

  4. Rapid, generalized adaptation to asynchronous audiovisual speech.

    Science.gov (United States)

    Van der Burg, Erik; Goodbourn, Patrick T

    2015-04-01

    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.

  5. Effect of asynchronous updating on the stability of cellular automata

    International Nuclear Information System (INIS)

    Highlights: ► An upper bound on the Lyapunov exponent of asynchronously updated CA is established. ► The employed update method has repercussions on the stability of CAs. ► A decision on the employed update method should be taken with care. ► Substantial discrepancies arise between synchronously and asynchronously updated CA. ► Discrepancies between different asynchronous update schemes are less pronounced. - Abstract: Although cellular automata (CAs) were conceptualized as utter discrete mathematical models in which the states of all their spatial entities are updated simultaneously at every consecutive time step, i.e. synchronously, various CA-based models that rely on so-called asynchronous update methods have been constructed in order to overcome the limitations that are tied up with the classical way of evolving CAs. So far, only a few researchers have addressed the consequences of this way of updating on the evolved spatio-temporal patterns, and the reachable stationary states. In this paper, we exploit Lyapunov exponents to determine to what extent the stability of the rules within a family of totalistic CAs is affected by the underlying update method. For that purpose, we derive an upper bound on the maximum Lyapunov exponent of asynchronously iterated CAs, and show its validity, after which we present a comparative study between the Lyapunov exponents obtained for five different update methods, namely one synchronous method and four well-established asynchronous methods. It is found that the stability of CAs is seriously affected if one of the latter methods is employed, whereas the discrepancies arising between the different asynchronous methods are far less pronounced and, finally, we discuss the repercussions of our findings on the development of CA-based models.

  6. EEG-based asynchronous BCI control of a car in 3D virtual reality environments

    Institute of Scientific and Technical Information of China (English)

    ZHAO QiBin; ZHANG LiQing; CICHOCKI Andrzej

    2009-01-01

    Brain computer interface (BCl) aims at creating new communication channels without depending on brain's normal output channels of peripheral nerves and muscles.However,natural and sophisticated interactions manner between brain and computer still remain challenging.In this paper,we investigate how the duration of event-related desynchronization/synchronization (ERD/ERS) caused by motor im-agery (MI) can be modulated and used as an additional control parameter beyond simple binary deci-sions.Furthermore,using the non-time-locked properties of sustained (de)synchronization,we have developed an asynchronous BCl system for driving a car in 3D virtual reality environment (VRE) based on cumulative incremental control strategy.The extensive real time experiments confirmed that our new approach is able to drive smoothly a virtual car within challenging VRE only by the MI tasks with-out involving any muscular activities.

  7. IHadoop: Asynchronous iterations for MapReduce

    KAUST Repository

    Elnikety, Eslam Mohamed Ibrahim

    2011-11-01

    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

  8. Efficiency asynchronous application programming language Python

    OpenAIRE

    Толстікова, О. В.; Національний авіаційний університет; Мирошниченко, І. С.; Національний авіаційний університет; Коцюр, А. Б.; Національний авіаційний університет

    2016-01-01

    Consider tools that implement asynchronous programming in Python and allow more efficient use ofasynchronous programming applications. The efficiency of the module asyncio (PEP 3156) incomparison with classical spivprohramamy Рассмотрены инструменты, которые реализуют асинхронное программирование в языкеPython и позволяют повысить эффективность использования программирования асинхронныхприложений. Показана эффективность работы модуля asyncio (PEP 3156) по сравнению с классическими сопрогра...

  9. Asynchronous reference frame agreement in a quantum network

    Science.gov (United States)

    Islam, Tanvirul; Wehner, Stephanie

    2016-03-01

    An efficient implementation of many multiparty protocols for quantum networks requires that all the nodes in the network share a common reference frame. Establishing such a reference frame from scratch is especially challenging in an asynchronous network where network links might have arbitrary delays and the nodes do not share synchronised clocks. In this work, we study the problem of establishing a common reference frame in an asynchronous network of n nodes of which at most t are affected by arbitrary unknown error, and the identities of the faulty nodes are not known. We present a protocol that allows all the correctly functioning nodes to agree on a common reference frame as long as the network graph is complete and not more than t\\lt n/4 nodes are faulty. As the protocol is asynchronous, it can be used with some assumptions to synchronise clocks over a network. Also, the protocol has the appealing property that it allows any existing two-node asynchronous protocol for reference frame agreement to be lifted to a robust protocol for an asynchronous quantum network.

  10. Asynchronous event-based corner detection and matching.

    Science.gov (United States)

    Clady, Xavier; Ieng, Sio-Hoi; Benosman, Ryad

    2015-06-01

    This paper introduces an event-based luminance-free method to detect and match corner events from the output of asynchronous event-based neuromorphic retinas. The method relies on the use of space-time properties of moving edges. Asynchronous event-based neuromorphic retinas are composed of autonomous pixels, each of them asynchronously generating "spiking" events that encode relative changes in pixels' illumination at high temporal resolutions. Corner events are defined as the spatiotemporal locations where the aperture problem can be solved using the intersection of several geometric constraints in events' spatiotemporal spaces. A regularization process provides the required constraints, i.e. the motion attributes of the edges with respect to their spatiotemporal locations using local geometric properties of visual events. Experimental results are presented on several real scenes showing the stability and robustness of the detection and matching. PMID:25828960

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...

  12. A Novel Multiuser Detector for Asynchronous CDMA System

    Institute of Scientific and Technical Information of China (English)

    LIANGXint; SHANGYong; LIANGQinglin; XIANGHaige

    2004-01-01

    The decorrelating and the MMSE (Minimum mean square error) multiuser detector for asynchronous CDMA (Code devision multiple access) system are ideally anticausal infinite memory-length detectors. Asa result~ in practice they have to be approximately implemented with finite-memory structure, and the process delay in detection is unavoidable. Based on the analysis of a new signal model for asynchronous system, a novel multiuser detector for asynchronous CDMA system is proposed in this paper~ which is termed as DF-IC-MMSE (Decision ,feedback interference cancellation-MMSE) detector. It's the detection statistics that makes the DF-IC-MMSE-detector basically different from other traditional ones. The DF-IC-MMSE detector can be ideally implemented with Causal finite memory-length structure, and cause no delay in symbol detection. Simulations show that the performance of DF-IC-MMSE detector is almost identical to that of the ideal MMSE detector.

  13. Molecular mechanisms for synchronous, asynchronous, and spontaneous neurotransmitter release.

    Science.gov (United States)

    Kaeser, Pascal S; Regehr, Wade G

    2014-01-01

    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. PMID:24274737

  14. Asynchronous updating of threshold-coupled chaotic neurons

    Indian Academy of Sciences (India)

    Manish Dev Shirmali; Sudeshna Sinha; Kazuyuki Aihara

    2008-06-01

    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 dynamical switching of the individual neurons between two states. So varying the asynchronicity in the updating scheme can serve as a control mechanism to extract different responses, and this can have possible applications in computation and information processing.

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

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, Stephen L.

    2013-07-01

    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.

  16. 小波变换及其在异步电动机 转子断路故障诊断中的应用%Wavelet transform and its application in the fault diagnosis for the open-circuit rotor of asynchronous motor

    Institute of Scientific and Technical Information of China (English)

    董爱华; 王福忠; 艾永乐; 王芳

    2001-01-01

    Wavelet transform with the good partial characteristic in time-frequency regions is an effective way to make time-frequency analysis and processing of the signals.It has mainly discussed the basic theory of wavelet transform,and introduced the principle of the diagnosis in the open-circuit rotor of asychronous motor with wavelet transform.The construction of signal detection circuit is given as well.%小波变换具有良好的时-频局部化特性,是信号的时-频域分析和处理的有效方法.简要论述了有关小波变换的基本理论,介绍了小波变换在异步电动机转子断路故障诊断的原理,给出了信号检测电路的组成.

  17. Asynchronous rotation scan for synthetic aperture interferometric radiometer

    Institute of Scientific and Technical Information of China (English)

    WU Ji; ZHANG Cheng; LIU Hao; SUN WeiYing

    2009-01-01

    Synthetic aperture interferometric technique has wide applications in optics, radio astronomy and mi-crowave remote sensing areas. With the increasing demands of high resolution imaging observation, a new time-sharing sampling scheme of asynchronous rotation scan is proposed to meet the technical challenge of achieving a large equivalent aperture and overcome the operating barriers of space borne application. This configuration is basically composed by two asynchronously and concentrically ro-tating antenna groups, whose revolving radii and speeds are different. The synthetic aperture system with asynchronous rotation scanning scheme can effectively solve the trade-off problem of system complexity, and greatly simplify the system hardware at the cost of sacrificing a certain time resolution. The basic rules and design methods of asynchronous rotation scan are investigated The Gridding method is introduced to inverse the spiral sampling data for image reconstruction. The potential ap-plications of geostationary orbit (GEO) earth observation and solar polar orbit (SPO) plasma cloud observation are explored with numerical simulations to validate the significance and feasibility of this new imaging configuration.

  18. Asynchronous Linking in a Service –Oriented Architecture.

    OpenAIRE

    Vivek, Sanjay; Tso, Kenneth; Thompson, Mark; De Roure, David

    2002-01-01

    In this paper, we identify research issues in the development of system infrastructure support for asynchronous linkservices in a service-oriented architecture. We explore the suitability and applicability of using MQSeries Everyplace to provide a messaging backbone for linkservices that increases reliability, fault tolerance, and scalability. We identify and discuss some important problems and research issues related to this approach.

  19. RELAXED ASYNCHRONOUS ITERATIONS FOR THE LINEAR COMPLEMENTARITY PROBLEM

    Institute of Scientific and Technical Information of China (English)

    Zhong-zhi Bai; Yu-guang Huang

    2002-01-01

    We present a class of relaxed asynchronous parallel multisplitting iterative methods forsolving the linear complementarity problem on multiprocessor systems, and set up theirconvergence theories when the system matrix of the linear complementarity problem is anH-matrix with positive diagonal elements.

  20. Asynchronous Assessment in a Large Lecture Marketing Course

    Science.gov (United States)

    Downey, W. Scott; Schetzsle, Stacey

    2012-01-01

    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…

  1. Cyber Asynchronous versus Blended Cyber Approach in Distance English Learning

    Science.gov (United States)

    Ge, Zi-Gang

    2012-01-01

    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…

  2. Abstracting Asynchronous Multi-Valued Networks: An Initial Investigation

    CERN Document Server

    Steggles, L Jason

    2011-01-01

    Multi-valued networks provide a simple yet expressive qualitative state based modelling approach for biological systems. In this paper we develop an abstraction theory for asynchronous multi-valued network models that allows the state space of a model to be reduced while preserving key properties of the model. The abstraction theory therefore provides a mechanism for coping with the state space explosion problem and supports the analysis and comparison of multi-valued networks. We take as our starting point the abstraction theory for synchronous multi-valued networks which is based on the finite set of traces that represent the behaviour of such a model. The problem with extending this approach to the asynchronous case is that we can now have an infinite set of traces associated with a model making a simple trace inclusion test infeasible. To address this we develop a decision procedure for checking asynchronous abstractions based on using the finite state graph of an asynchronous multi-valued network to reas...

  3. Structure-Based Deadlock Checking of Asynchronous Circuits

    Institute of Scientific and Technical Information of China (English)

    Hong-Guang Ren; Zhi-Ying Wang; Doug Edwards

    2011-01-01

    It is important to verify the absence of deadlocks in asynchronous circuits.Much previous work relies on a reachability analysis of the circuits' states,with the use of binary decision diagrams (BDDs) or Petri nets to model the behaviors of circuits.This paper presents an alternative approach focusing on the structural properties of well-formed asynchronous circuits that will never suffer deadlocks.A class of data-driven asynchronous pipelines is targeted in this paper,which can be viewed as a network of basic components connected by handshake channels.The sufficient and necessary conditions for a component network consisting of Steer,Merge,Fork and Join are given.The slack elasticity of the channels is analyzed in order to introduce pipelining.As an application,a deadlock checking method is implemented in a syntax-directed asynchronous design tool - Teak.The proposed method shows a great runtime advantage when compared against previous Petri net based verification tools.

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    (perfect, statistical) have the same cause. We stress that all previous asynchronous MPC protocols inherently require t ...Multiparty computation (MPC) protocols among n parties secure against t active faults are known to exist if and only if t work we analyze the gap between these bounds, and show...

  5. Asynchronous rotation scan for synthetic aperture interferometric radiometer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Synthetic aperture interferometric technique has wide applications in optics,radio astronomy and mi-crowave remote sensing areas.With the increasing demands of high resolution imaging observation,a new time-sharing sampling scheme of asynchronous rotation scan is proposed to meet the technical challenge of achieving a large equivalent aperture and overcome the operating barriers of space borne application.This configuration is basically composed by two asynchronously and concentrically ro-tating antenna groups,whose revolving radii and speeds are different.The synthetic aperture system with asynchronous rotation scanning scheme can effectively solve the trade-off problem of system complexity,and greatly simplify the system hardware at the cost of sacrificing a certain time resolution.The basic rules and design methods of asynchronous rotation scan are investigated The Gridding method is introduced to inverse the spiral sampling data for image reconstruction.The potential ap-plications of geostationary orbit(GEO)earth observation and solar polar orbit(SPO)plasma cloud observation are explored with numerical simulations to validate the significance and feasibility of this new imaging configuration.

  6. Reconceptualising Moderation in Asynchronous Online Discussions Using Grounded Theory

    Science.gov (United States)

    Vlachopoulos, Panos; Cowan, John

    2010-01-01

    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…

  7. Reflections of Students in Their Use of Asynchronous Online Seminars

    Science.gov (United States)

    Groves, Mark; O'Donoghue, John

    2009-01-01

    This paper reports on research that has been carried out into the use, process, and effectiveness of an asynchronous online seminar within an undergraduate sports studies degree programme. Contemporary sources are used to justify the use of technology supported learning (TSL) in higher education and to inform a reflective and critical account of…

  8. Analysis of the Relevance of Posts in Asynchronous Discussions

    Science.gov (United States)

    Azevedo, Breno T.; Reategui, Eliseo; Behar, Patrícia A.

    2014-01-01

    This paper presents ForumMiner, a tool for the automatic analysis of students' posts in asynchronous discussions. ForumMiner uses a text mining system to extract graphs from texts that are given to students as a basis for their discussion. These graphs contain the most relevant terms found in the texts, as well as the relationships between them.…

  9. Teachers of the Gifted: Experiences with Asynchronous Development

    Science.gov (United States)

    Rosenberg, Jennifer

    2012-01-01

    Gifted students' development is asynchronous in the social, emotional, physical and cognitive domains. Because of this, unique interventions must be used by teachers of the gifted in order to best serve their developmental and educational needs. This qualitative study used transcendental phenomenology to examine and describe the experiences…

  10. Positive Semidefinite Integrated Covariance Estimation, Factorizations and Asynchronicity

    DEFF Research Database (Denmark)

    Boudt, Kris; Laurent, Sébastien; Lunde, Asger;

    An estimator of the ex-post covariation of log-prices under asynchronicity and microstructure noise is proposed. It uses the Cholesky factorization on the correlation matrix in order to exploit the heterogeneity in trading intensity to estimate the different parameters sequentially with as many...

  11. Asynchronous Multi-Party Computation with Quadratic Communication

    DEFF Research Database (Denmark)

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

    2008-01-01

    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...

  12. State assignment approach to asynchronous CMOS circuit design

    Science.gov (United States)

    Kantabutra, Vitit; Andreou, Andreas G.

    1994-04-01

    We present a new algorithm for state assignment in asynchronous circuits so that for each circuit state transition, only one (secondary) state variable switches. No intermediate unstable states are used. The resultant circuits operate at optimum speed in terms of the number of transitions made and use only static CMOS gates. By reducing the number of switching events per state transition, noise due to the switching events is reduced and dynamic power dissipation may also be reduced. Our approach is suitable for asynchronous sequential circuits that are designed from flow tables or state transition diagrams. The proposed approach may also be useful for designing synchronous circuits, but explorations into the subject of clock power would be necessary to determine its usefulness.

  13. Inference of asynchronous Boolean network from biological pathways.

    Science.gov (United States)

    Das, Haimabati; Layek, Ritwik Kumar

    2015-01-01

    Gene regulation is a complex process with multiple levels of interactions. In order to describe this complex dynamical system with tractable parameterization, the choice of the dynamical system model is of paramount importance. The right abstraction of the modeling scheme can reduce the complexity in the inference and intervention design, both computationally and experimentally. This article proposes an asynchronous Boolean network framework to capture the transcriptional regulation as well as the protein-protein interactions in a genetic regulatory system. The inference of asynchronous Boolean network from biological pathways information and experimental evidence are explained using an algorithm. The suitability of this paradigm for the variability of several reaction rates is also discussed. This methodology and model selection open up new research challenges in understanding gene-protein interactive system in a coherent way and can be beneficial for designing effective therapeutic intervention strategy.

  14. Students' Activity Focus in Online Asynchronous Peer Learning Forums

    Directory of Open Access Journals (Sweden)

    Naomi BOYER

    2010-04-01

    Full Text Available This qualitative study explores how using Peer Learning Forums (PLF in an online asynchronous computer programming course can be analyzed to derive information about Student Activity Focus (SAF for adult Information Technology students. Three instruments are proposed to assist instructors classify questions posted by students on these forums, obtain easy quantitative measures of their SAF, and use it to gain a better understanding of the type of learning barriers they are encountering. In addition, we also look at the difference in SAF between passing and failing students based on their exam performance. The PLF learning activity and the classification instruments are easily adaptable to other disciplines or courses and allow instructors and students alike to gain a better understanding of what kind of participation is helpful in online asynchronous discussion forums.

  15. Asynchronous Cooperative e-Learning System and Its Evaluation

    Science.gov (United States)

    Eto, Kazuhiro; Miyoshi, Takumi

    Much attention has been attracted to collaborative learning on an e-learning system. However, it is difficult to implement the collaborative environment to an asynchronous e-learning system since collaboration would be realized only when learners join the system at the same time. On the other hand, cooperative learning has been proposed. In this method, learners can study on their own pace without making mutual agreement but with receiving cognitive information from others. In this paper, the authors have developed the asynchronous cooperative e-learning system that provides learners' attendance and studying progress as the cognitive information. The subjective evaluation experiments show that our system is slightly inferior to the synchronous collaborative e-learning system, but it can motivate the learners more than the conventional system.

  16. Channel Estimation And Multiuser Detection In Asynchronous Satellite Communications

    CERN Document Server

    Chaouech, Helmi; 10.5121/ijwmn.2010.2411

    2010-01-01

    In this paper, we propose a new method of channel estimation for asynchronous additive white Gaussian noise channels in satellite communications. This method is based on signals correlation and multiuser interference cancellation which adopts a successive structure. Propagation delays and signals amplitudes are jointly estimated in order to be used for data detection at the receiver. As, a multiuser detector, a single stage successive interference cancellation (SIC) architecture is analyzed and integrated to the channel estimation technique and the whole system is evaluated. The satellite access method adopted is the direct sequence code division multiple access (DS CDMA) one. To evaluate the channel estimation and the detection technique, we have simulated a satellite uplink with an asynchronous multiuser access.

  17. Motor neglect.

    OpenAIRE

    Laplane, D.; Degos, J D

    1983-01-01

    Motor neglect is characterised by an underutilisation of one side, without defects of strength, reflexes or sensibility. Twenty cases of frontal, parietal and thalamic lesions causing motor neglect, but all without sensory neglect, are reported. It is proposed that the cerebral structures involved in motor neglect are the same as those for sensory neglect and for the preparation of movement. As in sensory neglect, the multiplicity of the structures concerned suggests that this interconnection...

  18. A STUDY ON ASYNCHRONOUS SERIAL COMMUNICATON BETWEEN COMPONENTS IN AUTOMOBILES

    OpenAIRE

    ŞAHİN, Yaşar Güneri

    2010-01-01

    ABSTRACTIn connection with the developments in the automobile sector, the number of in-automobile components, the amount of cable used for providing in-automobile communication between these components and costs are increased gradually. In this study, a method is presented in which asynchronous serial connection is used for decreasing the initial and maintenance costs by means of decreasing the amount of cables used in middle and lower class automobiles. The electronic circuits required to es...

  19. Abstractions for asynchronous distributed computing with malicious players

    OpenAIRE

    Vukolic, Marko; Guerraoui, Rachid

    2009-01-01

    In modern distributed systems, failures are the norm rather than the exception. In many cases, these failures are not benign. Settings such as the Internet might incur malicious (also called Byzantine or arbitrary) behavior and asynchrony. As a result, and perhaps not surprisingly, research on asynchronous Byzantine fault-tolerant (BFT) distributed systems is flourishing. Tolerating arbitrary behavior and asynchrony calls for very sophisticated algorithms. This is in particular the case with ...

  20. Teleoperation system using Asynchronous transfer mode, ATM network

    International Nuclear Information System (INIS)

    This paper examines the application of Asynchronous Transfer Mode (ATM) in a distributed industrial environment such as in teleoperation, which performs real time control manipulation from a remote location. In our study, two models of teleoperation are proposed; the first model is a point to point connection and the second model is through an ATM network. The performance results are analysed as to determine whether the two models can support the teleoperation traffics via simulation using commercial software design tool. (Author)

  1. Diversity Multiplexing Tradeoff of Asynchronous Cooperative Relay Networks

    CERN Document Server

    Krishnakumar, R N; Kumar, P Vijay

    2008-01-01

    The assumption of nodes in a cooperative communication relay network operating in synchronous fashion is often unrealistic. In the present paper, we consider two different models of asynchronous operation in cooperative-diversity networks experiencing slow fading and examine the corresponding diversity-multiplexing tradeoffs (DMT). For both models, we propose protocols and distributed space-time codes that asymptotically achieve the transmit diversity bound for all multiplexing gains and for any number of relays.

  2. A novel asynchronous access method with binary interfaces

    OpenAIRE

    Torres-Solis Jorge; Silva Jorge; Chau Tom; Mihailidis Alex

    2008-01-01

    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 as...

  3. An asynchronous controller for a daisychainable vme bus interrupter

    OpenAIRE

    Wollowski, Ralf; Beister, Jochen; Kuhn, Matthias

    1999-01-01

    An interrupter for use in a daisy-chained VME bus interrupt system has beendesigned and implemented as an asynchronous sequential circuit. The concur-rency of the processes posed a design problem that was solved by means of asystematic design procedure that uses Petri nets for specifying system and in-terrupter behaviour, and for deriving a primitive flow table. Classical designand additional measures to cope with non-fundamental mode operation yieldeda coded state-machine representation. Thi...

  4. On the convergence time of asynchronous distributed quantized averaging algorithms

    OpenAIRE

    ZHU, MINGHUI; Martinez, Sonia

    2010-01-01

    We come up with a class of distributed quantized averaging algorithms on asynchronous communication networks with fixed, switching and random topologies. The implementation of these algorithms is subject to the realistic constraint that the communication rate, the memory capacities of agents and the computation precision are finite. The focus of this paper is on the study of the convergence time of the proposed quantized averaging algorithms. By appealing to random walks on graphs, we derive ...

  5. Non-detection of nova shells around asynchronous polars

    Science.gov (United States)

    Pagnotta, Ashley; Zurek, David

    2016-05-01

    Asynchronous polars (APs) are accreting white dwarfs (WDs) that have different WD and orbital angular velocities, unlike the rest of the known polars, which rotate synchronously (i.e. their WD and orbital angular velocities are the same). Past nova eruptions are the predicted cause of the asynchronicity, in part due to the fact that one of the APs, V1500 Cyg, was observed to undergo a nova eruption in 1975. We used the Southern African Large Telescope 10 m class telescope and the MDM 2.4 m Hiltner telescope to search for nova shells around three of the remaining four APs (V1432 Aql, BY Cam, and CD Ind) as well as one Intermediate Polar with a high asynchronicity (EX Hya). We found no evidence of nova shells in any of our images. We therefore cannot say that any of the systems besides V1500 Cyg had nova eruptions, but because not all post-nova systems have detectable shells, we also cannot exclude the possibility of a nova eruption occurring in any of these systems and knocking the rotation out of sync.

  6. Non-Detection of Nova Shells Around Asynchronous Polars

    CERN Document Server

    Pagnotta, Ashley

    2016-01-01

    Asynchronous polars (APs) are accreting white dwarfs (WDs) that have different WD and orbital angular velocities, unlike the rest of the known polars, which rotate synchronously (i.e., their WD and orbital angular velocities are the same). Past nova eruptions are the predicted cause of the asynchronicity, in part due to the fact that one of the APs, V1500 Cyg, was observed to undergo a nova eruption in 1975. We used the Southern African Large Telescope 10m class telescope and the MDM 2.4m Hiltner telescope to search for nova shells around three of the remaining four APs (V1432 Aql, BY Cam, and CD Ind) as well as one Intermediate Polar with a high asynchronicity (EX Hya). We found no evidence of nova shells in any of our images. We therefore cannot say that any of the systems besides V1500 Cyg had nova eruptions, but because not all post-nova systems have detectable shells, we also cannot exclude the possibility of a nova eruption occurring in any of these systems and knocking the rotation out of sync.

  7. Asynchronous Stoichiometric Response in Lithium Iron Phosphate Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, William A. [State Univ. of New Jersey, Piscataway, NJ (United States); Akdogan, E. Koray [State Univ. of New Jersey, Piscataway, NJ (United States); Savkliyidiz, Ilyas [State Univ. of New Jersey, Piscataway, NJ (United States); Choksi, Ankur U. [State Univ. of New Jersey, Piscataway, NJ (United States); Silver, Scott X. [State Univ. of New Jersey, Piscataway, NJ (United States); Tsakalokos, Thomas [State Univ. of New Jersey, Piscataway, NJ (United States); Zhong, Zhong [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-11-11

    The operando energy-dispersive x-ray diffraction (EDXRD) was carried out on a newly formed 8 Ah lithium iron phosphate (LiFePO4) battery with the goal of elucidating the origin of asynchronous phase transformation commonly seen with in situ x-ray diffraction studies. The high-energy photons at the NSLS X17B1 beamline allow for penetration into a fully assembled battery and therefore negate any need for a specially designed in situ cell which often uses modified current collectors to minimize x-ray attenuation. Spatially-and-temporally resolved phase-mapping was conducted with a semiquantitative reference intensity ratio (RIR) analysis to estimate the relative abundance of the delithiated phase. The data show an asynchronous response in the stoichiometry versus the electrochemical profile and suggest limited diffusion in the electrode toward the end of discharge. These results confirm that the asynchronous electrode response is not just limited to specially designed cells but occurs in fully assembled cells alike. We attribute this behavior to be a consequence of performing a local measurement over a wide-area heterogeneous reaction.

  8. A novel asynchronous access method with binary interfaces

    Directory of Open Access Journals (Sweden)

    Torres-Solis Jorge

    2008-10-01

    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.

  9. Divorce and asynchronous arrival in common terns, Sterna hirundo.

    Science.gov (United States)

    GonzáLez-SolíS; Becker; Wendeln

    1999-11-01

    We investigated which of three hypotheses (better option, incompatibility or asynchronous arrival) best explains divorce in the common tern. One partner did not return the next year in 18.5% of 150 pairs. Among the 106 pairs in which both mates returned, the divorce rate was 18.9%. We found no significant differences in: breeding performance or condition in relation to the probability of divorce; quality of previous mates and new mates, mean age in relation to pair bond status; breeding success before and after divorce nor did this differ from breeding success of reunited pairs. Hence the better option and incompatibility hypotheses were not supported. However, divorce was more likely in pairs in which mates arrived asynchronously on the breeding grounds, supporting the asynchronous arrival hypothesis. Median arrival asynchrony for divorced pairs was 7.5 days and for reunited pairs 2 days; mates arriving more than 16 days apart always split up. About 20% of divorced birds lost breeding status in the year of divorce, probably as a consequence of their late arrival. Our results suggest that terns search for a new mate as soon as they arrive on the breeding grounds and that mates remain faithful to each other to avoid the costs of searching for a new partner. Thus, synchrony in arrival facilitates pair bond maintenance rather than asynchrony promoting divorce, since divorce appears to be a side-effect of asynchrony and not an active decision. Copyright 1999 The Association for the Study of Animal Behaviour. PMID:10564616

  10. Data Collection for Mobile Group Consumption: An Asynchronous Distributed Approach.

    Science.gov (United States)

    Zhu, Weiping; Chen, Weiran; Hu, Zhejie; Li, Zuoyou; Liang, Yue; Chen, Jiaojiao

    2016-01-01

    Mobile group consumption refers to consumption by a group of people, such as a couple, a family, colleagues and friends, based on mobile communications. It differs from consumption only involving individuals, because of the complex relations among group members. Existing data collection systems for mobile group consumption are centralized, which has the disadvantages of being a performance bottleneck, having single-point failure and increasing business and security risks. Moreover, these data collection systems are based on a synchronized clock, which is often unrealistic because of hardware constraints, privacy concerns or synchronization cost. In this paper, we propose the first asynchronous distributed approach to collecting data generated by mobile group consumption. We formally built a system model thereof based on asynchronous distributed communication. We then designed a simulation system for the model for which we propose a three-layer solution framework. After that, we describe how to detect the causality relation of two/three gathering events that happened in the system based on the collected data. Various definitions of causality relations based on asynchronous distributed communication are supported. Extensive simulation results show that the proposed approach is effective for data collection relating to mobile group consumption. PMID:27058544

  11. THE SIX-WHEEL FRIGHT TRUCK LOCOMOTIVE OF DOUBLE DELIVERY USES RADIO-FREQUENCY TRANSFER WITH PADDING AND ASYNCHRONIZED TRACTION IMPELLENTS

    Directory of Open Access Journals (Sweden)

    M. H. Visin

    2010-10-01

    Full Text Available Our research offers a new perspective loading pattern of the 12-wheel double-feed freight electric locomotive with the asynchronous tractive motor using an adapter transformer with the high-frequency uncoupler. This will make it possible to decrease the traction-feeding transformer mass 2.3 times, to remove the current pulse advancing on the track circuit and therefore the influence on the work of the ALSE and CBS. So the railway traffic safety will be increased considerably.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...

  13. Efficient IEC permanent magnet motor; Effizienter IEC Permanent-Magnetmotor (3 kW) - Jahresbericht 2007

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M.; Salathe, D.; Biner, H. P.; Evequoz, B.

    2007-07-01

    This annual report for the Swiss Federal Office of Energy (SFOE) takes a look at the work done at the Swiss Universities of Applied Sciences in Lucerne and Valais and the Circle Motor Company in 2007 on the economic feasibility, efficiency and limitations of permanent magnet motors. The higher efficiency of permanent-magnet motors in comparison with asynchronous motors for powers of over 100 kW is noted. Work done on the integration of a 3 kW permanent-magnet motor in an IEC-Standard housing is described. The construction of an efficient permanent magnet motor drive and its testing at the Valais University of Applied Sciences is discussed. The high efficiencies obtained both for the motor and its drive electronics are noted.

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

    Science.gov (United States)

    Frankel, Mitchell A; Mathews, V John; Clark, Gregory A; Normann, Richard A; Meek, Sanford G

    2016-01-01

    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. PMID:27679557

  15. Contrôle d'une machine asynchrone par estimation robuste de la vitesse

    Science.gov (United States)

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

    1992-03-01

    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.

  16. Motor homopolar

    OpenAIRE

    2007-01-01

    Mostramos la construcción de un modelo de motor homopolar, uno de los más antiguos tipos de motores eléctricos. Se caracterizan porque el campo magnético del imán mantiene siempre la misma polaridad (de ahí su nombre, del griego homos, igual), de modo que, cuando una corriente eléctrica atraviesa el campo magnético, aparece una fuerza que hace girar los elementos no fijados mecánicamente. En el sencillísimo motor homopolar colgado (Schlichting y Ucke 2004), el imán puede girar ...

  17. Application of stepping motor

    International Nuclear Information System (INIS)

    This book is divided into three parts, which is about practical using of stepping motor. The first part has six chapters. The contents of the first part are about stepping motor, classification of stepping motor, basic theory og stepping motor, characteristic and basic words, types and characteristic of stepping motor in hybrid type and basic control of stepping motor. The second part deals with application of stepping motor with hardware of stepping motor control, stepping motor control by microcomputer and software of stepping motor control. The last part mentions choice of stepping motor system, examples of stepping motor, measurement of stepping motor and practical cases of application of stepping motor.

  18. Arithmetic Operations and Factorization using Asynchronous P Systems

    Directory of Open Access Journals (Sweden)

    Takayuki Murakawa

    2012-07-01

    Full Text Available

    In the present paper, we consider the asynchronous parallelism in membrane computing, and propose asynchronous P systems that perform two basic arithmetic operations and factorization. Since there is no restrictive assumption for application of rules, sequential and maximal parallel executions are allowed on the asynchronous P system.

    We first propose a P system that computes addition of two binary numbers of m bits.  The P system works in O(m sequential and parallel steps using O(m types of objects. We next propose a P system for multiplication of the two binary numbers of m bits, and show that the P system works in O(m log m parallel steps or O(m3 sequential steps using O(m2 types of objects. Finally, we propose a P system for factorization of a positive integer of $m$ bits using the above P system as a sub-system. The P system computes the factorization in O(m log m parallel steps or O(4m 

  19. Wind Generator Stabilization with Doubly-Fed Asynchronous Machine

    Institute of Scientific and Technical Information of China (English)

    WU Li; WANG Zhi-xin

    2007-01-01

    This paper investigates the function of doubly-fed asynchronous machine(DASM) with emphasis placed on its ability to the stabilization of the power system including wind generators. P(active power) and Q(reactive power) compensation from DASM can be regulated independently through secondary-excitation controlling. Simulation results by power system computer aided design(PSCAD) show that DASM can restore the wind-generator system to a normal operating condition rapidly even following severe transmission-line failures. Comparison studies have also been performed between wind turbine pitch control and proposed method.

  20. Hyperplastic polyposis associated with two asynchronous colon cancers

    Institute of Scientific and Technical Information of China (English)

    Masaya Kurobe; Kuniko Abe; Naoe Kinoshita; Masanobu Anami; Hirotaka Tokai; Yoshinori Ryu; Chun Yang Wen; Takashi Kanematsu; Tomayoshi Hayashi

    2007-01-01

    We report a patient with hyperplastic polyposis who had two asynchronous colon cancers, a combined adenoma-hyperplastic polyp, a serrated adenoma, and tubular adenomas. Hyperplastic polyposis is thought to be a precancerous lesion; and adenocarcinoma arises from hyperplastic polyposis through the hyperplastic polyp-adenoma-carcinoma sequence. Most polyps in patients with hyperplastic polyposis present as blandlooking hyperplastic polyps, which are regarded as nonneoplastic lesions; however, the risk of malignancy should not be underestimated. In patients with multiple hyperplastic polyps, hyperplastic polyposis should be identified and followed up carefully in order to detect malignant transformation in the early stage.

  1. A wavelet approach to binary blackholes with asynchronous multitasking

    Science.gov (United States)

    Lim, Hyun; Hirschmann, Eric; Neilsen, David; Anderson, Matthew; Debuhr, Jackson; Zhang, Bo

    2016-03-01

    Highly accurate simulations of binary black holes and neutron stars are needed to address a variety of interesting problems in relativistic astrophysics. We present a new method for the solving the Einstein equations (BSSN formulation) using iterated interpolating wavelets. Wavelet coefficients provide a direct measure of the local approximation error for the solution and place collocation points that naturally adapt to features of the solution. Further, they exhibit exponential convergence on unevenly spaced collection points. The parallel implementation of the wavelet simulation framework presented here deviates from conventional practice in combining multi-threading with a form of message-driven computation sometimes referred to as asynchronous multitasking.

  2. DUSTY ENVIRONMENT IMPACT ON LIFESPAN OF THE INDUCTION MOTORS STATOR WINDING

    Directory of Open Access Journals (Sweden)

    V. E. Krivonosov

    2015-01-01

    Full Text Available Large quantity of asynchronous motors work in heavily dusted environments. On the end-winding insulation of the motors to 55 kW operating in the mining and smelting enterprise there is a 3 cm dust layer, which may lead to the asynchronous motor end-winding local overheat and consequent early breakdown. Contemporary literature allocates insufficient consideration to the issue of studying the impact the winding dust pollution has on the motor lifespan; for the most part they are experimental researches. The article investigates and establishes correlation relationship between the additional winding heating and the end-winding dust layer thickness. The investigation considers the induction motor winding to be a homogeneous solid and assumes the motor thermal conditions steady inasmuch as the winding insulation dust-cover forming time is much greater than the motor-heating time constant. The obtained expression permits determining the winding dust level by temperature variations; the dependence has linear character. Neither the motor type, size, nor the capacity do affect the local insulation overheating since the temperature difference between the windings being dust laden does not exceed 10 % for asynchronous motors of various capacity. The authors develop an appliance that enables the winding dustiness level monitoring and signals of necessity for the preventive cleaning measures implementation. The appliance operation principle is based on measuring results comparison of the two temperature-sensing devices mounted on the end-winding: one – in the upper part, and the other – in the bottom. The differential in the sensors reading-out allows estimating the dust layer sedimentation on the end-winding. A patent of invention has been issued on the investigation results. 

  3. Designing Asynchronous Online Discussion Environments: Recent Progress and Possible Future Directions

    Science.gov (United States)

    Gao, Fei; Zhang, Tianyi; Franklin, Teresa

    2013-01-01

    Asynchronous online discussion environments are important platforms to support learning. Research suggests, however, threaded forums, one of the most popular asynchronous discussion environments, do not often foster productive online discussions naturally. This paper explores how certain properties of threaded forums have affected or constrained…

  4. The Key Implementation Technology of Client/Server's Asynchronous Communication Programs

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper introduces the implementation method,key technology and flowchart of Client/Server's asynchronous communication programs on Linux or Unix,and further explains a few problems to which should pay attention for improving CPU's efficiency in implementing asynchronous communication programs.

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

    DEFF Research Database (Denmark)

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

    1998-01-01

    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...

  6. Grain Refining of Flange Plate for Welded H Section Steel Made under Asynchronous Rolling Condition

    Institute of Scientific and Technical Information of China (English)

    DAI Hui; SUN Jiquan; TANG Di

    2011-01-01

    Asynchronous rolling technology was adopted for the accumulated ten passes cold rolling,flange plate steel,and for welded H section steel,respectively.The metallographic microstructure analysis,tensile test and annealing test were carried out for cold rolled pieces; thus the ratio of length to width of grain,tensile strength,relationship between the grain size and asynchronous rolling process parameters after annealing can be obtained.The experimental results show that the relationship between the asynchronous rolling and the shearing deformation of rolled pieces can make a reasonable interpretation of the mechanism that asynchronous rolling may improve the strain accumulated energy of rolled pieces and the strength of flange plate steel.This paper provides a theoretical basis for the application of asynchronous rolling in improving the strength of flange plate steel.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    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....... This adds hardware complexity and increases area and power consumption. We propose to use asynchronous routers in order to achieve a simpler, more robust and globally-asynchronous NOC, and this represents an unexplored point in the design space. The paper presents a range of alternative router designs. All...... routers have been synthesized for a 65nm CMOS technology, and the paper reports post-layout figures for area, speed and energy and compares the asynchronous designs with an existing mesochronous clocked router. The results show that an asynchronous router is 2 times smaller, marginally slower...

  8. Experience with synchronous and asynchronous digital control systems

    Science.gov (United States)

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

    1986-01-01

    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. Cooperative and asynchronous stereo vision for dynamic vision sensors

    International Nuclear Information System (INIS)

    Dynamic vision sensors (DVSs) encode visual input as a stream of events generated upon relative light intensity changes in the scene. These sensors have the advantage of allowing simultaneously high temporal resolution (better than 10 µs) and wide dynamic range (>120 dB) at sparse data representation, which is not possible with clocked vision sensors. In this paper, we focus on the task of stereo reconstruction. The spatiotemporal and asynchronous aspects of data provided by the sensor impose a different stereo reconstruction approach from the one applied for synchronous frame-based cameras. We propose to model the event-driven stereo matching by a cooperative network (Marr and Poggio 1976 Science 194 283–7). The history of the recent activity in the scene is stored in the network, which serves as spatiotemporal context used in disparity calculation for each incoming event. The network constantly evolves in time, as events are generated. In our work, not only the spatiotemporal aspect of the data is preserved but also the matching is performed asynchronously. The results of the experiments prove that the proposed approach is well adapted for DVS data and can be successfully used for disparity calculation. (paper)

  10. Spatiotemporal Features for Asynchronous Event-based Data

    Directory of Open Access Journals (Sweden)

    Xavier eLagorce

    2015-02-01

    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.

  11. The Role of Online Instructors in Asynchronous Discussion Forums

    Science.gov (United States)

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

    2007-05-01

    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.

  12. Asynchronous Code-Division Random Access Using Convex Optimization

    CERN Document Server

    Applebaum, Lorne; Duarte, Marco F; Calderbank, Robert

    2011-01-01

    Many applications in cellular systems and sensor networks involve a random subset of a large number of users asynchronously reporting activity to a base station. This paper examines the problem of multiuser detection (MUD) in random access channels for such applications. Traditional orthogonal signaling ignores the random nature of user activity in this problem and limits the total number of users to be on the order of the number of signal space dimensions. Contention-based schemes, on the other hand, suffer from delays caused by colliding transmissions and the hidden node problem. In contrast, this paper presents a novel asynchronous (non-orthogonal) code-division random access scheme along with a convex optimization-based MUD algorithm that overcomes the issues associated with orthogonal signaling and contention-based methods. Two key distinguishing features of the proposed algorithm are that it does not require knowledge of the delay or channel state information of every user and it has polynomial-time com...

  13. Algebraic Number Precoded OFDM Transmission for Asynchronous Cooperative Multirelay Networks

    Directory of Open Access Journals (Sweden)

    Hua Jiang

    2014-01-01

    Full Text Available This paper proposes a space-time block coding (STBC transmission scheme for asynchronous cooperative systems. By combination of rotated complex constellations and Hadamard transform, these constructed codes are capable of achieving full cooperative diversity with the analysis of the pairwise error probability (PEP. Due to the asynchronous characteristic of cooperative systems, orthogonal frequency division multiplexing (OFDM technique with cyclic prefix (CP is adopted for combating timing delays from relay nodes. The total transmit power across the entire network is fixed and appropriate power allocation can be implemented to optimize the network performance. The relay nodes do not require decoding and demodulation operation, resulting in a low complexity. Besides, there is no delay for forwarding the OFDM symbols to the destination node. At the destination node the received signals have the corresponding STBC structure on each subcarrier. In order to reduce the decoding complexity, the sphere decoder is implemented for fast data decoding. Bit error rate (BER performance demonstrates the effectiveness of the proposed scheme.

  14. Asynchronous replica exchange software for grid and heterogeneous computing

    Science.gov (United States)

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

    2015-11-01

    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.

  15. 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)

    2014-01-01

    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.

  16. Designing Parallel Bus Using Universal Asynchronous Receiver Transmitter

    Directory of Open Access Journals (Sweden)

    Satyandra Sharad

    2013-04-01

    Full Text Available This paper entitled “DESIGNING PARALLEL BUSUSING UNIVERSAL ASYNCHRONOUS RECEIVER TRANSMITTER” is designed to the core of a UART interface module, which includes both receive and transmit modules, and the command parser. This paper will be a viable solution to design parallel buses with the help of UART. In the test bench , there is a RFM(register file model to which we write/read back data from just to check our design .The txt file issues serial inputs to the core and the core outputs parallel data and address in the form of bus. This bus is connected to our RFM (register file model instantiated in the test bench along with the design. This makes easy to retrieve parallel data from serial input. The base of the paper is to use microcontroller along with other components to interface with the physical world. In contrast, most serial communication must first be converted back into parallel form by a universal asynchronous receiver/transmitter (UART before they may be directly connected to a data bus. Both Transmissions (Parallel and Serial are used to connect peripheral devices and enable us to communicate with these devices. The UART core described here is designed using VHDL and implemented on Xilinx Vertex FPGA.

  17. Asynchronous glaciation at Nanga Parbat, northwestern Himalaya Mountains, Pakistan

    Science.gov (United States)

    Phillips, William M.; Sloan, Valerie F.; Shroder, John F., Jr.; Sharma, Pankaj; Clarke, Michèle L.; Rendell, Helen M.

    2000-05-01

    We present a new glacial chronology demonstrating asynchroneity between advances of Himalayan glaciers and Northern Hemisphere ice-sheet volumes. Glaciers at Nanga Parbat expanded during the early to middle Holocene ca. 9.0 5.5 ka. No major advances at Nanga Parbat during the last global glacial stage of marine oxygen isotope stage 2 (MIS-2) between 24 and 11 ka were identified. Preliminary evidence also indicates advances between ca. 60 and 30 ka. These periods of high ice volume coincide with warm, wet regional climates dominated by a strong southwest Asian summer monsoon. The general lack of deposits dating from MIS-2 suggests that Nanga Parbat was too arid to support expanded ice during this period of low monsoon intensity. Advances during warm, wet periods are possible for the high-altitude summer accumulation glaciers typical of the Himalayas, and explain asynchronous behavior. However, the Holocene advances at Nanga Parbat appear to have been forced by an abrupt drop in temperature ca. 8.4 8.0 ka and an increase in winter precipitation ca. 7 5.5 ka. These results highlight the overall sensitivity of Himalayan glaciation to orbital forcing of monsoon intensity, and on millennial or shorter time scales, to changes in North Atlantic circulation.

  18. Asynchronous Task-Based Polar Decomposition on Manycore Architectures

    KAUST Repository

    Sukkari, Dalal

    2016-10-25

    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.

  19. A Parallel Particle Swarm Optimization Algorithm Accelerated by Asynchronous Evaluations

    Science.gov (United States)

    Venter, Gerhard; Sobieszczanski-Sobieski, Jaroslaw

    2005-01-01

    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. Economic viability, applications and limits of efficient permanent magnet motors - Summary and update; Wirtschaftlichkeit, Anwendungen und Grenzen von effizienten Permanent-Magnet-Motoren - Zusammenfassung und Update - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H.-P.; Evequoz, B. [Hochschule Westschweiz, Delemont (Switzerland); Salathe, D. [Hochschule Luzern Technik und Architektur, Horw (Switzerland)

    2009-06-15

    This final report for the Swiss Federal Office of Energy (SFOE), takes a look at the economic viability, applications and limits of efficient permanent magnet motors. Permanent magnet motors are compared with standard IEC asynchronous motors. In a theoretical part of the report, it is discussed how the increasing size of the motor influences efficiency, weight, volume and power. The results of practical tests carried out on six motors are presented. Three standard motors with varying efficiency were compared with three permanent-magnet motors for the power range around 3 kW. Market-oriented considerations concerning permanent-magnet motors are discussed. Operational criteria for the choice of the type of motor to be used are also examined.

  1. Asynchronous API Pattern and its Application%异步接口模式及其应用

    Institute of Scientific and Technical Information of China (English)

    何华海; 丁柯

    2002-01-01

    In distributed systems,high efficiency can be achieved using asynchronous API between client and server.This paper provides an architectural pattern that implements asynchronous API generally. Asynchronous methods donot execute operations directly,however,they delegate the sending and receiving process to individual threads via aqueue ,the client deals with results by means of callback ,wait or check. Synchronous API is implemented on the baseof asynchronous API. Presently the asynchronous API pattern has been employed in the implementation of messagequeue middleware ISMQ.

  2. THE MOTOR

    DEFF Research Database (Denmark)

    Gammelgaard Nielsen, Anders

    2011-01-01

    MOTOR is the first assignment that students at Unit 1a of the School of Architecture are introduced to. The purpose of the assignment is to shake up the students and their preconceptions of what architec- ture is. This is done by introducing them to a working method that al- lows them to develop...

  3. Motor Magnates

    Institute of Scientific and Technical Information of China (English)

    ISABEL DING

    2008-01-01

    @@ The automotive industry is often seen as a man's world. Wang Fengying (王风英) begs to differ. The 38-year-old has presided over Great Wall Motors (长城汽车), the leading pick-up truck and Sport Utility Vehicle(SUV) manufacturer in China for the past five years.

  4. Motor radiculopathy

    OpenAIRE

    Khan, Afsha; Camilleri, Jeremy

    2012-01-01

    A 48-year-old immunosuppressed woman presented to a rheumatology follow-up clinic after suffering from herpes zoster infection. She had manifestations of foot drop 3 months after the initial infection. She was diagnosed with motor radiculopathy following herpes zoster infection that was effectively managed by physiotherapy and amitriptyline.

  5. Numerical Simulation of Asynchronous Simulated Moving Bed Chromatography

    Institute of Scientific and Technical Information of China (English)

    卢建刚

    2004-01-01

    Asynchronous simulated moving bed chromatography (ASMBC), known also as the "VARICOL" process, is more efficient and flexible than the well-known and traditional simulated moving bed chromatography (SMBC). A detailed model of ASMBC, taking account of non-linear competitive isotherms, mass transfer parameters, and complex port switching schedule parameters, was developed to simulate the complex dynamics of ASMBC.The simulated performance is in close agreement with the experimental data of chiral separation reported in the literature. The simulation results show that ASMBC can achieve the performance similar to SMBC with fewer columns and can achieve better performance than SMBC with the same total column number. All design and operation parameters can be chosen correctly by numerical simulation. This detailed ASMBC model and the numerical technique are useful for design, operation, optimization and scale-up of ASMBC.

  6. An Asynchronous Cellular Automata-Based Adaptive Illumination Facility

    Science.gov (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.

  7. Estimation of delays in generalized asynchronous Boolean networks.

    Science.gov (United States)

    Das, Haimabati; Layek, Ritwik Kumar

    2016-10-20

    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. PMID:27464825

  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)

    2011-02-15

    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.

    Science.gov (United States)

    Das, Haimabati; Layek, Ritwik Kumar

    2016-10-20

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

    Directory of Open Access Journals (Sweden)

    Xiaoqiang Sun

    2016-01-01

    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.

  11. Normalized and Asynchronous Mirror Alignment for Cherenkov Telescopes

    CERN Document Server

    Ahnen, M L; Balbo, M; Bergmann, M; Biland, A; Blank, M; Bretz, T; Bruegge, K A; Buss, J; Domke, M; Dorner, D; Einecke, S; Hempfling, C; Hildebrand, D; Hughes, G; Lustermann, W; Mannheim, K; Mueller, S A; Neise, D; Neronov, A; Noethe, M; Overkemping, A -K; Paravac, A; Pauss, F; Rhode, W; Shukla, A; Temme, F; Thaele, J; Toscano, S; Vogler, P; Walter, R; Wilbert, A

    2016-01-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) need imaging optics with large apertures and high image intensities to map the faint Cherenkov light emitted from cosmic ray air showers onto their image sensors. Segmented reflectors fulfill these needs, and as they are composed from mass production mirror facets they are inexpensive and lightweight. However, as the overall image is a superposition of the individual facet images, alignment is a challenge. Here we present a computer vision based star tracking alignment method, which also works for limited or changing star light visibility. Our method normalizes the mirror facet reflection intensities to become independent of the reference star's intensity or the cloud coverage. Using two CCD cameras, our method records the mirror facet orientations asynchronously of the telescope drive system, and thus makes the method easy to integrate into existing telescopes. It can be combined with remote facet actuation, but does not require one to work. Furthermore, it ca...

  12. Commande vectorielle d'un moteur asynchrone sans capteur

    OpenAIRE

    Ourth, T.

    1993-01-01

    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 comma...

  13. Asynchronous Multilateral Control for Simplified Walking Haptic System

    Science.gov (United States)

    Okura, Takeshi; Katsura, Seiichiro

    Recently, there has been extensive development in remote communication technologies such as telephone, radio, and television. Haptic information is studied as the third type of multimedia information. Real-world haptics is getting attention not only for the feedback of real-world haptic information in teleoperation but also as the key technology for future human support. Most of the objects of study in haptics are stationary. Therefore, the moving range of such haptic systems is limited. This paper proposes a novel haptic device that receives force feedback of walking motion from a remote environment and manipulates remote system. Thus, its moving range is unrestricted. To drive this haptic system, the paper also proposes asynchronous multilateral control. By using this control, an operator can operate the remote system without changing his/her position. The proposed haptic system is expected to act as an effective interface for virtual reality applications and teleoperation.

  14. The Formation of the Wide Asynchronous Binary Asteroid Population

    CERN Document Server

    Jacobson, Seth A; McMahon, Jay

    2013-01-01

    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semi-major 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, planetary flybys and directly from rotational fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (i) these systems are formed from rotational fission, (ii) their satellites are tidally locked, (iii) their orbits are expanded by the BYORP effect, (iv) their satellites de-synchronize due to the adiabatic invariance between the libration of the secondary and the mutual orbit, and (v) the secondary avoids resynchronization due to the 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 torq...

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

    Directory of Open Access Journals (Sweden)

    Mark P. Nelder

    2009-01-01

    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. LOAD CONTROL OF A 3-Ø SELF- EXCITED ASYNCHRONOUS GENERATOR

    Directory of Open Access Journals (Sweden)

    SUBRAMANIAN KULANDHAIVELU

    2011-02-01

    Full Text Available This paper describes the simulation based performance study of a 3-Ø self-excited asynchronous generator (SEASG in constant power operation. A feed back voltage based controller by using a load control technique to control and retain the generator terminal voltage constant. This technique mostly used in uncontrolled hydroturbine driven induction generators in a stand-alone power generator. The results has been validate by the steady state equivalent circuit analysis of a 2.2kW, 415Volts, 4.7A, Star connected, 1440-rpm induction generator. The proposed study system has been simulated using Mat lab/Simulink version-7.0.The simulated results arepresented.

  17. Indoor Positioning for Smartphones Using Asynchronous Ultrasound Trilateration

    Directory of Open Access Journals (Sweden)

    James D. Carswell

    2013-06-01

    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.

  18. Operational aspects of asynchronous filtering for hydrological forecasting

    Directory of Open Access Journals (Sweden)

    O. Rakovec

    2015-03-01

    Full Text Available This study investigates the suitability of the Asynchronous Ensemble Kalman Filter (AEnKF and a partitioned updating scheme for hydrological forecasting. The AEnKF requires forward integration of the model for the analysis and enables assimilation of current and past observations simultaneously at a single analysis step. The results of discharge assimilation into a grid-based hydrological model for the Upper Ourthe catchment in the Belgian Ardennes show that including past predictions and observations in the data assimilation method improves the model forecasts. Additionally, we show that elimination of the strongly non-linear relation between the soil moisture storage and assimilated discharge observations from the model update becomes beneficial for improved operational forecasting, which is evaluated using several validation measures.

  19. The Efficacy of Deliberate Practice Delivered Using Asynchronous Training Technology

    Directory of Open Access Journals (Sweden)

    Colleen E. McEdwards

    2014-04-01

    Full Text Available Employee productivity is key to survival in business. Senior employees require access to advanced training that does not necessitate extended periods away from their work. Once performance begins to plateau, it can be difficult to reach experienced employees with cost-effective, timely, and relevant training opportunities. Organizations must find ways to enhance employee performance; however, research suggests workplace training is too expensive and is too often without lasting benefit. The purpose of this study is to further quantify deliberate practice as a potentially efficient, customizable mode of training using asynchronous e-learning. The study compared traditional seminars with online deliberate practice training. While additional research is needed in wider learning contexts and with larger sample sizes, improvements among the deliberate practice groups were significant. Using a mixed methods pretest/posttest research design, the deliberate practice training showed improved performance and increased satisfaction compared with the traditional seminar approach.

  20. Minor Planet 1016 Anitra: A Likely Asynchronous Binary

    Science.gov (United States)

    Pilcher, Frederick; Benishek, Vladimir; Jacobsen, Jens; Kristensen, Leif Hugo; Lang, Kim; Larsen, Frank R.; Odden, Caroline; Pravec, Petr

    2016-07-01

    Analysis of photometry data for 1016 Anitra using a single period analysis shows a lightcurve with a period of 5.9296 hours and amplitude of 0.30 mag, with short period fluctuations. A simultaneous two-period analysis of the data found two smooth bimodal lightcurves with periods and amplitudes of P1 = 5.92951 h, A1 = 0.30 mag and P2 = 2.609143 h, A2 = 0.10 mag. These results are interpreted as the rotation of the two components of an asynchronous binary system. Four additional attenuations were observed that may have been caused by satellite mutual events, but those data were insufficient to yield an orbital period.

  1. AN IMPROVED DOA ESTIMATION ALGORITHM FOR ASYNCHRONOUS MULTIPATH CDMA SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Yang Wei; Chen Junshi; Tan Zhenhui; Takis Mathiopoulos

    2006-01-01

    This paper proposes an improved Direction Of Arrival(DOA) estimation algorithm for asynchronous multipath Code Division Multiple Access(CDMA) system. The algorithm is based on the correlation matrices of outputs of decorrelator, which is a Multi-User Detection(MUD) approach, one of the key techniques for CDMA system. Through decorrelating processing, the desired user's mulipath signals can be resolved and all the other resolved multipath signal interference is eliminated. So the proposed algorithm is expected to perform much better than algorithm such as that based directly on the Matched Filter(MF) bank outputs. Simulation results confirm this. While the improved algorithm performs better and better as Signal-to-Noise Ratio(SNR)increases, the performance of algorithm based directly on the MF bank outputs can not be improved.

  2. Asynchronous data-driven classification of weapon systems

    International Nuclear Information System (INIS)

    This communication addresses real-time weapon classification by analysis of asynchronous acoustic data, collected from microphones on a sensor network. The weapon classification algorithm consists of two parts: (i) feature extraction from time-series data using symbolic dynamic filtering (SDF), and (ii) pattern classification based on the extracted features using the language measure (LM) and support vector machine (SVM). The proposed algorithm has been tested on field data, generated by firing of two types of rifles. The results of analysis demonstrate high accuracy and fast execution of the pattern classification algorithm with low memory requirements. Potential applications include simultaneous shooter localization and weapon classification with soldier-wearable networked sensors. (rapid communication)

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

    Directory of Open Access Journals (Sweden)

    Edward K. Lew

    2016-06-01

    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.

  4. UNIVERSAL REGULAR AUTONOMOUS ASYNCHRONOUS SYSTEMS: ω-LIMIT SETS, INVARIANCE AND BASINS OF ATTRACTION

    Directory of Open Access Journals (Sweden)

    Serban Vlad

    2011-07-01

    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.

  5. Advanced Motors

    Energy Technology Data Exchange (ETDEWEB)

    Knoth, Edward A.; Chelluri, Bhanumathi; Schumaker, Edward J.

    2012-12-14

    Project Summary Transportation energy usage is predicted to increase substantially by 2020. Hybrid vehicles and fuel cell powered vehicles are destined to become more prominent as fuel prices rise with the demand. Hybrid and fuel cell vehicle platforms are both dependent on high performance electric motors. Electric motors for transportation duty will require sizeable low-speed torque to accelerate the vehicle. As motor speed increases, the torque requirement decreases which results in a nearly constant power motor output. Interior permanent magnet synchronous motors (IPMSM) are well suited for this duty. , , These rotor geometries are configured in straight lines and semi circular arc shapes. These designs are of limited configurations because of the lack of availability of permanent magnets of any other shapes at present. We propose to fabricate rotors via a novel processing approach where we start with magnet powders and compact them into a net shape rotor in a single step. Using this approach, widely different rotor designs can be implemented for efficiency. The current limitation on magnet shape and thickness will be eliminated. This is accomplished by co-filling magnet and soft iron powders at specified locations in intricate shapes using specially designed dies and automatic powder filling station. The process fundamentals for accomplishing occurred under a previous Applied Technology Program titled, “Motors and Generators for the 21st Century”. New efficient motor designs that are not currently possible (or cost prohibitive) can be accomplished by this approach. Such an approach to

  6. Process and circuit for operating an electric locomotive with several drive motors working in parallel from one inverter. Verfahren und Schaltungsanordnung zum Betrieb eines elektrischen Triebfahrzeugs mit mehreren an einem Umrichter parallel arbeitenden Antriebsmotoren

    Energy Technology Data Exchange (ETDEWEB)

    Niehage, H.

    1985-01-31

    With several asynchronous motors fed in parallel via one inverter from an intermediate DC circuit, which drive the various sets of wheels of an electric locomotive, one should prevent that if the slip between the wheel and the rail increases on one set of wheels, the torque of the synchronous motor driving the slipping set of wheels from being transferred to the other parallel asynchronous motors. For this reason each asynchronous motor has a current transformer, which detects the phase currents and takes them to a measurement circuit forming the sum of the phase currents. The sum of the phase currents for each asynchronous motor is compared with the current in the intermediate DC circuit, which is detected via a DC converter and is reduced to a reference level by a quantity forming circuit. The dynamic differences between the motor currents occurring during slipping are detected in difference circuits and are added in a subsequent quantity forming circuit. The signal supplied from this latter circuit is treated by a function forming circuit, which gives a quick reduction of the intermediate circuit power via the control circuit of the intermediate circuit of the inverter.

  7. New Method for Accurate Parameter Estimation of Induction Motors Based on Artificial Bee Colony Algorithm

    OpenAIRE

    Jamadi, Mohammad; Merrikh-Bayat, Farshad

    2014-01-01

    This paper proposes an effective method for estimating the parameters of double-cage induction motors by using Artificial Bee Colony (ABC) algorithm. For this purpose the unknown parameters in the electrical model of asynchronous machine are calculated such that the sum of the square of differences between full load torques, starting torques, maximum torques, starting currents, full load currents, and nominal power factors obtained from model and provided by manufacturer is minimized. In orde...

  8. Distributed Consensus of Stochastic Delayed Multi-agent Systems Under Asynchronous Switching.

    Science.gov (United States)

    Wu, Xiaotai; Tang, Yang; Cao, Jinde; Zhang, Wenbing

    2016-08-01

    In this paper, the distributed exponential consensus of stochastic delayed multi-agent systems with nonlinear dynamics is investigated under asynchronous switching. The asynchronous switching considered here is to account for the time of identifying the active modes of multi-agent systems. After receipt of confirmation of mode's switching, the matched controller can be applied, which means that the switching time of the matched controller in each node usually lags behind that of system switching. In order to handle the coexistence of switched signals and stochastic disturbances, a comparison principle of stochastic switched delayed systems is first proved. By means of this extended comparison principle, several easy to verified conditions for the existence of an asynchronously switched distributed controller are derived such that stochastic delayed multi-agent systems with asynchronous switching and nonlinear dynamics can achieve global exponential consensus. Two examples are given to illustrate the effectiveness of the proposed method.

  9. 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;

    2014-01-01

    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 repetiti...

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

    Directory of Open Access Journals (Sweden)

    Nikos Sklavos

    2002-01-01

    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.

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

    OpenAIRE

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

    2008-01-01

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

    Data.gov (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...

  13. The double-temperature ratchet model and current reversal of coupled Brownian motors

    CERN Document Server

    Li, Chen-pu; Zheng, Zhi-gang

    2016-01-01

    Based on the transport features and experimental phenomena observed in studies of molecular motors, we proposed the double-temperature ratchet model of coupled motors to reveal the dynamical mechanism of cooperative transport of motors with two heads, where the interactions and the asynchronous between two motor heads are taken into account. We investigated the collective unidirectional transport of coupled system, and find that the direction of motion can be inversed under certain conditions. Inverse motion can be achieved by modulating the coupling strength, the coupling free length and the asymmetric efficient of the periodic potential, which is understood in terms of the effective-potential theory. The dependence of directed current on various parameters is studied systematically. Directed transport of coupled Brownian motors can be manipulated and optimized by adjusting pulsating period or the phase shift of the pulsating temperature.

  14. On the basins of attraction of the regular autonomous asynchronous systems

    OpenAIRE

    Vlad, Serban E.

    2012-01-01

    The Boolean autonomous dynamical systems, also called regular autonomous asynchronous systems are systems whose 'vector field' is a function {\\Phi}:{0,1}^{n}{\\to}{0,1}^{n} and time is discrete or continuous. While the synchronous systems have their coordinate functions {\\Phi}_{1},...,{\\Phi}_{n} computed at the same time: {\\Phi},{\\Phi}{\\circ}{\\Phi},{\\Phi}{\\circ}{\\Phi}{\\circ}{\\Phi},... the asynchronous systems have {\\Phi}_{1},...,{\\Phi}_{n} computed independently on each other. The purpose of t...

  15. INVESTIGATION OF ASYNCHRONOUS OPTICAL COMMUNICATION CHANNEL THROUGHPUT CONTAINING A RECEIVER ON THE BASIS OF PHOTON COUNTER

    Directory of Open Access Journals (Sweden)

    I. R. Gulakov

    2013-01-01

    Full Text Available A mathematical model of asynchronous optical communication channel with a photon counter applied as a receiving module has been built. The expression for calculating of data throughput of this channel has been obtained. As a result of implemented experimental investigations it has been established that the data throughput of asynchronous optical communication channel containing a photon counter on the basis of avalanche photodetector as a receiving module depends on optical radiation and photodetector supply voltage.

  16. Asynchronous growth and competition in a two-sex age-structured population model

    OpenAIRE

    Iannelli, Mimmo; Ripoll, Jordi

    2009-01-01

    Asynchronous exponential growth has been extensively studied in population dynamics. In this paper we find out the asymptotic behaviour in a non-linear age-dependent model which takes into account sexual reproduction interactions. The main feature of our model is that the non-linear process converges to a linear one as the solution becomes large, so that the population undergoes asynchronous growth. The steady states analysis and the corresponding stability analysis are completely made and ...

  17. Document Flow Model: A Formal Notation for Modelling Asynchronous Web Services Composition

    OpenAIRE

    Yang, Jingtao; Cirstea, Corina; Henderson, Peter

    2005-01-01

    This paper presents a formal notation for modelling asynchronous web services composition, using context and coordination mechanisms. Our notation specifies the messages that can be handled by different web services, and describes a system of inter-related web services as the flow of documents between them. The notation allows the typical web services composition pattern, asynchronous messaging, and has the capability to deal with long-running service-to-service interactions and dynamic confi...

  18. 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))

    1983-12-11

    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.

  19. 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.;

    2016-01-01

    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.......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....

  20. Batch Secret Sharing for Secure Multi-party Computation in Asynchronous Network

    Institute of Scientific and Technical Information of China (English)

    HUANG Zheng; GONG Zheng; LI Qiang

    2009-01-01

    This paper proposes an efficient batch secret sharing protocol among n players resilient to t < n/4 players in asynchronous network. The construction of our protocol is along the line of Hirt's protocol which works in synchronous model. Compared with the method of using secret share protocol m times to share m secrets, our protocol is quite efficient. The protocol can be used to improve the efficiency of secure multi-party computation (MPC) greatly in asynchronous network.

  1. Operational aspects of asynchronous filtering for improved flood forecasting

    Science.gov (United States)

    Rakovec, Oldrich; Weerts, Albrecht; Sumihar, Julius; Uijlenhoet, Remko

    2014-05-01

    Hydrological forecasts can be made more reliable and less uncertain by recursively improving initial conditions. A common way of improving the initial conditions is to make use of data assimilation (DA), a feedback mechanism or update methodology which merges model estimates with available real world observations. The traditional implementation of the Ensemble Kalman Filter (EnKF; e.g. Evensen, 2009) is synchronous, commonly named a three dimensional (3-D) assimilation, which means that all assimilated observations correspond to the time of update. Asynchronous DA, also called four dimensional (4-D) assimilation, refers to an updating methodology, in which observations being assimilated into the model originate from times different to the time of update (Evensen, 2009; Sakov 2010). This study investigates how the capabilities of the DA procedure can be improved by applying alternative Kalman-type methods, e.g., the Asynchronous Ensemble Kalman Filter (AEnKF). The AEnKF assimilates observations with smaller computational costs than the original EnKF, which is beneficial for operational purposes. The results of discharge assimilation into a grid-based hydrological model for the Upper Ourthe catchment in Belgian Ardennes show that including past predictions and observations in the AEnKF improves the model forecasts as compared to the traditional EnKF. Additionally we show that elimination of the strongly non-linear relation between the soil moisture storage and assimilated discharge observations from the model update becomes beneficial for an improved operational forecasting, which is evaluated using several validation measures. In the current study we employed the HBV-96 model built within a recently developed open source modelling environment OpenStreams (2013). The advantage of using OpenStreams (2013) is that it enables direct communication with OpenDA (2013), an open source data assimilation toolbox. OpenDA provides a number of algorithms for model calibration

  2. Mathematical Model of Asynchronous Machine in MATLAB Simulink

    Directory of Open Access Journals (Sweden)

    A A Ansari

    2010-05-01

    Full Text Available Different mathematical models have been used over the years to examine different problems associated with induction motors. These range from the simple equivalent circuit models to more complex d,q models and abc models which allow the inclusion of various forms of impedance and/or voltage unbalance. Recently, hybrid models have been developed which allow the inclusion of supply side unbalance but with the computational economy of the d,q models. This paper presents these models with typical results and provides guidelines for their use The dynamic simulation of small power induction motor based on mathematical modelling is proposed in this paper. The dynamic simulation is one of the key steps in the validation of the design process of the motor drive systems and it is needed for eliminating inadvertent design mistakes and the resulting error in the prototype construction and testing. This paper demonstrates the simulation of steady-state performance of induction motor by MATLAB Program Threephase induction motor is modeled and simulated with SIMULINK model.

  3. MATHEMATICAL MODELING OF AC ELECTRIC POINT MOTOR

    Directory of Open Access Journals (Sweden)

    S. YU. Buryak

    2014-03-01

    Full Text Available Purpose. In order to ensure reliability, security, and the most important the continuity of the transportation process, it is necessary to develop, implement, and then improve the automated methods of diagnostic mechanisms, devices and rail transport systems. Only systems that operate in real time mode and transmit data on the instantaneous state of the control objects can timely detect any faults and thus provide additional time for their correction by railway employees. Turnouts are one of the most important and responsible components, and therefore require the development and implementation of such diagnostics system.Methodology. Achieving the goal of monitoring and control of railway automation objects in real time is possible only with the use of an automated process of the objects state diagnosing. For this we need to know the diagnostic features of a control object, which determine its state at any given time. The most rational way of remote diagnostics is the shape and current spectrum analysis that flows in the power circuits of railway automatics. Turnouts include electric motors, which are powered by electric circuits, and the shape of the current curve depends on both the condition of the electric motor, and the conditions of the turnout maintenance. Findings. For the research and analysis of AC electric point motor it was developed its mathematical model. The calculation of parameters and interdependencies between the main factors affecting the operation of the asynchronous machine was conducted. The results of the model operation in the form of time dependences of the waveform curves of current on the load on engine shaft were obtained. Originality. During simulation the model of AC electric point motor, which satisfies the conditions of adequacy was built. Practical value. On the basis of the constructed model we can study the AC motor in various mode of operation, record and analyze current curve, as a response to various changes

  4. Normalized and asynchronous mirror alignment for Cherenkov telescopes

    Science.gov (United States)

    Ahnen, M. L.; Baack, D.; Balbo, M.; Bergmann, M.; Biland, A.; Blank, M.; Bretz, T.; Bruegge, K. A.; Buss, J.; Domke, M.; Dorner, D.; Einecke, S.; Hempfling, C.; Hildebrand, D.; Hughes, G.; Lustermann, W.; Mannheim, K.; Mueller, S. A.; Neise, D.; Neronov, A.; Noethe, M.; Overkemping, A.-K.; Paravac, A.; Pauss, F.; Rhode, W.; Shukla, A.; Temme, F.; Thaele, J.; Toscano, S.; Vogler, P.; Walter, R.; Wilbert, A.

    2016-09-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) need imaging optics with large apertures and high image intensities to map the faint Cherenkov light emitted from cosmic ray air showers onto their image sensors. Segmented reflectors fulfill these needs, and as they are composed from mass production mirror facets they are inexpensive and lightweight. However, as the overall image is a superposition of the individual facet images, alignment is a challenge. Here we present a computer vision based star tracking alignment method, which also works for limited or changing star light visibility. Our method normalizes the mirror facet reflection intensities to become independent of the reference star's intensity or the cloud coverage. Using two CCD cameras, our method records the mirror facet orientations asynchronously of the telescope drive system, and thus makes the method easy to integrate into existing telescopes. It can be combined with remote facet actuation, but does not require one to work. Furthermore, it can reconstruct all individual mirror facet point spread functions without moving any mirror. We present alignment results on the 4 m First Geiger-mode Avalanche Cherenkov Telescope (FACT).

  5. Sparse asynchronous cortical generators can produce measurable scalp EEG signals.

    Science.gov (United States)

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

    2016-09-01

    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. PMID:27262240

  6. Inferring gene regulatory networks from asynchronous microarray data with AIRnet

    Directory of Open Access Journals (Sweden)

    Lai Chun Wan J

    2010-11-01

    Full Text Available Abstract Background Modern approaches to treating genetic disorders, cancers and even epidemics rely on a detailed understanding of the underlying gene signaling network. Previous work has used time series microarray data to infer gene signaling networks given a large number of accurate time series samples. Microarray data available for many biological experiments is limited to a small number of arrays with little or no time series guarantees. When several samples are averaged to examine differences in mean value between a diseased and normal state, information from individual samples that could indicate a gene relationship can be lost. Results Asynchronous Inference of Regulatory Networks (AIRnet provides gene signaling network inference using more practical assumptions about the microarray data. By learning correlation patterns for the changes in microarray values from all pairs of samples, accurate network reconstructions can be performed with data that is normally available in microarray experiments. Conclusions By focussing on the changes between microarray samples, instead of absolute values, increased information can be gleaned from expression data.

  7. Commande vectorielle d'un moteur asynchrone sans capteur

    Science.gov (United States)

    Ourth, T.

    1993-06-01

    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.

  8. Asynchronous Dual-Rail Transition Logic for Enhanced DPA Resistance

    Directory of Open Access Journals (Sweden)

    Rajath Srivathsav N

    2015-02-01

    Full Text Available An Asynchronous Dual–Rail Transition Logic (ADTL is proposed in this paper. The new logic style can be used in the encryption circuit of cryptography to counter the differential power analysis (DPA attacks. The resistance to the DPA attacks is achieved by randomizing the power dissipated in the circuit through Manchester input signal coding and unpredictable initial state of the toggle flip-flops (TFF. The proposed logic uses two wires to transmit the signal, in the form of a single transition on either one of the two wires to indicate the input logic value. T-FFs are employed to randomize the power dissipated by the circuit. The randomizing is made possible by making the initial states of the flip-flops un-deterministic. Furthermore, the clock is completely eliminated in the conceived design, thus realizing increased power randomization and resistance to the DPA attacks. The design is demonstrated through the systematic simulations on a typical encryption circuit. The validation of the ADTL is made through extensive comparisons with the existing Dual-rail Transition Logic (DTL for power, delay and the DPA resistance. Industry standard EDA tools with 90nm technology libraries provided by the UMC foundry have been employed in the designs.

  9. Progresses in the Analysis of Stochastic 2D Cellular Automata: a Study of Asynchronous 2D Minority

    CERN Document Server

    Regnault, Damien; Thierry, Éric

    2007-01-01

    Cellular automata are often used to model systems in physics, social sciences, biology that are inherently asynchronous. Over the past 20 years, studies have demonstrated that the behavior of cellular automata drastically changed under asynchronous updates. Still, the few mathematical analyses of asynchronism focus on one-dimensional probabilistic cellular automata, either on single examples or on specific classes. As for other classic dynamical systems in physics, extending known methods from one- to two-dimensional systems is a long lasting challenging problem. In this paper, we address the problem of analysing an apparently simple 2D asynchronous cellular automaton: 2D Minority where each cell, when fired, updates to the minority state of its neighborhood. Our experiments reveal that in spite of its simplicity, the minority rule exhibits a quite complex response to asynchronism. By focusing on the fully asynchronous regime, we are however able to describe completely the asymptotic behavior of this dynamics...

  10. THE MOTOR

    DEFF Research Database (Denmark)

    Gammelgaard Nielsen, Anders

    2011-01-01

    MOTOR is the first assignment that students at Unit 1a of the School of Architecture are introduced to. The purpose of the assignment is to shake up the students and their preconceptions of what architec- ture is. This is done by introducing them to a working method that al- lows them to develop...... architecture that resides beyond their own imag- inative capabilities. In other words the core aim of the assignment is to equip students with an understand- ing that architecture can be devel- oped through a predetermined ge- neric process and that through this process opportunities exist to devel- op...... something original and genuine that decisively challenges the limits of the field of architecture. This un- derstanding is important if students are to avoid mimicking an existing world of imagery in architecture or fragments of it. The point of departure for the MO- TOR assignment is that a car engine...

  11. Motor Neuron Diseases

    Science.gov (United States)

    ... Awards Enhancing Diversity Find People About NINDS Motor Neuron Diseases Fact Sheet See a list of all ... can I get more information? What are motor neuron diseases? The motor neuron diseases (MNDs) are a ...

  12. Towards Cloud-based Asynchronous Elasticity for Iterative HPC Applications

    Science.gov (United States)

    da Rosa Righi, Rodrigo; Facco Rodrigues, Vinicius; André da Costa, Cristiano; Kreutz, Diego; Heiss, Hans-Ulrich

    2015-10-01

    Elasticity is one of the key features of cloud computing. It allows applications to dynamically scale computing and storage resources, avoiding over- and under-provisioning. In high performance computing (HPC), initiatives are normally modeled to handle bag-of-tasks or key-value applications through a load balancer and a loosely-coupled set of virtual machine (VM) instances. In the joint-field of Message Passing Interface (MPI) and tightly-coupled HPC applications, we observe the need of rewriting source codes, previous knowledge of the application and/or stop-reconfigure-and-go approaches to address cloud elasticity. Besides, there are problems related to how profit this new feature in the HPC scope, since in MPI 2.0 applications the programmers need to handle communicators by themselves, and a sudden consolidation of a VM, together with a process, can compromise the entire execution. To address these issues, we propose a PaaS-based elasticity model, named AutoElastic. It acts as a middleware that allows iterative HPC applications to take advantage of dynamic resource provisioning of cloud infrastructures without any major modification. AutoElastic provides a new concept denoted here as asynchronous elasticity, i.e., it provides a framework to allow applications to either increase or decrease their computing resources without blocking the current execution. The feasibility of AutoElastic is demonstrated through a prototype that runs a CPU-bound numerical integration application on top of the OpenNebula middleware. The results showed the saving of about 3 min at each scaling out operations, emphasizing the contribution of the new concept on contexts where seconds are precious.

  13. iHadoop: Asynchronous Iterations Support for MapReduce

    KAUST Repository

    Elnikety, Eslam

    2011-08-01

    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

  14. Research on inverter test system of synchronous motor using modbus communication

    Science.gov (United States)

    Cao, Wenlun; Chen, Bei; He, Yuyao

    2013-03-01

    In this paper, the hardware architecture of the servo system composed by self-made inverter and permanent magnet synchronous motor is introduced as well as its measurement and control system software features. Basing on the Modbus-RTU protocols which contain the CRC data verification between IPC and the inverter, we have built a communication system. The measurement and control software of servo system are realized, which consists of self-made inverter and PMSM. Compared with the servo system which consists of Schindler's ATV31 inverter and SIMO's asynchronous motor, the results are given. The experiment parameters include harmonic content which is contained by phase current and voltage, and also the motor speed. The results show that the measurement and control system are stable and reliable. Both the harmonic content of the Inverter output and the motor speed meet the requirements.

  15. The Block Diagram for the Synchronous Motors used for the Compensation of the Reactive Power

    Directory of Open Access Journals (Sweden)

    Iulius Petrica

    2013-05-01

    Full Text Available The optimal control system for the compensation of the reactive power in an energetic consumer assembly is presented, containing one or more synchronous motors, connected to the same power bars in parallel, including asynchronous motors and static converters. The compensation of the reactive power absorbed from the system by the consumers is possible, using a optimal control system that controls the reactive power provided on the bars by the synchronous motors on condition that the power losses in the created whole are zero. A limited functional block diagram of the synchronous motor, which is the controlled object completed with the control circuits of the exciting tension and current is obtained having as set value the sum of all reactive currents of the consumers from the power assembly. The optimization is obtained using the module criterion of Kessler.

  16. Exploration of a Few Different AC Motor Autorotation%几种不同交流电机“自转”的探究

    Institute of Scientific and Technical Information of China (English)

    秦常贵

    2011-01-01

    Applying magnetic field theory and higher mathematics and human-computer interaction software, the reasons why three-phase asynchronous motor and single-phase asynchronous motor can "autorotate" in the pulsating magnetic field, but AC servo motor, operating principle of which is similar to that of single-phase asynchronous motor, cannot be studied in detail. Besides, the author put forward the statement "elimination of AC servo motor autorotation " is defective.%应用磁场理论、高等数学和人机交互软件,对三相异步电动机和单相异步电动机为什么会产生“自转”,而与单相异步电动机工作原理非常相似的二相交流伺服电动机却为什么不会产生“自转”的原因进行了详尽的研究.

  17. High efficiency motors; Motores de alta eficiencia

    Energy Technology Data Exchange (ETDEWEB)

    Uranga Favela, Ivan Jaime [Energia Controlada de Mexico, S. A. de C. V., Mexico, D. F. (Mexico)

    1992-12-31

    This paper is a technical-financial study of the high efficiency and super-premium motors. As it is widely known, more than 60% of the electrical energy generated in the country is used for the operation of motors, in industry as well as in commerce. Therefore the importance that the motors have in the efficient energy use. [Espanol] El presente trabajo es un estudio tecnico-financiero de los motores de alta eficiencia y los motores super premium. Como es ampliamente conocido, mas del 60% de la energia electrica generada en el pais, es utilizada para accionar motores, dentro de la industria y el comercio. De alli la importancia que los motores tienen en el uso eficiente de la energia.

  18. Modelling and Simulation of Asynchronous Real-Time Systems using Timed Rebeca

    CERN Document Server

    Aceto, Luca; Ingolfsdottir, Anna; Reynisson, Arni Hermann; Sigurdarson, Steinar Hugi; Sirjani, Marjan; 10.4204/EPTCS.58.1

    2011-01-01

    In this paper we propose an extension of the Rebeca language that can be used to model distributed and asynchronous systems with timing constraints. We provide the formal semantics of the language using Structural Operational Semantics, and show its expressiveness by means of examples. We developed a tool for automated translation from timed Rebeca to the Erlang language, which provides a first implementation of timed Rebeca. We can use the tool to set the parameters of timed Rebeca models, which represent the environment and component variables, and use McErlang to run multiple simulations for different settings. Timed Rebeca restricts the modeller to a pure asynchronous actor-based paradigm, where the structure of the model represents the service oriented architecture, while the computational model matches the network infrastructure. Simulation is shown to be an effective analysis support, specially where model checking faces almost immediate state explosion in an asynchronous setting.

  19. EXPERIMENTAL STUDY OF THE ASYNCHRONOUS MULTISPLITTING RELAXATION METHODS FOR THE LINEAR COMPLEMENTARITY PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Zhong-zhi Bai

    2002-01-01

    We study the numerical behaviours of the relaxed asynchronous multisplitting methods for the linear complementarity problems by solving some typical problems from practical applications on a real multiprocessor system. Numerical results show that the parallel multisplitting relaxation methods always perform much better than the corresponding sequential alternatives, and that the asynchronous multisplitting relaxation methods often outperform their corresponding synchronous counterparts. Moreover, the two-sweep relaxed multisplitting methods have better convergence properties than their corresponding one-sweep relaxed ones in the sense that they have larger convergence domains and faster convergence speeds. Hence, the asynchronous multisplitting unsymmetric relaxation iterations should be the methods of choice for solving the large sparse linear complementarity problems in the parallel computing environments.

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

    Directory of Open Access Journals (Sweden)

    Sarah Williams PhD

    2012-09-01

    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.

  1. On the Outage Behavior of Asynchronous OFDM DF and AF Cooperative Networks

    CERN Document Server

    Torbatian, Mehdi

    2009-01-01

    The outage behavior of various relaying protocols over a general one hop asynchronous cooperative network is examined when orthogonal frequency division multiplexing (OFDM) is used to combat synchronization error among the relays. We consider non-orthogonal selection decode-and-forward (NSDF), orthogonal selection decode-and-forward (OSDF), non-orthogonal amplify-and-forward (NAF), and orthogonal amplify-and-forward (OAF) relaying protocols and analyze the diversity multiplexing gain tradeoff (DMT) in all scenarios. The transmitting nodes cooperatively construct an asynchronous OFDM space-time code by re-sending the source messages over a common time interval and a common frequency bandwidth. It is shown that in decode-and-forward (DF) type protocols, the asynchronous network provides a diversity gain greater than or equal to the one of the corresponding synchronous network in the limit of code word length and throughout the range of multiplexing gain. In amplify-and-forward (AF) type protocols, in which the ...

  2. Simulating the operation action of an asynchronized turbogenerator under loss of excitation

    Institute of Scientific and Technical Information of China (English)

    SANGARE Adama Fanhiri; YANG Shunchang; LIU Ren

    2004-01-01

    The control strategy tor asynchronized turbogenerators (ASTGs) was studied by using two-axis equations. Simulation of the process of an asynchronized turbogenerator with faults of d or q axis or d and q axes in the excitation system was carried out with the simulating models including the model of the reverse thyristors in the excitation system established by Saber software. The simulation results show that at the loss of excitation at both windings or one winding of the rotor, the ASTGs can be automatically driven into an asynchronous or single axis excitation operation mode without a power unit tripping, and the characteristics for ASTGs with faults in the excitation system appear in good order.

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

    DEFF Research Database (Denmark)

    Kasapaki, Evangelia

    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......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...

  4. Asynchronous Video Interviewing as a New Technology in Personnel Selection: The Applicant's Point of View.

    Science.gov (United States)

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

    2016-01-01

    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

  5. Gigabit Ethernet signal transmission using asynchronous optical code division multiple access.

    Science.gov (United States)

    Ma, Philip Y; Fok, Mable P; Shastri, Bhavin J; Wu, Ben; Prucnal, Paul R

    2015-12-15

    We propose and experimentally demonstrate a novel architecture for interfacing and transmitting a Gigabit Ethernet (GbE) signal using asynchronous incoherent optical code division multiple access (OCDMA). This is the first such asynchronous incoherent OCDMA system carrying GbE data being demonstrated to be working among multi-users where each user is operating with an independent clock/data rate and is granted random access to the network. Three major components, the GbE interface, the OCDMA transmitter, and the OCDMA receiver are discussed in detail. The performance of the system is studied and characterized through measuring eye diagrams, bit-error rate and packet loss rate in real-time file transfer. Our Letter also addresses the near-far problem and realizes asynchronous transmission and detection of signal.

  6. THE ROLE OF OFFLINE METALANGUAGE TALK IN ASYNCHRONOUS COMPUTER-MEDIATED COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Keiko Kitade

    2008-02-01

    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. FAST: A fully asynchronous and status-tracking pattern for geoprocessing services orchestration

    Science.gov (United States)

    Wu, Huayi; You, Lan; Gui, Zhipeng; Gao, Shuang; Li, Zhenqiang; Yu, Jingmin

    2014-09-01

    Geoprocessing service orchestration (GSO) provides a unified and flexible way to implement cross-application, long-lived, and multi-step geoprocessing service workflows by coordinating geoprocessing services collaboratively. Usually, geoprocessing services and geoprocessing service workflows are data and/or computing intensive. The intensity feature may make the execution process of a workflow time-consuming. Since it initials an execution request without blocking other interactions on the client side, an asynchronous mechanism is especially appropriate for GSO workflows. Many critical problems remain to be solved in existing asynchronous patterns for GSO including difficulties in improving performance, status tracking, and clarifying the workflow structure. These problems are a challenge when orchestrating performance efficiency, making statuses instantly available, and constructing clearly structured GSO workflows. A Fully Asynchronous and Status-Tracking (FAST) pattern that adopts asynchronous interactions throughout the whole communication tier of a workflow is proposed for GSO. The proposed FAST pattern includes a mechanism that actively pushes the latest status to clients instantly and economically. An independent proxy was designed to isolate the status tracking logic from the geoprocessing business logic, which assists the formation of a clear GSO workflow structure. A workflow was implemented in the FAST pattern to simulate the flooding process in the Poyang Lake region. Experimental results show that the proposed FAST pattern can efficiently tackle data/computing intensive geoprocessing tasks. The performance of all collaborative partners was improved due to the asynchronous mechanism throughout communication tier. A status-tracking mechanism helps users retrieve the latest running status of a GSO workflow in an efficient and instant way. The clear structure of the GSO workflow lowers the barriers for geospatial domain experts and model designers to

  8. The Effects of Metacognitive Instruction Embedded within an Asynchronous Learning Network on Scientific Inquiry Skills. Research Report

    Science.gov (United States)

    Zion, Michal; Michalsky, Tova; Mevarech, Zemira R.

    2005-01-01

    The study is aimed at investigating the effects of four learning methods on students' scientific inquiry skills. The four learning methods are: (a) metacognitive-guided inquiry within asynchronous learning networked technology (MINT); (b) an asynchronous learning network (ALN) with no metacognitive guidance; (c) metacognitive-guided inquiry…

  9. Good Quality Discussion Is Necessary but Not Sufficient in Asynchronous Tuition: A Brief Narrative Review of the Literature

    Science.gov (United States)

    Fear, William James; Erikson-Brown, Andrew

    2014-01-01

    Online learning is a growing field of education with a corresponding increase in the use of asynchronous discussion. Asynchronous discussion is a form of interaction that is mediated rather than direct and where there is a time lag in the interactions between discussants. In this paper we conducted a brief narrative review of the literature on…

  10. Enhancing Discussions in the Asynchronous Online Classroom: The Lack of Face-to-Face Interaction Does Not Lessen the Lesson

    Science.gov (United States)

    Comer, Debra R.; Lenaghan, Janet A.

    2013-01-01

    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…

  11. Finite-time quantised feedback asynchronously switched control of sampled-data switched linear systems

    Science.gov (United States)

    Wang, Ronghao; Xing, Jianchun; Li, Juelong; Xiang, Zhengrong

    2016-10-01

    This paper studies the problem of stabilising a sampled-data switched linear system by quantised feedback asynchronously switched controllers. The idea of a quantised feedback asynchronously switched control strategy originates in earlier work reflecting actual system characteristic of switching and quantising, respectively. A quantised scheme is designed depending on switching time using dynamic quantiser. When sampling time, system switching time and controller switching time are all not uniform, the proposed switching controllers guarantee the system to be finite-time stable by a piecewise Lyapunov function and the average dwell-time method. Simulation examples are provided to show the effectiveness of the developed results.

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

    DEFF Research Database (Denmark)

    Bjerregaard, Tobias; Sparsø, Jens

    2005-01-01

    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......) scheduling, which provides latency and bandwidth guarantees in accessing a shared media, e.g. a physical link shared between a number of virtual channels. ALG overcomes the drawbacks of existing scheduling disciplines, in particular the coupling between latency and bandwidth guarantees. A 0.12 &956;m CMOS...

  13. Motor Priming in Neurorehabilitation

    OpenAIRE

    Stoykov, Mary Ellen; Madhavan, Sangeetha

    2015-01-01

    Priming is a type of implicit learning wherein a stimulus prompts a change in behavior. Priming has been long studied in the field of psychology. More recently, rehabilitation researchers have studied motor priming as a possible way to facilitate motor learning. For example, priming of the motor cortex is associated with changes in neuroplasticity that are associated with improvements in motor performance. Of the numerous motor priming paradigms under investigation, only a few ...

  14. 浅谈潜水电动机的型式及设计特点%Types and Design Features of Submersible Motors

    Institute of Scientific and Technical Information of China (English)

    黄家友; 鲍晓华; 荚小健

    2011-01-01

    As a special three phase asynchronous motor, the submersible motor has its unique features. The paper introduces the classification of submersible motors, taking water filled submersible motors as example analyses the feature of structure design and electromagnetic design, and finally discusses the progressive trend of submersible motors and pressing task which submersible motors industry faced.%作为一种特殊型式的三相异步电机,潜水电动机有其独特的特点.本文主要介绍了潜水电动机的分类,以充水式潜水电动机为例分析了潜水电动机的结构和电磁设计特点,探讨了潜水电机的发展趋势和潜水电机行业面临的紧迫任务.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...

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

    OpenAIRE

    Vlad, Serban E.

    2012-01-01

    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.

  17. A Model for Evaluating the Process of Learning in Asynchronous Computer Conferencing.

    Science.gov (United States)

    Schrire, Sarah

    2003-01-01

    Presents a qualitative multiple-case study of three online asynchronous computer conferences that were part of a doctoral program at Nova Southeastern University. Examines the learning process from the points of view of interaction, cognition, and discourse analysis and proposes a model for assessing sociocognitive processes in computer…

  18. An Approach for Asynchronous Awareness Support in Collaborative Non-Linear Storytelling

    NARCIS (Netherlands)

    Schumann, J.; Buttler, T.; Lukosch, S.

    2012-01-01

    Workspace awareness support is mandatory for group support systems. It allows users not only to follow actions of others, but to understand and respond to any changes others make to the workspace. In this paper, we present a novel approach for asynchronous awareness support by offering different fil

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

    DEFF Research Database (Denmark)

    Nielsen, Lars Skovby; Sparsø, Jens

    1996-01-01

    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...

  20. Research Notes ~ Simulating the Computer Science Closed Laboratory in an Asynchronous Learning Network

    Directory of Open Access Journals (Sweden)

    Timothy Margush

    2002-10-01

    Full Text Available The quiz tool that is part of the WebCT package is used to provide an asynchronous simulation of a (synchronous closed laboratory experience to beginner computer science students. The technique suggested in this paper and which may be applied to other disciplines, offers students a guided path through an exploratory, discovery based learning experience.

  1. Effects of Asynchronous Music on Students' Lesson Satisfaction and Motivation at the Situational Level

    Science.gov (United States)

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

    2014-01-01

    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…

  2. Trajectory exploration within asynchronous binary asteroid systems using refined Lagrangian coherent structures

    Science.gov (United States)

    Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan

    2016-09-01

    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.

  3. Selected Issues in Persistent Asynchronous Adaptive Specialization for Generic Functional Array Programming

    NARCIS (Netherlands)

    C. Grelck; H. Wiesinger

    2014-01-01

    Asynchronous adaptive specialization of rank- and shape-generic code for processing immutable (purely functional) multi-dimensional arrays has proven to be an effective technique to reconcile the desire for abstract specifications with the need to achieve reasonably high performance in sequential as

  4. Tagging Thinking Types in Asynchronous Discussion Groups: Effects on Critical Thinking

    Science.gov (United States)

    Schellens, T.; Van Keer, H.; De Wever, B.; Valcke, M.

    2009-01-01

    The present study focuses on the use of thinking types as a possible way to structure university students' discourse in asynchronous discussion groups and consequently promote their learning. More specifically, the aim of the study is to determine how requiring students to label their contributions by means of De Bono's (1991) thinking hats…

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

    KAUST Repository

    Pearce, Roger

    2010-11-01

    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.

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

    NARCIS (Netherlands)

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

    2004-01-01

    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

  7. Participation in Asynchronous Online Discussion Forums Does Improve Student Learning of Gross Anatomy

    Science.gov (United States)

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

    2014-01-01

    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…

  8. Computer Learner Corpora: Analysing Interlanguage Errors in Synchronous and Asynchronous Communication

    Science.gov (United States)

    MacDonald, Penny; Garcia-Carbonell, Amparo; Carot, Sierra, Jose Miguel

    2013-01-01

    This study focuses on the computer-aided analysis of interlanguage errors made by the participants in the telematic simulation IDEELS (Intercultural Dynamics in European Education through on-Line Simulation). The synchronous and asynchronous communication analysed was part of the MiLC Corpus, a multilingual learner corpus of texts written by…

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

    Directory of Open Access Journals (Sweden)

    Serban E. Vlad

    2012-02-01

    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.

  10. A Study of Synchronous versus Asynchronous Collaboration in an Online Business Writing Class

    Science.gov (United States)

    Mabrito, Mark

    2006-01-01

    A case study examined the collaborative experiences of students in an online business writing classroom. The purpose was to examine the same groups of students working on collaborative writing assignments in both a synchronous (real-time) and an asynchronous (non-real-time) discussion forum. This study focused on examining the amount, pattern, and…

  11. Asynchronous Knowledge Sharing and Conversation Interaction Impact on Grade in an Online Business Course

    Science.gov (United States)

    Strang, Kenneth David

    2011-01-01

    Student knowledge sharing and conversation theory interactions were coded from asynchronous discussion forums to measure the effect of learning-oriented utterances on academic performance. The sample was 3 terms of an online business course (in an accredited MBA program) at a U.S.-based university. Correlation, stepwise regression, and multiple…

  12. Asynchronous P300 classification in a reactive brain-computer interface during an outlier detection task

    Science.gov (United States)

    Krumpe, Tanja; Walter, Carina; Rosenstiel, Wolfgang; Spüler, Martin

    2016-08-01

    Objective. In this study, the feasibility of detecting a P300 via an asynchronous classification mode in a reactive EEG-based brain-computer interface (BCI) was evaluated. The P300 is one of the most popular BCI control signals and therefore used in many applications, mostly for active communication purposes (e.g. P300 speller). As the majority of all systems work with a stimulus-locked mode of classification (synchronous), the field of applications is limited. A new approach needs to be applied in a setting in which a stimulus-locked classification cannot be used due to the fact that the presented stimuli cannot be controlled or predicted by the system. Approach. A continuous observation task requiring the detection of outliers was implemented to test such an approach. The study was divided into an offline and an online part. Main results. Both parts of the study revealed that an asynchronous detection of the P300 can successfully be used to detect single events with high specificity. It also revealed that no significant difference in performance was found between the synchronous and the asynchronous approach. Significance. The results encourage the use of an asynchronous classification approach in suitable applications without a potential loss in performance.

  13. The Role of Technology-Based Scaffolding in Problem-Based Online Asynchronous Discussion

    Science.gov (United States)

    Ak, Serife

    2016-01-01

    This study examined the effects of technology-based scaffolds that were composed through the use of the seven-stage, problem-based learning strategy on knowledge construction in a problem-based online asynchronous discussion. In a quasi-experimental setting, 60 students in an undergraduate Instructional Technology and Material Design course were…

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    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...

  15. Designing a Discussion Environment to Enhance Connectivity and Sustainability in Asynchronous Online Discussion

    Science.gov (United States)

    Gao, Fei

    2011-01-01

    Lack of connectivity and sustainability are two common problems in asynchronous online discussions. In this paper, the author proposes that the two problems may have to do with the structure of threaded forums, that is, the design of threaded forums may constrain participants from having well-connected and sustained discussions. A new discussion…

  16. Asynchronous Pipeline Micro—Control—Unit (MCU) Chip Design

    Institute of Scientific and Technical Information of China (English)

    ZHOUQian; XUKe; MINHao

    2003-01-01

    The work of this paper includes a researchon asynch ronous design methodology, and a design and implementation of an asynchronous 8-Bit micro-control-unit (MCU). This paper introduces a new application of New-Instruction-Fetching method to detect new instruc-tion which makes this chip fit for demand changeable sys-tem. The instruction set of this asynchronous MCU is compatible with PIC16C6X (Sicrochip Technology Inc).This paper also introduces a new architecture of pipeline,which increases the average speed of chip operation. The asynchronous low power MCU has been fabricated with CSMC (central semiconductor manufacturing corporation)0.6μm CMOS process in Aug 2001. The chip size is about 1.60mm*2.00mm (without taking account of PAD size).Now the test work has been accomplished and the test-ing result of this chip is also presented. The testing result shows that the asynchronous architecture could fulfill all the expected functions, additionally with higher processs peed and lower power consumption than its synchronous counterpart under the same supply voltage.

  17. Cooperative Learning in Graduate Student Projects: Comparing Synchronous versus Asynchronous Collaboration

    Science.gov (United States)

    Strang, Kenneth

    2013-01-01

    Cooperative learning was applied in a graduate project management course to compare the effectiveness of asynchronous versus synchronous online team meetings. An experiment was constructed to allocate students to project teams while ensuring there was a balance of requisite skills, namely systems analysis and design along with HTML/Javascript…

  18. Factor Validity of the Motivated Strategies for Learning Questionnaire (MSLQ) in Asynchronous Online Learning Environments (AOLE)

    Science.gov (United States)

    Cho, Moon-Heum; Summers, Jessica

    2012-01-01

    The purpose of this study was to investigate the factor validity of the Motivated Strategies for Learning Questionnaire (MSLQ) in asynchronous online learning environments. In order to check the factor validity, confirmatory factor analysis (CFA) was conducted with 193 cases. Using CFA, it was found that the original measurement model fit for…

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

    Science.gov (United States)

    Perveen, Ayesha

    2016-01-01

    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…

  20. Flipping the Online Classroom with Web 2.0: The Asynchronous Workshop

    Science.gov (United States)

    Cummings, Lance

    2016-01-01

    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…

  1. "Intentional Repetition" and Learning Style: Increasing Efficient and Cohesive Interaction in Asynchronous Online Discussions

    Science.gov (United States)

    Topcu, Abdullah

    2008-01-01

    This study verified the efficacy of the intentional repetition technique in improving interaction in asynchronous online discussions by taking into account the learning styles of the participants. A conceptual framework served for the development of the technique, which conceptualises efficient and cohesive interaction on a continuum of process…

  2. Evaluation of a Computer-Based, Asynchronous Activity on Student Learning of Leadership Concepts.

    Science.gov (United States)

    Boyd, Barry L.; Murphrey, Theresa Pesl

    2002-01-01

    Students taught leadership and ethics using asynchronous computer simulation (n=83) were compared with 113 taught conventionally. The treatment group performed better on questions written at the knowledge, comprehension, and analysis levels of Bloom's Taxonomy, regardless of learning mode preferences. (Contains 26 references.) (SK)

  3. Pedagogical Dimensions of Effective Online Asynchronous Teacher Communication in Higher Education

    NARCIS (Netherlands)

    A. Smits; J. Voogt

    2015-01-01

    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 ack

  4. A model of asynchronous left ventricular relaxation predicting the bi-exponential pressure decay

    NARCIS (Netherlands)

    R.W. Brower (Ronald); S. Meij (Simon); P.W.J.C. Serruys (Patrick)

    1983-01-01

    textabstractA new model for the pressure relaxation of the left ventricle is proposed. The model presumes that the myocardium relaxes asynchronously, but that when regions begin to relax, after a delay, the local wall stress decays as a mono-exponential process. This formulation results in an appare

  5. Credit Hours with No Set Time: A Study of Credit Policies in Asynchronous Online Education

    Science.gov (United States)

    Prasuhn, Frederick Carl

    2014-01-01

    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…

  6. Comparing Asynchronous Online Discussions and Face-to-Face Discussions in a Classroom Setting

    Science.gov (United States)

    Wang, Qiyun; Woo, Huay Lit

    2007-01-01

    The purpose of this study is to investigate the perceived differences between asynchronous online discussions and face-to-face discussions in a classroom setting. The students' reflections were analysed by following a qualitative research approach. The results showed that atmosphere, response, efficiency, interactivity and communication were the…

  7. VOLTAGE REGULATORS AND FREQUENCY OF CURRENT OF ASYNCHRONOUS GENERATORS OF WIND POWER INSTALLATIONS

    Directory of Open Access Journals (Sweden)

    Grigorash O. V.

    2013-10-01

    Full Text Available In the article we have considered the technical solutions of voltage regulators and the frequency of current of the asynchronous generators of the wind power installations executed with the help of the direct frequency transformers. The comparative analysis of them has been carried out as well

  8. An Examination of Computer Engineering Students' Perceptions about Asynchronous Discussion Forums

    Science.gov (United States)

    Ozyurt, Ozcan; Ozyurt, Hacer

    2013-01-01

    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…

  9. Facing Off: Comparing an In-Person Library Orientation Lecture with an Asynchronous Online Library Orientation

    Science.gov (United States)

    Gall, Dan

    2014-01-01

    A study to compare the effectiveness of an in-person library orientation with an online asynchronous orientation was conducted with three sections of Social Work Research Methods, a required course in the University of Iowa's Master of Social Work program. Two sections of the course received an online orientation involving short videos, text…

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...

  11. Using the Community of Inquiry Model to Investigate Students' Knowledge Construction in Asynchronous Online Discussions

    Science.gov (United States)

    Liu, Chien-Jen; Yang, Shu Ching

    2014-01-01

    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…

  12. Electric motor handbook

    CERN Document Server

    Chalmers, B J

    2013-01-01

    Electric Motor Handbook aims to give practical knowledge in a wide range of capacities such as plant design, equipment specification, commissioning, operation and maintenance. The book covers topics such as the modeling of steady-state motor performance; polyphase induction, synchronous, and a.c. commutator motors; ambient conditions, enclosures, cooling and loss dissipation; and electrical supply systems and motor drives. Also covered are topics such as variable-speed drives and motor control; materials and motor components; insulation types, systems, and techniques; and the installation, sit

  13. Directed flux motor

    Science.gov (United States)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2011-01-01

    A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.

  14. Handbook on linear motor application

    International Nuclear Information System (INIS)

    This book guides the application for Linear motor. It lists classification and speciality of Linear Motor, terms of linear-induction motor, principle of the Motor, types on one-side linear-induction motor, bilateral linear-induction motor, linear-DC Motor on basic of the motor, linear-DC Motor for moving-coil type, linear-DC motor for permanent-magnet moving type, linear-DC motor for electricity non-utility type, linear-pulse motor for variable motor, linear-pulse motor for permanent magneto type, linear-vibration actuator, linear-vibration actuator for moving-coil type, linear synchronous motor, linear electromagnetic motor, linear electromagnetic solenoid, technical organization and magnetic levitation and linear motor and sensor.

  15. 笼型异步磁力耦合器机械特性与试验%Mechanical properties and testing for squirrel cage asynchronous magnetic coupler

    Institute of Scientific and Technical Information of China (English)

    葛研军; 袁直; 贾峰; 杨均悦; 周凯凯

    2016-01-01

    为有效解决目前机械传动系统中选用电机时功率裕度过大而普遍存在的能源利用效率较低问题,提出一种基于三相异步电机鼠笼转子的异步磁力耦合器(squirrel cage asynchronous magnetic coupler,SCAMC).结合SCAMC具体结构特点,采用标量磁位法及二维场边界条件,建立气隙磁场数理模型;在气隙磁通密度中引入时间变量,推导出感生电流随时间变化的表达式;基于电流叠加性,将笼条电流折算到转子表面,并沿圆周方向对感生电流所形成的洛伦兹力进行积分,建立了SCAMC的电磁转矩模型.基于上述理论及技术基础,设计并制造出一台37 kW SCAMC样机,并对其机械特性进行理论计算、仿真验证及试验测试.结果表明:转差率相同时,所得的仿真及试验数据与理论计算值相比,误差不超过5%;SCAMC与同容量的三相异步电机相比,线性工作区更宽,过载能力更强,但其机械特性偏软,可有效缓解负载对电机的冲击.该研究可为磁力耦合器在大惯量、难启动及经常性过载机械设备中的应用提供参考.%In order to effectively solve the problem of the motor's power margin too adequate to ensure the stable operation of the equipment which widely exists in the current mechanical transmission system, a kind of squirrel cage asynchronous magnetic coupler (SCAMC) is proposed based on the principle of three-phase asynchronous motor. The SCAMC has the advantages of the simplicity of mechanical structure, high reliability in successive operation, simple maintenance, weak skin effect of the squirrel cage rotor and adjustable slip ratio and so on. According to the specific characteristics of the SCAMC structure, the mathematical model of air gap magnetic flux density is established by using the scalar magnetic potential method and two-dimensional field boundary conditions. The air gap magnetic flux density generated by the permanent magnet in SCAMC can be decomposed into

  16. Chronic motor tic disorder

    Science.gov (United States)

    Chronic vocal tic disorder; Tic - chronic motor tic disorder ... Chronic motor tic disorder is more common than Tourette syndrome . Chronic tics may be forms of Tourette syndrome. Tics usually start ...

  17. Fine motor control

    Science.gov (United States)

    ... figure out the child's developmental age. Children develop fine motor skills over time, by practicing and being taught. To have fine motor control, children need: Awareness and planning Coordination ...

  18. Study on Asynchronous MES Teaching Approach for Discipline of College Japanese in Characteristic Campus of Agriculture-related Universities

    Institute of Scientific and Technical Information of China (English)

    Ming; XU

    2015-01-01

    This paper made scientific analysis on asynchronous MES for discipline of College Japanese in characteristic campus of agriculturerelated universities. It made modular design for discipline of College Japanese in emotional concept,language skill,language knowledge,learning strategy,and cultural quality combining students’ demands and education and teaching rules. Relying on Internet and Mobile Internet aided teaching platform,it came up with " Integration- Separation- Integration" asynchronous teaching approach. The practice indicates that teaching effect of such approach is remarkable. However,asynchronous MES for discipline of College Japanese raises higher requirement for interaction between teachers and students and voluntary effort of teachers.

  19. Edinburgh Motor Assessment (EMAS)

    OpenAIRE

    Bak, Thomas

    2013-01-01

    Edinburgh Motor Assessment (EMAS) is a brief motor screening test, specifically designed for assessment of patients with dementia, aphasia and other cognitive disorders. It focuses, therefore, on those motor symptoms, which are known to occur in association with these diseases, such as extrapyramidal, amyotrophic, and cerebellar features as well as complex cognitive‐motor phenomena such as apraxia. EMAS has been developed by a team of neurologists and psychiatrists at the ...

  20. CONSOLIDATION OF MOTOR MEMORY

    OpenAIRE

    Krakauer, John W.; Shadmehr, Reza

    2005-01-01

    A question of great recent interest is whether motor memory consolidates in a manner analogous to declarative memories, with the formation of a memory that progresses over time from a fragile state, susceptible to interference by a lesion or a conflicting motor task, to a stabilized state, resistant to such interference. Here, we first review studies that examine the anatomical basis for motor consolidation: evidence implicates cerebellar circuitry for two types of associative motor learning,...

  1. Motor Neurons that Multitask

    OpenAIRE

    Goulding, Martyn

    2012-01-01

    Animals use a form of sensory feedback termed proprioception to monitor their body position and modify the motor programs that control movement. In this issue of Neuron, Wen et al. (2012) provide evidence that a subset of motor neurons function as proprioceptors in C. elegans, where B-type motor neurons sense body curvature to control the bending movements that drive forward locomotion.

  2. Quantum motor and future

    CERN Document Server

    Fateev, Evgeny G

    2013-01-01

    In a popular language, the possibilities of the Casimir expulsion effect are presented, which can be the basis of quantum motors. Such motors can be in the form of a special multilayer thin film with periodic and complex nanosized structures. Quantum motors of the type of the Casimir platforms can be the base of transportation, energy and many other systems in the future.

  3. Solid propellant motor

    Science.gov (United States)

    Shafer, J. I.; Marsh, H. E., Jr. (Inventor)

    1978-01-01

    A case bonded end burning solid propellant rocket motor is described. A propellant with sufficiently low modulus to avoid chamber buckling on cooling from cure and sufficiently high elongation to sustain the stresses induced without cracking is used. The propellant is zone cured within the motor case at high pressures equal to or approaching the pressure at which the motor will operate during combustion. A solid propellant motor with a burning time long enough that its spacecraft would be limited to a maximum acceleration of less than 1 g is provided by one version of the case bonded end burning solid propellant motor of the invention.

  4. Motor/generator

    Science.gov (United States)

    Hickam, Christopher Dale

    2008-05-13

    A motor/generator is provided for connecting between a transmission input shaft and an output shaft of a prime mover. The motor/generator may include a motor/generator housing, a stator mounted to the motor/generator housing, a rotor mounted at least partially within the motor/generator housing and rotatable about a rotor rotation axis, and a transmission-shaft coupler drivingly coupled to the rotor. The transmission-shaft coupler may include a clamp, which may include a base attached to the rotor and a plurality of adjustable jaws.

  5. THE INFLUENCE OF POWER STATOR WINDINGS OF THE ASYNCHRONOUS TRACTION MOTORS FOR DYNAMIC WORKLOAD ELEMENTS OF TRACTION DRIVE LOCOMOTIVE

    Directory of Open Access Journals (Sweden)

    O. M. Bondarev

    2010-01-01

    Full Text Available The results of studies on determination of loading level of tractive drive elements in some operating conditions, when the values of frequencies of the change of feeding currents of stator windings are to be obtained in both subcritical and ultracritical zones for two types of the tractive gear are presented in the paper.

  6. Synchronous and asynchronous multiplexer circuits for medical imaging realized in CMOS 0.18um technology

    Science.gov (United States)

    Długosz, R.; Iniewski, K.

    2007-05-01

    Multiplexers are one of the most important elements in readout front-end ASICs for multi-element detectors in medical imaging. The purpose of these ASICs is to detect signals appearing randomly in many channels and to collect the detected data in an ordered fashion (de-randomization) in order to send it to an external ADC. ASIC output stage functionality can be divided into two: pulse detection and multiplexing. The pulse detection block is responsible for detecting maximum values of signals arriving from the shaper, sending a flag signal indicating that the peak signal has been detected and storing the pulse in an analog memory until read by ADC. The multiplexer in turn is responsible for searching for active flags, controlling the channel that has detected the peak signal and performing reset functions after readout. There are several types of multiplexers proposed in this paper, which can be divided into several classes: synchronous, synchronized and asynchronous. Synchronous circuits require availability of the multiphase clock generator, which increases the power dissipation, but simultaneously provide very convenient mechanism that enables unambiguous choice of the active channel. This characteristics leads to 100% effectiveness in data processing and no data loss. Asynchronous multiplexers do not require clock generators and because of that have simpler structure, are faster and more power efficient, especially when data samples occur seldom at the ASIC's inputs. The main problem of the asynchronous solution is when data on two or more inputs occur almost at the same time, shorter than the multiplexer's reaction time. In this situation some data can be lost. In many applications loss of the order of 1% of the data is acceptable, which makes use of asynchronous multiplexers possible. For applications when the lower loss is desirable a new hierarchy mechanism has been introduced. One of proposed solutions is a synchronized binary tree structure, that uses many

  7. A control strategy for induction motors fed from single phase supply

    DEFF Research Database (Denmark)

    Søndergård, Lars Møller

    1993-01-01

    It is often required that a three-phased asynchronous motor can run at variable speed, which makes it necessary to use a three-phase inverter driven from a DC-source. Today, most inverters are driven from the network using a simple diode bridge and an electrolytic capacitor. The problem with the ......It is often required that a three-phased asynchronous motor can run at variable speed, which makes it necessary to use a three-phase inverter driven from a DC-source. Today, most inverters are driven from the network using a simple diode bridge and an electrolytic capacitor. The problem...... with the simple diode bridge and the electrolytic capacitor is that current is only drawn for short periods, which gives rise to harmonic currents in the network. For small drive systems (motor+inverter), i.e. less than 1.5 kW, a single phase network outlet is often used. The author describes a method whereby...

  8. Motor degradation prediction methods

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-12-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

  9. Piezoelectric Motors, an Overview

    Directory of Open Access Journals (Sweden)

    Karl Spanner

    2016-02-01

    Full Text Available Piezoelectric motors are used in many industrial and commercial applications. Various piezoelectric motors are available in the market. All of the piezoelectric motors use the inverse piezoelectric effect, where microscopically small oscillatory motions are converted into continuous or stepping rotary or linear motions. Methods of obtaining long moving distance have various drive and functional principles that make these motors categorized into three groups: resonance-drive (piezoelectric ultrasonic motors, inertia-drive, and piezo-walk-drive. In this review, a comprehensive summary of piezoelectric motors, with their classification from initial idea to recent progress, is presented. This review also includes some of the industrial and commercial applications of piezoelectric motors that are presently available in the market as actuators.

  10. Neuroplasticity & Motor Learning

    DEFF Research Database (Denmark)

    Jensen, Jesper Lundbye

    is a measure of our ability to form and store a motor memory of the task. However, the initial memory of the task is labile and may be subject to interference. During and following motor learning plastic changes occur within the central nervous system. On one hand these changes are driven by motor practice......, on the other hand the changes underlie the formation of motor memory and the retention of improved motor performance. During motor learning changes may occur at many different levels within the central nervous system dependent on the type of task and training. Here, we demonstrate different studies from our......Practice of a new motor task is usually associated with an improvement in performance. Indeed, if we stop practicing and return the next day to the same task, we find that our performance has been maintained and may even be better than it was at the start of the first day. This improvement...

  11. Efficiency increase of a high-efficient IEC 3 kW permanent-magnet-motor - Implementation in a pump system; Effizienzsteigerung eines hocheffizienten IEC 3 kW Permanent-Magnet-Motors inklusiv energetische Messung als Pumpenanwendung - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H.-P.; Evequoz, B. [University of Applied Sciences, Western Switzerland, Delemont (Switzerland); Salathe, D. [Fachhochschule Luzern, Technik und Architektur, Horw (Switzerland)

    2009-11-15

    The IEC norm 60034-30 defines new international standards for efficiency of electric motors. IE1 is standard efficiency, IE2 is high efficiency, and IE3/IE4 are the premium class. Circle Motor AG assumes that the premium class efficiency factor for motors with power less than 22 kW is easier to achieve with Permanent-Magnet-Motors enhanced by electric inverters than with asynchronous motors. The goal of this work is to achieve an overall 'efficiency factor' of 90% through a high-efficiency 3 kW-rated input Permanent-Magnet-Motor enhanced with an electric inverter, and then to perform measurements on the pump drive. The 'efficiency factor' measurement results showed worse performance than expected for both the inverter and the motor. One reason is due to high iron losses in the motor that are produced by high frequency currents of inverter. Another reason is the relatively high ohmic resistance of the copper motor winding caused by the chosen coil production method. By filtering high frequency currents at the rated power, the motor efficiency factor reaches up to 89.5%, which complies with premium class IE3. In generator mode the efficiency reaches 92.8%. We note that the positive result of this work is that the inverter can be produced with very low standby power losses - in our current work with 160 mW. It is necessary to admit that every detail can be responsible for success or failure during research and development activities of premium class motors. The optimization activities mainly belong to the area of additional losses of electric machines. In this report we have encountered all research results on the theme of Additional Losses that resulted from the current research work. The concept of drive control from the previous research project has shown itself as efficiency aware. The total efficiency factor of 90% can be reached by a system coupling a drive controller with a synchronous motor and the 'know how' from this work. The

  12. 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;

    2011-01-01

    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....

  13. N-CANDA data integration: anatomy of an asynchronous infrastructure for multi-site, multi-instrument longitudinal data capture

    OpenAIRE

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

    2013-01-01

    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 ...

  14. PERFORMANCE ANALYSIS OF GATED RING OSCILLATOR DESIGNED FOR AUDIO FREQUENCY RANGE ASYNCHRONOUS ADC

    Directory of Open Access Journals (Sweden)

    Anita Arvind Deshmukh

    2014-12-01

    Full Text Available This paper presents performance analysis of Gated Ring Oscillator (GRO. Proposed GRO is designed to employ in implementation of Time to Digital Converter (TDC block of Asynchronous ADC. For an audio frequency range ADC, minimum GRO stages are designed using asynchronous technique. So leads to reduced area and power. Compared to conventional Ring Oscillator (RO, we avoided to employ the gated clock; to evade clock design related problems like jitter, additional area and power. Instead we preferred gating of ring oscillator itself. Consequently during sleep mode, GRO disables automatically which saves the dynamic power. Furthermore it also provides first order noise shaping of the quantization and mismatch noise. Proposed GRO is implemented with 0.18µm CMOS Digital Technology in Cadence Virtuso environment. GRO performance analysis shows oscillation frequency as 286 KHz with 327ps jitter and average power consumption of 1.08µW.

  15. A 0.6-V 8.3-ENOB asynchronous SAR ADC for biomedical applications

    Science.gov (United States)

    Yan, Song; Zhongming, Xue; Pengcheng, Yan; Jueying, Zhang; Li, Geng

    2014-08-01

    A microwatt asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) is presented. The supply voltage of the SAR ADC is decreased to 0.6 V to fit the low voltage and low power requirements of biomedical systems. The tail capacitor of the DAC array is reused for least significant bit conversion to decrease the total DAC capacitance thus reducing the power. Asynchronous control logic avoids the high frequency clock generator and further reduces the power consumption. The prototype ADC is fabricated with a standard 0.18 μm CMOS technology. Experimental results show that it achieves an ENOB of 8.3 bit at a 300-kS/s sampling rate. Very low power consumption of 3.04 μW is achieved, resulting in a figure of merit of 32 fJ/conv.-step.

  16. Event-Based Tone Mapping for Asynchronous Time-Based Image Sensor.

    Science.gov (United States)

    Simon Chane, Camille; Ieng, Sio-Hoi; Posch, Christoph; Benosman, Ryad B

    2016-01-01

    The asynchronous time-based neuromorphic image sensor ATIS is an array of autonomously operating pixels able to encode luminance information with an exceptionally high dynamic range (>143 dB). This paper introduces an event-based methodology to display data from this type of event-based imagers, taking into account the large dynamic range and high temporal accuracy that go beyond available mainstream display technologies. We introduce an event-based tone mapping methodology for asynchronously acquired time encoded gray-level data. A global and a local tone mapping operator are proposed. Both are designed to operate on a stream of incoming events rather than on time frame windows. Experimental results on real outdoor scenes are presented to evaluate the performance of the tone mapping operators in terms of quality, temporal stability, adaptation capability, and computational time. PMID:27642275

  17. Performance Analysis of Gated Ring Oscillator Designed for Audio Frequency Range Asynchronous ADC

    Directory of Open Access Journals (Sweden)

    Anita Arvind Deshmukh

    2014-12-01

    Full Text Available This paper presents performance analysis of Gated R ing Oscillator (GRO. Proposed GRO is designed to employ in implementation of Time to Digital Convert er (TDC block of Asynchronous ADC. For an audio frequency range ADC, minimum GRO stages are designe d using asynchronous technique. So leads to reduced area and power. Compared to conventional Ri ng Oscillator (RO, we avoided to employ the gated clock; to evade clock design related problems like jitter, additional area and power. Instead we prefe rred gating of ring oscillator itself. Consequently duri ng sleep mode, GRO disables automatically which sav es the dynamic power. Furthermore it also provides fir st order noise shaping of the quantization and mismatch noise. Proposed GRO is implemented with 0. 18 μ m CMOS Digital Technology in Cadence Virtuso environment. GRO performance analysis shows oscillation frequency as 286 KHz with 327ps jitter and average power consumption of 1.08 μ W.

  18. Asynchronous H∞ filtering for linear switched systems with average dwell time

    Science.gov (United States)

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

    2016-09-01

    This paper is concerned with the H∞ filtering problem for a class of continuous-time linear switched systems with the asynchronous behaviours, where 'asynchronous' means that the switching of the filters to be designed has a lag to the switching of the system modes. By using the Lyapunov-like functions and the average dwell time technique, a sufficient condition is obtained to guarantee the asymptotic stability with a weighted H∞ performance index for the filtering error system. Moreover, the results are formulated in the form of linear matrix inequalities that are numerical feasible. As a result, the filter design problem is solved. Finally, an illustrative numerical example is presented to show the effectiveness of the results.

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

    CERN Document Server

    Moutinho, Filipe de Carvalho

    2016-01-01

    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...

  20. A 0.6-V 8.3-ENOB asynchronous SAR ADC for biomedical applications

    International Nuclear Information System (INIS)

    A microwatt asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) is presented. The supply voltage of the SAR ADC is decreased to 0.6 V to fit the low voltage and low power requirements of biomedical systems. The tail capacitor of the DAC array is reused for least significant bit conversion to decrease the total DAC capacitance thus reducing the power. Asynchronous control logic avoids the high frequency clock generator and further reduces the power consumption. The prototype ADC is fabricated with a standard 0.18 μm CMOS technology. Experimental results show that it achieves an ENOB of 8.3 bit at a 300-kS/s sampling rate. Very low power consumption of 3.04 μW is achieved, resulting in a figure of merit of 32 fJ/conv.-step. (semiconductor integrated circuits)

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

    Directory of Open Access Journals (Sweden)

    Yunzi Li

    2014-03-01

    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.

  2. A Proficient Design of Hybrid Synchronous and Asynchronous Digital FIR Filter using FPGA

    Directory of Open Access Journals (Sweden)

    B.Paulchamy

    2012-07-01

    Full Text Available In this paper, a hybrid synchronous and asynchronous digital FIR filter is designed and implemented in FPGA using VHDL. The digital FIR filter of high throughput, low latency operating at above 1.3 GHz was designed. An adaptive high capacity pipelined was introduced in the hybrid synchronous asynchronous design of the filter. The degree of the pipelining is dynamically variable depending upon the input. Concurrent execution of software or program can be achieved in FPGA through parallel processing. The designed digital FIR filter is simulated using ModelSim and implemented using Xilinx. The simulation results are presented for different order such as 3, 6 and 15. The FIR filter designed is synthesized in Xilinx 9.1i and the device utilization report is presented for filter of order 3, 6 and 15.

  3. 基于Javascript的异步编程分析%Javascript-based Asynchronous Programming Analysis

    Institute of Scientific and Technical Information of China (English)

    陈浩

    2015-01-01

    异步编程带来的问题在客户端Javascript中并不明显,但随着服务器端Javascript越来越广的被使用,大量的异步IO操作使得该问题变得明显。许多不同的方法都可以解决这个问题,本文针对此问题讨论了一些方法。%Asynchronous programming problems caused by the client Javascript is not obvious, but with the server-side Javascript is used more widely, a large number of asynchronous IO operation so that the problem becomes apparent. Many different methods can solve this problem, this paper discusses some of the ways this problem.

  4. Dual stator winding variable speed asynchronous generator: optimal design and experiments

    Science.gov (United States)

    Tutelea, L. N.; Deaconu, S. I.; Popa, G. N.

    2015-06-01

    In the present paper is carried out a theoretical and experimental study of dual stator winding squirrel cage asynchronous generator (DSWA) behavior 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 to optimal design using a Matlab code. Issue is limited to three phase range of double stator winding cage-induction 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].

  5. The Combine Effect of Synchronous and Asynchronous E-Learning on Distance Education

    Directory of Open Access Journals (Sweden)

    Iqrar Ahmad

    2013-01-01

    Full Text Available The aim of this paper is to highlight the combine effect of synchronous as well as asynchronous in E-learning environment. Both type of learning have importance in different scenario. Not one of them can fulfill whole requirement individually. Synchronous training is done in real-time with a live instructor facilitating the training. Everyone logs in at a set time and can communicate directly with the instructor and with each other. It lasts for a set amount of time - from a single session to several weeks, months or even years. Asynchronous is e-learning in the more traditional sense of the word. It involves self-paced learning, CD-ROM-based, Network-based, Intranet-based or Internet-based. It may include access to instructors through on-line bulletin boards, on-line discussion groups and e-mail.

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

    CERN Document Server

    Romanelli, F; Vaccari, F

    2002-01-01

    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...

  7. An asynchronous metamodel-assisted memetic algorithm for CFD-based shape optimization

    Science.gov (United States)

    Kontoleontos, Evgenia A.; Asouti, Varvara G.; Giannakoglou, Kyriakos C.

    2012-02-01

    This article presents an asynchronous metamodel-assisted memetic algorithm for the solution of CFD-based optimization problems. This algorithm is appropriate for use on multiprocessor platforms and may solve computationally expensive optimization problems in reduced wall-clock time, compared to conventional evolutionary or memetic algorithms. It is, in fact, a hybridization of non-generation-based (asynchronous) evolutionary algorithms, assisted by surrogate evaluation models, a local search method and the Lamarckian learning process. For the objective function gradient computation, in CFD applications, the adjoint method is used. Issues concerning the 'smart' implementation of local search in multi-objective problems are discussed. In this respect, an algorithmic scheme for reducing the number of calls to the adjoint equations to just one, irrespective of the number of objectives, is proposed. The algorithm is applied to the CFD-based shape optimization of the tubes of a heat exchanger and of a turbomachinery cascade.

  8. Extended ℋ∞ Estimation for Two-Dimensional Markov Jump Systems under Asynchronous Switching

    Directory of Open Access Journals (Sweden)

    Rui Zhang

    2013-01-01

    Full Text Available This paper is concerned with the problem of designing ℋ∞ filters for a class of two-dimensional (2D Markov jump systems under asynchronous switching. The problem under consideration is primarily motivated by a realistic situation that the switching of candidate filters may have a lag to the switching of system modes. Different from conventional techniques, by a suitable augmentation, the jumping process of the error system is represented by a two-component Markov chain. Then, the extended transition probabilities are provided for the error system. A stochastic Lyapunov function approach is proposed for the design of desired filters that ensure a prescribed ℋ∞ performance for admissible asynchronous switching. Finally, a numerical example is given to illustrate the effectiveness of the developed method.

  9. Asynchronous update based networked predictive control system using a novel proactive compensation strategy.

    Science.gov (United States)

    Duan, Yingyao; Zuo, Xin; Liu, Jianwei

    2016-01-01

    Networked predictive control system (NPCS) has been proposed to address random delays and data dropouts in networked control systems (NCSs). A remaining challenge of this approach is that the controller has uncertain information about the actual control inputs, which leads to the predicted control input errors. The main contribution of this paper is to develop an explicit mechanism running in the distributed network nodes asynchronously, which enables the controller node to keep informed of the states of the actuator node without a priori knowledge about the network. Based on this mechanism, a novel proactive compensation strategy is proposed to develop asynchronous update based networked predictive control system (AUBNPCS). The stability criterion of AUBNPCS is derived analytically. A simulation experiment based on Truetime demonstrates the effectiveness of the scheme. PMID:26582090

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

    Directory of Open Access Journals (Sweden)

    F. Khammar

    2016-01-01

    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.

  11. Analysis of an FBMC/OQAM scheme for asynchronous access in wireless communications

    Science.gov (United States)

    Mattera, Davide; Tanda, Mario; Bellanger, Maurice

    2015-12-01

    The OFDM/OQAM transceiver belongs to the filter-bank-based multicarrier (FBMC) family and, unlike OFDM schemes, it is particularly able to meet the requirements of the physical layer of cognitive radio networks such as high level of adjacent channel leakage ratio and asynchronous communications. The paper proposes and analyzes a new implementation structure, named frequency spreading, for the OFDM/OQAM transceiver. On flat channels, it is equivalent to the standard one in terms of input-output relations, though more complex. On multipath channels, it offers a crucial advantage in terms of equalization, which is performed in the frequency domain, leading to high performance and no additional delay. With its flexibility and level of performance, the analyzed scheme has the potential to outperform OFDM in the asynchronous access context and in cognitive radio networks.

  12. Desynchronization of neocortical networks by asynchronous release of GABA at autaptic and synaptic contacts from fast-spiking interneurons.

    Directory of Open Access Journals (Sweden)

    Frédéric Manseau

    Full Text Available Networks of specific inhibitory interneurons regulate principal cell firing in several forms of neocortical activity. Fast-spiking (FS interneurons are potently self-inhibited by GABAergic autaptic transmission, allowing them to precisely control their own firing dynamics and timing. Here we show that in FS interneurons, high-frequency trains of action potentials can generate a delayed and prolonged GABAergic self-inhibition due to sustained asynchronous release at FS-cell autapses. Asynchronous release of GABA is simultaneously recorded in connected pyramidal (P neurons. Asynchronous and synchronous autaptic release show differential presynaptic Ca(2+ sensitivity, suggesting that they rely on different Ca(2+ sensors and/or involve distinct pools of vesicles. In addition, asynchronous release is modulated by the endogenous Ca(2+ buffer parvalbumin. Functionally, asynchronous release decreases FS-cell spike reliability and reduces the ability of P neurons to integrate incoming stimuli into precise firing. Since each FS cell contacts many P neurons, asynchronous release from a single interneuron may desynchronize a large portion of the local network and disrupt cortical information processing.

  13. The Flipped Classroom: A Modality for Mixed Asynchronous and Synchronous Learning in a Residency Program

    OpenAIRE

    Young, Timothy P.; Bailey, Caleb J.; Guptill, Mindi; Thorp, Andrea W.; Thomas, Tamara L

    2014-01-01

    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 sy...

  14. Asynchronous and Synchronous Communication in College English Writing in Web-based Learning Environment

    Institute of Scientific and Technical Information of China (English)

    丁洁

    2009-01-01

    In web-based learning environment,College English writing has always been a thorny issue.Here both asynchronous and synchronous communications in college English writing mean the new interactive teaching belief. This paper attempts to do the blending of two in the traditional writing learning and teaching in college English in order to promote a more flexible,efficient and interactive learning environment in accordance with students' interests and needs.

  15. Asynchronous and Synchronous Communication in College English Writing in Web-based Learning Environment

    Institute of Scientific and Technical Information of China (English)

    丁洁

    2009-01-01

    In web-based learning environment,College English writing has always been a thorny issue.Here both asynchronous and synchronous communications in college English writing mean the new interactive teaching belief. This paper attempts to do the blending of two in the traditional writing learning and teaching in college English in order to promote a more flexible, efficient and interactive learning environment in accordance with students' interests and needs.

  16. Punctuated equilibrium in thoroughbred evolution and its model based on asynchronous clocks

    International Nuclear Information System (INIS)

    Evolutionary patterns of thoroughbreds are estimated in terms of distribution of life-spans, avalanche size of extinction and lineage size. All of them show power-law distribution with exponent of -2.0, and show the characteristics of a particular evolutionary pattern called punctuated equilibrium. In addition, we propose a model based on modulation among asynchronous clocks to explain this kind of power-law distribution

  17. Punctuated equilibrium in thoroughbred evolution and its model based on asynchronous clocks

    Energy Technology Data Exchange (ETDEWEB)

    Takachi, Yasuhiro; Gunji, Yukio-Pegio

    2004-02-01

    Evolutionary patterns of thoroughbreds are estimated in terms of distribution of life-spans, avalanche size of extinction and lineage size. All of them show power-law distribution with exponent of -2.0, and show the characteristics of a particular evolutionary pattern called punctuated equilibrium. In addition, we propose a model based on modulation among asynchronous clocks to explain this kind of power-law distribution.

  18. A New Parallel Algorithm in Power Flow Calculation: Dynamic Asynchronous Parallel Algorithm

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the general methods in power flow calculation of power system and onconceptions and classifications of parallel algorithm, a new approach named DynamicAsynchronous Parallel Algorithm that applies to the online analysis and real-time dispatching and controlling of large-scale power network was put forward in this paper. Its performances of high speed and dynamic following have been verified on IEEE-14 bus system.

  19. Cut Reduction in Linear Logic as Asynchronous Session-Typed Communication

    OpenAIRE

    DeYoung, Henry; Caires, Luís; Pfenning, Frank; Toninho, Bernardo

    2012-01-01

    Prior work has shown that intuitionistic linear logic can be seen as a session-type discipline for the pi-calculus, where cut reduction in the sequent calculus corresponds to synchronous process reduction. In this paper, we exhibit a new process assignment from the asynchronous, polyadic pi-calculus to exactly the same proof rules. Proof-theoretically, the difference between these interpretations can be understood through permutations of inference rules that preserve observ...

  20. Using Team-Based Learning in an Online, Asynchronous Information Literacy Course

    OpenAIRE

    Allison Hosier

    2013-01-01

    Making information literacy instruction engaging to learners can be a challenge. Making it engaging in an online, asynchronous setting can be even more daunting. As students seek more opportunities for online learning, it’s becoming increasingly important to develop information literacy instruction that will promote engagement and enhance learning in the online environment. Team-Based Learning is a method of instruction that has transformed the atmosphere of a face-to-face information literac...

  1. Propagation of external regulation and asynchronous dynamics in random Boolean networks

    OpenAIRE

    Mahmoudi, Hamed; Pagnani, Andrea; Weigt, Martin; Zecchina, Riccardo

    2007-01-01

    Boolean Networks and their dynamics are of great interest as abstract modeling schemes in various disciplines, ranging from biology to computer science. Whereas parallel update schemes have been studied extensively in past years, the level of understanding of asynchronous updates schemes is still very poor. In this paper we study the propagation of external information given by regulatory input variables into a random Boolean network. We compute both analytically and numerically the time evol...

  2. Synaptotagmin-7 is an asynchronous calcium sensor for synaptic transmission in neurons expressing SNAP-23.

    Directory of Open Access Journals (Sweden)

    Jens P Weber

    Full Text Available 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.

  3. Research of methods of providing of temporal transparency of asynchronous TK network

    OpenAIRE

    Нашат, Галеб Саммур Альбдур

    2011-01-01

    Work is devoted development and research of new methods of indemnification of jittera by the additional delay of barns in the buffer of knot of commutation at the different levels of his load for providing of sentinel transparency of asynchronous telecommunication networks. The method of calculation of indexes of sentinel transparency of network is offered, which takes into account necessary quality of service traffic and allows to forecast the mean value of delay an...

  4. A Novel Approach to Asynchronous MVP Data Interpretation Based on Elliptical-Vectors

    Science.gov (United States)

    Kruglyakov, M.; Trofimov, I.; Korotaev, S.; Shneyer, V.; Popova, I.; Orekhova, D.; Scshors, Y.; Zhdanov, M. S.

    2014-12-01

    We suggest a novel approach to asynchronous magnetic-variation profiling (MVP) data interpretation. Standard method in MVP is based on the interpretation of the coefficients of linear relation between vertical and horizontal components of the measured magnetic field.From mathematical point of view this pair of linear coefficients is not a vector which leads to significant difficulties in asynchronous data interpretation. Our approach allows us to actually treat such a pair of complex numbers as a special vector called an ellipse-vector (EV). By choosing the particular definitions of complex length and direction, the basic relation of MVP can be considered as the dot product. This considerably simplifies the interpretation of asynchronous data. The EV is described by four real numbers: the values of major and minor semiaxes, the angular direction of the major semiaxis and the phase. The notation choice is motivated by historical reasons. It is important that different EV's components have different sensitivity with respect to the field sources and the local heterogeneities. Namely, the value of major semiaxis and the angular direction are mostly determined by the field source and the normal cross-section. On the other hand, the value of minor semiaxis and the phase are responsive to local heterogeneities. Since the EV is the general form of complex vector, the traditional Schmucker vectors can be explicitly expressed through its components.The proposed approach was successfully applied to interpretation the results of asynchronous measurements that had been obtained in the Arctic Ocean at the drift stations "North Pole" in 1962-1976.

  5. Agent-based Collaborative Design Framework Supporting Synchronization and Asynchronization on Internet

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    On the basis of analysis of the research issues and requirement of collaborativ e design, we propose the overall framework of agent based collaborative design on Internet. Then, we describe the implementation of synchronous and asynchronous collaborative design process based on standardized design activiti es under the overall framework. In order to realize design message passing, the DMP Protocol is proposed as well in this paper and described in detail.

  6. Asynchronous Heterogeneous Mechanism for Hyper-Distributed Hyper-Parallel AI Processing

    Institute of Scientific and Technical Information of China (English)

    SHUAI Dianxun

    1999-01-01

    This paper proposes an asynchronousheterogeneous propagation approach of concurrent competitive waves forhyper-distributed hyper-parallel heuristic problem-solving. Thisapproach is much more powerful than the synchronous homogeneousmechanisms and the asynchronous superimposition algorithms, and hasuniversal validity and availability. The basic conception, concurrentalgorithm and its properties are discussed. The theory and conclusionsdrawn in this paper are of essential importance for the hardwareimplementation of hyper-distributed hyper-parallel processing based onchaotic cellular networks.

  7. Asychronous [i.e. asynchronous] data fusion for AUV navigation using extended Kalman filtering.

    OpenAIRE

    Thorne, Richard L.

    1997-01-01

    A truly Autonomous Vehicle must be able to determine its global position in the absence of external transmitting devices. This requires the optimal integration of all available organic vehicle attitude and velocity sensors. This thesis investigates the extended Kalman filtering method to merge asynchronous heading, heading rate, velocity, and DGPS information to produce a single state vector. Different complexities of Kalman filters, with biases and currents, are investigated with data from F...

  8. S.A.T.E.P. : Synchronous-Asynchronous Tele-education Platform

    OpenAIRE

    Lazaridis, Lazaros; Papatsimouli, Maria; Fragulis, George F.

    2014-01-01

    S.A.T.E.P. means Synchronous Asynchronous Tele education Platform is a software application for educational purposes, with a lot of parametrizing features written entirely from scratch. It aims at the training and examination of computer skills, a platform that can be adjusted to the needs of each lesson. In the application the trainer and the administrator can define the number of the lectures and upload files for each one of them. Furthermore, he can insert, modify and delete questions whic...

  9. Asynchronous telepsychiatry in Maharashtra, India: Study of feasibility and referral pattern

    OpenAIRE

    Vanshree Patil Balasinorwala; Shah, Nilesh B.; Chatterjee, Soumya D.; Kale, Vinayak P.; Yusuf A Matcheswalla

    2014-01-01

    Context: There is a paucity of published telepsychiatry results in India. Aims: This study was conducted to assess the feasibility of asynchronous telepsychiatry and to study the referral patterns. Settings and Design: This study was conducted in the telemedicine unit of a tertiary care center and design was retrospective analysis of 94 cases, which were diagnosed and treated by telepsychiatry. Materials and Methods: All 94 patients who were referred between January 2007 and August 2013 for t...

  10. Asynchronous local dynamics contributes to stability of a seagrass bed in Tokyo Bay

    OpenAIRE

    Yamakita, Takehisa; Watanabe,Kentaro; Nakaoka, Masahiro

    2011-01-01

    It is known that asynchronous temporal variations in local populations can contribute to the stability of metapopulations. However, studies evaluating the hierarchical organization of multiple spatial scales are rare for continuous marine landscapes, especially for marine vegetation such as seagrass beds. In this study, long-term observation (26 years) of temporal changes and nested spatial analyses were combined for an extensive seagrass meadow in Tokyo Bay, Japan, using remote sensing and g...

  11. A Leader Election Protocol for Fault Recovery in Asynchronous Fully-Connected Networks

    OpenAIRE

    Franceschetti, Massimo; Bruck, Jehoshua

    1998-01-01

    We introduce a new algorithm for consistent failure detection in asynchronous systems. Informally, consistent failure detection requires processes in a distributed system to distinguish between two different populations: a fault free population and a faulty one. The major contribution of this paper is in combining ideas from group membership and leader election, in order to have an election protocol for a fault manager whose convergence is delayed until a new consistent view ...

  12. Critical thinking in asynchronous online discussions: examining the role of the student facilitator

    OpenAIRE

    Hew, KF; Cheung, WS; Jumain, SN

    2010-01-01

    This paper is part of a larger study that investigates the types of facilitation techniques exhibited by student facilitators and how these techniques may foster in-depth levels of critical thinking in asynchronous online discussions. Data were collected from ten discussion forums, involving education major students. The top 30% of forums in terms of the most number of in-depth critical thinking incidences were first identified (i.e., higher-level group). Next, the bottom 30% forums were iden...

  13. A full asynchronous serial transmission converter for network-on-chips

    International Nuclear Information System (INIS)

    Large transmission power consumptions and excessive interconnection lines are two shortcomings which exist in conventional network-on-chips. To improve performance in these areas, this paper proposes a full asynchronous serial transmission converter for network-on-chips. By grouping the parallel data between routers into smaller data blocks, interconnection lines between routers can be greatly reduced, which finally brings about saving of power overheads in the transmission process. Null convention logic units are used to make the circuit quasi-delay insensitive and highly robust. The proposed serial transmission converter and serial channel are implemented based on SMIC 0.18 μm standard CMOS technology. Results demonstrate that this full asynchronous serial transmission converter can save up to three quarters of the interconnection line resources and also reduce up to two-thirds of the power consumption under 32 bit data widths. The proposed full asynchronous serial transmission converter can apply to the on chip network which is sensitive to area and power. (semiconductor integrated circuits)

  14. An FDES-Based Shared Control Method for Asynchronous Brain-Actuated Robot.

    Science.gov (United States)

    Liu, Rong; Wang, Yong-Xuan; Zhang, Lin

    2016-06-01

    The asynchronous brain-computer interface (BCI) offers more natural human-machine interaction. However, it is still considered insufficient to control rapid and complex sequences of movements for a robot without any advanced control method. This paper proposes a new shared controller based on the supervisory theory of fuzzy discrete event system (FDES) for brain-actuated robot control. The developed supervisory theory allows the more reliable control mode to play a dominant role in the robot control which is beneficial to reduce misoperation and improve the robustness of the system. The experimental procedures consist of real-time direct manual control and BCI control tests from ten volunteers. Both tests have shown that the proposed method significantly improves the performance and robustness of the robotic control. In an online BCI experiment, eight of the participants successfully controlled the robot to circumnavigate obstacles and reached the target with a three mental states asynchronous BCI while the other two participants failed in all the BCI control sessions. Furthermore, the FDES-based shared control method also helps to reduce the workload. It can be stated that the asynchronous BCI, in combination with FDES-based shared controller, is feasible for the real-time and robust control of robotics.

  15. 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.

  16. A Low-Power Asynchronous Step-Down DC-DC Converter for Implantable Devices.

    Science.gov (United States)

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

    2011-06-01

    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.

  17. From asynchronous logic to the standard model to superflight to the stars

    CERN Document Server

    Blaha, Stephen

    2011-01-01

    This edition is the latest in a series of books by this author that have appeared in the past ten years that seek to make sense of the form of The Standard Model. Previously The Standard Model was viewed as a hodgepodge of particles symmetries and features that worked experimentally but was only an approximation to a "true" fundamental theory. The overall purpose of this series of books was to show that the form of The Standard Model is based on certain fundamental principles that ultimately emanate from Logic, Asynchronous Logic in particular. Physical phenomena are asynchronous. The simplest form of Asynchronous Logic has a 4-valued logic that maps naturally to Dirac-like equations. Upon this bridge The Standard Model is constructed with parity violation, particle symmetries SU(3)SU(2)U(1)U(1), and a spin ½ fermion spectrum with four generations of four fermion species split into quarks and leptons. Two species of WIMPs are also derived. A new formulation of Logic is presented. A major application...

  18. Asynchronous data change notification between database server and accelerator controls system

    International Nuclear Information System (INIS)

    Database data change notification (DCN) is a commonly used feature. Not all database management systems (DBMS) provide an explicit DCN mechanism. Even for those DBMS's which support DCN (such as Oracle and MS SQL server), some server side and/or client side programming may be required to make the DCN system work. This makes the setup of DCN between database server and interested clients tedious and time consuming. In accelerator control systems, there are many well established software client/server architectures (such as CDEV, EPICS, and ADO) that can be used to implement data reflection servers that transfer data asynchronously to any client using the standard SET/GET API. This paper describes a method for using such a data reflection server to set up asynchronous DCN (ADCN) between a DBMS and clients. This method works well for all DBMS systems which provide database trigger functionality. Asynchronous data change notification (ADCN) between database server and clients can be realized by combining the use of a database trigger mechanism, which is supported by major DBMS systems, with server processes that use client/server software architectures that are familiar in the accelerator controls community (such as EPICS, CDEV or ADO). This approach makes the ADCN system easy to set up and integrate into an accelerator controls system. Several ADCN systems have been set up and used in the RHIC-AGS controls system.

  19. Low Power Analysis of Network-Level On-chip communication using Asynchronous AMBA protocol

    Directory of Open Access Journals (Sweden)

    E. Sakthivel

    2012-07-01

    Full Text Available Network on-chip (NoC is a novel structuraldesign template, which can be defied for complicatedsystem level on-chip design. NoC has a potential tolimit and present the bus-based communication. In thispaper, the crisis to discuss is Low power consumptionin an Asynchronous Network on-chip (NoC levelcommunication. NoC is implemented using FPGAwhich has less fabrication cost and reduces thecomplexity. An Asynchronous NoC has beenimplemented in Spartan kit using Xilinx FPGA ISEtools and its network interface is AdvancedMicrocontroller Bus Architecture (AMBA whichfeatures numerous bus masters and a sole clock edgeevolution and so on. Here the AMBA highperformance 32-bit AHB bus is employed in which ithas a high clock frequency system and it is the heart ofour bus system. To accomplish low power consumptionby interfacing SoC with AMBA- AHB protocol. TheAHB model and an Asynchronous NoC are employedand executed using VHDL programming module

  20. Two-Particle Asynchronous Quantum Correlation: Wavefunction Collapse Acting as a Beamsplitter

    Science.gov (United States)

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

    2016-03-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Ren Xiaoguang

    2014-01-01

    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%.

  2. AP-IO: asynchronous pipeline I/O for hiding periodic output cost in CFD simulation.

    Science.gov (United States)

    Xiaoguang, Ren; Xinhai, Xu

    2014-01-01

    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%. PMID:24955390

  3. A modular control architecture for real-time synchronous and asynchronous systems

    International Nuclear Information System (INIS)

    This paper describes a control architecture for real-time control of complex robotic systems. The Modular Integrated Control Architecture (MICA), which is actually two complementary control systems, recognizes and exploits the differences between asynchronous and synchronous control. The asynchronous control system simulates shared memory on a heterogeneous network. For control information, a portable event-scheme is used. This scheme provides consistent interprocess coordination among multiple tasks on a number of distributed systems. The machines in the network can vary with respect to their native operating systems and the intemal representation of numbers they use. The synchronous control system is needed for tight real-time control of complex electromechanical systems such as robot manipulators, and the system uses multiple processors at a specified rate. Both the synchronous and asynchronous portions of MICA have been developed to be extremely modular. MICA presents a simple programming model to code developers and also considers the needs of system integrators and maintainers. MICA has been used successfully in a complex robotics project involving a mobile 7-degree-of-freedom manipulator in a heterogeneous network with a body of software totaling over 100,000 lines of code. MICA has also been used in another robotics system, controlling a commercial long-reach manipulator

  4. Rational Secret Sharing over an Asynchronous Broadcast Channel with Information Theoretic Security

    CERN Document Server

    Moses, William K; 10.5121/ijnsa.2011.3601

    2011-01-01

    We consider the problem of rational secret sharing introduced by Halpern and Teague [1], where the players involved in secret sharing play only if it is to their advantage. This can be characterized in the form of preferences. Players would prefer to get the secret than to not get it and secondly with lesser preference, they would like as few other players to get the secret as possible. Several positive results have already been published to efficiently solve the problem of rational secret sharing but only a handful of papers have touched upon the use of an asynchronous broadcast channel. [2] used cryptographic primitives, [3] used an interactive dealer, and [4] used an honest minority of players in order to handle an asynchronous broadcast channel. In our paper, we propose an m-out-of-n rational secret sharing scheme which can function over an asynchronous broadcast channel without the use of cryptographic primitives and with a non-interactive dealer. This is possible because our scheme uses a small number, ...

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

    Directory of Open Access Journals (Sweden)

    Ching-Hsing Luo

    2011-07-01

    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.

  6. Designing a WISHBONE Protocol Network Adapter for an Asynchronous Network-on-Chip

    Directory of Open Access Journals (Sweden)

    Ahmed H M Soliman

    2011-07-01

    Full Text Available The Scaling of microchip technologies, from micron to submicron and now to deep sub-micron (DSM range, has enabled large scale systems-on-chip (SoC. In future deep submicron (DSM designs, the interconnect effect will definitely dominate performance. Network-on-Chip (NoC has become a promising solution to bus-based communication infrastructure limitations. NoC designs usually targets Application Specific Integrated Circuits (ASICs, however, the fabrication process costs a lot. Implementing a NoC on an FPGA does not only reduce the cost but also decreases programming and verification cycles. In this paper, an Asynchronous NoC has been implemented on a SPARTAN-3Eandamp;reg; device. The NoC supports basic transactions of both widely used on-chip interconnection standards, the Open Core Protocol (OCP and the WISHBONE Protocol. Although, FPGA devices are synchronous in nature, it has been shown that they can be used to prototype a Global Asynchronous Local Synchronous (GALS systems, comprising an Asynchronous NoC connecting IP cores operating in different clock domains.

  7. Motor degradation prediction methods

    International Nuclear Information System (INIS)

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor's duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures

  8. Motor Axon Pathfinding

    OpenAIRE

    Bonanomi, Dario; Pfaff, Samuel L

    2010-01-01

    Motor neurons are functionally related, but represent a diverse collection of cells that show strict preferences for specific axon pathways during embryonic development. In this article, we describe the ligands and receptors that guide motor axons as they extend toward their peripheral muscle targets. Motor neurons share similar guidance molecules with many other neuronal types, thus one challenge in the field of axon guidance has been to understand how the vast complexity of brain connection...

  9. Cryogenic Electric Motor Tested

    Science.gov (United States)

    Brown, Gerald V.

    2004-01-01

    Technology for pollution-free "electric flight" is being evaluated in a number of NASA Glenn Research Center programs. One approach is to drive propulsive fans or propellers with electric motors powered by fuel cells running on hydrogen. For large transport aircraft, conventional electric motors are far too heavy to be feasible. However, since hydrogen fuel would almost surely be carried as liquid, a propulsive electric motor could be cooled to near liquid hydrogen temperature (-423 F) by using the fuel for cooling before it goes to the fuel cells. Motor windings could be either superconducting or high purity normal copper or aluminum. The electrical resistance of pure metals can drop to 1/100th or less of their room-temperature resistance at liquid hydrogen temperature. In either case, super or normal, much higher current density is possible in motor windings. This leads to more compact motors that are projected to produce 20 hp/lb or more in large sizes, in comparison to on the order of 2 hp/lb for large conventional motors. High power density is the major goal. To support cryogenic motor development, we have designed and built in-house a small motor (7-in. outside diameter) for operation in liquid nitrogen.

  10. Control motor brushless sensorless

    OpenAIRE

    Solchaga Pérez de Lazárraga, Gonzalo

    2015-01-01

    El proyecto consiste en la creación de un circuito capaz de controlar la velocidad de un motor brushless sensorless. Este tipo de motores eléctricos tienen como característica que no tienen escobillas para cambiar la polaridad del bobinado de su interior y tampoco precisan de un sensor que indique que ha realizado una vuelta. Los motores brushless que son controlados por este tipo de circuitos son específicos para aeronaves no tripuladas y requieren un diseño diferente a un motor brushless pe...

  11. Analysis and control of excitation, field weakening and stability in direct torque controlled electrically excited synchronous motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Pyrhoenen, O.

    1998-12-31

    Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor`s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque

  12. Energy efficient electric drives. Fundamentals, power electronics, operational behaviour and regulation of the three-phase motor; Energieeffiziente elektrische Antriebe. Grundlagen, Leistungselektronik, Betriebsverhalten und Regelung von Drehstrommotoren

    Energy Technology Data Exchange (ETDEWEB)

    Teigelkoetter, Johannes [Hochschule Aschaffenburg (Germany)

    2013-02-01

    An efficient utilization of electric power in the electric drive technology is necessary because nearly two thirds of the generated electric power is consumed. The textbook under consideration reports on the technical fundamentals and methods for the increase of energy efficiency in the electric drive technology. Especially, a detailed understanding of modern drives with asynchronous motors as well as synchronous motors is enabled by a thorough introduction to the space-vector calculation. In addition to electrical machines, also the handling procedures for pulse inverters, control methods and sensors for electrical drives are described. Each chapter concludes with calculated exercises in order to deepen the content of teaching.

  13. Experimental Study of Brushless Doubly-Fed Machine With Cage Rotor at the Asynchronous Operation Mode%笼型转子无刷双馈电机异步运行模式的实验研究

    Institute of Scientific and Technical Information of China (English)

    杜江; 韩力; 欧先朋; 韩雪峰

    2016-01-01

    By changing the control winding connection and feeding method of brushless doubly-fed machine (BDFM), many different operation modes can be obtained, such as asynchronous, synchronous, doubly-fed sub-synchronous and super-synchronous models. However, the detailed research about the asynchronous operation mode of BDFM is seldom. The concepts of “singly-fed asynchronous” and “doubly-fed asynchronous” operation modes were proposed. The basic electromagnetic relationship of these asynchronous operation modes were described in detail based on the features of BDFM with cage rotor. The air-gap magnetic field waveforms were analyzed by finite element, which verified that the constant electromagnetic torque could be produced at two different asynchronous operation modes. The results of finite element analysis and the comparisons of the test data show that the operating characteristics of BDFM singly-fed asynchronous mode are similar with induction motor, the speed still meet the characteristics of BDFM and can be adjusted by changing the external series resistance of control winding at doubly-fed asynchronous operation mode. The results can provide reference for studying the operation rules of BDFM in the further.%无刷双馈电机(brushless doubly-fed machine,BDFM)通过改变控制绕组的联接与馈电方式,可实现异步、同步、双馈亚同步和超同步等多种不同运行方式。然而,目前尚缺乏对BDFM异步运行模式的详细研究。该文提出了BDFM“单馈异步”和“双馈异步”运行模式的概念,结合笼型转子 BDFM的特点,阐述了两种异步运行模式的基本电磁关系,利用有限元分析得到了 BDFM 样机的气隙磁场波形,从而验证了两种运行模式均能产生恒定电磁转矩。通过对BDFM 样机在两种异步运行模式下的有限元分析和实验数据对比,表明 BDFM 单馈异步运行模式与普通异步电动机的运行特性相类似,在双馈异步运

  14. Organizing motor imageries.

    Science.gov (United States)

    Hanakawa, Takashi

    2016-03-01

    Over the last few decades, motor imagery has attracted the attention of researchers as a prototypical example of 'embodied cognition' and also as a basis for neuro-rehabilitation and brain-machine interfaces. The current definition of motor imagery is widely accepted, but it is important to note that various abilities rather than a single cognitive entity are dealt with under a single term. Here, motor imagery has been characterized based on four factors: (1) motor control, (2) explicitness, (3) sensory modalities, and (4) agency. Sorting out these factors characterizing motor imagery may explain some discrepancies and variability in the findings from previous studies and will help to optimize a study design in accordance with the purpose of each study in the future. PMID:26602980

  15. MISR Motor Data V003

    Data.gov (United States)

    National Aeronautics and Space Administration — This file contains the output for the Level 1A Motor data (Suggested Usage: MISR SCF processing needs the MISR motor data samples for the analysis of motor...

  16. Isolation of TRPV1 independent mechanisms of spontaneous and asynchronous glutamate release at primary afferent to NTS synapses.

    Science.gov (United States)

    Fenwick, Axel J; Wu, Shaw-Wen; Peters, James H

    2014-01-01

    Cranial visceral afferents contained within the solitary tract (ST) contact second-order neurons in the nucleus of the solitary tract (NTS) and release the excitatory amino acid glutamate via three distinct exocytosis pathways; synchronous, asynchronous, and spontaneous release. The presence of TRPV1 in the central terminals of a majority of ST afferents conveys activity-dependent asynchronous glutamate release and provides a temperature sensitive calcium conductance which largely determines the rate of spontaneous vesicle fusion. TRPV1 is present in unmyelinated C-fiber afferents and these facilitated forms of glutamate release may underlie the relative strength of C-fibers in activating autonomic reflex pathways. However, pharmacological blockade of TRPV1 signaling eliminates only ~50% of the asynchronous profile and attenuates the temperature sensitivity of spontaneous release indicating additional thermosensitive calcium influx pathways may exist which mediate these forms of vesicle release. In the present study we isolate the contribution of TRPV1 independent forms of glutamate release at ST-NTS synapses. We found ST afferent innervation at NTS neurons and synchronous vesicle release from TRPV1 KO mice was not different to control animals; however, only half of TRPV1 KO ST afferents completely lacked asynchronous glutamate release. Further, temperature driven spontaneous rates of vesicle release were not different from 33 to 37°C between control and TRPV1 KO afferents. These findings suggest additional temperature dependent mechanisms controlling asynchronous and thermosensitive spontaneous release at physiological temperatures, possibly mediated by additional thermosensitive TRP channels in primary afferent terminals.

  17. Improve Motor System Efficiency for a Broad Range of Motors with MotorMaster+ International

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-05-01

    Available at no charge, MotorMaster+ International is designed to support motor systems improvement planning at industrial facilities by identifying the most cost-effective choice when deciding to repair or replace older motor models.

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

    Directory of Open Access Journals (Sweden)

    John Walmsley

    2015-07-01

    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

  19. XMPP for cloud computing in bioinformatics supporting discovery and invocation of asynchronous web services

    Directory of Open Access Journals (Sweden)

    Willighagen Egon L

    2009-09-01

    Full Text Available Abstract Background Life sciences make heavily use of the web for both data provision and analysis. However, the increasing amount of available data and the diversity of analysis tools call for machine accessible interfaces in order to be effective. HTTP-based Web service technologies, like the Simple Object Access Protocol (SOAP and REpresentational State Transfer (REST services, are today the most common technologies for this in bioinformatics. However, these methods have severe drawbacks, including lack of discoverability, and the inability for services to send status notifications. Several complementary workarounds have been proposed, but the results are ad-hoc solutions of varying quality that can be difficult to use. Results We present a novel approach based on the open standard Extensible Messaging and Presence Protocol (XMPP, consisting of an extension (IO Data to comprise discovery, asynchronous invocation, and definition of data types in the service. That XMPP cloud services are capable of asynchronous communication implies that clients do not have to poll repetitively for status, but the service sends the results back to the client upon completion. Implementations for Bioclipse and Taverna are presented, as are various XMPP cloud services in bio- and cheminformatics. Conclusion XMPP with its extensions is a powerful protocol for cloud services that demonstrate several advantages over traditional HTTP-based Web services: 1 services are discoverable without the need of an external registry, 2 asynchronous invocation eliminates the need for ad-hoc solutions like polling, and 3 input and output types defined in the service allows for generation of clients on the fly without the need of an external semantics description. The many advantages over existing technologies make XMPP a highly interesting candidate for next generation online services in bioinformatics.

  20. Asynchronous response of tropical forest leaf phenology to seasonal and el Nino-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.

  1. Participation in asynchronous online discussion forums does improve student learning of gross anatomy.

    Science.gov (United States)

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

    2014-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Postoronca S.

    2008-08-01

    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.

  3. Contribution à la commande robuste de la machine asynchrone à double alimentation

    OpenAIRE

    Salloum, Georges

    2007-01-01

    Le travail présenté dans cette thèse apporte, entre autres, une contribution aux méthodes d'analyse et de synthèse de la commande robuste des Machines Asynchrones à Double Alimentation (MADA) alimentées par deux onduleurs de tension avec deux bus continus distincts. Nous introduisons, dans un premier chapitre, la commande vectorielle classique de la MADA munie de capteurs mécaniques. Ce chapitre se distingue par une nouvelle approche pour assurer le découplage des courants de la MADA dans un ...

  4. High-quality asynchronous heralded single-photon source at telecom wavelength

    International Nuclear Information System (INIS)

    We report on the experimental realization and characterization of an asynchronous heralded single-photon source based on spontaneous parametric down-conversion. Photons at 1550 nm are heralded as being inside a single-mode fibre with more than 60% probability, and the multi-photon emission probability is reduced by a factor of up to more than 500 compared to Poissonian light sources. These figures of merit, together with the choice of telecom wavelength for the heralded photons, are compatible with practical applications needing very efficient and robust single-photon sources

  5. The Paralleling of High Power High Frequency Amplifier Based on Synchronous and Asynchronous Control

    Institute of Scientific and Technical Information of China (English)

    程荣仓; 刘正之

    2004-01-01

    The vertical position of plasma in the HT-7U Tokamak is inherently unstable. In order to realize active stabilization, the response rate of the high-power high-frequency amplifier feeding the active control coils must be fast enough. This paper analyzes the paralleling scheme of the power amplifier through two kinds of control mode. One is the synchronous control; the other is the asynchronous control. Via the comparison of the two kinds of control mode, both of their characteristics are given in the text. At last, the analyzed result is verified by a small power experiment.

  6. Asynchronous accelerator with RFQ injection for active longitudinal compression of accelerated bunches

    CERN Document Server

    Tumanyan, A R; Nikhogosyan, V C; Akopov, N Z; Guiragossian, Z G T; Martirosov, R M; Martirosyan, Yu.L.

    2000-01-01

    An asynchronous accelerator is described, in which the principle of itsoperation permits the active longitudinal bunch compression of acceleratedproton beams, to overcome the space charge limitation effects of intensebunches. It is shown that accelerated bunches from an RFQ linac can be adaptedfor Asynchronac injection for a multiple of choices in the accelerationfrequencies of the RFQ and the Asynchronac. The offered new type of acceleratorsystem is especially suitable to accelerate proton beams for up to 100MeVenergy and hundreds of mA average current.

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

    CERN Document Server

    Farkhooi, Farzad

    2015-01-01

    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.

  8. Proximity-Based Asynchronous Messaging Platform for Location-Based Internet of Things Service

    Directory of Open Access Journals (Sweden)

    Hyeong gon Jo

    2016-07-01

    Full Text Available The Internet of Things (IoT opens up tremendous opportunities to provide location-based applications. However, despite the services around a user being physically adjacent, common IoT platforms use a centralized structure, like a cloud-computing architecture, which transfers large amounts of data to a central server. This raises problems, such as traffic concentration, long service latency, and high communication cost. In this paper, we propose a physical distance-based asynchronous messaging platform that specializes in processing personalized data and location-based messages. The proposed system disperses traffic using a location-based message-delivery protocol, and has high stability.

  9. Robust stabilisation and L2 -gain analysis for switched systems with actuator saturation under asynchronous switching

    Science.gov (United States)

    Wang, Juan; Zhao, Jun

    2016-09-01

    Robust stabilisation and L2-gain analysis for a class of switched systems with actuator saturation are studied in this paper. The switching signal of the controllers lags behind that of the system modes, which leads to the asynchronous switching between the candidate controllers and the subsystems. By combining the piecewise Lyapunov function method with the convex hull technique, sufficient conditions in terms of LMIs for the solvability of the robust stabilisation and weighted L2-gain problems are presented respectively under the dwell time scheme. Finally, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed results.

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

    DEFF Research Database (Denmark)

    den Otter, Ad; Emmitt, Stephen

    2007-01-01

    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....

  11. Full flex-grid asynchronous multiplexing demonstrated with Nyquist pulse-shaping.

    Science.gov (United States)

    Schindler, P C; Schmogrow, R; Wolf, S; Baeuerle, B; Nebendahl, B; Koos, C; Freude, W; Leuthold, J

    2014-05-01

    We demonstrate full flex-grid operation with Nyquist frequency division multiplexing. The technique supports high spectral efficiency, asynchronous operation of channels, variable channel loading with different modulation formats and dynamic bandwidth allocation. Data from different sources with different bit and symbol rates are encoded onto electrical Nyquist pulses with different electrical subcarrier frequencies, and then transmitted optically. We give details on the transceiver design with digital signal processing and investigate the implementation penalty as a function of several design parameters such as limited filter length and effective number of bits. Finally, experiments are performed for receivers with direct detection, intradyne and remote heterodyne reception.

  12. Asynchronous Object Storage with QoS for Scientific and Commercial Big Data

    Energy Technology Data Exchange (ETDEWEB)

    Brim, Michael J [ORNL; Dillow, David A [ORNL; Oral, H Sarp [ORNL; Settlemyer, Bradley W [ORNL; Wang, Feiyi [ORNL

    2013-01-01

    This paper presents our design for an asynchronous object storage system intended for use in scientific and commercial big data workloads. Use cases from the target workload do- mains are used to motivate the key abstractions used in the application programming interface (API). The architecture of the Scalable Object Store (SOS), a prototype object stor- age system that supports the API s facilities, is presented. The SOS serves as a vehicle for future research into scalable and resilient big data object storage. We briefly review our research into providing efficient storage servers capable of providing quality of service (QoS) contracts relevant for big data use cases.

  13. Internal end-effect problem in a linear asynchronous MHD machine with arbitrary current load

    Energy Technology Data Exchange (ETDEWEB)

    Vilnitis, A.Ya.

    1977-01-01

    The internal end-effect problem in a bilateral linear asynchronous engine is solved by variation of constants for a surface current load of any type, including discrete conductors. Mathematically correct formulae for this case are given for computing the mechanical force on wound coils and the active power. Known methods of end-effect compensation are examined. The requirements for the surface load of inductors were found for the case where the requirements may be limited to an internal problem and scattering along the magnetic circuit ends.

  14. Chroma key without color restrictions based on asynchronous amplitude modulation of background illumination on retroreflective screens

    Science.gov (United States)

    Vidal, Borja; Lafuente, Juan A.

    2016-03-01

    A simple technique to avoid color limitations in image capture systems based on chroma key video composition using retroreflective screens and light-emitting diodes (LED) rings is proposed and demonstrated. The combination of an asynchronous temporal modulation onto the background illumination and simple image processing removes the usual restrictions on foreground colors in the scene. The technique removes technical constraints in stage composition, allowing its design to be purely based on artistic grounds. Since it only requires adding a very simple electronic circuit to widely used chroma keying hardware based on retroreflective screens, the technique is easily applicable to TV and filming studios.

  15. Asynchronous transfer of individually addressable optical channels through a multimode fiber using phase conjugation

    CERN Document Server

    Czarske, Jueurgen W; Koukourakis, Nektarios; Buettner, Lars

    2016-01-01

    Multimode fibers are attractive for a variety of applications such as internet data transfer, data center hubs, micromanipulation, optogenetics and other biomedical applications. A major hurdle for imaging through multimode fibers is the occurring scrambling, resulting in a randomization of light. Recently, clear imaging has been successfully accomplished using wavefront shaping, but the spatial information was transferred synchronously only. We demonstrate asynchronous information transmission using individual phase conjugations by employing only one spatial light modulator with multiple windows. Our findings pave the way towards individual signal transfer inside strongly scattering media.

  16. 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;

    2016-01-01

    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-terminatin......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...... between 1992 and 2013. These observations point out the fact that the UI glaciers are reacting to climate change on different timescales. The asynchronous behavior of the four neighboring glaciers is explained in terms of the individual glaciersâĂŹ geometry and terminus position. The northernmost glacier...

  17. Asynchronous Video Interviewing as a New Technology in Personnel Selection: The Applicant’s Point of View

    Science.gov (United States)

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

    2016-01-01

    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

  18. System and method for motor parameter estimation

    Energy Technology Data Exchange (ETDEWEB)

    Luhrs, Bin; Yan, Ting

    2014-03-18

    A system and method for determining unknown values of certain motor parameters includes a motor input device connectable to an electric motor having associated therewith values for known motor parameters and an unknown value of at least one motor parameter. The motor input device includes a processing unit that receives a first input from the electric motor comprising values for the known motor parameters for the electric motor and receive a second input comprising motor data on a plurality of reference motors, including values for motor parameters corresponding to the known motor parameters of the electric motor and values for motor parameters corresponding to the at least one unknown motor parameter value of the electric motor. The processor determines the unknown value of the at least one motor parameter from the first input and the second input and determines a motor management strategy for the electric motor based thereon.

  19. Motor Vehicle Safety

    Science.gov (United States)

    ... these crashes is one part of motor vehicle safety. Here are some things you can do to ... speed or drive aggressively Don't drive impaired Safety also involves being aware of others. Share the ...

  20. Congenital Ocular Motor Apraxia

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2007-06-01

    Full Text Available The clinical and neuroradiological findings, and long-term intellectual prognosis in 10 patients (4 boys and 6 girls with congenital ocular motor apraxia (COMA are reviewed by researchers at Tottori University, Yonago, Japan.

  1. Partial motor status epilepticus

    OpenAIRE

    Gilberto Rebello de Mattos; José C. Rollemberg Filho

    1992-01-01

    We report the case of a young female patient with photosensitive primary epilepsy who presented partial motor status epilepticus provoked by the act of shutting the eyes. Clinical, EEG and neuroimage data are presented and discussed.

  2. Congenital Ocular Motor Apraxia

    OpenAIRE

    J Gordon Millichap

    2007-01-01

    The clinical and neuroradiological findings, and long-term intellectual prognosis in 10 patients (4 boys and 6 girls) with congenital ocular motor apraxia (COMA) are reviewed by researchers at Tottori University, Yonago, Japan.

  3. Nonautistic Motor Stereotypies

    OpenAIRE

    J Gordon Millichap

    2008-01-01

    Clinical features and long-term outcomes of 100 children (62 boys and 35 girls) with motor stereotypies were evaluated by review of records and telephone interviews at Johns Hopkins Hospital, Baltimore, MD.

  4. Heritability of motor control and motor learning

    OpenAIRE

    Missitzi, Julia; Gentner, Reinhard; Misitzi, Angelica; Geladas, Nickos; Politis, Panagiotis; Klissouras, Vassilis; Classen, Joseph

    2013-01-01

    Abstract The aim of this study was to elucidate the relative contribution of genes and environment on individual differences in motor control and acquisition of a force control task, in view of recent association studies showing that several candidate polymorphisms may have an effect on them. Forty‐four healthy female twins performed brisk isometric abductions with their right thumb. Force was recorded by a transducer and fed back to the subject on a computer screen. The task was to place the...

  5. ANALYSIS OF PROCESSES IN AN INDEPENDENT GENERATOR WITH A NONCONTACT CASCADE THREE-PHASE MODULATED EXCITER VIA A STAR-CONNECTED CIRCUIT WITH A COMMON MODULATOR PHASE CONNECTION UNDER OPERATION TO AN INDUCTION MOTORS SITE

    Directory of Open Access Journals (Sweden)

    K.M. Vasyliv

    2013-04-01

    Full Text Available By means of a mathematical experiment, electromagnetic and electromechanical processes in an independent electric power supply system based on an asynchronized generator with a three-phase modulated exciter are investigated. The processes are analyzed to specify the working capacity of the power supply system during its operation to an induction motors site. Regularities of the electromagnetic and electromechanical processes behavior versus load intensity and the switch control system parameters are identified.

  6. 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

    2012-01-01

    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.

  7. Development of motor control

    OpenAIRE

    Schellekens, Johannes Maria Hubertus

    1985-01-01

    In this thesis, the results of a series of investigations into the barrier function of human skin are presented. In these investigations, the barrier function was assessed by water vapour loss measurements of the skin using a method based on gradient estimation. The aim of this thesis is to study the role and efficiency of motor control and anticipation processes in the development of children with and without disturbances in the motor system. Chapter I is a general introduction to the subjec...

  8. Congenital ocular motor apraxia

    OpenAIRE

    Carrasquinho, S; Teixeira, S.; Cadete, A; Bernardo, M.; Pêgo, P; Prieto, I.

    2008-01-01

    PURPOSE: Congenital ocular motor apraxia is a rare disease characterized by defective or absent voluntary and optically induced horizontal saccadic movements. Jerky head movements or thrusts on attempted lateral gaze are a compensatory sign. Most affected children have delayed motor and speech development. Cases associated with systemic diseases, neurologic maldevelopment, metabolic deficits, and chromosomal abnormalities have been described. METHODS: Case report and review of the scienti...

  9. Motor neurone disease

    OpenAIRE

    Talbot, K.

    2002-01-01

    Motor neurone disease (MND), or amyotrophic lateral sclerosis (ALS), is a neurodegenerative disorder of unknown aetiology. Progressive motor weakness and bulbar dysfunction lead to premature death, usually from respiratory failure. Confirming the diagnosis may initially be difficult until the full clinical features are manifest. For all forms of the disease there is a significant differential diagnosis to consider, including treatable conditions, and therefore specialist neurological opinion ...

  10. Symmetric Brownian motor

    OpenAIRE

    Gomez-Marin, A.; Sancho, J. M.

    2004-01-01

    In this paper we present a model of a symmetric Brownian motor (SBM) which changes the sign of its velocity when the temperature gradient is inverted. The velocity, external work and efficiency are studied as a function of the temperatures of the baths and other relevant parameters. The motor shows a current reversal when another parameter (a phase shift) is varied. Analytical predictions and results from numerical simulations are performed and agree very well. Generic properties of this type...

  11. Multifocal motor neuropathy

    OpenAIRE

    Thy P Nguyen; Vinay Chaudhry

    2011-01-01

    Multifocal motor neuropathy (MMN) is a unique disorder characterized by slowly progressive, asymmetric, distal and upper limb predominant weakness without significant sensory abnormalities. Electrophysiology is crucial to the diagnosis, revealing the hallmark partial conduction block. MMN is considered immune mediated due to the association with anti-GM1 antibodies and the response to immunomodulatory treatment. It is paramount to recognize MMN from other motor neuronopathies or peripheral ne...

  12. Starter Motor Protection

    OpenAIRE

    Gerhardsson, Daniel

    2010-01-01

    Starter motors are sensitive for overheating. By estimating the temperature and preventing cranking in time, there is an option to avoid the dangerous temperatures. The truck manufacturer Scania CV AB proposed a master thesis that should evaluate the need of an overheating protection for the starter motor. The aim is to evaluate any positive effects of implementing an algorithm that can estimate the brush temperature instead of using the available time constrain, which allows 35 seconds of cr...

  13. Designing a WISHBONE Protocol Network Adapter for an Asynchronous Network-on-Chip

    CERN Document Server

    Soliman, Ahmed H M; El-Bably, M; Keshk, Hesham M A M

    2012-01-01

    The Scaling of microchip technologies, from micron to submicron and now to deep sub-micron (DSM) range, has enabled large scale systems-on-chip (SoC). In future deep submicron (DSM) designs, the interconnect effect will definitely dominate performance. Network-on-Chip (NoC) has become a promising solution to bus-based communication infrastructure limitations. NoC designs usually targets Application Specific Integrated Circuits (ASICs), however, the fabrication process costs a lot. Implementing a NoC on an FPGA does not only reduce the cost but also decreases programming and verification cycles. In this paper, an Asynchronous NoC has been implemented on a SPARTAN-3E\\textregistered device. The NoC supports basic transactions of both widely used on-chip interconnection standards, the Open Core Protocol (OCP) and the WISHBONE Protocol. Although, FPGA devices are synchronous in nature, it has been shown that they can be used to prototype a Global Asynchronous Local Synchronous (GALS) systems, comprising an Asynchr...

  14. APFA: Asynchronous Parallel Finite Automaton for Deep Packet Inspection in Cloud Computing

    Science.gov (United States)

    Li, Yang; Li, Zheng; Yu, Nenghai; Ma, Ke

    Security in cloud computing is getting more and more important recently. Besides passive defense such as encryption, it is necessary to implement real-time active monitoring, detection and defense in the cloud. According to the published researches, DPI (deep packet inspection) is the most effective technology to realize active inspection and defense. However, most recent works of DPI aim at space reduction but could not meet the demands of high speed and stability in the cloud. So, it is important to improve regular methods of DPI, making it more suitable for cloud computing. In this paper, an asynchronous parallel finite automaton named APFA is proposed, by introducing the asynchronous parallelization and the heuristically forecast mechanism, which significantly decreases the time consumed in matching while still keeps reducing the memory required. What is more, APFA is immune to the overlapping problem so that the stability is also enhanced. The evaluation results show that APFA achieves higher stability, better performance on time and memory. In short, APFA is more suitable for cloud computing.

  15. Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore.

    Science.gov (United States)

    Searle, Kate R; Rice, Mindy B; Anderson, Charles R; Bishop, Chad; Hobbs, N T

    2015-10-01

    Understanding how spatial and temporal heterogeneity influence ecological processes forms a central challenge in ecology. Individual responses to heterogeneity shape population dynamics, therefore understanding these responses is central to sustainable population management. Emerging evidence has shown that herbivores track heterogeneity in nutritional quality of vegetation by responding to phenological differences in plants. We quantified the benefits mule deer (Odocoileus hemionus) accrue from accessing habitats with asynchronous plant phenology in northwest Colorado over 3 years. Our analysis examined both the direct physiological and indirect environmental effects of weather and vegetation phenology on mule deer winter body condition. We identified several important effects of annual weather patterns and topographical variables on vegetation phenology in the home ranges of mule deer. Crucially, temporal patterns of vegetation phenology were linked with differences in body condition, with deer tending to show poorer body condition in areas with less asynchronous vegetation green-up and later vegetation onset. The direct physiological effect of previous winter precipitation on mule deer body condition was much less important than the indirect effect mediated by vegetation phenology. Additionally, the influence of vegetation phenology on body fat was much stronger than that of overall vegetation productivity. In summary, changing annual weather patterns, particularly in relation to seasonal precipitation, have the potential to alter body condition of this important ungulate species during the critical winter period. This finding highlights the importance of maintaining large contiguous areas of spatially and temporally variable resources to allow animals to compensate behaviourally for changing climate-driven resource patterns. PMID:26009244

  16. Significance of microbial asynchronous anabolism to soil carbon dynamics driven by litter inputs

    Science.gov (United States)

    Fan, Zhaosheng; Liang, Chao

    2015-04-01

    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.

  17. Sensor placement on Canton Tower for health monitoring using asynchronous-climb monkey algorithm

    International Nuclear Information System (INIS)

    Heuristic optimization algorithms have become a popular choice for solving complex and intricate sensor placement problems which are difficult to solve by traditional methods. This paper proposes a novel and interesting methodology called the asynchronous-climb monkey algorithm (AMA) for the optimum design of sensor arrays for a structural health monitoring system. Different from the existing algorithms, the dual-structure coding method is designed and adopted for the representation of the design variables. The asynchronous-climb process is incorporated in the proposed AMA that can adjust the trajectory of each individual dynamically in the search space according to its own experience and other monkeys. The concept of ‘monkey king’ is introduced in the AMA, which reflects the Darwinian principle of natural selection and can create an interaction network to correctly guide the movement of other monkeys. Numerical experiments are carried out using two different objective functions by considering the Canton Tower in China with or without the antenna mast to evaluate the performance of the proposed algorithm. Investigations have indicated that the proposed AMA exhibits faster convergence characteristics and can generate sensor configurations superior in all instances when compared to the conventional monkey algorithm. For structures with stiffness mutation such as the Canton Tower, the sensor placement needs to be considered for each part separately. (paper)

  18. Asynchronous Amazon forest canopy phenology indicates adaptation to both water and light availability

    International Nuclear Information System (INIS)

    Amazon forests represent nearly half of all tropical vegetation biomass and, through photosynthesis and respiration, annually process more than twice the amount of estimated carbon (CO2) from fossil fuel emissions. Yet the seasonality of Amazon canopy cover, and the extent to which seasonal fluctuations in water availability and photosynthetically available radiation influence these processes, is still poorly understood. Implementing six remotely sensed data sets spanning nine years (2003–2011), with reported field and flux tower data, we show that southern equatorial Amazon forests exhibit a distinctive seasonal signal. Seasonal timing of water availability, canopy biomass growth and net leaf flush are asynchronous in regions with short dry seasons and become more synchronous across a west-to-east longitudinal moisture gradient of increasing dry season. Forest cover is responsive to seasonal disparities in both water and solar radiation availability, temporally adjusting net leaf flush to maximize use of these generally abundant resources, while reducing drought susceptibility. An accurate characterization of this asynchronous behavior allows for improved understanding of canopy phenology across contiguous tropical forests and their sensitivity to climate variability and drought. (letter)

  19. An Autonomous Wireless Sensor Node With Asynchronous ECG Monitoring in 0.18 μ m CMOS.

    Science.gov (United States)

    Mansano, Andre L; Li, Yongjia; Bagga, Sumit; Serdijn, Wouter A

    2016-06-01

    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. PMID:26812734

  20. Data-Aware Retrodiction for Asynchronous Harmonic Measurement in a Cyber-Physical Energy System.

    Science.gov (United States)

    Liu, Youda; Wang, Xue; Liu, Yanchi; Cui, Sujin

    2016-08-18

    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.

  1. Fuzzy delay model based fault simulator for crosstalk delay fault test generation in asynchronous sequential circuits

    Indian Academy of Sciences (India)

    S Jayanthy; M C Bhuvaneswari

    2015-02-01

    In this paper, a fuzzy delay model based crosstalk delay fault simulator is proposed. As design trends move towards nanometer technologies, more number of new parameters affects the delay of the component. Fuzzy delay models are ideal for modelling the uncertainty found in the design and manufacturing steps. The fault simulator based on fuzzy delay detects unstable states, oscillations and non-confluence of settling states in asynchronous sequential circuits. The fuzzy delay model based fault simulator is used to validate the test patterns produced by Elitist Non-dominated sorting Genetic Algorithm (ENGA) based test generator, for detecting crosstalk delay faults in asynchronous sequential circuits. The multi-objective genetic algorithm, ENGA targets two objectives of maximizing fault coverage and minimizing number of transitions. Experimental results are tabulated for SIS benchmark circuits for three gate delay models, namely unit delay model, rise/fall delay model and fuzzy delay model. Experimental results indicate that test validation using fuzzy delay model is more accurate than unit delay model and rise/fall delay model.

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

    Directory of Open Access Journals (Sweden)

    Takeshi eSakurada

    2013-09-01

    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.

  3. Asynchronous data change notification between database server and accelerator control systems

    International Nuclear Information System (INIS)

    Database data change notification (DCN) is a commonly used feature, it allows to be informed when the data has been changed on the server side by another client. Not all database management systems (DBMS) provide an explicit DCN mechanism. Even for those DBMS's which support DCN (such as Oracle and MS SQL server), some server side and/or client side programming may be required to make the DCN system work. This makes the setup of DCN between database server and interested clients tedious and time consuming. In accelerator control systems, there are many well established software client/server architectures (such as CDEV, EPICS, and ADO) that can be used to implement data reflection servers that transfer data asynchronously to any client using the standard SET/GET API. This paper describes a method for using such a data reflection server to set up asynchronous DCN (ADCN) between a DBMS and clients. This method works well for all DBMS systems which provide database trigger functionality. (authors)

  4. Simple and Flexible Self-Reproducing Structures in Asynchronous Cellular Automata and Their Dynamics

    Science.gov (United States)

    Huang, Xin; Lee, Jia; Yang, Rui-Long; Zhu, Qing-Sheng

    2013-03-01

    Self-reproduction on asynchronous cellular automata (ACAs) has attracted wide attention due to the evident artifacts induced by synchronous updating. Asynchronous updating, which allows cells to undergo transitions independently at random times, might be more compatible with the natural processes occurring at micro-scale, but the dark side of the coin is the increment in the complexity of an ACA in order to accomplish stable self-reproduction. This paper proposes a novel model of self-timed cellular automata (STCAs), a special type of ACAs, where unsheathed loops are able to duplicate themselves reliably in parallel. The removal of sheath cannot only allow various loops with more flexible and compact structures to replicate themselves, but also reduce the number of cell states of the STCA as compared to the previous model adopting sheathed loops [Y. Takada, T. Isokawa, F. Peper and N. Matsui, Physica D227, 26 (2007)]. The lack of sheath, on the other hand, often tends to cause much more complicated interactions among loops, when all of them struggle independently to stretch out their constructing arms at the same time. In particular, such intense collisions may even cause the emergence of a mess of twisted constructing arms in the cellular space. By using a simple and natural method, our self-reproducing loops (SRLs) are able to retract their arms successively, thereby disentangling from the mess successfully.

  5. Structural elements that underlie Doc2β function during asynchronous synaptic transmission.

    Science.gov (United States)

    Xue, Renhao; Gaffaney, Jon D; Chapman, Edwin R

    2015-08-01

    Double C2-like domain-containing proteins alpha and beta (Doc2α and Doc2β) are tandem C2-domain proteins proposed to function as Ca(2+) sensors for asynchronous neurotransmitter release. Here, we systematically analyze each of the negatively charged residues that mediate binding of Ca(2+) to the β isoform. The Ca(2+) ligands in the C2A domain were dispensable for Ca(2+)-dependent translocation to the plasma membrane, with one exception: neutralization of D220 resulted in constitutive translocation. In contrast, three of the five Ca(2+) ligands in the C2B domain are required for translocation. Importantly, translocation was correlated with the ability of the mutants to enhance asynchronous release when overexpressed in neurons. Finally, replacement of specific Ca(2+)/lipid-binding loops of synaptotagmin 1, a Ca(2+) sensor for synchronous release, with corresponding loops from Doc2β, resulted in chimeras that yielded slower kinetics in vitro and slower excitatory postsynaptic current decays in neurons. Together, these data reveal the key determinants of Doc2β that underlie its function during the slow phase of synaptic transmission. PMID:26195798

  6. Data-Aware Retrodiction for Asynchronous Harmonic Measurement in a Cyber-Physical Energy System

    Directory of Open Access Journals (Sweden)

    Youda Liu

    2016-08-01

    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.

  7. Data-Aware Retrodiction for Asynchronous Harmonic Measurement in a Cyber-Physical Energy System.

    Science.gov (United States)

    Liu, Youda; Wang, Xue; Liu, Yanchi; Cui, Sujin

    2016-01-01

    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. PMID:27548171

  8. Visual and Auditory Components in the Perception of Asynchronous Audiovisual Speech.

    Science.gov (United States)

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

    2015-12-01

    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.

  9. Global Exponential Stability for Complex-Valued Recurrent Neural Networks With Asynchronous Time Delays.

    Science.gov (United States)

    Liu, Xiwei; Chen, Tianping

    2016-03-01

    In this paper, we investigate the global exponential stability for complex-valued recurrent neural networks with asynchronous time delays by decomposing complex-valued networks to real and imaginary parts and construct an equivalent real-valued system. The network model is described by a continuous-time equation. There are two main differences of this paper with previous works: 1) time delays can be asynchronous, i.e., delays between different nodes are different, which make our model more general and 2) we prove the exponential convergence directly, while the existence and uniqueness of the equilibrium point is just a direct consequence of the exponential convergence. Using three generalized norms, we present some sufficient conditions for the uniqueness and global exponential stability of the equilibrium point for delayed complex-valued neural networks. These conditions in our results are less restrictive because of our consideration of the excitatory and inhibitory effects between neurons; so previous works of other researchers can be extended. Finally, some numerical simulations are given to demonstrate the correctness of our obtained results.

  10. THE RESEARCH OF GRADATION FUSION ALGORITHM BASED ON MULTISENSOR ASYNCHRONOUS SAMPLING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This letter explores the distributed multisensor dynamic system, which has uniform sampling velocity and asynchronous sampling data for different sensors, and puts forward a new gradation fusion algorithm of multisensor dynamic system. As the total forecasted increment value between the two adjacent moments is the forecasted estimate value of the corresponding state increment in the fusion center, the new algorithm models the state and the forecasted estimate value of every moment. Kalman filter and all measurements arriving sequentially in the fusion period are employed to update the evaluation of target state step by step, on the condition that the system has obtained the target state evaluation that is based on the overall information in the previous fusion period. Accordingly, in the present period, the fusion evaluation of the target state at each sampling point on the basis of the overall information can be obtained. This letter elaborates the form of this new algorithm. Computer simulation demonstrates that this new algorithm owns greater precision in estimating target state than the present asynchronous fusion algorithm calibrated in time does.

  11. An asynchronous pipeline architecture for the low-power AES S-box

    Institute of Scientific and Technical Information of China (English)

    Zeng Yonghong; Zou Xuecheng; Liu Zhenglin

    2008-01-01

    To obtain a low-power and compact implementation of the advanced encryption standard (AES) S-box, an asynchronous pipeline architecture over composite field arithmetic was proposed in this paper. In the presented S-box, some improvements were made as follows. (1) Level-sensitive latches were inserted in data path to block the propagation of the dynamic hazards, which lowered the power of data path circuit. (2) Operations of latches were controlled by latch controllers based on presented asynchronous sequence element: LC-element, which utilized static asymmetric C-element to construct a simple and power-efficient circuit structure. (3) Implementation of the data path circuit was a semi-custom standard-cell circuit on 0.25μm complementary mental oxide semiconductor (CMOS) process; and the full-custom design methodology was adopted in the handshake circuit design. Experimental results show that the resulting circuit achieves nearly 46% improvement with moderate area penalty (11.7%) compared with the related composite field S-box in power performance. The presented S-box circuit can be a hardware intelligent property (IP) embedded in the targeted systems such as wireless sensor networks (WSN), smartcards and radio frequency identification (RFID).

  12. Modifying Dialogical Strategy in Asynchronous Critical Discussions for Cross-Strait Chinese Learners

    Directory of Open Access Journals (Sweden)

    Jean Yiching Chiu

    2014-09-01

    Full Text Available In this global era, critical thinking has become crucial for educators and learners. The purpose of this research was to explore how modifying a dialogical strategy in asynchronous online discussion forums impacted Chinese learners’ critical thinking. Due to the Chinese cultural impact of social harmony, the majority of learners tend to maintain silent and avoid critical discussions in instructional settings. The author deployed an affectively supportive model in a modified dialogical strategy to structure Chinese EFL learners’ asynchronous critical postings by probing and questioning while requiring labeling of each cross-referencing posting as Agree/Disagree/Challenge/New Perspective. The participants were two cohorts of similar cultural background but under different political systems in China and Taiwan, here engaged together in cultural interactions. This study employed two research methods: standardized critical thinking tests, and focus groups. Findings reveal that learners in both cohorts indicated some improvement in their critical thinking skills. Nevertheless, there remain affective and cultural issues. Future studies are thus recommended to further investigate the potential of an adaptive model to engage critical discussions with English native speakers and optimize critical thinking for Chinese learners in an EFL environment.

  13. Data-Aware Retrodiction for Asynchronous Harmonic Measurement in a Cyber-Physical Energy System

    Science.gov (United States)

    Liu, Youda; Wang, Xue; Liu, Yanchi; Cui, Sujin

    2016-01-01

    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. PMID:27548171

  14. Electric vehicle motors and controllers

    Science.gov (United States)

    Secunde, R. R.

    1981-01-01

    Improved and advanced components being developed include electronically commutated permanent magnet motors of both drum and disk configuration, an unconventional brush commutated motor, and ac induction motors and various controllers. Test results on developmental motors, controllers, and combinations thereof indicate that efficiencies of 90% and higher for individual components, and 80% to 90% for motor/controller combinations can be obtained at rated power. The simplicity of the developmental motors and the potential for ultimately low cost electronics indicate that one or more of these approaches to electric vehicle propulsion may eventually displace presently used controllers and brush commutated dc motors.

  15. Markov Process of Muscle Motors

    CERN Document Server

    Kondratiev, Yu; Pirogov, S

    2007-01-01

    We study a Markov random process describing a muscle molecular motor behavior. Every motor is either bound up with a thin filament or unbound. In the bound state the motor creates a force proportional to its displacement from the neutral position. In both states the motor spend an exponential time depending on the state. The thin filament moves at its velocity proportional to average of all displacements of all motors. We assume that the time which a motor stays at the bound state does not depend on its displacement. Then one can find an exact solution of a non-linear equation appearing in the limit of infinite number of the motors.

  16. Shape memory alloy based motor

    Indian Academy of Sciences (India)

    S V Sharma; M M Nayak; N S Dinesh

    2008-10-01

    Design and characterization of a new shape memory alloy wire based Poly Phase Motor has been reported in this paper. The motor can be used either in stepping mode or in servo mode of operation. Each phase of the motor consists of an SMA wire with a spring in series. The principle of operation of the poly phase motor is presented. The motor resembles a stepper motor in its functioning though the actuation principles are different and hence has been characterized similar to a stepper motor. The motor can be actuated in either direction with different phase sequencing methods, which are presented in this work. The motor is modelled and simulated and the results of simulations and experiments are presented. The experimental model of the motor is of dimension 150 mm square, 20 mm thick and uses SMA wire of 0·4 mm diameter and 125 mm of length in each phase.

  17. A New Type of Motor: Pneumatic Step Motor.

    Science.gov (United States)

    Stoianovici, Dan; Patriciu, Alexandru; Petrisor, Doru; Mazilu, Dumitru; Kavoussi, Louis

    2007-02-01

    This paper presents a new type of pneumatic motor, a pneumatic step motor (PneuStep). Directional rotary motion of discrete displacement is achieved by sequentially pressurizing the three ports of the motor. Pulsed pressure waves are generated by a remote pneumatic distributor. The motor assembly includes a motor, gearhead, and incremental position encoder in a compact, central bore construction. A special electronic driver is used to control the new motor with electric stepper indexers and standard motion control cards. The motor accepts open-loop step operation as well as closed-loop control with position feedback from the enclosed sensor. A special control feature is implemented to adapt classic control algorithms to the new motor, and is experimentally validated. The speed performance of the motor degrades with the length of the pneumatic hoses between the distributor and motor. Experimental results are presented to reveal this behavior and set the expectation level. Nevertheless, the stepper achieves easily controllable precise motion unlike other pneumatic motors. The motor was designed to be compatible with magnetic resonance medical imaging equipment, for actuating an image-guided intervention robot, for medical applications. For this reason, the motors were entirely made of nonmagnetic and dielectric materials such as plastics, ceramics, and rubbers. Encoding was performed with fiber optics, so that the motors are electricity free, exclusively using pressure and light. PneuStep is readily applicable to other pneumatic or hydraulic precision-motion applications. PMID:21528106

  18. How People Learn in an Asynchronous Online Learning Environment: The Relationships between Graduate Students' Learning Strategies and Learning Satisfaction

    Science.gov (United States)

    Choi, Beomkyu

    2016-01-01

    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…

  19. 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)

    Ion VONCILA

    2003-12-01

    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.

  20. Developing Students' Metacognitive Awareness in Asynchronous Learning Networks in Comparison to Face-to-Face Discussion Groups

    Science.gov (United States)

    Michalsky, Tova; Zion, Michal; Mevarech, Zemira R.

    2007-01-01

    The main goal of the present study is to investigate empirically the effects of Asynchronic Learning Network (ALN) embedded within metacognitive instruction (META) on two components of metacognitive awareness: Knowledge about Cognition (KC) and Regulation of Cognition (RC). Participants were 202 tenth grade students: 102 students who studied under…

  1. Minimizing asynchronism to improve the performances of anaerobic co-digestion of food waste and corn stover.

    Science.gov (United States)

    Zhou, Qi; Shen, Fei; Yuan, Hairong; Zou, Dexun; Liu, Yanping; Zhu, Baoning; Jaffu, Muhanmad; Chufo, Akiber; Li, Xiujin

    2014-08-01

    To investigate the existence of the asynchronism during the anaerobic co-digestion of different substrates, two typical substrates of food waste and corn stover were anaerobically digested with altering organic loadings (OL). The results indicated that the biodegradability of food waste and corn stover was calculated to be 81.5% and 55.1%, respectively, which was main reason causing the asynchronism in the co-digestion. The asynchronism was minimized by NaOH-pretreatment for corn stover, which could improve the biodegradability by 36.6%. The co-digestion with pretreatment could increase the biomethane yield by 12.2%, 3.2% and 0.6% comparing with the co-digestion without pretreatment at C/N ratios of 20, 25 and 30 at OL of 35 g-VS/L, respectively. The results indicated that the digestibility synchronism of food waste and corn stover was improved through enhancing the accessibility and digestibility of corn stover. The biomethane production could be increased by minimizing the asynchronism of two substrates in co-digestion.

  2. Participant Approaches to and Reflections on Learning to Play a 12-Bar Blues in an Asynchronous E-Learning Environment

    Science.gov (United States)

    Seddon, Frederick; Biasutti, Michele

    2009-01-01

    This study investigated the viability of learning to play an improvised 12-bar blues on keyboard with both hands together in an asynchronous e-learning environment. The study also sought to reveal participant approaches to and reflections on this learning experience. Participants were video-taped as they engaged with six "Blues Activities",…

  3. Asynchronous Conferencing with a Twist of Synchronicity: In Search for Tools for Collaborative Moderation in Online Discussions.

    Science.gov (United States)

    Hietala, Pentti; Koivunen, Kimmo

    Carrying out argumentative discussion online has become rather common in higher education. This task is traditionally supported by asynchronous collaboration tools, but this paper suggests that also synchronous supports could be useful. This paper focuses on scaffolding the knowledge construction: the work of two student moderators jointly…

  4. Facilitation Prompts and Rubrics on Higher-Order Thinking Skill Performance Found in Undergraduate Asynchronous Discussion Boards

    Science.gov (United States)

    Giacumo, Lisa A.; Savenye, Wilhelmina; Smith, Nichole

    2013-01-01

    Over the past 20 years, researchers have begun to examine data from asynchronous computer-mediated student discussions in courses. Some results have shown students to demonstrate lower or mid-level thinking skills, while others suggest students routinely demonstrate higher-order thinking skills. The authors investigated the relationship between…

  5. An Analysis of Peer-Submitted and Peer-Reviewed Answer Rationales, in an Asynchronous Peer Instruction Based Learning Environment

    Science.gov (United States)

    Bhatnagar, Sameer; Lasry, Nathaniel; Desmarais, Michel; Dugdale, Michael; Whittaker, Chris; Charles, Elizabeth S.

    2015-01-01

    This paper reports on an analyis of data from a novel "Peer Instruction" application, named DALITE. The Peer Instruction paradigm is well suited to take advantage of peer-input in web-based learning environments. DALITE implements an asynchronous instantiation of peer instruction: after submitting their answer to a multiple-choice…

  6. The Effect of Asynchronous/Synchronous Approaches on English Vocabulary Achievement: A Study of Iranian EFL Learners

    Science.gov (United States)

    Khodaparast, Fatemeh; Ghafournia, Narjes

    2015-01-01

    The contribution of computer-assisted instructional programs to language learning process has been the focus of researchers for about two decades. However, the effect of synchronous and asynchronous computer-assisted approaches of language teaching on improving L2 vocabulary has been scarcely investigated. This study explored whether synchronous,…

  7. 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

    2007-01-01

    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 sett

  8. 应用于风力发电机的永磁双转子电机%Permanent Magnet Double Rotor Motor used in Wind Power Generator

    Institute of Scientific and Technical Information of China (English)

    孙屹东; 黄坚

    2015-01-01

    Permanent magnet double rotor motor is a kind of novel composite motor, composed of a stator and the inner, outer two rotors, the motor has the characteristics of asynchronous motor and synchronous motor. Based on the characteristics of double rotor permanent magnet motor, it was used in wind power generation system. Compared with the traditional wind power system, this motor is simple, easy maintenance and other advantages. And this motor can improve the power factor of power generation system, efficiency and reliability, and obviously reduce the investment cost of wind power generation system etc.%永磁双转子电机是由一个定子和内、外二个转子构成的新颖的复合电机,该电机具有异步电动机运行的特点,且兼顾同步电机的电气特性。基于永磁双转子电机这一特点,应用于风力发电机,与传统的风力发电系统相比,具有发电系统简单、维护方便等优势,同时可提高发电系统的功率因数、效率和可靠性,并可明显降低风力发电系统的投资费用等。

  9. Advanced AC Motor Control

    Energy Technology Data Exchange (ETDEWEB)

    Kazmierkowski, M.P. [Institute of Control and Industrial Electronics, Warsaw University of Technology, Warszawa (Poland)

    1997-12-31

    In this paper a review of control methods for high performance PWM inverter-fed induction motor drives is presented. Starting from the description of an induction motor by the help of the space vectors, three basic control strategic are discussed. As first, the most popular Field Oriented Control (FOC) is described. Secondly, the Direct Torque and Flux vector Control (DTFC) method, which - in contrast to FOC - depart from idea of coordinate transformation and analogy with DC motor, is briefly characterized. The last group is based on Feedback Linearization Control (FLC) and can be easy combined with sliding mode control. The simulation and experimental oscillograms that illustrate the performance of the discussed control strategies are shown. (orig.) 35 refs.

  10. Flood-proof motors

    International Nuclear Information System (INIS)

    Even before the Fukushima event occurred some German nuclear power plants (NPP) have considered flooding scenarios. As a result of one of these studies, AREVA performed an upgrade project in NPP Isar 1 with flood-proof motors as a replacement of existing air-cooled low-voltage and high-voltage motors of the emergency cooling chain. After the Fukushima event, in which the cooling chains failed, the topic flood-proof equipment gets more and more into focus. This compact will introduce different kinds of flood-proof electrical motors which are currently installed or planned for installation into NPPs over the world. Moreover the process of qualification, as it was performed during the project in NPP Isar 1, will be shown. (orig.)

  11. Mechanical design of electric motors

    CERN Document Server

    Tong, Wei

    2014-01-01

    Rapid increases in energy consumption and emphasis on environmental protection have posed challenges for the motor industry, as has the design and manufacture of highly efficient, reliable, cost-effective, energy-saving, quiet, precisely controlled, and long-lasting electric motors.Suitable for motor designers, engineers, and manufacturers, as well as maintenance personnel, undergraduate and graduate students, and academic researchers, Mechanical Design of Electric Motors provides in-depth knowledge of state-of-the-art design methods and developments of electric motors. From motor classificati

  12. Step Motor Control System

    Institute of Scientific and Technical Information of China (English)

    ZhangShuochengt; WangDan; QiaoWeimin; JingLan

    2003-01-01

    All kinds of step motors and servomotors are widely used in CSR control system, such as many vacuum valves control that set on the HIRFL-CSR; all kinds of electric switches and knobs of ECR Ion Source; equipment of CSR Beam Diagnostics and a lot of large equipment like Inside Gun Toroid and Collector Toroid of HIRFL. A typical control system include up to 32 16-I/O Control boards, and each 16-I/O Control board can control 4 motors at the same time (including 8 Limit Switches).

  13. Transformers and motors

    CERN Document Server

    Shultz, George

    1991-01-01

    Transformers and Motors is an in-depth technical reference which was originally written for the National Joint Apprenticeship Training Committee to train apprentice and journeymen electricians. This book provides detailed information for equipment installation and covers equipment maintenance and repair. The book also includes troubleshooting and replacement guidelines, and it contains a minimum of theory and math.In this easy-to-understand, practical sourcebook, you'll discover:* Explanations of the fundamental concepts of transformers and motors* Transformer connections and d

  14. The functional alterations associated with motor imagery training: a comparison between motor execution and motor imagery of sequential finger tapping

    Science.gov (United States)

    Zhang, Hang; Yao, Li; Long, Zhiying

    2011-03-01

    Motor imagery training, as an effective strategy, has been more and more applied to mental disorders rehabilitation and motor skill learning. Studies on the neural mechanism underlying motor imagery have suggested that such effectiveness may be related to the functional congruence between motor execution and motor imagery. However, as compared to the studies on motor imagery, the studies on motor imagery training are much fewer. The functional alterations associated with motor imagery training and the effectiveness of motor imagery training on motor performance improvement still needs further investigation. Using fMRI, we employed a sequential finger tapping paradigm to explore the functional alterations associated with motor imagery training in both motor execution and motor imagery task. We hypothesized through 14 consecutive days motor imagery training, the motor performance could be improved and the functional congruence between motor execution and motor imagery would be sustained form pre-training phase to post-training phase. Our results confirmed the effectiveness of motor imagery training in improving motor performance and demonstrated in both pre and post-training phases, motor imagery and motor execution consistently sustained the congruence in functional neuroanatomy, including SMA (supplementary motor cortex), PMA (premotor area); M1( primary motor cortex) and cerebellum. Moreover, for both execution and imagery tasks, a similar functional alteration was observed in fusiform through motor imagery training. These findings provided an insight into the effectiveness of motor imagery training and suggested its potential therapeutic value in motor rehabilitation.

  15. Vectorial Command of Induction Motor Pumping System Supplied by a Photovoltaic Generator

    Science.gov (United States)

    Makhlouf, Messaoud; Messai, Feyrouz; Benalla, Hocine

    2011-01-01

    With the continuous decrease of the cost of solar cells, there is an increasing interest and needs in photovoltaic (PV) system applications following standard of living improvements. Water pumping system powered by solar-cell generators are one of the most important applications. The fluctuation of solar energy on one hand, and the necessity to optimise available solar energy on the other, it is useful to develop new efficient and flexible modes to control motors that entrain the pump. A vectorial control of an asynchronous motor fed by a photovoltaic system is proposed. This paper investigates a photovoltaic-electro mechanic chain, composed of a PV generator, DC-AC converter, a vector controlled induction motor and centrifugal pump. The PV generator is forced to operate at its maximum power point by using an appropriate search algorithm integrated in the vector control. The optimization is realized without need to adding a DC-DC converter to the chain. The motor supply is also ensured in all insolation conditions. Simulation results show the effectiveness and feasibility of such an approach.

  16. Tuning Multiple Motor Travel Via Single Motor Velocity

    Science.gov (United States)

    Xu, Jing; Shu, Zhanyong; King, Stephen J.; Gross, Steven P.

    2012-01-01

    Microtubule-based molecular motors often work in small groups to transport cargos in cells. A key question in understanding transport (and its regulation in vivo) is to identify the sensitivity of multiple-motor-based motion to various single molecule properties. Whereas both single-motor travel distance and microtubule binding rate have been demonstrated to contribute to cargo travel, the role of single-motor velocity is yet to be explored. Here, we recast a previous theoretical study, and make explicit a potential contribution of velocity to cargo travel. We test this possibility experimentally, and demonstrate a strong negative correlation between single-motor velocity and cargo travel for transport driven by two motors. Our study thus discovers a previously unappreciated role of single-motor velocity in regulating multiple-motor transport. PMID:22672518

  17. DESIGN OF A LOW LATENCY ASYNCHRONOUS ADDER USING EARLY COMPLETION DETECTION

    Directory of Open Access Journals (Sweden)

    KOK KEONG LAI

    2014-12-01

    Full Text Available A new method for designing completion detection for asynchronous adders is introduced. The new completion detection is based on the property of a carrymerge tree for parallel-prefix adders where a generate bit at one level will have the same value as that in the previous level if there is no carry into the sequence of bits. This method has the advantages of a bundled data approach, allowing the use of single-rail completion detection design methodology, yet it allows the detection of early completion with very minimal gate count overhead. An alternative to "speculative completion," this method has approximately 10% improvement in performance at the costs of a 4% increase in area and a negligible increase in power consumption for Hybrid Skalansky Carry-Select and self-timed Kogge-Stone parallel prefix adders.

  18. Wind-powered asynchronous AC/DC/AC converter system. [for electric power supply regulation

    Science.gov (United States)

    Reitan, D. K.

    1973-01-01

    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.

  19. 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)

    2009-12-15

    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.

  20. A theoretical study on the water-mediated asynchronous addition between urea and formaldehyde

    Institute of Scientific and Technical Information of China (English)

    Tao-Hong Li; Xiao-Guang Xie; Guan-Ben Du

    2013-01-01

    The reaction between urea and formaldehyde in water solution was theoretically investigated by using B3LYP and MP2 methods,It was found that the addition of the nitrogen atom in urea to the carbonyl group in formaldehyde precedes the proton transfer and the proton migration from water to the carbonyl group occurs before the proton abstraction from the nitrogen,With one or two water molecules involved in the TS,the activation energy barrier is lowered compared to the TS of the mechanism with no water participation.The energy change along the reaction coordinate clearly shows that a zwitterionic-like intermediate does not exist on the PES.The reaction between urea and formaldehyde occurs in a concerted mechanism but with asynchronous characters.This is different from the stepwise mechanism recently found for the amination reactions of formaldehyde.