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Sample records for asynchronous neuro-osseous growth

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-15

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

  2. Relative shortening and functional tethering of spinal cord in adolescent scoliosis - Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE.

    Science.gov (United States)

    Chu, Winnie Cw; Lam, Wynnie Mw; Ng, Bobby Kw; Tze-Ping, Lam; Lee, Kwong-Man; Guo, Xia; Cheng, Jack Cy; Burwell, R Geoffrey; Dangerfield, Peter H; Jaspan, Tim

    2008-01-01

    There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine the spinal cord to vertebral growth interaction during adolescence in scoliosis. Using the multi-planar reconstruction technique of magnetic resonance imaging they investigated the relative length of spinal cord to vertebral column including ratios in 28 girls with AIS (mainly thoracic or double major curves) and 14 age-matched normal girls. Also evaluated were cerebellar tonsillar position, somatosensory evoked potentials (SSEPs), and clinical neurological examination. In severe AIS compared with normal controls, the vertebral column is significantly longer without detectable spinal cord lengthening. They speculate that anterior spinal column overgrowth relative to a normal length spinal cord exerts a stretching tethering force between the two ends, cranially and caudally leading to the initiation and progression of thoracic AIS. They support and develop the Roth-Porter concept of uncoupled neuro-osseous growth in the pathogenesis of AIS which now they prefer to term 'asynchronous neuro-osseous growth'. Morphological evidence about the curve apex suggests that the spinal cord is also affected, and a 'double pathology' is suggested. AIS is viewed as a disorder with a wide spectrum and a common neuroanatomical abnormality namely, a spinal cord of normal length but short relative to an abnormally lengthened anterior vertebral column. Neuroanatomical changes and/or abnormal neural function may be expressed only in severe cases. This asynchronous neuro-osseous growth concept is regarded as

  3. Relative shortening and functional tethering of spinal cord in adolescent scoliosis – Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE

    Science.gov (United States)

    Chu, Winnie CW; Lam, Wynnie MW; Ng, Bobby KW; Tze-ping, Lam; Lee, Kwong-man; Guo, Xia; Cheng, Jack CY; Burwell, R Geoffrey; Dangerfield, Peter H; Jaspan, Tim

    2008-01-01

    There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine the spinal cord to vertebral growth interaction during adolescence in scoliosis. Using the multi-planar reconstruction technique of magnetic resonance imaging they investigated the relative length of spinal cord to vertebral column including ratios in 28 girls with AIS (mainly thoracic or double major curves) and 14 age-matched normal girls. Also evaluated were cerebellar tonsillar position, somatosensory evoked potentials (SSEPs), and clinical neurological examination. In severe AIS compared with normal controls, the vertebral column is significantly longer without detectable spinal cord lengthening. They speculate that anterior spinal column overgrowth relative to a normal length spinal cord exerts a stretching tethering force between the two ends, cranially and caudally leading to the initiation and progression of thoracic AIS. They support and develop the Roth-Porter concept of uncoupled neuro-osseous growth in the pathogenesis of AIS which now they prefer to term 'asynchronous neuro-osseous growth'. Morphological evidence about the curve apex suggests that the spinal cord is also affected, and a 'double pathology' is suggested. AIS is viewed as a disorder with a wide spectrum and a common neuroanatomical abnormality namely, a spinal cord of normal length but short relative to an abnormally lengthened anterior vertebral column. Neuroanatomical changes and/or abnormal neural function may be expressed only in severe cases. This asynchronous neuro-osseous growth concept is regarded as

  4. Relative shortening and functional tethering of spinal cord in adolescent scoliosis – Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE

    Directory of Open Access Journals (Sweden)

    Burwell R Geoffrey

    2008-06-01

    Full Text Available Abstract There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS. As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE introduced the electronic focus group (EFG as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine the spinal cord to vertebral growth interaction during adolescence in scoliosis. Using the multi-planar reconstruction technique of magnetic resonance imaging they investigated the relative length of spinal cord to vertebral column including ratios in 28 girls with AIS (mainly thoracic or double major curves and 14 age-matched normal girls. Also evaluated were cerebellar tonsillar position, somatosensory evoked potentials (SSEPs, and clinical neurological examination. In severe AIS compared with normal controls, the vertebral column is significantly longer without detectable spinal cord lengthening. They speculate that anterior spinal column overgrowth relative to a normal length spinal cord exerts a stretching tethering force between the two ends, cranially and caudally leading to the initiation and progression of thoracic AIS. They support and develop the Roth-Porter concept of uncoupled neuro-osseous growth in the pathogenesis of AIS which now they prefer to term 'asynchronous neuro-osseous growth'. Morphological evidence about the curve apex suggests that the spinal cord is also affected, and a 'double pathology' is suggested. AIS is viewed as a disorder with a wide spectrum and a common neuroanatomical abnormality namely, a spinal cord of normal length but short relative to an abnormally lengthened anterior vertebral column. Neuroanatomical changes and/or abnormal neural function may be expressed only in severe cases. This asynchronous neuro-osseous growth

  5. Uncoupled neuro-osseous growth in adolescent idiopathic scoliosis? A preliminary study of 90 adolescents with whole-spine three-dimensional magnetic resonance imaging.

    Science.gov (United States)

    Lao, Li-Feng; Shen, Jian-Xiong; Chen, Zheng-Guang; Wang, Yi-Peng; Wen, Xi-Sheng; Qiu, Gui-Xing

    2011-07-01

    Previous literatures revealed abnormal cross-sectional morphology of spinal cord in AIS, suggesting the presence of disproportional growth between the neural and skeletal system. No accurate measurement of whole spine by MRI multiplanar reconstruction and their correlation with Cobb angle were studied. In this study, MRI three-dimensional reconstruction of the whole spine was performed in 90 adolescents (49 AIS with thoracic/thoracolumbar curve, and 41 age-matched healthy controls). Measurements of the ratio of anteroposterior (AP) and transverse (TS) diameter of the cord, the concave and convex lateral cord space (LCS) were obtained at the apical level in AIS patients. Cerebellar tonsillar level related to the basion-opsithion line, location of conus medullaris, cord length, vertebral column length, cord/vertebral column length ratio were obtained. All of the same parameters were also measured in healthy controls at matched vertebral levels and their correlations with Cobb angle were made. We notice that AP, TS, AP/TS and LCS ratio were increased in AIS subjects with low-lying position of cerebellar tonsillar level and elevating position of conus medullary when compared with healthy controls (P Cord length and vertebral column length were not significantly different between AIS and control group. However, cord/vertebral column length ratio was significantly smaller in AIS group (P Cord length, vertebral column length and cord/vertebral column length ratio were not related with age or Cobb angle (P > 0.05). These data suggest the presence of uncoupled neuro-osseous growth along the longitudinal axis of spinal cord with associated morphologic changes of cross-sectional configuration and relative position of the cord. Some changes are significantly relevant with Cobb angle, which may indicate pathogenesis of AIS. PMID:20552379

  6. Relative shortening and functional tethering of spinal cord in adolescent scoliosis – Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE

    OpenAIRE

    Burwell R Geoffrey; Cheng Jack CY; Guo Xia; Lee Kwong-man; Tze-ping Lam; Ng Bobby KW; Lam Wynnie MW; Chu Winnie CW; Dangerfield Peter H; Jaspan Tim

    2008-01-01

    Abstract There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine ...

  7. 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 ...

  8. Centriole Age Underlies Asynchronous Primary Cilium Growth in Mammalian Cells

    OpenAIRE

    Anderson, Charles T; Stearns, Tim

    2009-01-01

    Primary cilia are microtubule-based sensory organelles that are present in most mammalian tissues and play important roles in development and disease [1]. They are required for the Sonic hedgehog (Shh) [2-4] and PDGF [5] signalling pathways. Primary cilia grow from the older of the two centrioles of the centrosome, referred to as the mother centriole. In cycling cells the cilium typically grows in G1 and is lost before mitosis, but the regulation of its growth is poorly understood. Centriole ...

  9. VOLTAGE REGULATORS ASYNCHRONOUS GENERATORS

    OpenAIRE

    Grigorash O. V.; Bogatyrev N. I.; Hitskova A. O.

    2015-01-01

    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 m...

  10. 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.

  11. Assimilation of Synchronous and Asynchronous Active/Passive Microwave Observations at Different Spatial Scales for Improved Soil Moisture and Crop Growth

    Science.gov (United States)

    Judge, J.; Liu, P. W.; Monsivais-Huertero, A.; Steele-Dunne, S. C.; Bongiovanni, T. E.; Bindlish, R.; Jackson, T. J.

    2014-12-01

    Assimilation of active and passive (AP) microwave observations at L-band in the crop simulation models is able to improve estimates of soil moisture (SM) and crop growth in the models. These observations provide complementary information for dynamic heterogeneous landscapes. Active observations are more sensitive to soil surface roughness and vegetation structure, while passive observations are more sensitive to SM. These observations may be available at different spatial and temporal resolutions from different satellite platforms. For example, the present ESA Soil Moisture Ocean Salinity (SMOS) mission provides passive observations at 1.41 GHz at 25 km every 2-3 days, while the NASA/CONAE Aquarius mission provides L-band AP observations at spatial resolution of 150 km with a repeat coverage of 7 days for global SM products. The planned NASA Soil Moisture Active Passive mission (SMAP) will provide AP observations at 1.26 and 1.41 GHz at the spatial resolutions of 3 and 30 km, respectively, with a repeat coverage of 2-3 days, starting early 2015. The goal of this study is to develop an Ensemble Kalman Filter-based methodology that assimilates synchronously and asynchronously available backscattering coefficients (σ0) and brightness temperatures (TB) at different spatial scales from SMOS and Aquarius. The Decision Support System for Agrotechnology Transfer (DSSAT) that contains a suite of crop simulation models will be linked to microwave emission and scattering models (DSSAT-A-P) for the assimilation. The methodology will be implemented in the rain fed agricultural region of the Brazilian La Plata Basin in South America, where soybean is the primary crop. The augmented state vector will include both model states and parameters related to soil and vegetation during the growing season. The methodology will be evaluated using a synthetic experiment and also using observations from SMOS and Aquarius. In preliminary results with synthetic experiment, using asynchronous

  12. 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.

  13. 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

  14. Asynchronous Variational Contact Mechanics

    CERN Document Server

    Vouga, Etienne; Tamstorf, Rasmus; Grinspun, Eitan

    2010-01-01

    An asynchronous, variational method for simulating elastica in complex contact and impact scenarios is developed. Asynchronous Variational Integrators (AVIs) are extended to handle contact forces by associating different time steps to forces instead of to spatial elements. By discretizing a barrier potential by an infinite sum of nested quadratic potentials, these extended AVIs are used to resolve contact while obeying momentum- and energy-conservation laws. A series of two- and three-dimensional examples illustrate the robustness and good energy behavior of the method.

  15. 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.

  16. 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...

  17. 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.

  18. Asynchronous Multiparty Computation

    DEFF Research Database (Denmark)

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

    2009-01-01

    We propose an asynchronous protocol for general multiparty computation. The protocol has perfect security and communication complexity  where n is the number of parties, |C| is the size of the arithmetic circuit being computed, and k is the size of elements in the underlying field. The protocol...... multithreading. Benchmarking of a VIFF implementation of our protocol confirms that it is applicable to practical non-trivial secure computations....

  19. 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...

  20. Asynchronous Bounded Expected Delay Networks

    OpenAIRE

    Bakhshi, Rena; Endrullis, Jörg; Fokkink, Wan; Pang, Jun

    2010-01-01

    The commonly used asynchronous bounded delay (ABD) network models assume a fixed bound on message delay. We propose a probabilistic network model, called asynchronous bounded expected delay (ABE) model. Instead of a strict bound, the ABE model requires only a bound on the expected message delay. While the conditions of ABD networks restrict the set of possible executions, in ABE networks all asynchronous executions are possible, but executions with extremely long delays are less probable. In ...

  1. 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.

  2. 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

  3. Reducing energy with asynchronous circuits

    OpenAIRE

    Rivas Barragan, Daniel

    2012-01-01

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

  4. Asynchronous Distributed Searchlight Scheduling

    CERN Document Server

    Obermeyer, Karl J; Bullo, Francesco

    2011-01-01

    This paper develops and compares two simple asynchronous distributed searchlight scheduling algorithms for multiple robotic agents in nonconvex polygonal environments. A searchlight is a ray emitted by an agent which cannot penetrate the boundary of the environment. A point is detected by a searchlight if and only if the point is on the ray at some instant. Targets are points which can move continuously with unbounded speed. The objective of the proposed algorithms is for the agents to coordinate the slewing (rotation about a point) of their searchlights in a distributed manner, i.e., using only local sensing and limited communication, such that any target will necessarily be detected in finite time. The first algorithm we develop, called the DOWSS (Distributed One Way Sweep Strategy), is a distributed version of a known algorithm described originally in 1990 by Sugihara et al \\cite{KS-IS-MY:90}, but it can be very slow in clearing the entire environment because only one searchlight may slew at a time. In an ...

  5. Asynchronous interactive control systems

    Science.gov (United States)

    Vuskovic, M. I.; Heer, E.

    1980-01-01

    A class of interactive control systems is derived by generalizing interactive manipulator control systems. The general structural properties of such systems are discussed and an appropriate general software implementation is proposed. This is based on the fact that tasks of interactive control systems can be represented as a network of a finite set of actions which have specific operational characteristics and specific resource requirements, and which are of limited duration. This has enabled the decomposition of the overall control algorithm into a set of subalgorithms, called subcontrollers, which can operate simultaneously and asynchronously. Coordinate transformations of sensor feedback data and actuator set-points have enabled the further simplification of the subcontrollers and have reduced their conflicting resource requirements. The modules of the decomposed control system are implemented as parallel processes with disjoint memory space communicating only by I/O. The synchronization mechanisms for dynamic resource allocation among subcontrollers and other synchronization mechanisms are also discussed in this paper. Such a software organization is suitable for the general form of multiprocessing using computer networks with distributed storage.

  6. 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’.

  7. Starting with a handicap: effects of asynchronous hatching on growth rate, oxidative stress and telomere dynamics in free-living great tits.

    Science.gov (United States)

    Stier, Antoine; Massemin, Sylvie; Zahn, Sandrine; Tissier, Mathilde L; Criscuolo, François

    2015-12-01

    A trade-off between resource investment into growth rate and body self-maintenance is likely to occur, but the underlying molecular mediators of such a trade-off remain to be determined. In many altricial birds, hatching asynchrony creates a sibling competitive hierarchy within the brood, with first-hatched nestlings enjoying substantial advantages compared to last-hatched nestlings. We used this opportunity to test for a trade-off between growth and self-maintenance processes (oxidative stress, telomere erosion) in great tit nestlings, since resource availability and allocation are likely to differ between first-hatched and last-hatched nestlings. We found that despite their starting competitive handicap (i.e. being smaller/lighter before day 16), last-hatched nestlings exhibited growth rate and mass/size at fledging similar to first-hatched ones. However, last-hatched nestlings suffered more in terms of oxidative stress, and ended growth with shorter telomeres than first-hatched ones. Interestingly, growth rate was positively related to plasma antioxidant capacity and early life telomere length (i.e. at 7 days old), but among last-hatched nestlings, those exhibiting the faster body size growth were also those exhibiting the greatest telomere erosion. Last-hatched nestlings exhibited elevated levels of plasma testosterone (T), but only at day 7. T levels were positively associated with oxidative damage levels and plasma antioxidant capacity, the latter being only significant for first-hatched nestlings. Our results suggest that last-hatched nestlings present a specific trade-off between growth rate and self-maintenance processes, which is possibly driven by their need to compete with their older siblings and potentially mediated by elevated levels of T. PMID:26314343

  8. 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...

  9. Acquiring Knowledge from Asynchronous Discussion

    Science.gov (United States)

    Teo, Yiong Hwee; Webster, Len

    2008-01-01

    This article discusses a study which was designed to explore how online scaffolding can be incorporated to support knowledge acquisition in asynchronous discussion. A group of Singapore preservice teachers engaged in collaborative critiquing of videos before they embarked on their video projects to illustrate what constitutes good and bad video…

  10. Asynchronous sequential machine design and analysis

    CERN Document Server

    Tinder, Richard

    2009-01-01

    Asynchronous Sequential Machine Design and Analysis provides a lucid, in-depth treatment of asynchronous state machine design and analysis presented in two parts: Part I on the background fundamentals related to asynchronous sequential logic circuits generally, and Part II on self-timed systems, high-performance asynchronous programmable sequencers, and arbiters.Part I provides a detailed review of the background fundamentals for the design and analysis of asynchronous finite state machines (FSMs). Included are the basic models, use of fully documented state diagrams, and the design and charac

  11. 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 ...

  12. Asynchronous Anytime Sequential Monte Carlo

    OpenAIRE

    Paige, Brooks; Wood, Frank; Doucet, Arnaud; Teh, Yee Whye

    2014-01-01

    We introduce a new sequential Monte Carlo algorithm we call the particle cascade. The particle cascade is an asynchronous, anytime alternative to traditional particle filtering algorithms. It uses no barrier synchronizations which leads to improved particle throughput and memory efficiency. It is an anytime algorithm in the sense that it can be run forever to emit an unbounded number of particles while keeping within a fixed memory budget. We prove that the particle cascade is an unbiased mar...

  13. 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...

  14. GAMIFICATION IN ASYNCHRONOUS EDUCATION PROCESS

    Directory of Open Access Journals (Sweden)

    B. P. Dyakonov

    2016-03-01

    Full Text Available The author of the paper discourses on the prospects of education in the context of the global tendency towards informatization and virtualization of the modern world, influence of these processes on personalized senses of education and educational values and related problems of methodological and technological education in relation to the personalized meanings and educational values. Educational individualization is defined by the author as the most expected way of educational evolution. Distance learning is studied as the main example of the modern transformative educational model. Asynchronous education is explored and characterized as one of the distance learning examples. While defining what asynchronous distance learning is, the author explores its role in the specifics of forming a subject to subject educational approach, while forecasting difficulties in creating holistic asynchronous educational environment. Gamification techniques in the educational process are studied with their respective opportunities and threats, examples in grad and post grad professional studies are provided, including but not limited to foreign language studies. Addictiveness as the goal and means of a build in gamification process is explored as the way to bridge the gap between students and the educators. The author studies gamification in the context of minimizing negative connotations from the educational process, while controversies between pain and game approaches of getting knowledge are brought into light.

  15. Chromatin remodeling in plant cell culture: patterns of DNA methylation and histone H3 and H4 acetylation vary during growth of asynchronous potato cell suspensions.

    Science.gov (United States)

    Law, R David; Suttle, Jeffrey C

    2005-06-01

    Changes in DNA cytosine methylation and core histone multi-acetylation were determined in cell suspension cultures of potato (Solanum tuberosum L. cv. Russet Burbank) during 15 days of in vitro culture. Cell subculture induced a transient 33% decrease in genome-wide 5-methylcytosine (5mC) content and a transient threefold increase in transcription rates that were most evident at 6 and 9 days after subculture, respectively. In contrast to the global reduction in 5mC content, subculture resulted in a transient twofold increase in 5mC levels within 5'-CCGG-3' sequences and no detectable change in 5'-CG-3' methylation. Multi-acetylation of histones H3.1, H3.2 and H4 rose 2-, 1.5- and 3-fold by 9, 9 and 12 days after subculture, respectively. All observed epigenetic changes were reset during aging of cell cultures. Inclusion of the histone deacetylase inhibitor trichostatin A (TSA) and/or the cytosine methylation inhibitor 5-azacytidine (5AC) in culture sequentially decreased genome-wide 5mC levels by approximately 25% at day 9, then decreased 5'-mCmCGG-3' by 30-50% and increased H3 and H4 multi-acetylation by 30-60% at day 15, compared to controls. Treatment with 5AC or TSA alone or in combination had no effect on RNA synthesis at day 9. At day 15, 5AC treatment remained ineffective, while de novo RNA synthesis was approximately twofold higher in cells grown in both inhibitors or in TSA alone. Collectively, these results demonstrate that in potato suspension cultures, rapid, reversible changes in 5mC levels precede regulatory post-translational acetylation of core histones, and suggest that interactions between these epigenetic processes appear to be necessary to power transcription and growth induction in potato cells. PMID:15922608

  16. EXPLORING THE UNUSUALLY HIGH BLACK-HOLE-TO-BULGE MASS RATIOS IN NGC 4342 AND NGC 4291: THE ASYNCHRONOUS GROWTH OF BULGES AND BLACK HOLES

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, Akos; Forman, William R.; Kraft, Ralph P.; Li, Zhiyuan; Vikhlinin, Alexey; Nulsen, Paul E. J.; Jones, Christine [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Zhuravleva, Irina; Churazov, Eugene [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-str. 1, 85741 Garching bei Muenchen (Germany); Mihos, J. Christopher; Harding, Paul [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106 (United States); Guo, Qi [Partner Group of the Max Planck Institute for Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Schindler, Sabine, E-mail: abogdan@cfa.harvard.edu [Institut fuer Astro- und Teilchenphysik, Universitaet Innsbruck, Technikerstrasse 25, 6020 Innsbruck (Austria)

    2012-07-10

    We study two nearby early-type galaxies, NGC 4342 and NGC 4291, that host unusually massive black holes relative to their low stellar mass. The observed black-hole-to-bulge mass ratios of NGC 4342 and NGC 4291 are 6.9{sup +3.8}{sub -2.3}% and 1.9% {+-} 0.6%, respectively, which significantly exceed the typical observed ratio of {approx}0.2%. As a consequence of the exceedingly large black-hole-to-bulge mass ratios, NGC 4342 and NGC 4291 are Almost-Equal-To 5.1{sigma} and Almost-Equal-To 3.4{sigma} outliers from the M{sub .}-M{sub bulge} scaling relation, respectively. In this paper, we explore the origin of the unusually high black-hole-to-bulge mass ratio. Based on Chandra X-ray observations of the hot gas content of NGC 4342 and NGC 4291, we compute gravitating mass profiles, and conclude that both galaxies reside in massive dark matter halos, which extend well beyond the stellar light. The presence of dark matter halos around NGC 4342 and NGC 4291 and a deep optical image of the environment of NGC 4342 indicate that tidal stripping, in which {approx}> 90% of the stellar mass was lost, cannot explain the observed high black-hole-to-bulge mass ratios. Therefore, we conclude that these galaxies formed with low stellar masses, implying that the bulge and black hole did not grow in tandem. We also find that the black hole mass correlates well with the properties of the dark matter halo, suggesting that dark matter halos may play a major role in regulating the growth of the supermassive black holes.

  17. EXPLORING THE UNUSUALLY HIGH BLACK-HOLE-TO-BULGE MASS RATIOS IN NGC 4342 AND NGC 4291: THE ASYNCHRONOUS GROWTH OF BULGES AND BLACK HOLES

    International Nuclear Information System (INIS)

    We study two nearby early-type galaxies, NGC 4342 and NGC 4291, that host unusually massive black holes relative to their low stellar mass. The observed black-hole-to-bulge mass ratios of NGC 4342 and NGC 4291 are 6.9+3.8–2.3% and 1.9% ± 0.6%, respectively, which significantly exceed the typical observed ratio of ∼0.2%. As a consequence of the exceedingly large black-hole-to-bulge mass ratios, NGC 4342 and NGC 4291 are ≈5.1σ and ≈3.4σ outliers from the M.-Mbulge scaling relation, respectively. In this paper, we explore the origin of the unusually high black-hole-to-bulge mass ratio. Based on Chandra X-ray observations of the hot gas content of NGC 4342 and NGC 4291, we compute gravitating mass profiles, and conclude that both galaxies reside in massive dark matter halos, which extend well beyond the stellar light. The presence of dark matter halos around NGC 4342 and NGC 4291 and a deep optical image of the environment of NGC 4342 indicate that tidal stripping, in which ∼> 90% of the stellar mass was lost, cannot explain the observed high black-hole-to-bulge mass ratios. Therefore, we conclude that these galaxies formed with low stellar masses, implying that the bulge and black hole did not grow in tandem. We also find that the black hole mass correlates well with the properties of the dark matter halo, suggesting that dark matter halos may play a major role in regulating the growth of the supermassive black holes.

  18. Hitting Families of Schedules for Asynchronous Programs

    OpenAIRE

    Chistikov, Dmitry; Majumdar, Rupak; Niksic, Filip

    2016-01-01

    Asynchronous programming is a ubiquitous idiom for concurrent programming, where sequential units of code, called events, are scheduled and run atomically by a scheduler. While running, an event can post additional events for future execution by the scheduler. Asynchronous programs can have subtle bugs due to the non-deterministic scheduling of events, and a lot of recent research has focused on systematic testing of these programs. Empirically, many bugs in asynchronous programs have small b...

  19. A method for designing asynchronous probabilistic processes

    OpenAIRE

    Abbes, Samy

    2013-01-01

    We present a method for constructing asynchronous probabilistic processes. The asynchronous probabilistic processes thus obtained are called invariant. They generalize the familiar independent and identically distributed sequences of random variables to an asynchronous framework. Invariant processes are shown to be characterised by a finite family of real numbers, their characteristic numbers. Our method provides first a way to obtaining necessary and sufficient normalization conditions for a...

  20. 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...

  1. Asynchronous Discussions and Assessment in Online Learning

    Science.gov (United States)

    Vonderwell, Selma; Liang, Xin; Alderman, Kay

    2007-01-01

    This case study explored asynchronous online discussions, assessment processes, and the meaning students derived from their experiences in five online graduate courses at the Colleges of Education of two Midwestern higher education institutions. The findings suggest that asynchronous online discussions facilitate a multidimensional process of…

  2. 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.

  3. Abstracting Asynchronous Multi-Valued Networks

    Directory of Open Access Journals (Sweden)

    J. Steggles

    2011-01-01

    Full Text Available Multi-valued networks (MVNs provide a simple yet expressive qualitative state based modelling approach for biological systems. In this paper we develop an abstraction theory for asynchronous MVNs that allows the state space of a model to be reduced while preserving key properties. The abstraction theory therefore provides a mechanism for coping with the state space explosion problem and supports the analysis and comparison of MVNs. We take as our starting point the abstraction theory for synchronous MVNs which uses the under- approximation approach of trace set inclusion. We show this definition of asynchronous abstraction allows the sound inference of analysis properties and preserves other interesting model properties. One problem that arises in the asynchronous case is that the trace set of an MVN can be infinite making a simple trace set inclusion check infeasible. To address this we develop a decision procedure for checking asynchronous abstractions based on using the finite state graph of an asynchronous MVN to reason about its trace semantics and formally show that this decision procedure is correct. We illustrate the abstraction techniques developed by considering two detailed case studies in which asynchronous abstractions are identified and validated for existing asynchronous MVN models taken from the literature.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. 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.

  10. 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...

  11. 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.

  12. 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)

  13. 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

  14. 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…

  15. 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.

  16. 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...

  17. 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…

  18. 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.

  19. CCS, locations and asynchronous transition systems

    DEFF Research Database (Denmark)

    Mukund, Madhavan; Nielsen, Mogens

    system for CCS by introducing labels on the transitions with information about the locations of events. We then show that the resulting transition system is an asynchronous transition system which has the additional property of being elementary, which means that it can also be represented by a 1-safe net...

  20. 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...

  1. Computing by Temporal Order: Asynchronous Cellular Automata

    Directory of Open Access Journals (Sweden)

    Michael Vielhaber

    2012-08-01

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

  2. 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

  3. Direct Torque Control of the Asynchronous Motor

    Directory of Open Access Journals (Sweden)

    Peter Girovský

    2008-05-01

    Full Text Available This contribution deals with the proposal of direct torque control (DTC of asynchronous motor (AMwith the help of fuzzy logic. The whole structure of DTC is designed in software Matlab – Simulink, the fuzzy regulator is designed with the help of Fuzzy Toolbox. The results of DTC with fuzzy regulator are compared with DTC with the help of Depenbrock method and DTC with the help of Takahashi method.

  4. Direct Torque Control of the Asynchronous Motor

    OpenAIRE

    Peter Girovský; Jaroslava Žilková; Ľubomír Cibuľa; Jaroslav Timko

    2008-01-01

    This contribution deals with the proposal of direct torque control (DTC) of asynchronous motor (AM)with the help of fuzzy logic. The whole structure of DTC is designed in software Matlab – Simulink, the fuzzy regulator is designed with the help of Fuzzy Toolbox. The results of DTC with fuzzy regulator are compared with DTC with the help of Depenbrock method and DTC with the help of Takahashi method.

  5. 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.

  6. Rapid, generalized adaptation to asynchronous audiovisual speech

    OpenAIRE

    Van der Burg, Erik; Goodbourn, Patrick T.

    2015-01-01

    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...

  7. 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...

  8. Quantitative phase microscopy with asynchronous digital holography

    OpenAIRE

    Chalut, Kevin J.; Brown, William J.; Wax, Adam

    2007-01-01

    We demonstrate a new method of measuring quantitative phase in imaging of biological materials. This method, asynchronous digital holography, employs knowledge of a moving fringe created by acousto-optic modulators to execute phase-shifting interferometry using two near-simultaneous interferograms. The method can be used to obtain quantitative phase images of dynamic biological samples on millisecond time scales. We present results on a standard sample, and on live cell samples.

  9. 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.

  10. Enabling techniques for asynchronous coherent OCDMA

    Science.gov (United States)

    Wang, Xu; Wada, Naoya; Kitayama, Ken-ichi

    2005-11-01

    The coherent OCDMA system could suffer from severe multiple access interference (MAI) and beat noise, which limit the maximum number of active users that can be supported in a network. One effective method to reduce the beat noise as well as the MAI noise is to lower the interference level by adopting ultra-long optical code. Applying optical thresholding technique is also crucial to enable data-rate detection for achieving a practical OCDMA system. In this paper, we review the recent progress in the key enabling techniques for asynchronous coherent OCDMA: the novel encoder/decoders including spatial lightwave phase modulator, micro-ring resonator for spectral phase coding and superstructured FBG (SSFBG) and AWG type encode/decoder for time-spreading coding; optical thresholding techniques with PPLN and nonlinearity in fiber. The FEC has also been applied in OCDMA system recently. With 511-chip SSFBG and SC-based optical thresholder, 10-user, truly-asynchronous gigabit OCDMA transmission has been successfully achieved. Most recently, a record throughput 12×10.71 Gbps truly-asynchronous OCDMA has been demonstrated by using the 16×16 ports AWG-type encoder/decoder and FEC transmit ITU-T G.709 OTN frames.

  11. Designing asynchronous circuits using NULL convention logic (NCL)

    CERN Document Server

    Smith, Scott

    2009-01-01

    Designing Asynchronous Circuits using NULL Convention Logic (NCL) begins with an introduction to asynchronous (clockless) logic in general, and then focuses on delay-insensitive asynchronous logic design using the NCL paradigm. The book details design of input-complete and observable dual-rail and quad-rail combinational circuits, and then discusses implementation of sequential circuits, which require datapath feedback. Next, throughput optimization techniques are presented, including pipelining, embedding registration, early completion, and NULL cycle reduction. Subsequently, low-power design

  12. 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 in the...... 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...

  13. 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...

  14. Simulating Quantitative Cellular Responses Using Asynchronous Threshold Boolean Network Ensembles

    Directory of Open Access Journals (Sweden)

    Shah Imran

    2011-07-01

    Full Text Available Abstract Background With increasing knowledge about the potential mechanisms underlying cellular functions, it is becoming feasible to predict the response of biological systems to genetic and environmental perturbations. Due to the lack of homogeneity in living tissues it is difficult to estimate the physiological effect of chemicals, including potential toxicity. Here we investigate a biologically motivated model for estimating tissue level responses by aggregating the behavior of a cell population. We assume that the molecular state of individual cells is independently governed by discrete non-deterministic signaling mechanisms. This results in noisy but highly reproducible aggregate level responses that are consistent with experimental data. Results We developed an asynchronous threshold Boolean network simulation algorithm to model signal transduction in a single cell, and then used an ensemble of these models to estimate the aggregate response across a cell population. Using published data, we derived a putative crosstalk network involving growth factors and cytokines - i.e., Epidermal Growth Factor, Insulin, Insulin like Growth Factor Type 1, and Tumor Necrosis Factor α - to describe early signaling events in cell proliferation signal transduction. Reproducibility of the modeling technique across ensembles of Boolean networks representing cell populations is investigated. Furthermore, we compare our simulation results to experimental observations of hepatocytes reported in the literature. Conclusion A systematic analysis of the results following differential stimulation of this model by growth factors and cytokines suggests that: (a using Boolean network ensembles with asynchronous updating provides biologically plausible noisy individual cellular responses with reproducible mean behavior for large cell populations, and (b with sufficient data our model can estimate the response to different concentrations of extracellular ligands. Our

  15. Localized radio frequency communication using asynchronous transfer mode protocol

    Science.gov (United States)

    Witzke, Edward L.; Robertson, Perry J.; Pierson, Lyndon G.

    2007-08-14

    A localized wireless communication system for communication between a plurality of circuit boards, and between electronic components on the circuit boards. Transceivers are located on each circuit board and electronic component. The transceivers communicate with one another over spread spectrum radio frequencies. An asynchronous transfer mode protocol controls communication flow with asynchronous transfer mode switches located on the circuit boards.

  16. 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…

  17. 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…

  18. Teaching Presence and Communication Timeliness in Asynchronous Online Courses

    Science.gov (United States)

    Skramstad, Erik; Schlosser, Charles; Orellana, Anymir

    2012-01-01

    This study examined student perceptions of teaching presence and communication timeliness in asynchronous online courses. Garrison, Anderson, and Archer's (2000) community of inquiry model provided the framework for the survey research methodology used. Participants were 59 student volunteers taking 1 or more asynchronous online graduate courses.…

  19. Considerations regarding asynchronous motor rotor parameters determination by FEM

    Directory of Open Access Journals (Sweden)

    Olivian Chiver

    2010-12-01

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

  20. Considerations regarding asynchronous motor rotor parameters determination by FEM

    OpenAIRE

    Olivian Chiver; Liviu Neamt; Zoltan Erdei; Eleonora Pop

    2010-01-01

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

  1. 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.

  2. 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.)

  3. 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.

  4. 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.

  5. 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.

  6. A Comparison of Distance Education Competencies Delivered Synchronously and Asynchronously.

    Science.gov (United States)

    Dooley, Kim E.; Lindner, James R.; Richards, Lance J.

    2003-01-01

    Comparison of agriculture courses delivered synchronously via interactive television (20 students) and asynchronously via the Web (22 students) showed similar achievement of core distance education competencies: adult learning, technology knowledge, instructional design, communication skills, graphic design, administration) regardless of delivery…

  7. 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.

  8. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  10. Dynamic interactions between asynchronous grids interconnected through an MTDC system

    OpenAIRE

    Endegnanew, Atsede Gualu; Beerten, Jef; Uhlen, Kjetil

    2015-01-01

    The large-scale integration of renewable energy sources in the power system, combined with the need for an increased transmission capacity has led to a growing interest in multi-terminal high voltage dc (MTDC) grids. In the future, these grids will be integrated with different existing asynchronous ac grids, eventually resulting in hybrid AC/DC power systems. This paper investigates interactions between asynchronous ac grids in a hybrid AC/DC power system. In the study, a symmetrical monopola...

  11. The Engine Mechanical Coordinates Measuring in the Asynchronous Motor

    Directory of Open Access Journals (Sweden)

    Dementyev Yuriy N.

    2014-01-01

    Full Text Available The article considers indirect control devices for the mechanical coordinate’s measurement of a three-phase asynchronous electric motor, which detects the temperature of the stator winding conductors and the basic frequency of stator voltage. Characteristics of mechanical coordinate’s simulation of the asynchronous motor are provided to assess the accuracy of the mechanical coordinate’s measurement in the dynamic modes.

  12. The Engine Mechanical Coordinates Measuring in the Asynchronous Motor

    OpenAIRE

    Dementyev Yuriy N.; Umurzakova Anara D.

    2014-01-01

    The article considers indirect control devices for the mechanical coordinate’s measurement of a three-phase asynchronous electric motor, which detects the temperature of the stator winding conductors and the basic frequency of stator voltage. Characteristics of mechanical coordinate’s simulation of the asynchronous motor are provided to assess the accuracy of the mechanical coordinate’s measurement in the dynamic modes.

  13. Tidal Flows in asynchronous binaries: The beta-factor

    CERN Document Server

    Koenigsberger, Gloria

    2013-01-01

    We discuss the potential role that tidal flows in asynchronous binary stars may play in transporting chemically enriched material from deep layers towards the surface and the corresponding observational consequences of these processes. We suggest that the time-dependent velocity field induced by asynchronous rotation may contribute significantly to the mixing, thus providing a channel for the formation of chemically enriched slowly rotating massive stars.

  14. 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.

  15. Asynchronous event-based hebbian epipolar geometry.

    Science.gov (United States)

    Benosman, Ryad; Ieng, Sio-Hoï; Rogister, Paul; Posch, Christoph

    2011-11-01

    Epipolar geometry, the cornerstone of perspective stereo vision, has been studied extensively since the advent of computer vision. Establishing such a geometric constraint is of primary importance, as it allows the recovery of the 3-D structure of scenes. Estimating the epipolar constraints of nonperspective stereo is difficult, they can no longer be defined because of the complexity of the sensor geometry. This paper will show that these limitations are, to some extent, a consequence of the static image frames commonly used in vision. The conventional frame-based approach suffers from a lack of the dynamics present in natural scenes. We introduce the use of neuromorphic event-based--rather than frame-based--vision sensors for perspective stereo vision. This type of sensor uses the dimension of time as the main conveyor of information. In this paper, we present a model for asynchronous event-based vision, which is then used to derive a general new concept of epipolar geometry linked to the temporal activation of pixels. Practical experiments demonstrate the validity of the approach, solving the problem of estimating the fundamental matrix applied, in a first stage, to classic perspective vision and then to more general cameras. Furthermore, this paper shows that the properties of event-based vision sensors allow the exploration of not-yet-defined geometric relationships, finally, we provide a definition of general epipolar geometry deployable to almost any visual sensor. PMID:21954205

  16. 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. PMID:25716790

  17. Managing Asynchronous Data in ATLAS's Concurrent Framework

    CERN Document Server

    Baines, John; 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...

  18. 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.

  19. 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...

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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...

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

    DEFF Research Database (Denmark)

    Sparsø, Jens

    2009-01-01

    .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...

  6. 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.

  7. 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

    Multiparty computation (MPC) protocols among n parties secure against t active faults are known to exist if and only if t < n/2, when the channels are synchronous, and t < n/3, when the channels are asynchronous, respectively.   In this work we analyze the gap between these bounds, and show that in...... the cryptographic setting (with setup), the sole reason for it is the distribution of inputs: given an oracle for input distribution, cryptographically-secure asynchronous MPC is possible with the very same condition as synchronous MPC, namely t < n/2. We do not know whether the gaps in other security...

  8. 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.

  9. DPA on quasi delay insensitive asynchronous circuits : formalization and improvement

    CERN Document Server

    Bouesse, G F; Dumont, S; Germain, F

    2007-01-01

    The purpose of this paper is to formally specify a flow devoted to the design of Differential Power Analysis (DPA) resistant QDI asynchronous circuits. The paper first proposes a formal modeling of the electrical signature of QDI asynchronous circuits. The DPA is then applied to the formal model in order to identify the source of leakage of this type of circuits. Finally, a complete design flow is specified to minimize the information leakage. The relevancy and efficiency of the approach is demonstrated using the design of an AES crypto-processor.

  10. The Influence of Asynchronous Video Communication on Learner Social Presence: A Narrative Analysis of Four Cases

    Science.gov (United States)

    Borup, Jered; West, Richard E.; Graham, Charles R.

    2013-01-01

    Online courses are increasingly using asynchronous video communication. However, little is known about how asynchronous video communication influences students' communication patterns. This study presents four narratives of students with varying characteristics who engaged in asynchronous video communication. The extrovert valued the efficiency of…

  11. 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…

  12. 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.

  13. APPLICATION OF ASYNCHRONOUS GENERATOR FOR INDUCTION MOTOR’S FEEDING

    OpenAIRE

    Bogdan A. V.; Ilchenko Y. A.; Sobol A. N.; Erokhov M. V.

    2014-01-01

    In the article, the following items are represented: mathematical formulation of system including: asynchronous generator with cage rotor, condenser’s for excitation, induction load. Electromagnetic and electromechanical processes of induction motor’s connecting and feeding are described. Equations of voltage stability, equations of current, equations of rotor are used for describing of electricity circuits of generator

  14. 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.…

  15. GPU-Based Asynchronous Global Optimization with Particle Swarm

    International Nuclear Information System (INIS)

    The recent upsurge in research into general-purpose applications for graphics processing units (GPUs) has made low cost high-performance computing increasingly more accessible. Many global optimization algorithms that have previously benefited from parallel computation are now poised to take advantage of general-purpose GPU computing as well. In this paper, a global parallel asynchronous particle swarm optimization (PSO) approach is employed to solve three relatively complex, realistic parameter estimation problems in which each processor performs significant computation. Although PSO is readily parallelizable, memory bandwidth limitations with GPUs must be addressed, which is accomplished by minimizing communication among individual population members though asynchronous operations. The effect of asynchronous PSO on robustness and efficiency is assessed as a function of problem and population size. Experiments were performed with different population sizes on NVIDIA GPUs and on single-core CPUs. Results for successful trials exhibit marked speedup increases with the population size, indicating that more particles may be used to improve algorithm robustness while maintaining nearly constant time. This work also suggests that asynchronous operations on the GPU may be viable in stochastic population-based algorithms to increase efficiency without sacrificing the quality of the solutions.

  16. 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…

  17. Psychological Type and Asynchronous Written Dialogue in Adult Learning

    Science.gov (United States)

    Lin, Lin; Cranton, Patricia; Bridglall, Beatrice

    2005-01-01

    This study explores how adults learn from asynchronous written dialogue through the lens of psychological type preferences. We asked participants to discover their dominant and auxiliary psychological preferences using the Personal Empowerment through Type inventory. Participants then completed an open-ended survey in which they described their…

  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. 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...

  20. Asynchronous Torque Characteristics of VR Type Vernier Motor

    Science.gov (United States)

    Suda, Hiroshi; Matsushima, Yoshitaro; Xu, Li; Anazawa, Yoshihisa

    Recently, various types of vernier motor are developed. The VR type vernier motor is a kind of three-phase reluctance motor, and its stator has slots and distributed three-phase windings. The rotor is slotted iron core without windings. Relationship between S, R and P is S = R±2, where S and R are the numbers of stator and rotor slots per pair of poles, and the number of poles P is two. The rotor of the vernier motor moves at a sub-multiple of the angular velocity of the stator mmf. The multiplying factor is P/R. Authors had reported that the VR type vernier motors are analyzed as a three-phase reluctance motor, and have obtained the voltage equations on the γ-δ axis and expression of the torque.However, the asynchronous characteristics of the vernier motor are not clear yet. In this paper, the asynchronous characteristics of the vernier motors are analyzed with the symmetric components transformation and the commutator transformation. The voltage equations on the symmetrical co-ordinates and asynchronous and synchronous torque expression at steady state condition are obtained. The tests were performed on the trial motor. The calculated asynchronous torque has agreed well with the measured values.

  1. 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...

  2. 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.

  3. 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.

  4. 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)

  5. The impact of asynchronous online course design for professional development on science-teacher self-efficacy

    Science.gov (United States)

    Long, Caryn L. Smith

    This dissertation examines how various designs of asynchronous online courses for teacher professional development may impact science-teacher self-efficacy. Mayer's studies, providing the cognitive theory of multimedia learning, targeted designs of asynchronous online learning and the point where contributions of written, auditory, and visual information on these sites could cause cognitive overload (Mayer, 2005). With increasing usage of online resources for educators to gain teaching credits, understanding how to construct these professional development offerings is critical. Teacher self-efficacy can affect how well information from these courses relays to students in their classroom. This research explored the connection between online asynchronous professional development design and teacher self-efficacy through analysis of a physics-based course in three distinct course-design offerings, while collecting content-acquisition data and self-efficacy effects before and after participation. Results from this research showed teacher self-efficacy had improved in all online treatments which included a text-only, text and audio and text, audio and animation version of the same physics content. Content knowledge was most effected by the text-only and text and audio treatments with significan growth occurring in the remember, apply, and analyze levels of bloom's taxonomy. Due to the small number of participants, it cannot be said that these results are conclusive.

  6. 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.

  7. 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...

  8. 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.

  9. Indoor Positioning for Smartphones Using Asynchronous Ultrasound Trilateration

    OpenAIRE

    James D. Carswell; Viacheslav Filonenko; Charlie Cullen

    2013-01-01

    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 t...

  10. Research on DSP-based Asynchronous Motor Control Technology

    OpenAIRE

    Jun Yao; Xiangxin Qiao; Xin Wang

    2013-01-01

    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 D...

  11. Applications of Maximum Likelihood Algorithm in Asynchronous CDMA Systems

    OpenAIRE

    Xiao, P; Strom, E

    2002-01-01

    We treat the problems of propagation delay and channel estimation as well as data detection of orthogonally modulated signals in an asynchronous DS-CDMA system over fading channels using the maximum likelihood (ML) approach. The overwhelming computational complexity of the ML algorithm makes it unfeasible for implementation. The emphasis of this paper is to reduce its complexity by some approximation methods. The derived approximative ML schemes are compared with conventional algorithms as we...

  12. Asynchronous Discourse Analysis in the Quality of Expected Learning

    OpenAIRE

    Schalk-Quintanar, Ana-Elena; Marcelo-García, Carlos

    2010-01-01

    Universities are gradually implementing virtual learning processes. However, research still remains limited in examining the internal processes that occur in learning in virtual environments. This article presents an investigation that seeks to describe the relationship between the quality of interaction in asynchronous discussion forums in training experiences in e-learning, and the quality of learning offered and achieved. The main objective was to determine how interactions in online envir...

  13. 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 ...

  14. 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 ...

  15. 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...

  16. Design and Implementation of an Asynchronous Pipelined FFT Processor

    OpenAIRE

    Claesson, Jonas

    2003-01-01

    FFT processors are today one of the most important blocks in communication equipment. They are used in everything from broadband to 3G and digital TV to Radio LANs. This master's thesis project will deal with pipelined hardware solutions for FFT processors with long FFT transforms, 1K to 8K points. These processors could be used for instance in OFDM communication systems. The final implementation of the FFT processor uses a GALS (Globally Asynchronous Locally Synchronous) architecture, that ...

  17. 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)

  18. Middleware for Processing Message Queues with Elasticity Support and Sequential Integrity of Asynchronous Message Processing

    Science.gov (United States)

    Henrique Teixeira, Eduardo; Patrícia Favacho de Araújo, Aletéia

    2015-10-01

    Elasticity in computing refers to dynamically adjusting the amount of allocated resources to process a distributed application. In order to achieve this, mechanisms are needed to avoid the phenomenon of the elasticity threshold detection moving constantly up or down. The existing work fails to deliver sequential integrity of asynchronous messages processing and the asymmetries of data distribution to achieve parallel consumption. This paper fills this gaps and proposes a middleware solution to dynamically analyze the flow of message queue, and a mechanism to increase the parallelized consumption based on the output behavior. An architecture for IOD (Increase On Demand) middleware is presented, with support for the increase and decrease of thread's to cope with the growth of message queues, using the technique of limit-based heuristics over a given period of time and grouping messages into sub-queues based on classification criteria.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. Asynchronous signal-dependent non-uniform sampler

    Science.gov (United States)

    Can-Cimino, Azime; Chaparro, Luis F.; Sejdić, Ervin

    2014-05-01

    Analog sparse signals resulting from biomedical and sensing network applications are typically non-stationary with frequency-varying spectra. By ignoring that the maximum frequency of their spectra is changing, uniform sampling of sparse signals collects unnecessary samples in quiescent segments of the signal. A more appropriate sampling approach would be signal-dependent. Moreover, in many of these applications power consumption and analog processing are issues of great importance that need to be considered. In this paper we present a signal dependent non-uniform sampler that uses a Modified Asynchronous Sigma Delta Modulator which consumes low-power and can be processed using analog procedures. Using Prolate Spheroidal Wave Functions (PSWF) interpolation of the original signal is performed, thus giving an asynchronous analog to digital and digital to analog conversion. Stable solutions are obtained by using modulated PSWFs functions. The advantage of the adapted asynchronous sampler is that range of frequencies of the sparse signal is taken into account avoiding aliasing. Moreover, it requires saving only the zero-crossing times of the non-uniform samples, or their differences, and the reconstruction can be done using their quantized values and a PSWF-based interpolation. The range of frequencies analyzed can be changed and the sampler can be implemented as a bank of filters for unknown range of frequencies. The performance of the proposed algorithm is illustrated with an electroencephalogram (EEG) signal.

  4. 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.

  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. Asynchronous Remote Medical Consultation for Ghana

    CERN Document Server

    Luk, Rowena; Aoki, Paul M

    2008-01-01

    Computer-mediated communication systems can be used to bridge the gap between doctors in underserved regions with local shortages of medical expertise and medical specialists worldwide. To this end, we describe the design of a prototype remote consultation system intended to provide the social, institutional and infrastructural context for sustained, self-organizing growth of a globally-distributed Ghanaian medical community. The design is grounded in an iterative design process that included two rounds of extended design fieldwork throughout Ghana and draws on three key design principles (social networks as a framework on which to build incentives within a self-organizing network; optional and incremental integration with existing referral mechanisms; and a weakly-connected, distributed architecture that allows for a highly interactive, responsive system despite failures in connectivity). We discuss initial experiences from an ongoing trial deployment in southern Ghana.

  7. 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

  8. Impact of thermoelectric cooling modules on the efficiency of a single-phase asynchronous machine

    OpenAIRE

    Gouws, Rupert; Van Jaarsveldt, Heino

    2014-01-01

    In this paper, the authors present the impact of thermoelectric cooling modules (TECMs) on the efficiency of a single-phase asynchronous machine. TECMs are used to lower the stator winding temperature and core temperature of the single-phase asynchronous machine. A similar effect might be possible by operating the asynchronous machine in a controlled lower temperature environment or by using other means of improved controlled cooling. An overview on the materials an...

  9. Pharmacists’ Perception of Synchronous Versus Asynchronous Distance Learning for Continuing Education Programs

    OpenAIRE

    Buxton, Eric C.

    2014-01-01

    Objective. To evaluate and compare pharmacists’ satisfaction with the content and learning environment of a continuing education program series offered as either synchronous or asynchronous webinars.

  10. 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 

  11. 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.

  12. Entry of Ebola Virus is an Asynchronous Process.

    Science.gov (United States)

    Reynard, Olivier; Volchkov, Viktor E

    2015-10-01

    Ebola virus (EBOV) is responsible for a severe fever with a high mortality rate. The diverse nature of the attachment of the virus to the cell surface, the initial step of virus entry, raises questions concerning the kinetics of the virus internalization process. We investigated EBOV entry kinetics using the activity of a particular monoclonal antibody that neutralizes virus infectivity. We demonstrate that inoculation of cells with EBOV results in an asynchronous entry process, as revealed by the ability of the virus to remain in a cell-bound state for an extended period of time before it is internalized. PMID:25941332

  13. 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.

  14. The Mechanical Transient Process at Asynchronous Motor Oscillating Mode

    Science.gov (United States)

    Antonovičs, Uldis; Bražis, Viesturs; Greivulis, Jānis

    2009-01-01

    The research object is squirrel-cage asynchronous motor connected to single-phase sinusoidal. There are shown, that by connecting to the stator windings a certain sequence of half-period positive and negative voltage, a motor rotor is rotated, but three times slower than in the three-phase mode. Changing the connecting sequence of positive and negative half-period voltage to stator windings, motor can work in various oscillating modes. It is tested experimentally. The mechanical transient processes had been researched in rotation and oscillating modes.

  15. Positive Semidefinite Integrated Covariance Estimation, Factorizations and Asynchronicity

    DEFF Research Database (Denmark)

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

    observations as possible. The estimator is guaranteed positive semidefinite. Monte Carlo simulations confirm good finite sample properties. In the application we forecast portfolio Value-at-Risk and sector risk exposures for a portfolio of 52 stocks. We find that forecasts obtained from dynamic models......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...... utilizing the proposed high-frequency estimator provide statistically and economically superior forecasts to models using daily returns....

  16. Electrotechnics - AC motors. Asynchronous and brush-less motors - Lecture and exercises with solutions; Electrotechnique - Moteurs a courant alternatif. Moteurs asynchrones et brushless - Cours et problemes resolus

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, D.

    2005-07-01

    This book proposes a presentation of AC electric motors essentially based on physics and technology. Its originality consists in avoiding to use mathematical formulations (like Park's transformation). The modeling retained, which only uses magnetic momentum, magnetic fields and reluctance concepts, leads simply and naturally to the vectorial control principle. The book develops some lecture elements which includes some topics rarely considered like the dimensioning of an asynchronous motor or of a single-phase brush-less motor. Experimental results illustrate the physical phenomena described and many original problems are resolved and commented at the end of each chapter. Content: signals and systems in electrotechnics, torque and rotating magnetic fields generation, asynchronous machine in permanent regime, speed variation of the asynchronous motor, special asynchronous motors, synchronous machine in permanent regime, brush-less motor, note about step motors, note about inverters, index. (J.S.)

  17. 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

  18. 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.

  19. 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…

  20. Anonymity and Motivation in Asynchronous Discussions and L2 Vocabulary Learning

    Science.gov (United States)

    Polat, Nihat; Mancilla, Rae; Mahalingappa, Laura

    2013-01-01

    This study investigates L2 attainment in asynchronous online environments, specifically possible relationships among anonymity, L2 motivation, participation in discussions, quality of L2 production, and success in L2 vocabulary learning. It examines, in asynchronous discussions, (a) if participation and (b) motivation contribute to L2 vocabulary…

  1. Using Television Sitcoms to Facilitate Asynchronous Discussions in the Online Communication Course

    Science.gov (United States)

    Tolman, Elizabeth; Asbury, Bryan

    2012-01-01

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

  2. The Role of Offline Metalanguage Talk in Asynchronous Computer-Mediated Communication

    Science.gov (United States)

    Kitade, Keiko

    2008-01-01

    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…

  3. 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.

  4. 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.

  5. 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)

  6. Asynchronous compressed beamformer for portable diagnostic ultrasound systems.

    Science.gov (United States)

    Zhou, Jun; Hoyos, Sebastian; Sadler, Brian

    2014-11-01

    State-of-the-art portable ultrasound imaging systems employ a small transducer array and a low carrier frequency to fit stringent constraints on power and form factor, and this tends to compromise the ultrasound imaging quality. In this paper, we present a low-complexity low-power asynchronous compressed beamformer (ACB) for portable diagnostic ultrasound. The proposed ACB integrates asynchronous sampling and compressive sensing (CS), and is capable of reducing data conversion power and handling a large data volume at the mixed-signal interface. A high-rate continuoustime ternary encoding (CT-TE) scheme eliminates the need for interpolation filters and coordinate rotation digital computer (CORDIC) units typically used in a conventional architecture. A split-projection least squares (SPLS) signal reconstruction algorithm is applied that replaces high-cost nonlinear signal recovery with a series of low-complexity and independent linear problems. Experiments with measured ultrasound data demonstrate the proposed ACB architecture, and the SPLS reconstruction algorithm achieves 9-fold data compression compared with Nyquist sampling. PMID:25389158

  7. 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.

  8. 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.

  9. 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.

  10. Asynchronous Transfer Mode Quality-of-Service Testing

    Science.gov (United States)

    Ivancic, William D.

    1998-01-01

    In support of satellite-ATM interoperability, researchers at the NASA Lewis Research Center performed asynchronous transfer mode (ATM) quality-of-service experiments using MPEG-2 (ATM application layer 5, AAL5) over ATM over an emulated satellite link. The purpose of these experiments was to determine the free-space link quality necessary to use the ATM protocol to transmit high-quality multimedia information. The experimental results have been submitted to various International Telecommunications Union (ITU) study groups in order to improve and modify current standards and recommendations for the telecommunications industry. Quality-of-service parameters for Class I, stringent class requirements for ITU-T I.356 are currently being debated. The experimental results presented will help to establish these quality-of-service thresholds. This material will also be useful in the development of the ITU-R WP-4B's Draft Preliminary New Recommendation on the Transmission of Asynchronous Transfer Mode Traffic via Satellite (Rec. S.atm).

  11. 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.

  12. Design and test of asynchronous eSFQ circuits

    International Nuclear Information System (INIS)

    We designed and tested new energy-efficient single flux quantum (eSFQ) circuits. The eSFQ design approach is based on biasing logic gates via decision-making pairs (DMPs) which connect clock lines to synchronous gates. The eSFQ design of asynchronous gates is more challenging, since these gates are not clocked. We demonstrate eSFQ designs of asynchronous circuits and implemented two versions of eSFQ toggle flip-flops (eTFF) cells embedded in a synchronous shift register environment. The first design is based on the bias-free version of a TFF operating in the ballistic mode. In the second design, the TFFs dc bias is applied symmetrically, while the necessary half-quantum phase skew is achieved by magnetic flux bias, which can also be done with a pi-junction phase shifter. Surrounding shift registers are the eSFQ versions of the RSFQ shift register with two junctions per bit. In this work, we report the functional operation of these eSFQ circuits and their energy consumption. (paper)

  13. An Examination of Asynchronous Communication Experiences and Perspectives of Students in an Online Course: A Case Study.

    Science.gov (United States)

    Vonderwell, Selma

    2003-01-01

    Explores asynchronous communication perspectives and experiences of undergraduate students in an online course. Interviews with 22 preservice teachers, student-to-instructor email transcripts, asynchronous discussion transcripts, and two independent reviewers' reviews of the asynchronous discussions were used to collect and analyze the data.…

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  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. 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.

  20. 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.

  1. 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...

  2. Multi-rate asynchronous sampling of bandwidth-limited signals

    CERN Document Server

    Feldster, Alfred; Horowitz, Moshe; Rosenthal, Amir; Zach, Shlomo; Singer, Lea

    2008-01-01

    We demonstrate experimentally an optical system for under-sampling several bandwidth limited signals with carrier frequencies that are not known apriori that can be located anywhere within a very broad frequency region between 0-18 GHz. The system is based on under-sampling asynchronously at three different sampling rates. The pulses required for the under-sampling are generated by a combination of an electrical comb generator and an electro-absorption modulator. To reduce loss and improve performance the implementation of the optical system is based on a wavelength division multiplexing technique. An accurate reconstruction of both the phase and the amplitude of the signals was obtained when two chirped signals generated simultaneously were sampled.

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. Asynchronous Variational Integration of Interaction Potentials for Contact Mechanics

    CERN Document Server

    Vouga, Etienne; Tamstorf, Rasmus; Grinspun, Eitan

    2009-01-01

    Asynchronous Variational Integrators (AVIs) have demonstrated long-time good energy behavior. It was previously conjectured that this remarkable property is due to their geometric nature: they preserve a discrete multisymplectic form. Previous proofs of AVIs' multisymplecticity assume that the potentials are of an elastic type, i.e., specified by volume integration over the material domain, an assumption violated by interaction-type potentials, such as penalty forces used to model mechanical contact. We extend the proof of AVI multisymplecticity, showing that AVIs remain multisymplectic under relaxed assumptions on the type of potential. The extended theory thus accommodates the simulation of mechanical contact in elastica (such as thin shells) and multibody systems (such as granular materials) with no drift of conserved quantities (energy, momentum) over long run times, using the algorithms in [3]. We present data from a numerical experiment measuring the long time energy behavior of simulated contact, compa...

  8. 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)

  9. 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.

  10. 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.

  11. Argo: A Time-Elastic Time-Division-Multiplexed NOC using Asynchronous Routers

    DEFF Research Database (Denmark)

    Kasapaki, Evangelia; Sparsø, Jens

    In this paper we explore the use of asynchronous routers in a time-division-multiplexed (TDM) network-on-chip (NOC), Argo, that is being developed for a multi-processor platform for hard real-time systems. TDM inherently requires a common time reference, and existing TDM-based NOC designs are...... either synchronous or mesochronous. We use asynchronous routers to achieve a simpler, smaller, and more robust, self-timed design. Our design exploits the fact that pipelined asynchronous circuits also behave as ripple FIFOs. Thus, it avoids the need for explicit synchronization FIFOs between the routers...

  12. Research Related Electromechanical Processes in an Asynchronous Traction Motor - Asynchronous Generator with Common Shaft Based on Field Model

    Directory of Open Access Journals (Sweden)

    Yury Kazakov

    2015-01-01

    Full Text Available Creating energy efficiency traction induction motors with frequency control for hybrid drive vehicles defines practical interest for new methods of testing and simulation. Tests of these machines, it is desirable to carry out with energy recovery in the motor-generator, where a common shaft unites the machines. At present, the system simulation of motor-generator is carried out on simplified models without saturation, surface effect, jagged cores, and non-sinusoidal voltage of frequency converters. A refined interrelated mathematical model of asynchronous motor and generator operating with a common shaft, based on the theory of electrical circuits and field theory. Models allow the related modelling and study of static and dynamic modes electrical machines taking into account the saturation, skin effect, toothed cores, non-sinusoidal voltage of the frequency inverter, and variation parameters of the windings.

  13. STRUCTURAL RELIABILITY OF TRACTION INVERTER FOR MULTI-SYSTEM ELECTRIC LOCOMOTIVE WITH ASYNCHRONOUS TRACTION MOTORS

    Directory of Open Access Journals (Sweden)

    A. M. Muha

    2009-04-01

    Full Text Available In the article the structural reliability of different variants of structured schemes of the steady-state converter for traction drive of promising multi-system electric locomotives with asynchronous traction engines is compared.

  14. 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....

  15. 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

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

    Directory of Open Access Journals (Sweden)

    Masanori Sato

    2014-01-01

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

  17. A reverse mode of three-phase asynchronous motors with hexaphase windings

    OpenAIRE

    V.D. Lushchyk; S.Yu. Polezin

    2014-01-01

    A reverse operation feasibility in three-phase asynchronous motors with the stator hexaphase windings is proved. In the reverse mode, the hexaphase windings are shown to keep all their declared advantages.

  18. 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...

  19. 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.

  20. Speed estimation of vector controlled squirrel cage asynchronous motor with artificial neural networks

    International Nuclear Information System (INIS)

    In this paper, the artificial neural networks as a sensorless speed estimator in indirect vector controlled squirrel cage asynchronous motor control are defined. High dynamic performance power semi conductors obtainable from direct current motors can also be obtained from asynchronous motor through developments in digital signal processors (DSP) and control techniques. With using of field diverting control in asynchronous motors, the flux and moment can be controlled independently. The process of estimating the speed information required in control of vector controlled asynchronous motor without sensors has been obtained with artificial neural networks (ANN) in this study. By examining the data obtained from the experimental study concluded on the DSP application circuit, the validity and high performance of the ANN speed estimator on real-time speed estimation has been demonstrated.

  1. 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.

  2. 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

    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...... description language Balsa [1]. This ”conventional” template architecture allows us to adapt traditional synchronous synthesis techniques for resource sharing, scheduling, binding etc, to the domain of asynchronous circuits. A prototype tool has been implemented on top of the Balsa framework, and the method...... is illustrated through the implementation of a set of example circuits. The main contributions of the paper are: the fundamental idea, the template architecture and its implementation using asynchronous handshake components, and the implementation of a prototype tool....

  3. ELECTROMAGNETIC CALCULATION OF THREE-PHASE ASYNCHRONOUS MOTORS WITH A SIX-PHASE WINDING

    OpenAIRE

    S.Yu. Polezіn; Kiryanov, V. V.; V.D. Lushchyk

    2013-01-01

    Features of electromagnetic computation of three-phase asynchronous motors with a six-phase winding in the stator are described. Experimental data on a conveyor motor with two six-phase windings are given.

  4. ELECTROMAGNETIC CALCULATION OF THREE-PHASE ASYNCHRONOUS MOTORS WITH A SIX-PHASE WINDING

    Directory of Open Access Journals (Sweden)

    S.Yu. Polezіn

    2013-02-01

    Full Text Available Features of electromagnetic computation of three-phase asynchronous motors with a six-phase winding in the stator are described. Experimental data on a conveyor motor with two six-phase windings are given.

  5. A reverse mode of three-phase asynchronous motors with hexaphase windings

    Directory of Open Access Journals (Sweden)

    V.D. Lushchyk

    2014-04-01

    Full Text Available A reverse operation feasibility in three-phase asynchronous motors with the stator hexaphase windings is proved. In the reverse mode, the hexaphase windings are shown to keep all their declared advantages.

  6. Temperature, paternity and asynchronous hatching influence early developmental characteristics of larval Atlantic cod, Gadus morhua

    DEFF Research Database (Denmark)

    Politis, Sebastian Nikitas; Dahlke, Flemming T.; Butts, Ian A.E.;

    2014-01-01

    Offspring, especially during early development, are influenced by both intrinsic properties endowed to them by their parents, extrinsic environmental factors as well as the interplay between genes and the environment. We investigated the effects of paternity (P), temperature (T), and asynchronous...... Atlantic (5.4±0.1 to 2.6±0.3days from 2.0 to 10.0°C) and Baltic larvae (6.2±0.4 to 5.0±0.6days from 6.5 to 12.5°C) and LN increased and AY decreased for every subsequent day of hatch. Deformities increased with increasing T and P × T explained 52.3 and 26.8% of the variance for Atlantic and Baltic larvae......, respectively. In Baltic larvae, size at peak hatch tended to decrease with increasing T and P × T explained 34.6% of the variance. In Atlantic larvae, growth, YUR and YUE were influenced by T while P alone explained 26.0% of the variance in YUE and up to 66.4% of variance in morphological traits at 4 DPH...

  7. 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.

  8. Linearity, Persistence and Testing Semantics in the Asynchronous Pi-Calculus

    OpenAIRE

    Cacciagrano, Diletta; Flavio CORRADINI; Aranda, Jesus; Valencia, Frank,

    2007-01-01

    In [CSVV06] the authors studied the expressiveness of persistence in the asynchronous pi calculus (Api) wrt weak barbed congruence. The study is incomplete because it ignores the issue of divergence. In this paper we present an expressiveness study of persistence in the asynchronous pi-calculus (Api) wrt DeNicola and Hennesy's testing scenario which is sensitive to divergence. We consider Api and theree sub-languages of it, each capturing one source of persistence: the persistent-input calcul...

  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 repetitive......-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...

  10. Strict optical orthogonal codes for purely asynchronous code-division multiple-access applications.

    Science.gov (United States)

    Zhang, J G

    1996-12-10

    Strict optical orthogonal codes are presented for purely asynchronous optical code-division multiple-access (CDMA) applications. The proposed code can strictly guarantee the peaks of its cross-correlation functions and the sidelobes of any of its autocorrelation functions to have a value of 1 in purely asynchronous data communications. The basic theory of the proposed codes is given. An experiment on optical CDMA systems is also demonstrated to verify the characteristics of the proposed code. PMID:21151299

  11. 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...

  12. Simulation of the Double-closed Loop Three-phase Asynchronous Variable Voltage Control System

    OpenAIRE

    Shuhua Jiang

    2011-01-01

    When controlling the voltage and speed of the asynchronous motor, to expand the speed control range and reduce the speed fluctuation, the speed control system adopts two feedback control loops, i.e. the speed feedback control loop and the current feedback control loop. The principle and components of the double-closed loop three-phase asynchronous variable voltage control system are studied, and the simulation model and the test result based on MATLAB/Simulink are provided in this article thr...

  13. 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...

  14. 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.

  15. Enhancing ESL Learners Speaking Skills through Asynchronous Online Discussion Forum

    Directory of Open Access Journals (Sweden)

    Nadzrah Abu Bakar

    2013-05-01

    Full Text Available Communicating orally in a second or foreign language such as English can be a difficult task especially for the low proficiency learners as they may lack the confidence and feel shy and apprehensive when interacting verbally in the target language. This may hold them back from expressing themselves vocally though they are fully aware that in order to be fluent in the target language, they need to practise speaking not only in the classroom but also outside the classroom. This paper discusses the use of an asynchronous online discussion forum (AODF as a communication tool to assist the low proficiency ESL learners to build their confidence and practise using the target language orally. As an online discussion forum, the Multimedia Enhance Discussion Forum (MEDiF was specifically designed to be used by a selected group of low proficiency ESL learners at tertiary level for one academic semester. This online forum allows the learners to audio and video-record their discussions, listen to the recorded discussions and respond to their friends’ ideas and opinions. Interviews and observations of the discussions on the MEDiF were conducted to gather data. The findings generally indicate positive responses from the ESL learners although there were also some obstacles faced by them while utilizing the MEDiF.

  16. Asynchronous vehicle pose correction using visual detection of ground features

    Science.gov (United States)

    Harnarinesingh, Randy E. S.; Syan, Chanan S.

    2014-07-01

    The inherent noise associated with odometry manifests itself as errors in localization for autonomous vehicles. Visual odometry has been previously used in order to supplement classical vehicle odometry. However, visual odometry is limited in its ability to reduce errors in localization for large travel distances that entail the cumulative summing of individual frame-to-frame image errors. In this paper, a novel machine vision approach for tiled surfaces is proposed to address this problem. Tile edges in a laboratory environment are used to define a travel trajectory for the Quansar Qbot (autonomous vehicle) built on the iRobot iRoomba platform with a forward facing camera. Tile intersections are used to enable asynchronous error recovery for vehicle position and orientation. The proposed approach employs real-time image classification and is feasible for error mitigation for large travel distances. The average position error for an 8m travel distance using classical odometry was measured to be 0.28m. However, implementation of the proposed approach resulted in an error of 0.028m. The proposed approach therefore significantly reduces pose estimation error and could be used to supplement existing modalities such as GPS and Laser-based range sensors.

  17. 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

  18. 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.

  19. Obstacle avoidance in social groups: new insights from asynchronous models.

    Science.gov (United States)

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

    2015-05-01

    For moving animals, the successful avoidance of hazardous obstacles is an important capability. Despite this, few models of collective motion have addressed the relationship between behavioural and social features and obstacle avoidance. We develop an asynchronous individual-based model for social movement which allows social structure within groups to be included. We assess the dynamics of group navigation and resulting collision risk in the context of information transfer through the system. In agreement with previous work, we find that group size has a nonlinear effect on collision risk. We implement examples of possible network structures to explore the impact social preferences have on collision risk. We show that any social heterogeneity induces greater obstacle avoidance with further improvements corresponding to groups containing fewer influential individuals. The model provides a platform for both further theoretical investigation and practical application. In particular, we argue that the role of social structures within bird flocks may have an important role to play in assessing the risk of collisions with wind turbines, but that new methods of data analysis are needed to identify these social structures. PMID:25833245

  20. 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...

  1. 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

  2. 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

  3. 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.

  4. The Use of Efficient Broadcast Protocols in Asynchronous Distributed Systems. Ph.D. Thesis

    Science.gov (United States)

    Schmuck, Frank Bernhard

    1988-01-01

    Reliable broadcast protocols are important tools in distributed and fault-tolerant programming. They are useful for sharing information and for maintaining replicated data in a distributed system. However, a wide range of such protocols has been proposed. These protocols differ in their fault tolerance and delivery ordering characteristics. There is a tradeoff between the cost of a broadcast protocol and how much ordering it provides. It is, therefore, desirable to employ protocols that support only a low degree of ordering whenever possible. This dissertation presents techniques for deciding how strongly ordered a protocol is necessary to solve a given application problem. It is shown that there are two distinct classes of application problems: problems that can be solved with efficient, asynchronous protocols, and problems that require global ordering. The concept of a linearization function that maps partially ordered sets of events to totally ordered histories is introduced. How to construct an asynchronous implementation that solves a given problem if a linearization function for it can be found is shown. It is proved that in general the question of whether a problem has an asynchronous solution is undecidable. Hence there exists no general algorithm that would automatically construct a suitable linearization function for a given problem. Therefore, an important subclass of problems that have certain commutativity properties are considered. Techniques for constructing asynchronous implementations for this class are presented. These techniques are useful for constructing efficient asynchronous implementations for a broad range of practical problems.

  5. A Rewriting Approach to Replace Asynchronous ROMs with Synchronous Ones for the Circuits with Cycles

    Directory of Open Access Journals (Sweden)

    Yasuaki Ito

    2012-07-01

    Full Text Available

    Field Programmable Gate Arrays (FPGAs are a dominant implementation medium for digital circuits which are used  to embed a circuit designed by users instantly. FPGAs can be used for implementing parallel and hardware algorithms. Circuit design that minimizes the number of clock cycles is easy if we use asynchronous read operations. However, most of FPGAs support synchronous read operations, but do not support asynchronous read operations. The main contribution of this paper is to provide one of the potent approaches to resolve this problem. We assume that a circuit using asynchronous ROMs is given. In our previous work, we have presented a circuit rewriting algorithm to convert a circuit with asynchronous ROMs into an equivalent circuit with synchronous ones. The resulting circuit with synchronous ROMs can be embedded into FPGAs. However, this circuit rewriting algorithm can handle circuits represented by a directed acyclic graph and does not work for those with cycles. In this paper, we succeeded in relaxing the cycle-free condition of circuits. More specifically, we present an algorithm that automatically converts a circuit with cycles using asynchronous ROMs into an equivalent circuit using synchronous ROMs.

  6. Improving Learning of Programming Through E-Learning by Using Asynchronous Virtual Pair Programming

    Directory of Open Access Journals (Sweden)

    Sufian IDRIS

    2006-07-01

    Full Text Available The problem of learning programming subjects, especially through distance learning and E-Learning, has been widely reported in literatures. Many attempts have been made to solve these problems. This has led to many new approaches in the techniques of learning of programming. One of the approaches that have been proposed is the use of virtual pair programming (VPP. Most of the studies about VPP in distance learning or e-learning environment focus on the use of the synchronous mode of collaboration between learners. Not much research have been done about asynchronous VPP. This paper describes how we have implemented VPP and a research that has been carried out to study the effectiveness of asynchronous VPP for learning of programming. In particular, this research study the effectiveness of asynchronous VPP in the learning of object-oriented programming among students at Open University Malaysia (OUM. The result of the research has shown that most of the learners have given positive feedback, indicating that they are happy with the use of asynchronous VPP. At the same time, learners did recommend some extra features that could be added in making asynchronous VPP more enjoyable.

  7. 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.

  8. 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 ...

  9. 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...... reports on the design methodology, the architecture, the implementation, and the performance of the ARISC. This includes a comparison with the TR4101, and a detailed breakdown of the power consumption in the ARISC. ARISC is our first attempt at an asynchronous implementation and a number of simplifying...... decisions were made up front. Throughout the entire design we use four-phase handshaking in combination with a normally opaque latch controller. All logic is implemented using static logic standard cells. Despite this the ARISC performs surprisingly well: In 0.35 μm CMOS performance is 74-123 MIPS depending...

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

    Science.gov (United States)

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

    2016-02-01

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

  11. 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.

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

    International Nuclear Information System (INIS)

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

  13. 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

  14. 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.

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

    DEFF Research Database (Denmark)

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

    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...... synchronous or mesochronous, but both approaches have their limitations: a globally synchronous NOC is no longer feasible in today's sub micron technologies and a mesochronous NOC requires special FIFO-based synchronizers in all input ports of all routers in order to accommodate for clock phase differences....... 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...

  16. Network evolution induced by asynchronous stimuli through spike-timing-dependent plasticity.

    Directory of Open Access Journals (Sweden)

    Wu-Jie Yuan

    Full Text Available In sensory neural system, external asynchronous stimuli play an important role in perceptual learning, associative memory and map development. However, the organization of structure and dynamics of neural networks induced by external asynchronous stimuli are not well understood. Spike-timing-dependent plasticity (STDP is a typical synaptic plasticity that has been extensively found in the sensory systems and that has received much theoretical attention. This synaptic plasticity is highly sensitive to correlations between pre- and postsynaptic firings. Thus, STDP is expected to play an important role in response to external asynchronous stimuli, which can induce segregative pre- and postsynaptic firings. In this paper, we study the impact of external asynchronous stimuli on the organization of structure and dynamics of neural networks through STDP. We construct a two-dimensional spatial neural network model with local connectivity and sparseness, and use external currents to stimulate alternately on different spatial layers. The adopted external currents imposed alternately on spatial layers can be here regarded as external asynchronous stimuli. Through extensive numerical simulations, we focus on the effects of stimulus number and inter-stimulus timing on synaptic connecting weights and the property of propagation dynamics in the resulting network structure. Interestingly, the resulting feedforward structure induced by stimulus-dependent asynchronous firings and its propagation dynamics reflect both the underlying property of STDP. The results imply a possible important role of STDP in generating feedforward structure and collective propagation activity required for experience-dependent map plasticity in developing in vivo sensory pathways and cortices. The relevance of the results to cue-triggered recall of learned temporal sequences, an important cognitive function, is briefly discussed as well. Furthermore, this finding suggests a potential

  17. 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

  18. The development of mathematical model for the study of electromagnetic interference from the traction converters with asynchronous motor

    OpenAIRE

    V. I. Shcheka; HAVRYLIUK V.I.

    2010-01-01

    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.

  19. 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…

  20. 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…

  1. Evaluation of asynchronous E-learning in the geography curriculum: enriching learning quality in Saudi high schools

    OpenAIRE

    Al Dobaikhi, Hend; Woollard, John

    2011-01-01

    The impacts of emerging ICT into educational curricula Asynchronous discussion forum Discussion groups via e-learning environment Posting questions and comments Self-efficacy in asynchronous e-learning Web community participation Collaborative learning can be fostered Positive impacts on objectives of educational curriculum

  2. 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.

  3. The study of transient processes in the asynchronous starting of the synchronous motor

    Directory of Open Access Journals (Sweden)

    Alexandru Bârlea

    2012-12-01

    Full Text Available Starting synchronous motors can be achieved by several ethods: starting with an auxiliary motor launch, starting in asynchronous regim, by feeding from a variable frequency source, auto-synchronization with the network.. In our case we study the transient processes in a asynchronous regim . In this case the synchronous motor is started like a squirrel cage induction motor . To start, the synchronous motor is equipped with a starting winding cage placed in the pole pieces of polar inducers; later , during the operation, this acts as a damping winding. Large synchronous motors have pole pieces made from massive polar inducers fulfilling the role of a cage winding.

  4. On Input-to-State Stability of Switched Stochastic Nonlinear Systems Under Extended Asynchronous Switching.

    Science.gov (United States)

    Kang, Yu; Zhai, Di-Hua; Liu, Guo-Ping; Zhao, Yun-Bo

    2016-05-01

    An extended asynchronous switching model is investigated for a class of switched stochastic nonlinear retarded systems in the presence of both detection delay and false alarm, where the extended asynchronous switching is described by two independent and exponentially distributed stochastic processes, and further simplified as Markovian. Based on the Razumikhin-type theorem incorporated with average dwell-time approach, the sufficient criteria for global asymptotic stability in probability and stochastic input-to-state stability are given, whose importance and effectiveness are finally verified by numerical examples. PMID:26068932

  5. 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...

  6. Time-Efficient Read/Write Register in Crash-prone Asynchronous Message-Passing Systems

    OpenAIRE

    Mostefaoui, Achour; Raynal, Michel

    2016-01-01

    The atomic register is certainly the most basic object of computing science. Its implementation on top of an n-process asynchronous message-passing system has received a lot of attention. It has been shown that t \\textless{} n/2 (where t is the maximal number of processes that may crash) is a necessary and sufficient requirement to build an atomic register on top of a crash-prone asynchronous message-passing system. Considering such a context, this paper visits the notion of a fast implementa...

  7. 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.

  8. Adolescent idiopathic scoliosis (AIS): a multifactorial cascade concept for pathogenesis and embryonic origin.

    Science.gov (United States)

    Burwell, R Geoffrey; Clark, Emma M; Dangerfield, Peter H; Moulton, Alan

    2016-01-01

    This paper formulates a novel multifactorial Cascade Concept for the pathogenesis of adolescent idiopathic scoliosis (AIS). This Concept stems from the longitudinal findings of Clark et al. (J Bone Miner Res 29(8):1729-36, 2014) who identified leptin body composition factors at 10 years of age associated with a scoliosis deformity found at 15 years. We interpret these findings in the light of some concepts for AIS pathogenesis. In particular, we speculate that the leptin body composition effect is linked to central nervous system development and the initiation of the asynchronous neuro-osseous growth mechanism that involves the creation of a neuraxis tether of relative anterior vertebral overgrowth. The latter mechanism in combination with age and gender-related anatomical variants of vertebral backward tilt (dorsal shear concept), human upright posture, adolescent growth factors, Hueter-Volkmann effect in vertebrae and vertebral bone mass abnormalities, lead to AIS, possibly both initiation and progression of scoliosis curvatures. Being multifactorial, while the Cascade Concept cannot be tested for all its components, some components should be testable by the method of numerical simulation. Clark et al. (J Bone Miner Res 29(8):1729-36, 2014) also suggested the origin of scoliosis was in the embryonic stages of life from cell types, including adipocytes and osteoblasts, derived from the same progenitor cells, and myoblasts from mesodermal somites. The involvement of cell types from different developmental origins suggests a process acting in embryonic life at a similar time, probably environmental, as previously proposed from anthropometric studies. As a Complex disease, AIS will involve genetic, environmental and life style factors operating in development and growth; this possibility needs evaluating in epidemiological studies. PMID:27252984

  9. 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

  10. 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…

  11. 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

  12. 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…

  13. An iron free asynchronous pulsed generator for the production of pulsed high magnetic fields

    International Nuclear Information System (INIS)

    The production of long pulsed high fields (> 500 kgaus) with (tau > 1 s) with cryogenic coils requires an initial energy source of several megajoules. Iron free asynchronous pulsed generators are particulary well adapted to this application as they are able to produce this energy at a very competitive price

  14. 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...

  15. 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...

  16. "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…

  17. Visual Search in a Multi-Element Asynchronous Dynamic (MAD) World

    Science.gov (United States)

    Kunar, Melina A.; Watson, Derrick G.

    2011-01-01

    In visual search tasks participants search for a target among distractors in strictly controlled displays. We show that visual search principles observed in these tasks do not necessarily apply in more ecologically valid search conditions, using dynamic and complex displays. A multi-element asynchronous dynamic (MAD) visual search was developed in…

  18. Comparative Analysis of Preservice Teachers' Reflective Thinking in Synchronous versus Asynchronous Online Case Discussions

    Science.gov (United States)

    Levin, Barbara B.; He, Ye; Robbins, Holly H.

    2006-01-01

    This study was undertaken to better understand the nature of preservice teachers' reflective thinking during case discussions about classroom management in two online formats: synchronous versus asynchronous. Findings indicated that when participants engaged in synchronous online case discussions they had higher levels of critical reflection than…

  19. 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.

  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. 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…

  2. 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…

  3. 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.

  4. 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…

  5. The Role of Beliefs and Motivation in Asynchronous Online Learning in College-Level Classes

    Science.gov (United States)

    Xie, Kui; Huang, Kun

    2014-01-01

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

  6. 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…

  7. 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.

  8. 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…

  9. A Study of Asynchronous and Synchronous Discussion on Cognitive Maps in a Distributed Learning Environment.

    Science.gov (United States)

    Bhattacharya, Madhumita

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

  10. 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.

  11. Anonymity to Promote Peer Feedback: Pre-Service Teachers' Comments in Asynchronous Computer-Mediated Communication

    Science.gov (United States)

    Howard, Craig D.; Barrett, Andrew F.; Frick, Theodore W.

    2010-01-01

    In this quasi-experimental case study, we compared five sections of a basic undergraduate technology course. Within an asynchronous web forum, pre-service teachers wrote short critiques of websites designed by their classmates. This peer feedback was provided anonymously by students in two classes (n = 35) whereas providers and recipients of peer…

  12. Socialization in the "Virtual Hallway": Instant Messaging in the Asynchronous Web-Based Distance Education Classroom.

    Science.gov (United States)

    Nicholson, Scott

    2002-01-01

    Examined differences in communication between masters degree students at Syracuse University who used instant messaging (IM) services and those who did not in the same asynchronous distance education Web-based course. Results showed that students who used IM found it easier to communicate and felt a stronger sense of community. (Author/LRW)

  13. Performance comparison of asynchronous orthogonal multi-carrier CDMA in frequency selective channel

    OpenAIRE

    Xiang, G; Ng, TS

    1998-01-01

    Bit error rate (BER) performance of an asynchronous multi-carrier code division multiple access (MC-CDMA) system for the uplink of the mobile communication system with equal gain combining and maximum ratio combining are obtained. Given a fixed bandwidth frequency selective channel, performance of MC-CDMA is compared with that of conventional CDMA and MC-DS-CDMA in numerical results.

  14. Asynchronous Orthogonal Multi-Carrier CDMA Using Equal Gain Combining in Multipath Rayleigh Fading Channel

    OpenAIRE

    Xiang, G; Ng, TS

    1998-01-01

    Performance of an asynchronous orthogonal multi-carrier code division multiple access (MC-CDMA) system for the reverse link of the mobile communication system with equal gain combining is obtained. The performance of MC-CDMA is compared with that of conventional CDMA and MC-DS-CDMA in numerical results in a multipath Rayleigh fading channel.

  15. 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

  16. 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…

  17. 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…

  18. 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…

  19. 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

  20. 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.

  1. Use of Podcasting as an Innovative Asynchronous E-Learning Tool for Students

    Science.gov (United States)

    Jalali, Alireza; Leddy, John; Gauthier, Martin; Sun, Rong; Hincke, Maxwell; Carnegie, Jacqueline

    2011-01-01

    Podcasting is an innovative, asynchronous communication tool. A pilot study was conducted to assess the utility of podcasting as an educational tool for undergraduate medical students. A paper-and-pencil questionnaire was developed and distributed to the 40 first-year students enrolled in the francophone stream of the medical curriculum at the…

  2. 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…

  3. 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…

  4. 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...

  5. 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.

  6. 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…

  7. Thematic Analysis of the "Games" Students Play in Asynchronous Learning Environments

    Science.gov (United States)

    MacMillan, Thalia; Forte, Michele; Grant, Cynthia

    2014-01-01

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

  8. Examining Facilitators' Habits of Mind in an Asynchronous Online Discussion Environment: A Two Cases Study

    Science.gov (United States)

    Cheung, Wing Sum; Hew, Khe Foon

    2010-01-01

    Asynchronous online discussion has been widely used by faculty members and students in schools and universities. Previous research has examined how factors such as the discussion activity, knowledge about the discussion topic, and the behaviour of other participants can affect learner participation. This study explored student facilitators'…

  9. 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...

  10. Developing Asynchronous Online Courses: Key Instructional Strategies in a Social Metacognitive Constructivist Learning Trajectory

    Science.gov (United States)

    Niess, Margaret; Gillow-Wiles, Henry

    2013-01-01

    This qualitative, design-based research study resulted in a proposal for a comprehensive set of best instructional practices immersed in a learning trajectory, outlining the tools, processes and the content development for online asynchronous, text-based learning in graduate level professional development courses. The outcome provides a rich…

  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. 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.

  13. Thought-Leaders in Asynchronous Online Learning Environments

    Science.gov (United States)

    Waters, Jim

    2012-01-01

    The growth of online learning has exposed fundamental gaps in our knowledge, both theoretical and pragmatic. This research investigated some questions of the role of emergent leaders in online leaning and the influence of different behaviors. Firstly are there any common factors that identify thought-leaders? Secondly does the presence of…

  14. 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

  15. Performance analysis of 2D asynchronous hard-limiting optical code-division multiple access system through atmospheric scattering channel

    Science.gov (United States)

    Zhao, Yaqin; Zhong, Xin; Wu, Di; Zhang, Ye; Ren, Guanghui; Wu, Zhilu

    2013-09-01

    Optical code-division multiple access (OCDMA) systems usually allocate orthogonal or quasi-orthogonal codes to the active users. When transmitting through atmospheric scattering channel, the coding pulses are broadened and the orthogonality of the codes is worsened. In truly asynchronous case, namely both the chips and the bits are asynchronous among each active user, the pulse broadening affects the system performance a lot. In this paper, we evaluate the performance of a 2D asynchronous hard-limiting wireless OCDMA system through atmospheric scattering channel. The probability density function of multiple access interference in truly asynchronous case is given. The bit error rate decreases as the ratio of the chip period to the root mean square delay spread increases and the channel limits the bit rate to different levels when the chip period varies.

  16. Comparison of synchronous and asynchronous generators on the level of losses in conditions of small hydroelectric power plants

    International Nuclear Information System (INIS)

    It is shown that the use of asynchronous generators instead of synchronous in conditions of small HPP leads to increase of losses of energy in the block the turbine - the generator - the transformer approximately on 30 % the cost of which during a year is commensurable with the cost of the generator. The use of asynchronous generators instead of synchronous in conditions of small HPP is inexpedient

  17. Asynchronous Computer-Mediated Corrective Feedback
And The Correct Use Of Prepositions: Is It Really Effective?

    OpenAIRE

    Seyyed Behrooz HOSSEINI

    2012-01-01

    An area that has recently attracted increasing attention is providing feedback on learners’ writing accuracy through the Internet. However, research in this area has largely focused on synchronous communication, i.e., chatting, with fewer studies assessing asynchronous technologies, i.e., e-mailing. Therefore, this study investigates the effectiveness of asynchronous computer-mediated corrective feedback-explicit and implicit, on increasing the correct use of prepositions. Forty-five Iranian ...

  18. 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 ...

  19. Improvable objects and attached dialogue: New literacy practices employed by learners to build knowledge together in asynchronous settings

    OpenAIRE

    Rebecca Ferguson; Denise Whitelock; Karen Littleton

    2010-01-01

    Asynchronous online dialogue offers advantages to learners, but has appeared to involve only limited use of new literacy practices. To investigate this, a multimodal approach was applied to asynchronous dialogue. The study analysed the online discussions of small groups of university students as they developed collaboratively authored documents. Sociocultural discourse analysis of the dialogue was combined with visual analysis of its structural elements. The groups were found to employ new li...

  20. An asynchronous communication system based on the hyperchaotic system of 6th-order cellular neural network

    Science.gov (United States)

    Wang, Xingyuan; Xu, Bing; Luo, Chao

    2012-11-01

    This paper proposes a novel asynchronous communication scheme. Based on this scheme, a model using the hyperchaotic system of 6th-order Cellular Neural Network (CNN) is designed. This scheme enhances the security of asynchronous communication compared to the conventional ones. It is noteworthy that the proposed communication scheme does not depend on synchronization, and almost all chaotic systems can be involved in this scheme. Numerical simulations show the effectiveness of this scheme.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

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

    DEFF Research Database (Denmark)

    Kasapaki, Evangelia

    Multi-processor architectures using networks-on-chip (NOCs) for communication are becoming the standard approach in the development of embedded systems and general purpose platforms. Typically, multi-processor platforms follow a globally asynchronous locally synchronous (GALS) timing organization...... important part of the T-CREST paltform and used in a number of configurations. The flexible timing organization of Argo combines asynchronous routers with mesochronous NIs, which are connected to individually clocked cores, supporting a GALS system organization. The mesochronous NIs operate at the same....... This thesis focuses on the design of Argo, a NOC targeted at hard real-time multi-processor platforms with a GALS timing organization. To support real-time communication, NOCs establish end-to-end connections and provide latency and throughput guarantees for these connections. Argo uses time division...

  7. 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...

  8. 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 t...... 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.......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...

  9. 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)

  10. 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...

  11. 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

  12. 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.

  13. 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.

  14. 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...

  15. 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

  16. 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.

  17. Web-scale Topic Models in Spark: An Asynchronous Parameter Server

    OpenAIRE

    Jagerman, Rolf; Eickhoff, Carsten

    2016-01-01

    In this paper, we train a Latent Dirichlet Allocation (LDA) topic model on the ClueWeb12 data set, a 27-terabyte Web crawl. We extend Spark, a popular framework for performing large-scale data analysis, with an asynchronous parameter server. Such a parameter server provides a distributed and concurrently accessed parameter space for the model. A Metropolis-Hastings based collapsed Gibbs sampler is implemented using this parameter server achieving an amortized O(1) sampling complexity. We comp...

  18. Frequency support among asynchronous AC systems through VSCs emulating power plants

    OpenAIRE

    Papangelis, Lampros; Guillaud, Xavier; Van Cutsem, Thierry

    2015-01-01

    This paper proposes a new control scheme for the Voltage Source Converters (VSCs) of a High Voltage Direct Current (HVDC) grid connecting asynchronous AC systems, so that the latter can mutually support their frequencies after a disturbance. The scheme involves no communication between VSCs. It is activated upon detection of a significant frequency deviation, with the possibility to limit the support requested from other AC systems. It relies on an integral control enforcing the frequency dro...

  19. 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.

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

    OpenAIRE

    Khammar, F; N. E. Debbache

    2016-01-01

    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 challeng...

  1. 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...

  2. 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...

  3. Exploiting Synchrony for Area and Performance Improvement in the Asynchronous Domain

    OpenAIRE

    Mahdi Jelodari Mamaghani, Will Toms, Andrew Bardsley, Jim Garside,

    2014-01-01

    This work proposes a synthesis process called ‘eTeak’ which exploits synchronous EDAs to improve the implemented circuits. In this regard, it incorporates the synchronous elastic protocol in the Teak synthesis flow to move fine-grained concurrency from the asynchronous into the synchronous domain where clocked CAD tools can optimise the data manipulation units. A transformation technique is also proposed to enable the designer to explore the level of elasticity in the network and trade off th...

  4. 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.

  5. Fault simulation and test pattern generation for synchronous and asynchronous sequential circuits

    OpenAIRE

    Lee, Hyung Ki

    1993-01-01

    In this dissertation, we propose two fault simulators, called HOPE and HOPE2, and an autolllatic test pattern generator (ATPG), called ATHENA, for synchronous and asynchronous sequential circuits. HOPE is a parallel fault simulator for synchronous sequential circuits. In HOPE, a packet of 32 faults is simulated in parallel. Several new heuristics are employed in HOPE to accelerate the parallel fault simulation. The heuristics are 1) a reduction of faults to be simulated ...

  6. Structuring asynchronous discussion groups by introducing roles: do students act in line with assigned roles?

    OpenAIRE

    Wever, Bram De; Schellens, Tammy; Van Keer, Hilde; Valcke, Martin

    2008-01-01

    This study focused on the introduction of roles as a scripting tool in asynchronous text-based discussion groups. Five roles were selected: source searcher, theoretician, summarizer, moderator, and starter. Because existing research on role assignment often neglects to check whether the role assignment is successful, the main goal was to examine to what extent the participants enacted assigned roles. The study took place in the 1st year of a university course in Instructional Sciences (N = 20...

  7. 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...

  8. 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.

  9. 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.

  10. 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...

  11. 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...

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

    OpenAIRE

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

    2000-01-01

    An asynchronous accelerator is described, in which the principle of its operation permits the active longitudinal bunch compression of accelerated proton beams, to overcome the space charge limitation effects of intense bunches. It is shown that accelerated bunches from an RFQ linac can be adapted for Asynchronac injection for a multiple of choices in the acceleration frequencies of the RFQ and the Asynchronac. The offered new type of accelerator system is especially suitable to accelerate pr...

  13. Performance of asynchronous orthogonal multicarrier CDMA system in frequency selective fading channel

    OpenAIRE

    Xiang, G; Ng, TS

    1999-01-01

    An asynchronous multicarrier (MC) direct-sequence (DS) code-division multiple-access (CDMA) scheme for the uplink of the mobile communication system operating in a frequency selective fading channel is analyzed. Bit error rate performance of the system with either equal-gain combining or maximum-ratio combining is obtained. Numerical results indicate that the system performs better than that of the conventional DS-CDMA system and another MC-DS-CDMA system.

  14. 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...

  15. 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 ...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

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

    Directory of Open Access Journals (Sweden)

    V. I. Lukovnikov

    2016-01-01

    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.

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

    OpenAIRE

    V. I. Lukovnikov; I. A. Rudchenko; A. V. Тurenkova

    2016-01-01

    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.

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

    OpenAIRE

    I. VLAD; CAMPEANU, A.; Enache, S.; PETROPOL, G.

    2014-01-01

    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 ene...

  3. Dynamic D-Q Axis Modeling Of Three-Phase Asynchronous Machine Using Matlab

    OpenAIRE

    SHAKUNTLA BOORA, S.K AGARWAL, K.S SANDHU

    2013-01-01

    Abstract:This paper presents a dynamic d-q axis model of three- phase asynchronous motor in synchronously rotating frame. The systems of differential equations representing the dynamic state behaviours of the machine as developed are implemented in MATLAB/SIMULINK. The effects of the stepped sequence of mechanical loading on the motor output variables namely: three-phase stator currents (ia, ib and ic), electromechanical torque and rotor speed, d-q stator and rotor currents (iqs, ids, iqr and...

  4. Application of Asynchronous Weak Commitment Search in Autonomous Quality of Service Provision in Cognitive Radio Networks

    OpenAIRE

    Sodagari, Shabnam

    2014-01-01

    This article presents a distributed solution to autonomous quality of service provision in cognitive radio networks. Specifically, cognitive STDMA and CDMA communication networks are studied. Based on asynchronous weak commitment search the task of QoS provision is distributed among different network nodes. Simulation results verify this scheme converges very fast to optimal solution, which makes it suitable for practical real time systems. This application of artificial intelligence in wirel...

  5. 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.

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

    Directory of Open Access Journals (Sweden)

    Ayesha Perveen

    2016-03-01

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

  7. 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

  8. DIRECT FREQUENCY CONVERTER WITH ARTIFICIAL AND NATURAL COMMUTATION FOR BRUSHLESS ASYNCHRONIZED MACHINES

    Directory of Open Access Journals (Sweden)

    А.М. Galynovskiy

    2015-11-01

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

  9. 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

  10. 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

  11. 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. PMID:26357416

  12. 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, ...

  13. An asynchronous multi-sensor micro control unit for wireless body sensor networks (WBSNs).

    Science.gov (United States)

    Chen, Chiung-An; Chen, Shih-Lun; Huang, Hong-Yi; Luo, Ching-Hsing

    2011-01-01

    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. PMID:22164000

  14. INVESTIGATING THE EFFECT OF ASYNCHRONOUS DISCUSSIONS ON STUDENTS’ LEARNING AND UNDERSTANDING OF MATHEMATICS SUBJECT

    Directory of Open Access Journals (Sweden)

    Ozcan OZYURT

    2011-10-01

    Full Text Available Recently, learning activities have gone beyond conventional environments and started to be performed via computer supported instruments. One of these instruments is asynchronous discussion forums (ADFs used as computer-supported collaborative learning means. Learners practice various learning activities in ADFs and produce knowledge construction. In the present study, document analysis was employed and all Turkish originated ADFs relating mathematics teaching were scanned and put subjected to content analysis. Besides, a survey was implemented on 86 high school and undergraduate students. Both qualitative and quantitative data were obtained through this survey. These data were put subjected to qualitative and quantitative data analysis. Attitudes of students towards computer-supported collaborative learning and asynchronous discussion forums as mathematics learning instrument were tried to be revealed via this study. Also, behaviors of the learners and their views relating the learning activities in these environments were evaluated by means of this study. Results of the study demonstrated that asynchronous discussion forums are widely and efficiently used as computer-supported collaborative learning instrument in terms of mathematics learning.

  15. 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.

  16. Self-calibration algorithm in an asynchronous P300-based brain-computer interface

    Science.gov (United States)

    Schettini, F.; Aloise, F.; Aricò, P.; Salinari, S.; Mattia, D.; Cincotti, F.

    2014-06-01

    Objective. Reliability is a desirable characteristic of brain-computer interface (BCI) systems when they are intended to be used under non-experimental operating conditions. In addition, their overall usability is influenced by the complex and frequent procedures that are required for configuration and calibration. Earlier studies examined the issue of asynchronous control in P300-based BCIs, introducing dynamic stopping and automatic control suspension features. This report proposes and evaluates an algorithm for the automatic recalibration of the classifier's parameters using unsupervised data. Approach. Ten healthy subjects participated in five P300-based BCI sessions throughout a single day. First, we examined whether continuous adaptation of control parameters improved the accuracy of the asynchronous system over time. Then, we assessed the performance of the self-calibration algorithm with respect to the no-recalibration and supervised calibration conditions with regard to system accuracy and communication efficiency. Main results. Offline tests demonstrated that continuous adaptation of the control parameters significantly increased the communication efficiency of asynchronous P300-based BCIs. The self-calibration algorithm correctly assigned labels to unsupervised data with 95% accuracy, effecting communication efficiency that was comparable with that of supervised repeated calibration. Significance. Although additional online tests that involve end-users under non-experimental conditions are needed, these preliminary results are encouraging, from which we conclude that the self-calibration algorithm is a promising solution to improve P300-based BCI usability and reliability.

  17. 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%.

  18. 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

  19. Identifying scale-emergent, nonlinear, asynchronous processes of wetland methane exchange

    Science.gov (United States)

    Sturtevant, Cove; Ruddell, Benjamin L.; Knox, Sara Helen; Verfaillie, Joseph; Matthes, Jaclyn Hatala; Oikawa, Patricia Y.; Baldocchi, Dennis

    2016-01-01

    Methane (CH4) exchange in wetlands is complex, involving nonlinear asynchronous processes across diverse time scales. These processes and time scales are poorly characterized at the whole-ecosystem level, yet are crucial for accurate representation of CH4 exchange in process models. We used a combination of wavelet analysis and information theory to analyze interactions between whole-ecosystem CH4 flux and biophysical drivers in two restored wetlands of Northern California from hourly to seasonal time scales, explicitly questioning assumptions of linear, synchronous, single-scale analysis. Although seasonal variability in CH4 exchange was dominantly and synchronously controlled by soil temperature, water table fluctuations, and plant activity were important synchronous and asynchronous controls at shorter time scales that propagated to the seasonal scale. Intermittent, subsurface water table decline promoted short-term pulses of methane emission but ultimately decreased seasonal CH4 emission through subsequent inhibition after rewetting. Methane efflux also shared information with evapotranspiration from hourly to multiday scales and the strength and timing of hourly and diel interactions suggested the strong importance of internal gas transport in regulating short-term emission. Traditional linear correlation analysis was generally capable of capturing the major diel and seasonal relationships, but mesoscale, asynchronous interactions and nonlinear, cross-scale effects were unresolved yet important for a deeper understanding of methane flux dynamics. We encourage wider use of these methods to aid interpretation and modeling of long-term continuous measurements of trace gas and energy exchange.

  20. 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.

  1. 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.

  2. 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.

  3. 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)

  4. Asynchronous exposure to global warming: freshwater resources and terrestrial ecosystems

    International Nuclear Information System (INIS)

    This modelling study demonstrates at what level of global mean temperature rise (ΔTg) regions will be exposed to significant decreases of freshwater availability and changes to terrestrial ecosystems. Projections are based on a new, consistent set of 152 climate scenarios (eight ΔTg trajectories reaching 1.5–5 ° C above pre-industrial levels by 2100, each scaled with spatial patterns from 19 general circulation models). The results suggest that already at a ΔTg of 2 ° C and mainly in the subtropics, higher water scarcity would occur in >50% out of the 19 climate scenarios. Substantial biogeochemical and vegetation structural changes would also occur at 2 ° C, but mainly in subpolar and semiarid ecosystems. Other regions would be affected at higher ΔTg levels, with lower intensity or with lower confidence. In total, mean global warming levels of 2 ° C, 3.5 ° C and 5 ° C are simulated to expose an additional 8%, 11% and 13% of the world population to new or aggravated water scarcity, respectively, with >50% confidence (while ∼1.3 billion people already live in water-scarce regions). Concurrently, substantial habitat transformations would occur in biogeographic regions that contain 1% (in zones affected at 2 ° C), 10% (3.5 ° C) and 74% (5 ° C) of present endemism-weighted vascular plant species, respectively. The results suggest nonlinear growth of impacts along with ΔTg and highlight regional disparities in impact magnitudes and critical ΔTg levels. (letter)

  5. 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.

  6. 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.

  7. Rational Secret Sharing Over an Asynchronous Broadcast Channel With Information Theoretic Security

    Directory of Open Access Journals (Sweden)

    William K. Moses Jr.

    2011-12-01

    Full Text Available 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, k+1, of honest players. The protocol is resilient to coalitions of size up to k and furthermore it is ε-resilient to coalitions of size up to and including m-1. The protocol will have a strict Nash equilibrium with probability Pr ( and an ε-Nash equilibrium with probability Pr ( . Furthermore, our protocol is immune to backward induction. Later on in the paper, we extend our results to include malicious players as well. We also show that our protocol handles the possibility of a player deviating in order to force anotherplayer to get a wrong value in what we believe to be a more time efficient manner than was done in Asharov and Lindell [5].

  8. 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

  9. 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.

  10. 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.

  11. A solid rotor iron free asynchronous generator for the production of high energy pulses

    International Nuclear Information System (INIS)

    A rotating machine capable of charging a noncooled magnetic storage coil is described. The rotor of the machine which is formed by metallic cylinder rotating at high speed, also behaves as a flywheel. The stator is composed of a three-phase winding connected to a system of rectifiers and power factor correcting condensers, thus forming an auto excited asynchronous generator. A very high power density is achieved because the machine has non ferrous winding, which permits a magnetic field of a few teslas. The basic machine theory and experimental model built are described

  12. 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.

  13. 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.

  14. 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.)

  15. 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 ...

  16. Capacity enhancement of wavelength/time/space asynchronous optical CDMA with relaxed cross-correlation

    Science.gov (United States)

    Singh, Jaswinder

    2013-12-01

    The analysis of a three-dimensional (3-D) wavelength/time/space (W-T-S) asynchronous optical CDMA code family is presented considering MAI only under relaxed cross-correlation (λc ⩾ 1). Based on the code performance, it is shown that for code-limited systems (when W and/or T are non-prime), the number of generated codes and hence the supported users can be significantly increased by relaxing the cross-correlation constraint if a slight degradation in code performance can be tolerated.

  17. 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.

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

    OpenAIRE

    Postoronca S.; Berzan V.P.; Ermurachi Iu

    2008-01-01

    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 genera...

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

    Directory of Open Access Journals (Sweden)

    Allison Hosier

    2013-01-01

    Full Text Available 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 literacy course. This article explores the design and implementation of an online version of the same course where many of the benefits of Team-Based Learning were successfully transferred to the online setting.

  20. Evaluation of QoS differentiation mechanisms in asynchronous bufferless optical packet-switched networks

    DEFF Research Database (Denmark)

    Overby, H.; Stol, N.; Nord, Martin

    2006-01-01

    suitable for a future all-optical network. Hence, new schemes are needed to support QoS differentiation in optical packet-switched (OPS) networks. In this article we first present an overview of existing QoS differentiation mechanisms suitable for asynchronous bufferless OPS. We then compare the......Existing quality of service differentiation schemes for today's IP over point-to-point optical WDM networks take advantage of electronic RAM to implement traffic management algorithms in order to isolate the service classes. Since practical optical RAM is not available, these techniques are not...

  1. 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.

  2. 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...

  3. 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

  4. 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.

  5. An asynchronous finite-state-machine-based buck-boost converter for on-chip adaptive power supply

    OpenAIRE

    Fernández, Daniel; Madrenas Boadas, Jordi; Alarcón Cot, Eduardo José

    2013-01-01

    In this paper we present an asynchronous finite-state machine digital controller co-integrated with an on-chip non-inverting buck-boost power converter with dynamic signal-tracking capabilities. The mostly-digital controller functionally implements a non-PWM zone-wise control law through asynchronous circuitry, thus exhibiting self-timed minimum latency and ultra low power operation due to gate switching activity. Experimental results on a 0.35 lm CMOS technology demonstrate an efficien...

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

    Directory of Open Access Journals (Sweden)

    Robin Goodfellow

    1998-12-01

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

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

    International Nuclear Information System (INIS)

    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 accelerograms using as input a set of parameters that describes, to the best of our knowledge, the geological structure and seismotectonic setting of the investigated area. (author)

  8. 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.

  9. 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

  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. 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.

  12. 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

  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. Asynchronous CDMA Systems with Random Spreading-Part I: Fundamental Limits

    CERN Document Server

    Cottatellucci, Laura; Debbah, Merouane

    2009-01-01

    Spectral efficiency for asynchronous code division multiple access (CDMA) with random spreading is calculated in the large system limit allowing for arbitrary chip waveforms and frequency-flat fading. Signal to interference and noise ratios (SINRs) for suboptimal receivers, such as the linear minimum mean square error (MMSE) detectors, are derived. The approach is general and optionally allows even for statistics obtained by under-sampling the received signal. All performance measures are given as a function of the chip waveform and the delay distribution of the users in the large system limit. It turns out that synchronizing users on a chip level impairs performance for all chip waveforms with bandwidth greater than the Nyquist bandwidth, e.g., positive roll-off factors. For example, with the pulse shaping demanded in the UMTS standard, user synchronization reduces spectral efficiency up to 12% at 10 dB normalized signal-to-noise ratio. The benefits of asynchronism stem from the finding that the excess bandw...

  15. 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.

  16. 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)

  17. 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).

  18. 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...

  19. 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.

  20. 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.

  1. 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)

  2. 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

  3. FPGA - Based Evaluation of Power Analysis Attacks and Its Countermeasures on Asynchronous S-Box

    Directory of Open Access Journals (Sweden)

    G. Gokulashree

    2013-12-01

    Full Text Available A novel asynchronous S-Box design for AES cryptosystems is proposed and validated. The S-Box is considered as the most critical component in AES crypto-circuits since it consumes the most power and leaks the most information against side channel attacks. The proposed design completely based on a delay insensitive logic paradigm known as Null Conversion Logic (NCL. Asynchronous S-Box is based on self-time logic referred to as NCL which supports few beneficial properties for resisting SCAs such as clock free, duail rail encoding and monotonic transitions so that it consumes less power therefore suitable for energy constrained mobile crypto-applications. These beneficial properties make it difficult for an attacker to decipher secret key embedded within the cryptographic circuits of the FPGA board. Resistant to SCAs of both existing and proposed S-Box design are presented using differential power analysis (DPA and correlation power analysis (CPA attacks. The power measurement result showed that the NCL S-Box had lower total power consumption than original and effective against DPA and CPA attacks.

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

    Directory of Open Access Journals (Sweden)

    KenjiKansaku

    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.

  5. 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

  6. Clonal expansion and linear genome evolution through breast cancer progression from pre-invasive stages to asynchronous metastasis

    DEFF Research Database (Denmark)

    Krøigård, Anne Bruun; Larsen, Martin Jakob; Lænkholm, Anne Vibeke; Knoop, Ann; Jensen, Jeanette Dupont; Bak, Martin; Mollenhauer, Jan; Kruse, Torben A; Thomassen, Mads

    2015-01-01

    progression from one breast cancer patient, including two different regions of Ductal Carcinoma In Situ (DCIS), primary tumor and an asynchronous metastasis. We identify a remarkable landscape of somatic mutations, retained throughout breast cancer progression and with new mutational events emerging at each...

  7. Clonal expansion and linear genome evolution through breast cancer progression from pre-invasive stages to asynchronous metastasis

    DEFF Research Database (Denmark)

    Krøigård, Anne Bruun; Larsen, Martin Jakob; Lænkholm, Anne Vibeke; Knoop, Ann; Jensen, Jeanette Dupont; Bak, Martin; Mollenhauer, Jan; Kruse, Torben A; Thomassen, Mads

    progression from one breast cancer patient, including two different regions of Ductal Carcinoma In Situ (DCIS), primary tumor and an asynchronous metastasis. We identify a remarkable landscape of somatic mutations, retained throughout breast cancer progression and with new mutational events emerging at each...

  8. 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…

  9. RESEARCH INTO VALVE-ENGINE TRANSDUCERS OF BRUSHLESS SYNCHRONOUS AND ASYNCHRONIZED MACHINES IN A CIRCUIT SIMULATION SYSTEM.

    Directory of Open Access Journals (Sweden)

    A.M. Galynovskiy

    2013-10-01

    Full Text Available Designing features for valve-engine transducers of brushless synchronous and asynchronized machines are described. Global analysis of research results on the transducer models in a MicroCap circuit simulation system is made, recommendations on the simulation system application in both scientific research and educational process given.

  10. 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…

  11. 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…

  12. Comparing the Social Knowledge Construction Behavioral Patterns of Problem-Based Online Asynchronous Discussion in E/M-Learning Environments

    Science.gov (United States)

    Lan, Yu-Feng; Tsai, Pei-Wei; Yang, Shih-Hsien; Hung, Chun-Ling

    2012-01-01

    In recent years, researchers have conducted various studies on applying wireless networking technology and mobile devices in education settings. However, research on behavioral patterns in learners' online asynchronous discussions with mobile devices is limited. The purposes of this study are to develop a mobile learning system, mobile interactive…

  13. 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. PMID:24880810

  14. 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,…

  15. 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.

  16. 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.

  17. A Particle Filter of Blind Equalization and Multiuser Detection in Asynchronous DS/CDMA Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing; DONG Jian-ping; ZHANG Qian

    2008-01-01

    The particle filter (PF) is proposed to be the asynchronous direct-sequence eude-division multiple-access (DS/CDMA) multiuser detector without knowing the channel state information. The PF performs symbol detection according to the joint posterior density probability of simulated particles including relative delays, fading gains and symbols via sequential importance sample and resample. A simplified scheme is also proposed by separating the independent relative delays and fading with symbols. These parameters are modeled as the extended aggressive processes and estimated by the Kalman fdter, so as to provide their arbitrary importance distribution for symbol detection. Simulation results show that the bit error rate of the PF is less than convntional detectors.Moreover, the complexity of PF is moderate comaparable to other nonlinear suboptimal approaches.

  18. Asynchronous combinatorial action of four regulatory factors activates Bcl11b for T cell commitment.

    Science.gov (United States)

    Kueh, Hao Yuan; Yui, Mary A; Ng, Kenneth K H; Pease, Shirley S; Zhang, Jingli A; Damle, Sagar S; Freedman, George; Siu, Sharmayne; Bernstein, Irwin D; Elowitz, Michael B; Rothenberg, Ellen V

    2016-08-01

    During T cell development, multipotent progenitors relinquish competence for other fates and commit to the T cell lineage by turning on Bcl11b, which encodes a transcription factor. To clarify lineage commitment mechanisms, we followed developing T cells at the single-cell level using Bcl11b knock-in fluorescent reporter mice. Notch signaling and Notch-activated transcription factors collaborate to activate Bcl11b expression irrespectively of Notch-dependent proliferation. These inputs work via three distinct, asynchronous mechanisms: an early locus 'poising' function dependent on TCF-1 and GATA-3, a stochastic-permissivity function dependent on Notch signaling, and a separate amplitude-control function dependent on Runx1, a factor already present in multipotent progenitors. Despite their necessity for Bcl11b expression, these inputs act in a stage-specific manner, providing a multitiered mechanism for developmental gene regulation. PMID:27376470

  19. Asynchronous Checkpoint Migration with MRNet in the Scalable Checkpoint / Restart Library

    Energy Technology Data Exchange (ETDEWEB)

    Mohror, K; Moody, A; de Supinski, B R

    2012-03-20

    Applications running on today's supercomputers tolerate failures by periodically saving their state in checkpoint files on stable storage, such as a parallel file system. Although this approach is simple, the overhead of writing the checkpoints can be prohibitive, especially for large-scale jobs. In this paper, we present initial results of an enhancement to our Scalable Checkpoint/Restart Library (SCR). We employ MRNet, a tree-based overlay network library, to transfer checkpoints from the compute nodes to the parallel file system asynchronously. This enhancement increases application efficiency by removing the need for an application to block while checkpoints are transferred to the parallel file system. We show that the integration of SCR with MRNet can reduce the time spent in I/O operations by as much as 15x. However, our experiments exposed new scalability issues with our initial implementation. We discuss the sources of the scalability problems and our plans to address them.

  20. Approximating Frequent Items in Asynchronous Data Stream over a Sliding Window

    DEFF Research Database (Denmark)

    Ting, Hing-Fung; Lee, Lap Kei; Chan, Ho-Leung;

    2011-01-01

    In an asynchronous data stream, the data items may be out of order with respect to their original timestamps. This paper studies the space complexity required by a data structure to maintain such a data stream so that it can approximate the set of frequent items over a sliding time window...... with sufficient accuracy. Prior to our work, the best solution is given by Cormode et al. [1], who gave an O (1/ε log W log (εB/ log W) min {log W, 1/ε} log |U|)- space data structure that can approximate the frequent items within an ε error bound, where W and B are parameters of the sliding window, and U...

  1. The asynchronous polar V1432 Aquilae and its path back to synchronism

    CERN Document Server

    Boyd, David; Allen, William; Bolt, Greg; Bonnardeau, Michel; Tut,; Campbell, Jeannie; Cejudo, David; Cook, Michael; de Miguel, Enrique; Ding, Claire; Dvorak, Shawn; Foote, Jerrold; Fried, Robert; Hambsch, Franz-Josef; Kemp, Jonathan; Krajci, Thomas; Monard, Berto; Ogmen, Yenal; Rea, Robert; Roberts, George; Skillman, David; Starkey, Donn; Ulowetz, Joseph; Uthas, Helena; Walker, Stan

    2014-01-01

    V1432 Aquilae is the only known eclipsing asynchronous polar. In this respect it is unique and therefore merits our attention. We report the results of a 15-year campaign by the globally distributed Center for Backyard Astrophysics to observe V1432 Aql and investigate its return to synchronism. Originally knocked out of synchrony by a nova explosion before observing records began, the magnetic white dwarf in V1432 Aql is currently rotating slower than the orbital period but is gradually catching up. The fortuitously high inclination of the binary orbit affords us the bonus of eclipses providing a regular clock against which these temporal changes can be assessed. At the present rate, synchronism should be achieved around 2100. The continually changing trajectory of the accretion stream as it follows the magnetic field lines of the rotating white dwarf produces a complex pattern of light emission which we have measured and documented, providing comprehensive observational evidence against which physical models...

  2. A MATCHED FILTER BANK BASED DOA ESTIMATION FOR ASYNCHRONOUS MULTIPATH CDMA CHANNELS

    Institute of Scientific and Technical Information of China (English)

    Yang Wei; Chen Junshi; Tan Zhenhui; Takis Mathiopoulos

    2005-01-01

    In this paper, a Direction Of Arrival (DOA) estimation algorithm is proposed for multiuser signals through uplink asynchronous multipath Code Division Multiple Access (CDMA)channels. The algorithm is based directly on the correlation matrices of matched filter bank outputs of desired user's multipath signals and it does not require that the elements of base station antenna array outnumber the multipath signals, which is necessary for the conventional sub-space based direction-finding algorithm. Simulation results show that the proposed algorithm estimates the DOA of multipath signals effectively and acceptably. The proposed algorithm has the prominent advantages of low complexity, simpleness and practicality, which make it much more suitable for practical application.

  3. Construction and performance analysis of variable-weight optical orthogonal codes for asynchronous OCDMA systems

    Science.gov (United States)

    Li, Chuan-qi; Yang, Meng-jie; Zhang, Xiu-rong; Chen, Mei-juan; He, Dong-dong; Fan, Qing-bin

    2014-07-01

    A construction scheme of variable-weight optical orthogonal codes (VW-OOCs) for asynchronous optical code division multiple access (OCDMA) system is proposed. According to the actual situation, the code family can be obtained by programming in Matlab with the given code weight and corresponding capacity. The formula of bit error rate (BER) is derived by taking account of the effects of shot noise, avalanche photodiode (APD) bulk, thermal noise and surface leakage currents. The OCDMA system with the VW-OOCs is designed and improved. The study shows that the VW-OOCs have excellent performance of BER. Despite of coming from the same code family or not, the codes with larger weight have lower BER compared with the other codes in the same conditions. By taking simulation, the conclusion is consistent with the analysis of BER in theory. And the ideal eye diagrams are obtained by the optical hard limiter.

  4. International service learning in the Dominican Republic: An asynchronous pilot in interprofessional education.

    Science.gov (United States)

    Foster, Jennifer; Pullen, Sara

    2016-03-01

    Despite the logistical barriers of asynchronous academic calendars, university students in nursing and physical therapy in one academic health centre piloted an international, interprofessional, service learning project in the Dominican Republic. Although the nursing students and physical therapy students were not able to be in-country at the same time, they provided care to a common caseload of traumatic injury patients and those with chronic, debilitating conditions. Interprofessional communication occurred with the development of SBAR (Situation, Background, Assessment, Recommendation) reports from the Team Training curriculum of the Agency for Healthcare Research and Quality. Students learned the depth of physical therapy and the breadth of nursing. The pilot led to a more refined design to pair nursing and PT students, requiring them to communicate via mobile phone regarding results of examinations, and suggestions for follow-up by the nursing students, to ensure continuity of care and a more comprehensive approach to services. PMID:26852786

  5. 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

  6. Asynchronous error-correcting secure communication scheme based on fractional-order shifting chaotic system

    Science.gov (United States)

    Chao, Luo

    2015-11-01

    In this paper, a novel digital secure communication scheme is firstly proposed. Different from the usual secure communication schemes based on chaotic synchronization, the proposed scheme employs asynchronous communication which avoids the weakness of synchronous systems and is susceptible to environmental interference. Moreover, as to the transmission errors and data loss in the process of communication, the proposed scheme has the ability to be error-checking and error-correcting in real time. In order to guarantee security, the fractional-order complex chaotic system with the shifting of order is utilized to modulate the transmitted signal, which has high nonlinearity and complexity in both frequency and time domains. The corresponding numerical simulations demonstrate the effectiveness and feasibility of the scheme.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. General-purpose stepping motor-encoder positioning subsystem with standard asynchronous serial-line interface

    International Nuclear Information System (INIS)

    A general-purpose mechanical positioning subsystem for open-loop control of experiment devices which have their positions established and read out by stepping motor-encoder combinations has been developed. The subsystem is to be used mainly for experiments to be conducted at the National Synchrotron Light Source at Brookhaven National Laboratory. The subsystem unit has been designed to be compatible with a wide variety of stepping motor and encoder types. The unit may be operated by any device capable of driving a standard RS-232-C asynchronous serial communication line. An informal survey has shown that several experiments at the Light Source will use one particular type of computer, operating system, and programming language. Accordingly, a library of subroutines compatible with this combination of computer system elements has been written to facilitate driving the positioning subsystem unit

  9. READ-EVAL-PRINT in Parallel and Asynchronous Proof-checking

    Directory of Open Access Journals (Sweden)

    Makarius Wenzel

    2013-07-01

    Full Text Available The LCF tradition of interactive theorem proving, which was started by Milner in the 1970-ies, appears to be tied to the classic READ-EVAL-PRINT-LOOP of sequential and synchronous evaluation of prover commands. We break up this loop and retrofit the read-eval-print phases into a model of parallel and asynchronous proof processing. Thus we explain some key concepts of the Isabelle/Scala approach to prover interaction and integration, and the Isabelle/jEdit Prover IDE as front-end technology. We hope to open up the scientific discussion about non-trivial interaction models for ITP systems again, and help getting other old-school proof assistants on a similar track.

  10. 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.

  11. Asynchronous Message Transmission Technique for Latency Requirements in Time Critical Ship-borne System

    Directory of Open Access Journals (Sweden)

    N. P. Shrivastava

    2016-01-01

    Full Text Available A solution to data ageing requirements in time critical ship system like fire control system is presented. In an operational sea borne platform, navigation requirements for the onboard systems are fulfilled by ring laser gyro-based inertial navigation system. For critical systems like fire control system, navigational data must be delivered in real time without any delay. However due to delay occurring in processing of raw information and transmission of data on interface bus some latency is introduced. Algorithm for an asynchronous message transmission technique from inertial navigation system to user system to meet its latency requirements is discussed. Latency requirement is achieved by sending a separate message with the time stamp for the instance the first byte of 100 Hz attitude data is received at the processing computer of navigation system.Defence Science Journal, Vol. 66, No. 1, January 2016, pp. 26-29, DOI: http://dx.doi.org/10.14429/dsj.66.8502

  12. Iterative Multiuser Receiver Based on Factor Graph for Asynchronous Coded CDMA Systems

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Factor graph, so named because it graphically represents function factorization, with which and its sum-product algorithm the iterative algorithm can be derived clearly. An iterative multiuser receiver based on factor graph for asynchronous coded CDMA system is proposed. In this paper, the a posteriori probability of users information bits conditioned on the noise-whitening filters output is represented by factor graphs, after numbers of iterations with the sum-product algorithm the information bits are estimated. The authors also propose a reduced complexity algorithm. Simulation results show that with this proposed receiver, near-single-user performance can be achieved, and small performance degradation for the reduced complexity algorithm with significant complexity reduction.

  13. 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.

  14. Increasing student interaction and the development of critical thinking in asynchronous threaded discussions

    Directory of Open Access Journals (Sweden)

    Fredricka Joyner

    2012-06-01

    Full Text Available The context for this case study is an online, undergraduate, 300-level organization behavior course that explores the intersection of individuals and organization systems at three levels of aggregation: individual, team/group, and organization system. The case study begins with a learning activity designed to use an asynchronous threaded discussion format to elicit, organize and meaningfully share prior knowledge. The case study goes on to detail the initial review, redesign, assessment and results of an improvement cycle aimed at addressing the challenges of stimulating meaningful interaction and critical thinking in this online format. The resulting redesigned learning activity used a collective visual metaphor, based on prior experience, to fuel the threaded discussion process. The case study includes pre- and post-redesign examples and specific instructions for those interested in applying this approach.

  15. Finite element analysis of a soft mounted 2-pole asynchronous machine concerning vibration stability

    International Nuclear Information System (INIS)

    The paper describes a finite element calculation concerning vibration stability of a 2-pole asynchronous machine with sleeve bearings and flexible shaft, mounted on soft foundation elements. The finite element model considers the rotor, stator, end shields and bearing housings, oil film stiffness and damping, the electromagnetic interaction between rotor and stator - deduced from an electromagnetic field calculation, the gyroscopic effect of the rotor and the influence of the foundation stiffness and damping. The critical mode shapes and natural frequencies are calculated for different rotor speeds and the eigenvalues are analyzed to receive the limit of stability. Therefore the paper shows a calculation method to optimize the vibration stability by considering foundation stiffness and damping.

  16. Asynchronous symmetry-based sequences for homonuclear dipolar recoupling in solid-state nuclear magnetic resonance

    International Nuclear Information System (INIS)

    We show a theoretical framework, based on triple-mode Floquet theory, to analyze recoupling sequences derived from symmetry-based pulse sequences, which have a non-vanishing effective field and are not rotor synchronized. We analyze the properties of one such sequence, a homonuclear double-quantum recoupling sequence derived from the C721 sequence. The new asynchronous sequence outperforms the rotor-synchronized version for spin pairs with small dipolar couplings in the presence of large chemical-shift anisotropy. The resonance condition of the new sequence is analyzed using triple-mode Floquet theory. Analytical calculations of second-order effective Hamiltonian are performed to compare the efficiency in suppressing second-order cross terms. Experiments and numerical simulations are shown to corroborate the results of the theoretical analysis

  17. FBMC receiver for multi-user asynchronous transmission on fragmented spectrum

    Science.gov (United States)

    Doré, Jean-Baptiste; Berg, Vincent; Cassiau, Nicolas; Kténas, Dimitri

    2014-12-01

    Relaxed synchronization and access to fragmented spectrum are considered for future generations of wireless networks. Frequency division multiple access for filter bank multicarrier (FBMC) modulation provides promising performance without strict synchronization requirements contrary to conventional orthogonal frequency division multiplexing (OFDM). The architecture of a FBMC receiver suitable for this scenario is considered. Carrier frequency offset (CFO) compensation is combined with intercarrier interference (ICI) cancellation and performs well under very large frequency offsets. Channel estimation and interpolation had to be adapted and proved effective even for heavily fragmented spectrum usage. Channel equalization can sustain large delay spread. Because all the receiver baseband signal processing functionalities are proposed in the frequency domain, the overall architecture is suitable for multiuser asynchronous transmission on fragmented spectrum.

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

    CERN Document Server

    Palandri, E M

    1974-01-01

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

  19. Asynchronous Group Key Distribution on top of the CC2420 Security Mechanisms for Sensor Networks

    DEFF Research Database (Denmark)

    Hansen, Morten Tranberg

    scheme with no time synchronization requirements. The scheme decreases the number of key updates by providing them on an as needed basis according to the amount of network traffic. We evaluate the CC2420 radio security mechanism and show how to use it as a basis to implement secure group communication......A sensor network is a network consisting of small, inexpensive, low-powered sensor nodes that communicate to complete a common task. Sensor nodes are characterized by having limited communication and computation capabilities, energy, and storage. They often are deployed in hostile environments...... creating a demand for encryption and authentication of the messages sent between them. Due to severe resource constraints on the sensor nodes, efficient key distribution schemes and secure communication protocols with low overhead are desired. In this paper we present an asynchronous group key distribution...

  20. Analysis and asynchronous detection of gradually unfolding errors during monitoring tasks.

    Science.gov (United States)

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

    2015-10-01

    Human studies on cognitive control processes rely on tasks involving sudden-onset stimuli, which allow the analysis of these neural imprints to be time-locked and relative to the stimuli onset. Human perceptual decisions, however, comprise continuous processes where evidence accumulates until reaching a boundary. Surpassing the boundary leads to a decision where measured brain responses are associated to an internal, unknown onset. The lack of this onset for gradual stimuli hinders both the analyses of brain activity and the training of detectors. This paper studies electroencephalographic (EEG)-measurable signatures of human processing for sudden and gradual cognitive processes represented as a trajectory mismatch under a monitoring task. Time-locked potentials and brain-source analysis of the EEG of sudden mismatches revealed the typical components of event-related potentials and the involvement of brain structures related to cognitive control processing. For gradual mismatch events, time-locked analyses did not show any discernible EEG scalp pattern, despite related brain areas being, to a lesser extent, activated. However, and thanks to the use of non-linear pattern recognition algorithms, it is possible to train an asynchronous detector on sudden events and use it to detect gradual mismatches, as well as obtaining an estimate of their unknown onset. Post-hoc time-locked scalp and brain-source analyses revealed that the EEG patterns of detected gradual mismatches originated in brain areas related to cognitive control processing. This indicates that gradual events induce latency in the evaluation process but that similar brain mechanisms are present in sudden and gradual mismatch events. Furthermore, the proposed asynchronous detection model widens the scope of applications of brain-machine interfaces to other gradual processes. PMID:26193332

  1. Computationally Efficient Blind Code Synchronization for Asynchronous DS-CDMA Systems with Adaptive Antenna Arrays

    Directory of Open Access Journals (Sweden)

    Chia-Chang Hu

    2005-04-01

    Full Text Available A novel space-time adaptive near-far robust code-synchronization array detector for asynchronous DS-CDMA systems is developed in this paper. There are the same basic requirements that are needed by the conventional matched filter of an asynchronous DS-CDMA system. For the real-time applicability, a computationally efficient architecture of the proposed detector is developed that is based on the concept of the multistage Wiener filter (MWF of Goldstein and Reed. This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigendecomposition of a covariance matrix. As a consequence, this detector achieves a complexity that is only a linear function of the size of antenna array (J, the rank of the MWF (M, the system processing gain (N, and the number of samples in a chip interval (S, that is, 𝒪(JMNS. The complexity of the equivalent detector based on the minimum mean-squared error (MMSE or the subspace-based eigenstructure analysis is a function of 𝒪((JNS3. Moreover, this multistage scheme provides a rapid adaptive convergence under limited observation-data support. Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the J-element antenna array, the amount of the L-sample support, and the rank of the M-stage MWF. The performance advantage of the proposed detector over other DS-CDMA detectors is investigated as well.

  2. Time Students Spend Reading Threaded Discussions in Online Graduate Courses Requiring Asynchronous Participation

    Directory of Open Access Journals (Sweden)

    Abbie H. Brown

    2009-12-01

    Full Text Available The authors report the results of a study that provides bases for comparison between the time necessary to participate in courses delivered asynchronously online and courses delivered in a traditional classroom setting. Weekly discussion threads from 21 sections of six courses offered as part of online, degree-granting, accredited, graduate programs were examined. The purpose of this research is to determine whether students are spending more or less time participating in an online course than in a traditional classroom.The discussion size (i.e., the number of words per discussion was determined using the automatic word count function in MS Word. Once the word counts for each course section were determined, the average words per discussion were calculated. The authors used 180 words per minute to calculate the average reading time, based on the work of Ziefle (1998 and Carver (1985, 1990, in order to determine the average minutes per week a student spent reading the discussions.The study indicates that a typical, graduate-level, online, asynchronous discussion requires about one hour a week of reading time, and the time commitment for participatory activity is similar to that of traditional, face-to-face courses, given that it takes under two hours to compose initial messages and responses to the discussion prompt.Although these findings are informative, further research is recommended in the area of time spent on online course activities in terms of student hours earned to enable a direct focus on various student characteristics, such as English language competency and student level.

  3. Analysis and asynchronous detection of gradually unfolding errors during monitoring tasks

    Science.gov (United States)

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

    2015-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Timothy P. Young

    2014-11-01

    Full Text Available Introduction: A “flipped classroom” educational model exchanges the traditional format of a classroom lecture and homework problem set. We piloted two flipped classroom sessions in our emergency medicine (EM residency didactic schedule. We aimed to learn about resident and faculty impressions of the sessions, in order to develop them as a regular component of our residency curriculum. Methods: We evaluated residents’ impression of the asynchronous video component and synchronous classroom component using four Likert items. We used open-ended questions to inquire about resident and faculty impressions of the advantages and disadvantages of the format. Results: For the Likert items evaluating the video lectures, 33/35 residents (94%, 95% CI 80%-99% responded that the video lecture added to their knowledge about the topic, and 33/35 residents felt that watching the video was a valuable use of their time. For items evaluating the flipped classroom format, 36/38 residents (95%, 95% CI 82%-99% preferred the format to a traditional lecture on the topic, and 38/38 residents (100%, 95% CI 89%-100% felt that the small group session was effective in helping them learn about the topic. Most residents preferred to see the format monthly in our curriculum and chose an ideal group size of 5.5 (first session and 7 (second session. Residents cited the interactivity of the sessions and access to experts as advantages of the format. Faculty felt the ability to assess residents’ understanding of concepts and provide feedback were advantages. Conclusion: Our flipped classroom model was positively received by EM residents. Residents preferred a small group size and favored frequent use of the format in our curriculum. The flipped classroom represents one modality that programs may use to incorporate a mixture of asynchronous and interactive synchronous learning and provide additional opportunities to evaluate residents. [West J Emerg Med. 2014;15(7:-0.

  5. A new asynchronous parallel algorithm for inferring large-scale gene regulatory networks.

    Directory of Open Access Journals (Sweden)

    Xiangyun Xiao

    Full Text Available The reconstruction of gene regulatory networks (GRNs from high-throughput experimental data has been considered one of the most important issues in systems biology research. With the development of high-throughput technology and the complexity of biological problems, we need to reconstruct GRNs that contain thousands of genes. However, when many existing algorithms are used to handle these large-scale problems, they will encounter two important issues: low accuracy and high computational cost. To overcome these difficulties, the main goal of this study is to design an effective parallel algorithm to infer large-scale GRNs based on high-performance parallel computing environments. In this study, we proposed a novel asynchronous parallel framework to improve the accuracy and lower the time complexity of large-scale GRN inference by combining splitting technology and ordinary differential equation (ODE-based optimization. The presented algorithm uses the sparsity and modularity of GRNs to split whole large-scale GRNs into many small-scale modular subnetworks. Through the ODE-based optimization of all subnetworks in parallel and their asynchronous communications, we can easily obtain the parameters of the whole network. To test the performance of the proposed approach, we used well-known benchmark datasets from Dialogue for Reverse Engineering Assessments and Methods challenge (DREAM, experimentally determined GRN of Escherichia coli and one published dataset that contains more than 10 thousand genes to compare the proposed approach with several popular algorithms on the same high-performance computing environments in terms of both accuracy and time complexity. The numerical results demonstrate that our parallel algorithm exhibits obvious superiority in inferring large-scale GRNs.

  6. Aide à l'apprentissage du discours oral dans un contexte de communication asynchrone Help with the learning of spoken discourse in an asynchronous context

    Directory of Open Access Journals (Sweden)

    John Fynn

    2007-11-01

    Full Text Available Nous avons développé VoiceForum pour résoudre un problème concernant l'aide à apporter aux apprenants engagés dans un travail d'interaction orale en L2. Dans le cadre d'une approche par tâches, facilitée par la tendance actuelle à développer des outils de type collecticiel, nous abordons la problématique de la rétroaction à chaud. Les formateurs sont confrontés au dilemme de savoir s'ils doivent privilégier le sens ou la forme. Nous constatons que privilégier la forme conduit à inhiber fortement les échanges. Pour contourner cet obstacle, VoiceForum fonctionne en mode asynchrone. Il permet à des apprenants de converser à l'oral en laissant des messages oraux sur un forum. Une autre fonction du logiciel est d'autoriser le tuteur à créer des aides personnalisées sous forme de rétroactions positives ou négatives liées aux messages envoyés. L'intérêt de ces aides, c'est qu'elles sont contextualisées et donc plus pertinentes pour les apprenants. Ces aides demeurent accessibles au sein du forum qui comporte un outil de recherche pour en faciliter la consultation. Nous faisons l'hypothèse que les aides créées constituent ainsi une nouvelle ressource évolutive qui sera plus efficace que la pratique courante de fournir aux participants une liste de rétroactions à la fin d'une séance de discussion.We have developed our VoiceForum software solution to solve a basic problem regarding how to help learners in L2 spoken interaction activities. In a task-based approach, which is facilitated by the present trend towards groupware solutions, we discuss the problem of giving learners immediate feedback on their oral work. At the centre of this problem, trainers are faced with the dilemma of knowing whether to focus on meaning or on form. We have observed that focusing on form greatly inhibits interaction.To get round this problem, VoiceForum works asynchronously. It enables learners to talk together by posting spoken messages

  7. Learning Together: A Positieve Experience.The effect of reflection on group processes in an asynchronous computer-supported collaboratieve learning environment.

    NARCIS (Netherlands)

    Dewiyanti, Silvia

    2007-01-01

    Dewiyanti, S. (2005).Learning Together: A Positieve Experience.The effect of reflection on group processes in an asynchronous computer-supported collaboratieve learning environment. Unpublished doctoral dissertation. Open University of the Netherlands, The Netherlands.

  8. Asynchronous detection of optical code division multiple access signals using a bandwidth-efficient and wavelength-aware receiver.

    Science.gov (United States)

    Fok, Mable P; Deng, Yanhua; Prucnal, Paul R

    2010-04-01

    We experimentally demonstrate what we believe to be a novel detection scheme for interfacing asynchronous optical code division multiple access (CDMA) signals with an electronic clock and data recovery system that operates only at the baseband bandwidth. This allows using a large optical bandwidth expansion factor in which the optical chip rate is much larger than the bandwidth of the optoelectronic receiver. The received optical CDMA signal is launched into a four-wave-mixing-based wavelength-aware all-optical front end that rejects multiaccess interference, followed by an amplitude-noise suppression stage comprised of a semiconductor optical amplifier. The clean signal is then converted into a non-return-to-zero-like signal by a baseband receiver. Using the proposed detection scheme, asynchronous transmission and detection of optical CDMA signals is implemented. With the novel detection scheme, the classic CDMA near-far problem is mitigated, and error-free detection is easily obtained. PMID:20364229

  9. Clonal expansion and linear genome evolution through breast cancer progression from pre-invasive stages to asynchronous metastasis

    DEFF Research Database (Denmark)

    Krøigård, Anne Bruun; Larsen, Martin Jakob; Lænkholm, Anne-Vibeke; Knoop, Ann S; Jensen, Jeanette D; Bak, Martin; Mollenhauer, Jan; Kruse, Torben A; Thomassen, Mads

    2015-01-01

    necessitates knowledge of the degree of genomic concordance between different steps of malignant progression as primary tumors often are used as surrogates of systemic disease. Based on exome sequencing we performed copy number profiling and point mutation detection on successive steps of breast cancer......Evolution of the breast cancer genome from pre-invasive stages to asynchronous metastasis is complex and mostly unexplored, but highly demanded as it may provide novel markers for and mechanistic insights in cancer progression. The increasing use of personalized therapy of breast cancer...... progression from one breast cancer patient, including two different regions of Ductal Carcinoma In Situ (DCIS), primary tumor and an asynchronous metastasis. We identify a remarkable landscape of somatic mutations, retained throughout breast cancer progression and with new mutational events emerging at each...

  10. Clonal expansion and linear genome evolution through breast cancer progression from pre-invasive stages to asynchronous metastasis

    DEFF Research Database (Denmark)

    Krøigård, Anne Bruun; Larsen, Martin Jakob; Lænkholm, Anne Vibeke; Knoop, Ann; Jensen, Jeanette Dupont; Bak, Martin; Mollenhauer, Jan; Kruse, Torben A; Thomassen, Mads

    necessitates knowledge of the degree of genomic concordance between different steps of malignant progression as primary tumors often are used as surrogates of systemic disease. Based on exome sequencing we performed copy number profiling and point mutation detection on successive steps of breast cancer......Evolution of the breast cancer genome from pre-invasive stages to asynchronous metastasis is complex and mostly unexplored, but highly demanded as it may provide novel markers for and mechanistic insights in cancer progression. The increasing use of personalized therapy of breast cancer...... progression from one breast cancer patient, including two different regions of Ductal Carcinoma In Situ (DCIS), primary tumor and an asynchronous metastasis. We identify a remarkable landscape of somatic mutations, retained throughout breast cancer progression and with new mutational events emerging at each...

  11. Asynchronous anti-noise hyper chaotic secure communication system based on dynamic delay and state variables switching

    International Nuclear Information System (INIS)

    This Letter designs an asynchronous hyper chaotic secure communication system, which possesses high stability against noise, using dynamic delay and state variables switching to ensure the high security. The relationship between the bit error ratio (BER) and the signal-to-noise ratio (SNR) is analyzed by simulation tests, the results show that the BER can be ensured to reach zero by proportionally adjusting the amplitudes of the state variables and the noise figure. The modules of the transmitter and receiver are implemented, and numerical simulations demonstrate the effectiveness of the system. -- Highlights: → Asynchronous anti-noise hyper chaotic secure communication system. → Dynamic delay and state switching to ensure the high security. → BER can reach zero by adjusting the amplitudes of state variables and noise figure.

  12. Considering High School Students’ Experience in Asynchronous and Synchronous Distance Learning Environments: QoE Prediction Model

    OpenAIRE

    Toni Malinovski; Marina Vasileva; Tatjana Vasileva-Stojanovska; Vladimir Trajkovik

    2014-01-01

    Early identification of relevant factors that influence students’ experiences is vitally important to the educational process since they play an important role in learning outcomes. The purpose of this study is to determine underlying constructs that predict high school students’ subjective experience and quality expectations during asynchronous and synchronous distance education activities, in a form of quality of experience (QoE). One hundred and fifty-eight students from different high sch...

  13. A Review of the World's Commercial Pipeline of GM Crops and Implications for Asynchronous Approvals and Trade

    OpenAIRE

    STEIN Alexander Jivraj; Rodriguez Cerezo, Emilio

    2009-01-01

    Commission's Joint Research Centre (JRC), Institute for Prospective Tech¬nological Studies (IPTS). The panel gathered GM technology developers (private and public), regulators and stakeholders involved in the commercialisation of GM crops worldwide. The main objective is to compile a world-wide pipeline of new GM crops that are to being commercialised in the short to medium term. This commercial pipeline of new GM crops will be analysed in view of asynchronous approval of GM cr...

  14. Starting-Up Impact of Powerful Asynchronous Motors Used at Gas-Compressor Units on GRID Mode

    Directory of Open Access Journals (Sweden)

    A. Hashimov

    2014-09-01

    Full Text Available The paper investigates starting-up modes of powerful asynchronous motors used at gas-compressor units which are applied for oil and gas production and transportation. Impact of motor starting-up on GRID mode for various variants of a scheme structure is considered in the paper. The paper presents investigation results taking 7 MW capacity motors as an example. The motors concerned are applied at compressor units used for oil production inAzerbaijan.

  15. Invertebrate muscles: thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle

    OpenAIRE

    Hooper, Scott L; Hobbs, Kevin H.; Jeffrey B Thuma

    2008-01-01

    This is the second in a series of canonical reviews on invertebrate muscle. We cover here thin and thick filament structure, the molecular basis of force generation and its regulation, and two special properties of some invertebrate muscle, catch and asynchronous muscle. Invertebrate thin filaments resemble vertebrate thin filaments, although helix structure and tropomyosin arrangement show small differences. Invertebrate thick filaments, alternatively, are very different from vertebrate stri...

  16. Asynchronous Superimposition Mechanisms of Concurrent Competitve Waves for Hyper-Distributed Hyper-Parallel Heuristic Problem Solving

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    This paper presents a new approach to hyper-distributed hyper-parallel heuristic AI problem solving,which is based on asynchronous superimposition of synchronous homogeneous concurrent propagations of competitive waves.In comparison with synchronous homogeneous mechanism,the proposed approach shows better generality,suitability and feasibility for real-time AI processing,especially for the search of implicit AND/OR graphs.

  17. Student Participation and Interactivity Using Asynchronous Computer-Mediated Communication for Resolution of an Undergraduate Capstone Management Case Study

    OpenAIRE

    Miller, Paulette J.

    2012-01-01

    Online discussion activities are designed for computer-mediated learning activities in face-to-face, hybrid, and totally online courses. The use of asynchronous computer-mediated communication (A-CMC) coupled with authentic workplace case studies provides students in the protected learning environment with opportunities to practice workplace decision making and communication. In this study, communication behaviors of transmitter and receiver were analyzed to determine participation and intera...

  18. Direct synchronous-asynchronous conversion system for hybrid electrical vehicle applications. An energy-based modeling approach

    OpenAIRE

    Muñoz-Aguilar, Raúl S.; Dòria-Cerezo, Arnau; Puleston, Pablo Federico

    2013-01-01

    This paper presents a proposal for a series hybrid electric vehicle propulsion system. This new configuration is based on a wound-rotor synchronous generator (WRSM) and a doubly-fed induction machine (DFIM). The energy-based model of the whole system is obtained taking advantage of the capabilities of the port-based modeling techniques. From the dq port-controlled Hamiltonian description of the WRSM and DFIM, the Hamiltonian model of the proposed Direct Synchronous-Asynchronous Conversion Sys...

  19. Instructional design and facilitation approaches that promote critical thinking in asynchronous online discussions: A review of the literature

    OpenAIRE

    Schindler, Laura A.; Burkholder, Gary J.

    2014-01-01

    Asynchronous online discussions (AODs) are often used to promote critical thinking in online courses; however, recent research suggests that levels of critical thinking in discussions remain low. Furthermore, there is a lack of consensus in the literature about the definition of critical thinking and many of the existing studies focus on one specific cognitive construct. Therefore, it is unknown which instructional approaches have the strongest empirical support for promoting critical thinkin...

  20. Static Frequency Converter with RNSIC Converter and Double Branch Inverter for Supplying Three-Phase Asynchronous Motors

    OpenAIRE

    Lazar, G. A.; ALEXA, D.; Lazar, A.; BUZATU, N. R.; MOISA, M.

    2010-01-01

    The paper presents the design and analysis of a three-phase static converter, composed of a Rectifier with Near Sinusoidal Input Currents (RNSIC), which ensures the DC bus voltage level for a three phase Incomplete Bridge Inverter (IBI), used to drive an asynchronous motor. The proposed circuit has a low input current harmonic content, can ensure the load overcurrent protection and has a better reliability. The converter can be designed to provide any required output maximum power under a ...

  1. Sustainable project of microgeneration systems based on asynchronous generator; Projeto sustentavel de sistemas de microgeracao baseados em gerador assincrono

    Energy Technology Data Exchange (ETDEWEB)

    Salazar Herrera, Victoria Alejandra; Romero, Jesus Franklin Andrade [Universidade Federal do ABC (CECS/UFABC), Santo Andre, SP (Brazil). Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas. Programa de Pos-Graduacao em Energia], emails: victoria.herrera@ufabc.edu.br, jesus.romero@ufabc.edu.br

    2010-07-01

    Recently, the interest in decentralized generation systems has increased considering a multidisciplinary and sustainable approach. In this sense, this work proposes the evaluation of isolated microgeneration systems, focusing the life cycle of the asynchronous generator, considering the technological, economic and environmental dimensions. By means of the generator efficiency, the unbalanced voltage percentage and the emissions factor, the work point out the relevance of health diagnosis of isolated microgeneration systems objectifying minimize the impacts caused by faulty operation of the generator. (author)

  2. The concept of "stability" in asynchronous distributed decision-making systems.

    Science.gov (United States)

    Lee, T S; Ghosh, S

    2000-01-01

    Asynchronous distributed decision-making (ADDM) systems constitute a special class of distributed problems and are characterized as large, complex systems wherein the principal elements are the geographically dispersed entities that communicate among themselves, asynchronously, through message passing and are permitted autonomy in local decision making. Such systems generally offer significant advantages over the traditional, centralized algorithms in the form of concurrency, scalability, high throughput, efficiency, low vulnerability to catastrophic failures, and robustness. A fundamental property of ADDM systems is stability that refers to their behavior under representative perturbations to their operating environments, given that such systems are intended to be real, complex, and to some extent, mission-critical, and are subject to unexpected changes in their operating conditions. This paper introduces the concept of stability in ADDM systems and proposes an intuitive yet practical and usable definition that is inspired by those used in control systems and physics. An ADDM system is defined as a stable system if it returns to a steady state in finite time, following perturbation, provided that it is initiated in a steady state. Equilibrium or steady state is defined through placing bounds on the measured error in the system. Where the final steady state is equivalent to the initial one, a system is referred to as strongly stable. If the final steady state is potentially worse then the initial one, a system is deemed marginally stable. When a system fails to return to steady state following the perturbation, it is unstable. The perturbations are classified as either changes in the input pattern or changes in one or more environmental characteristics of the system, such as hardware failures. For a given ADDM system, the definitions are based on the performance indices that must be judiciously identified by the system architect and are likely to be unique. To

  3. Breaking The Millisecond Barrier On SpiNNaker: Implementing Asynchronous Event-Based Plastic Models With Microsecond Resolution

    Directory of Open Access Journals (Sweden)

    Xavier eLagorce

    2015-06-01

    Full Text Available Spike-based neuromorphic sensors such as retinas and cochleas, change the way in which the world is sampled. Instead of producing data sampled at a constant rate, these sensors output spikes that are asynchronous and event driven. The event-based nature of neuromorphic sensors implies a complete paradigm shift in current perception algorithms towards those that emphasize the importance of precise timing. The spikes produced by these sensors usually have a time resolution in the order of microseconds. This high temporal resolution is a crucial factor in learning tasks. It is also widely used in the field of biological neural networks. Sound localization for instance relies on detecting time lags between the two ears which, in the barn owl, reaches a temporal resolution of 5 microseconds. Current available neuromorphic computation platforms such as SpiNNaker often limit their users to a time resolution in the order of milliseconds that is not compatible with the asynchronous outputs of neuromorphic sensors. To overcome these limitations and allow for the exploration of new types of neuromorphic computing architectures, we introduce a novel software framework on the SpiNNaker platform. This framework allows for simulations of spiking networks and plasticity mechanisms using a completely asynchronous and event-based scheme running with a microsecond time resolution. Results on two example networks using this new implementation are presented.

  4. Asynchronous Hybrid Kogge-Stone Structure Carry Select Adder Based IEEE-754 Double-Precision Floating-Point Adder

    Directory of Open Access Journals (Sweden)

    Abhijith Kini G.

    2011-09-01

    Full Text Available In this paper, the design and implementation of a generic fast asynchronous Hybrid Kogge-Stone Structure Carry Select based Adder (HKSS-CSA is described in detail and its application in the design of asynchronous Double Precision Floating-Point Adder (DPFPA is presented and the improved latency performance it provides is discussed. A detailed analysis in terms of maximum combinational delay, number of logic levels and logic resources used by both these adders is provided. The proposed HKSS-CSA adders performance is compared with a generic reference Carry Look-Ahead Adder (CLA in terms of the above parameters. For the same set of inputs, the HKSS-CSA resulted in approximately 40% (32-bit - 65% (128-bit reduction in the number of logic levels, thereby improving the overall latency by a factor of 2 (32-bit - 6 (128-bit times compared to a CLA. A 64-bit instance of this HKSS-CSA was made use of in the design of an asynchronous DPFPA and its performance compared with a reference DPFPA which makes use of a CLA in the intermediate stage. The reference DPFPA had a maximum combinational delay of 36.25ns while the newly suggested DPFPA had a delay of 18.60ns for the same set of inputs, giving about 50% improvement in overall latency performance, which can be mainly attributed to the latency improvement provided by the HKSS-CSA.

  5. Characterization of the three-dimensional free energy manifold for the uracil ribonucleoside from asynchronous replica exchange simulations.

    Science.gov (United States)

    Radak, Brian K; Romanus, Melissa; Lee, Tai-Sung; Chen, Haoyuan; Huang, Ming; Treikalis, Antons; Balasubramanian, Vivekanandan; Jha, Shantenu; York, Darrin M

    2015-02-10

    Replica exchange molecular dynamics has emerged as a powerful tool for efficiently sampling free energy landscapes for conformational and chemical transitions. However, daunting challenges remain in efficiently getting such simulations to scale to the very large number of replicas required to address problems in state spaces beyond two dimensions. The development of enabling technology to carry out such simulations is in its infancy, and thus it remains an open question as to which applications demand extension into higher dimensions. In the present work, we explore this problem space by applying asynchronous Hamiltonian replica exchange molecular dynamics with a combined quantum mechanical/molecular mechanical potential to explore the conformational space for a simple ribonucleoside. This is done using a newly developed software framework capable of executing >3,000 replicas with only enough resources to run 2,000 simultaneously. This may not be possible with traditional synchronous replica exchange approaches. Our results demonstrate 1.) the necessity of high dimensional sampling simulations for biological systems, even as simple as a single ribonucleoside, and 2.) the utility of asynchronous exchange protocols in managing simultaneous resource requirements expected in high dimensional sampling simulations. It is expected that more complicated systems will only increase in computational demand and complexity, and thus the reported asynchronous approach may be increasingly beneficial in order to make such applications available to a broad range of computational scientists. PMID:26580900

  6. An asynchronous and parallel time-marching method: Application to three-dimensional MHD simulation of solar wind

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    An asynchronous and parallel time-marching method for three-dimensional (3D) time-dependent magnetohydrodynamic (MHD) simulation is used for large-scale solar wind simulation. It uses different local time steps in the corona and the heliosphere according to the local Courant-Friedrichs-Levy (CFL) conditions. The solar wind background with observed solar photospheric magnetic field as input is first presented. The simulation time for the background solar wind by using the asynchronous method is <1/6 of that by using the normal synchronous time-marching method with the same computation precision. Then, we choose the coronal mass ejection (CME) event of 13 November, 2003 as a test case. The time-dependent variations of the pressure and the velocity configured from a CME model at the inner boundary are applied to generate transient structures in order to study the dynamical interaction of a CME with the background solar wind flow between 1 and 230 Rs. This time-marching method is very effective in terms of computation time for large-scale 3D time-dependent numerical MHD problem. In this validation study, we find that this 3D MHD model, with the asynchronous and parallel time-marching method, provides a relatively satisfactory comparison with the ACE spacecraft obser- vations at L1 point.

  7. Multiple-input single-output closed-loop isometric force control using asynchronous intrafascicular multi-electrode stimulation.

    Science.gov (United States)

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

    2011-06-01

    Although asynchronous intrafascicular multi-electrode stimulation (IFMS) can evoke fatigue-resistant muscle force, a priori determination of the necessary stimulation parameters for precise force production is not possible. This paper presents a proportionally-modulated, multiple-input single-output (MISO) controller that was designed and experimentally validated for real-time, closed-loop force-feedback control of asynchronous IFMS. Experiments were conducted on anesthetized felines with a Utah Slanted Electrode Array implanted in the sciatic nerve, either acutely or chronically ( n = 1 for each). Isometric forces were evoked in plantar-flexor muscles, and target forces consisted of up to 7 min of step, sinusoidal, and more complex time-varying trajectories. The controller was successful in evoking steps in force with time-to-peak of less than 0.45 s, steady-state ripple of less than 7% of the mean steady-state force, and near-zero steady-state error even in the presence of muscle fatigue, but with transient overshoot of near 20%. The controller was also successful in evoking target sinusoidal and complex time-varying force trajectories with amplitude error of less than 0.5 N and time delay of approximately 300 ms. This MISO control strategy can potentially be used to develop closed-loop asynchronous IFMS controllers for a wide variety of multi-electrode stimulation applications to restore lost motor function. PMID:21385670

  8. Control or non-control state: that is the question! An asynchronous visual P300-based BCI approach

    Science.gov (United States)

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

    2015-02-01

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

  9. Integrated application of transcriptomics and metabolomics yields insights into population-asynchronous ovary development in Coilia nasus.

    Science.gov (United States)

    Xu, Gangchun; Du, Fukuan; Li, Yan; Nie, Zhijuan; Xu, Pao

    2016-01-01

    Populations of Coilia nasus demonstrate asynchronous ovarian development, which severely restricts artificial breeding and large-scale cultivation. In this study, we used a combination of transcriptomic and metabolomic methods to identify the key signaling pathways and genes regulation affecting ovarian development. We identified 565 compounds and generated 47,049 unigenes from ovary tissue. Fifteen metabolites and 830 genes were significantly up-regulated, while 27 metabolites and 642 genes were significantly down-regulated from stage III to stage IV of ovary development. Meanwhile, 31 metabolites and 1,932 genes were significantly up-regulated, and four metabolites and 764 genes were down-regulated from stage IV to stage V. These differentially expressed genes and metabolites were enriched by MetScape. Forty-three and 50 signaling pathways had important functions from stage III-IV and from stage IV-V in the ovary, respectively. Among the above signaling pathways, 39 played important roles from ovarian stage III-V, including "squalene and cholesterol biosynthesis", "steroid hormone biosynthesis", and "arachidonate metabolism and prostaglandin formation" pathways which may thus have key roles in regulating asynchronous development. These results shed new light on our understanding of the mechanisms responsible for population-asynchronous development in fish. PMID:27545088

  10. Considering High School Students’ Experience in Asynchronous and Synchronous Distance Learning Environments: QoE Prediction Model

    Directory of Open Access Journals (Sweden)

    Toni Malinovski

    2014-09-01

    Full Text Available Early identification of relevant factors that influence students’ experiences is vitally important to the educational process since they play an important role in learning outcomes. The purpose of this study is to determine underlying constructs that predict high school students’ subjective experience and quality expectations during asynchronous and synchronous distance education activities, in a form of quality of experience (QoE. One hundred and fifty-eight students from different high schools participated in several asynchronous and synchronous learning sessions and provided relevant feedback with comparable opinions regarding different conditions. Structural equation modeling was used as an analytical procedure during data analysis which led to a QoE prediction model that identified relevant factors influencing students’ subjective QoE. The results demonstrated no significant difference related to students’ behavior and expectations during both distance education methods. Additionally, this study revealed that students’ QoE in any situation was mainly determined by motivational factors (intrinsic and extrinsic and moderately influenced by ease of use during synchronous or quality of content during asynchronous activities. We also found moderate support between technical performance and students’ QoE in both learning environments. However, opposed to existing technology acceptance models that stress the importance of attitude towards use, high school students’ attitude failed to predict their QoE.

  11. Measurements of atomic sodium in flames by asynchronous optical sampling: theory and experiment.

    Science.gov (United States)

    Fiechtner, G J; King, G B; Laurendeau, N M; Lytle, F E

    1992-05-20

    Asynchronous optical sampling (ASOPS) is a pump-probe method for the measurement of species concentrations in turbulent high-pressure flames. We show that rapid measurement of species number density can be achieved in a highly quenched environment by maintaining a constant beat frequency between the mode-locking frequencies of the pump and the probe lasers. A model for the ASOPS method based on rate equation theory for three- and four-level atoms is presented. A number of improvements are made to the basic ASOPS instrument, which result in a greatly enhanced signal-to-noise ratio. Atomic sodium is aspirated into an atmospheric pressure C(2)H(4)/O(2)/N(2) flame and detected with the ASOPS instrument. When excited-state lifetimes are fitted by using the ASOPS theory, a 3P((1/2),3/2) ? 3S((1/2)) quenching-rate coefficient of 1.72 x 10(9) s(-1) and a 3P(3/2) ? 3P((1/2)) doublet-mixing rate coefficient of 3.66 x 109 s(-1) are obtained, in excellent agreement with literature values. ASOPS signals obtained over a wide range of pump and probe beam powers validate the rate equation theory. Improvements are suggested to improve the signal-to-noise ratio, since the present results are limited to laminar flows. PMID:20725220

  12. Mutual and asynchronous anticipation and action in sports as globally competitive and locally coordinative dynamics

    Science.gov (United States)

    Fujii, Keisuke; Isaka, Tadao; Kouzaki, Motoki; Yamamoto, Yuji

    2015-11-01

    Humans interact by changing their actions, perceiving other’s actions and executing solutions in conflicting situations. Using oscillator models, nonlinear dynamics have been considered for describing these complex human movements as an emergence of self-organisation. However, these frameworks cannot explain the hierarchical structures of complex behaviours between conflicting inter-agent and adapting intra-agent systems, especially in sport competitions wherein mutually quick decision making and execution are required. Here we adopt a hybrid multiscale approach to model an attack-and-defend game during which both players predict the opponent’s movement and move with a delay. From both simulated and measured data, one synchronous outcome between two-agent (i.e. successful defence) can be described as one attractor. In contrast, the other coordination-breaking outcome (i.e. successful attack) cannot be explained using gradient dynamics because the asymmetric interaction cannot always assume a conserved physical quantity. Instead, we provide the asymmetric and asynchronous hierarchical dynamical models to discuss two-agent competition. Our framework suggests that possessing information about an opponent and oneself in local-coordinative and global-competitive scale enables us to gain a deeper understanding of sports competitions. We anticipate developments in the scientific fields of complex movement adapting to such uncontrolled environments.

  13. Triggering Different Brain States Using Asynchronous Serial Communication to the Rat Amygdala.

    Science.gov (United States)

    Mourão, Flávio Afonso Gonçalves; Lockmann, André Luiz Vieira; Castro, Gabriel Perfeito; de Castro Medeiros, Daniel; Reis, Marina Pádua; Pereira, Grace Schenatto; Massensini, André Ricardo; Moraes, Marcio Flávio Dutra

    2016-05-01

    Inputting information to the brain through direct electrical microstimulation must consider how underlying neural networks encode information. One unexplored possibility is that a single electrode delivering temporally coded stimuli, mimicking an asynchronous serial communication port to the brain, can trigger the emergence of different brain states. This work used a discriminative fear-conditioning paradigm in rodents in which 2 temporally coded microstimulation patterns were targeted at the amygdaloid complex. Each stimulus was a binary-coded "word" made up of 10 ms bins, with 1's representing a single pulse stimulus: A-1001111001 and B-1110000111. During 3 consecutive retention tests (i.e., day-word: 1-B; 2-A, and 3-B), only binary-coded words previously paired with a foot-electroshock elicited proper aversive behavior. To determine the neural substrates recruited by the different stimulation patterns, c-Fos expression was evaluated 90 min after the last retention test. Animals conditioned to word-B, after stimulation with word-B, demonstrated increased hypothalamic c-Fos staining. Animals conditioned to word-A, however, showed increased prefrontal c-Fos labeling. In addition, prefrontal-cortex and hypothalamic c-Fos staining for, respectively, word-B- and word-A-conditioned animals, was not different than that of an unpaired control group. Our results suggest that, depending on the valence acquired from previous learning, temporally coded microstimulation activates distinct neural networks and associated behavior. PMID:25609241

  14. Blind Synchronization in Asynchronous UWB Networks Based on the Transmit-Reference Scheme

    Directory of Open Access Journals (Sweden)

    Leus Geert

    2006-01-01

    Full Text Available Ultra-wideband (UWB wireless communication systems are based on the transmission of extremely narrow pulses, with a duration inferior to a nanosecond. The application of transmit reference (TR to UWB systems allows to side-step channel estimation at the receiver, with a tradeoff of the effective transmission bandwidth, which is reduced by the usage of a reference pulse. Similar to CDMA systems, different users can share the same available bandwidth by means of different spreading codes. This allows the receiver to separate users, and to recover the timing information of the transmitted data packets. The nature of UWB transmissions—short, burst-like packets—requires a fast synchronization algorithm, that can accommodate several asynchronous users. Exploiting the fact that a shift in time corresponds to a phase rotation in the frequency domain, a blind and computationally effcient synchronization algorithm that takes advantage of the shift invariance structure in the frequency domain is proposed in this paper. Integer and fractional delay estimations are considered, along with a subsequent symbol estimation step. This results in a collision-avoiding multiuser algorithm, readily applicable to a fast acquisition procedure in a UWB ad hoc network.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

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

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

    Directory of Open Access Journals (Sweden)

    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.

  17. A master equation formalism for macroscopic modeling of asynchronous irregular activity states.

    Science.gov (United States)

    El Boustani, Sami; Destexhe, Alain

    2009-01-01

    Many efforts have been devoted to modeling asynchronous irregular (AI) activity states, which resemble the complex activity states seen in the cerebral cortex of awake animals. Most of models have considered balanced networks of excitatory and inhibitory spiking neurons in which AI states are sustained through recurrent sparse connectivity, with or without external input. In this letter we propose a mesoscopic description of such AI states. Using master equation formalism, we derive a second-order mean-field set of ordinary differential equations describing the temporal evolution of randomly connected balanced networks. This formalism takes into account finite size effects and is applicable to any neuron model as long as its transfer function can be characterized. We compare the predictions of this approach with numerical simulations for different network configurations and parameter spaces. Considering the randomly connected network as a unit, this approach could be used to build large-scale networks of such connected units, with an aim to model activity states constrained by macroscopic measurements, such as voltage-sensitive dye imaging. PMID:19210171

  18. Enhancement of asynchronous release from fast-spiking interneuron in human and rat epileptic neocortex.

    Directory of Open Access Journals (Sweden)

    Man Jiang

    Full Text Available Down-regulation of GABAergic inhibition may result in the generation of epileptiform activities. Besides spike-triggered synchronous GABA release, changes in asynchronous release (AR following high-frequency discharges may further regulate epileptiform activities. In brain slices obtained from surgically removed human neocortical tissues of patients with intractable epilepsy and brain tumor, we found that AR occurred at GABAergic output synapses of fast-spiking (FS neurons and its strength depended on the type of connections, with FS autapses showing the strongest AR. In addition, we found that AR depended on residual Ca²⁺ at presynaptic terminals but was independent of postsynaptic firing. Furthermore, AR at FS autapses was markedly elevated in human epileptic tissue as compared to non-epileptic tissue. In a rat model of epilepsy, we found similar elevation of AR at both FS autapses and synapses onto excitatory neurons. Further experiments and analysis showed that AR elevation in epileptic tissue may result from an increase in action potential amplitude in the FS neurons and elevation of residual Ca²⁺ concentration. Together, these results revealed that GABAergic AR occurred at both human and rat neocortex, and its elevation in epileptic tissue may contribute to the regulation of epileptiform activities.

  19. VASA: Interactive Computational Steering of Large Asynchronous Simulation Pipelines for Societal Infrastructure.

    Science.gov (United States)

    Ko, Sungahn; Zhao, Jieqiong; Xia, Jing; Afzal, Shehzad; Wang, Xiaoyu; Abram, Greg; Elmqvist, Niklas; Kne, Len; Van Riper, David; Gaither, Kelly; Kennedy, Shaun; Tolone, William; Ribarsky, William; Ebert, David S

    2014-12-01

    We present VASA, a visual analytics platform consisting of a desktop application, a component model, and a suite of distributed simulation components for modeling the impact of societal threats such as weather, food contamination, and traffic on critical infrastructure such as supply chains, road networks, and power grids. Each component encapsulates a high-fidelity simulation model that together form an asynchronous simulation pipeline: a system of systems of individual simulations with a common data and parameter exchange format. At the heart of VASA is the Workbench, a visual analytics application providing three distinct features: (1) low-fidelity approximations of the distributed simulation components using local simulation proxies to enable analysts to interactively configure a simulation run; (2) computational steering mechanisms to manage the execution of individual simulation components; and (3) spatiotemporal and interactive methods to explore the combined results of a simulation run. We showcase the utility of the platform using examples involving supply chains during a hurricane as well as food contamination in a fast food restaurant chain. PMID:26356899

  20. Synchronization dynamics in diverse ensemble of noisy phase oscillators with asynchronous phase updates.

    Science.gov (United States)

    Belan, S

    2015-12-01

    Decentralized control of autonomous phase oscillators integrated into networked systems is of great interest for many technological applications, from clock synchronization in sensor nets to coordinated motion in swarm robotics. In the simplest distributed synchronization scheme, each oscillator updates its phase from time to time to a new value equal to the average of its present phase and the phases of its neighbors. Here we describe the resulting synchronization dynamics within a mean-field model where the update actions of different oscillators are completely asynchronous. In particular, it is shown how the steady-state level of synchrony depends on noise intensity and frequency diversity for any given rate of updates. The central part of the analysis is devoted to the case when the correction rate positively correlates with the degree of macroscopic coherence. We demonstrate that depending on relation between correction rate and phase coherence the oscillators may exhibit both continuous and discontinuous transition from incoherence to synchrony upon the change of interaction constant. To illustrate our analytical results, numerical simulations have been performed for a large population of phase oscillators with the proposed type of coupling. PMID:26764777

  1. Analysis of an unconfined aquifer subject to asynchronous dual-tide propagation

    Science.gov (United States)

    Rotzoll, K.; El-Kadi, A. I.; Gingerich, S.B.

    2008-01-01

    Most published solutions for aquifer responses to ocean tides focus on the one-sided attenuation of the signal as it propagates inland. However, island aquifers experience periodic forcing from the entire coast, which can lead to integrated effects of different tidal signals, especially on narrow high-permeability islands. In general, studies disregard a potential time lag as the tidal wave sweeps around the island. We present a one-dimensional analytical solution to the ground water flow equation subject to asynchronous and asymmetric oscillating head conditions on opposite boundaries and test it on data from an unconfined volcanic aquifer in Maui. The solution considers sediment-damping effects at the coastline. The response of Maui Aquifers indicate that water table elevations near the center of the aquifer are influenced by a combination of tides from opposite coasts. A better match between the observed ground water head and the theoretical response can be obtained with the proposed dual-tide solution than with single-sided solutions. Hydraulic diffusivity was estimated to be 2.3 ?? 107 m 2/d. This translates into a hydraulic conductivity of 500 m/d, assuming a specific yield of 0.04 and an aquifer thickness of 1.8 km. A numerical experiment confirmed the hydraulic diffusivity value and showed that the y-intercepts of the modal attenuation and phase differences estimated by regression can approximate damping factors caused by low-permeability units at the boundary.

  2. An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs)

    International Nuclear Information System (INIS)

    The development of a full-custom electronic acquisition system designed for readout of large-area active matrix flat-panel imaging arrays is reported. The arrays, which comprise two-dimensional matrices of pixels utilizing amorphous silicon thin-film transistors, are themselves under development for a wide variety of X-ray imaging applications. The acquisition system was specifically designed to facilitate detailed, quantitative investigations of the properties of these novel imaging arrays and contains significant enhancements compared to a previously developed acquisition system. These enhancements include pipelined preamplifier circuits to allow faster readout speed, expanded addressing capabilities allowing a maximum of 4096 array data lines, and on-board summing of image frames. The values of many acquisition system parameters, including timings and voltages, may be specified and downloaded from a host computer. Once acquisition is enabled, the system operates asynchronously of its host computer. The system allows image capture in both radiographic mode (corresponding to the capture of individual X-ray images), and fluoroscopic mode (corresponding to the capture of a continual series of X-ray images). A detailed description of the system architecture and the underlying motivations for the design is reported in this paper. (author)

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

    Directory of Open Access Journals (Sweden)

    Thomine O.

    2013-12-01

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

  4. An investigation of assessment and feedback practices in fully asynchronous online undergraduate mathematics courses

    Science.gov (United States)

    Trenholm, Sven; Alcock, Lara; Robinson, Carol

    2015-11-01

    Research suggests it is difficult to learn mathematics in the fully asynchronous online (FAO) instructional modality, yet little is known about associated teaching and assessment practices. In this study, we investigate FAO mathematics assessment and feedback practices in particular consideration of both claims and findings that these practices have a powerful influence on learning. A survey questionnaire was constructed and completed by 70 FAO undergraduate mathematics instructors, mostly from the USA, who were each asked to detail their assessment and feedback practices in a single FAO mathematics course. Alongside these questions, participants also answered the 16-item version of the Approaches to Teaching Inventory. In addition, a novel feedback framework was also created and used to examine how feedback practices may be related to participants' approaches to teaching. Results show that assessment and feedback practices are varied and complex: in particular, we found there was not a simple emphasis on summative assessment instruments, nor a concomitant expectation these would always be invigilated. Though richer assessment feedback appears to be emphasized, evidence suggests this feedback may not be primarily directed at advancing student learning. Moreover, we found evidence of a reliance on computer--human interactions (e.g. via computer-assisted assessment systems) and further evidence of a decline in human interactions, suggesting a dynamic that is both consistent with current online learning theory and claims FAO mathematics courses are becoming commodified. Several avenues for further research are suggested.

  5. Differentiating closed-loop cortical intention from rest: building an asynchronous electrocorticographic BCI

    Science.gov (United States)

    Williams, Jordan J.; Rouse, Adam G.; Thongpang, Sanitta; Williams, Justin C.; Moran, Daniel W.

    2013-08-01

    Objective. Recent experiments have shown that electrocorticography (ECoG) can provide robust control signals for a brain-computer interface (BCI). Strategies that attempt to adapt a BCI control algorithm by learning from past trials often assume that the subject is attending to each training trial. Likewise, automatic disabling of movement control would be desirable during resting periods when random brain fluctuations might cause unintended movements of a device. To this end, our goal was to identify ECoG differences that arise between periods of active BCI use and rest. Approach. We examined spectral differences in multi-channel, epidural micro-ECoG signals recorded from non-human primates when rest periods were interleaved between blocks of an active BCI control task. Main Results. Post-hoc analyses demonstrated that these states can be decoded accurately on both a trial-by-trial and real-time basis, and this discriminability remains robust over a period of weeks. In addition, high gamma frequencies showed greater modulation with desired movement direction, while lower frequency components demonstrated greater amplitude differences between task and rest periods, suggesting possible specialized BCI roles for these frequencies. Significance. The results presented here provide valuable insight into the neurophysiology of BCI control as well as important considerations toward the design of an asynchronous BCI system.

  6. An Asynchronous Many-Task Implementation of In-Situ Statistical Analysis using Legion.

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-11-01

    In this report, we propose a framework for the design and implementation of in-situ analy- ses using an asynchronous many-task (AMT) model, using the Legion programming model together with the MiniAero mini-application as a surrogate for full-scale parallel scientific computing applications. The bulk of this work consists of converting the Learn/Derive/Assess model which we had initially developed for parallel statistical analysis using MPI [PTBM11], from a SPMD to an AMT model. In this goal, we propose an original use of the concept of Legion logical regions as a replacement for the parallel communication schemes used for the only operation of the statistics engines that require explicit communication. We then evaluate this proposed scheme in a shared memory environment, using the Legion port of MiniAero as a proxy for a full-scale scientific application, as a means to provide input data sets of variable size for the in-situ statistical analyses in an AMT context. We demonstrate in particular that the approach has merit, and warrants further investigation, in collaboration with ongoing efforts to improve the overall parallel performance of the Legion system.

  7. APPROACH TO DETERMINATION OF MAGNETIC PARAMETERS OF THE COMPONENT OF THE OPERATED CASCADE ASYNCHRONOUS ELECTRIC DRIVE

    Directory of Open Access Journals (Sweden)

    Karandey V. Y.

    2015-12-01

    Full Text Available The current state of the industry and high level of development of technologies dictates the requirements to various electromechanical converters of energy and electric drives. Constantly there are new requirements to these types of devices and their characteristics that lead to creation of more and more difficult devices of the electric drive and control systems which example is cascade systems of electric drives. This type of drives solves part of problems of the modern industry. However, creation of such devices requires development of new approaches to design and creation of cascade systems of the electric drive and its components where one of the most complex challenges is determination of parameters of electromagnetic system. In the article, a new approach is given, in finding electromagnetic parameters of components of the operated cascade asynchronous electric drive, proceeding from the applied types of the electric windings distributed in space. This approach is realized at creation of the program complex, which is part of system of automatic design

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

    Directory of Open Access Journals (Sweden)

    Alessio Paolo Buccino

    Full Text Available Non-invasive Brain-Computer Interfaces (BCI have demonstrated great promise for neuroprosthetics and assistive devices. Here we aim to investigate methods to combine Electroencephalography (EEG and functional Near-Infrared Spectroscopy (fNIRS in an asynchronous Sensory Motor rhythm (SMR-based BCI. We attempted to classify 4 different executed movements, namely, Right-Arm-Left-Arm-Right-Hand-Left-Hand tasks. Previous studies demonstrated the benefit of EEG-fNIRS combination. However, since normally fNIRS hemodynamic response shows a long delay, we investigated new features, involving slope indicators, in order to immediately detect changes in the signals. Moreover, Common Spatial Patterns (CSPs have been applied to both EEG and fNIRS signals. 15 healthy subjects took part in the experiments and since 25 trials per class were available, CSPs have been regularized with information from the entire population of participants and optimized using genetic algorithms. The different features have been compared in terms of performance and the dynamic accuracy over trials shows that the introduced methods diminish the fNIRS delay in the detection of changes.

  9. Conceptualising and measuring collaborative critical thinking on asynchronous discussion forums: Challenges and possible solutions

    Directory of Open Access Journals (Sweden)

    Nazanin Ghodrati

    2015-04-01

    Full Text Available The use of asynchronous discussion forums (ADFs is thought to assist in enhancing students’ collaborative learning and critical thinking throughout higher education. However, previous research has mainly focused on individual critical thinking while the investigation of critical thinking during group work has been generally overlooked. Furthermore, few studies have investigated critical thinking processes of the individual and of the group in a single study to present a comprehensive picture of collaborative critical thinking (CCT. To address these gaps, I examined the demonstration of CCT on ADFs in a graduate subject at an Australian university over two academic semesters as students discussed topics online. In this paper, I discuss the ontological and methodological challenges in conducting the above research and present possible solutions to these challenges. At the ontological level, I discuss challenges in conceptualising and defining CCT. At the methodological level, I present challenges in constructing a coding scheme to measure the demonstration of CCT on ADFs. I then discuss ways to tackle the above challenges, propose an operational definition of CCT and present a synthetic coding scheme for measuring CCT in computer-supported collaborative learning contexts such as on ADFs.

  10. A self-adaptive full asynchronous bi-directional transmission channel for network-on-chips

    International Nuclear Information System (INIS)

    To improve two shortcomings of conventional network-on-chips, i.e. low utilization rate in channels between routers and excessive interconnection lines, this paper proposes a full asynchronous self-adaptive bi-directional transmission channel. It can utilize interconnection lines and register resources with high efficiency, and dynamically detect the data transmission state between routers through a direction regulator, which controls the sequencer to automatically adjust the transmission direction of the bi-directional channel, so as to provide a flexible data transmission environment. Null convention logic units are used to make the circuit quasi-delay insensitive and highly robust. The proposed bi-directional transmission channel is implemented based on SMIC 0.18 μm standard CMOS technology. Post-layout simulation results demonstrate that this self-adaptive bi-directional channel has better performance on throughput, transmission flexibility and channel bandwidth utilization compared to a conventional single direction channel. Moreover, the proposed channel can save interconnection lines up to 30% and can provide twice the bandwidth resources of a single direction transmission channel. The proposed channel can apply to an on-chip network which has limited resources of registers and interconnection lines. (semiconductor integrated circuits)

  11. 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.

  12. Synchronization dynamics in diverse ensemble of noisy phase oscillators with asynchronous phase updates

    Science.gov (United States)

    Belan, S.

    2015-12-01

    Decentralized control of autonomous phase oscillators integrated into networked systems is of great interest for many technological applications, from clock synchronization in sensor nets to coordinated motion in swarm robotics. In the simplest distributed synchronization scheme, each oscillator updates its phase from time to time to a new value equal to the average of its present phase and the phases of its neighbors. Here we describe the resulting synchronization dynamics within a mean-field model where the update actions of different oscillators are completely asynchronous. In particular, it is shown how the steady-state level of synchrony depends on noise intensity and frequency diversity for any given rate of updates. The central part of the analysis is devoted to the case when the correction rate positively correlates with the degree of macroscopic coherence. We demonstrate that depending on relation between correction rate and phase coherence the oscillators may exhibit both continuous and discontinuous transition from incoherence to synchrony upon the change of interaction constant. To illustrate our analytical results, numerical simulations have been performed for a large population of phase oscillators with the proposed type of coupling.

  13. Research and Design of Android Asynchronous Framework%Android异步框架的研究与设计

    Institute of Scientific and Technical Information of China (English)

    章蓬阳; 邵帅

    2016-01-01

    As an open-source mobile operating system based on Linux,Android has a wide range of user groups and an entire ecosystem.With the development of mobile network,the market share of Android is growing,meanwhile the techniques of Android is complicating.Nowadays almost every Android application applied asynchronous techniques to deal with asynchronous tasks such as network requests,background services,time-consuming calculations,etc.The implementation of these techniques also has a direct impact on user experience.In the diverse user requirements and situations,each asynchronous techniques has different range of application.This paper presents many kinds of asyn-chronous techniques by investigating asynchronous frameworks and techniques of Android,and indicating advantages and disadvantages of these techniques.At last this paper implements the ActionPot framework,which is flexible and scalable.%Android作为以Linux为基础的开源移动设备操作系统,有着广泛的用户群体以及完整的生态系统。随着移动互联网的发展,Android市场份额不断增加,Android应用也越来越趋于复杂,如今几乎所有 Android 应用都用到了异步技术,用以处理网络请求,后台服务,耗时计算等各种异步任务。这些技术的运用也对用户体验产生了直接的影响。并且,在不同需求和场景下,各异步技术也有不同的适用范围。本文通过对 Android 异步技术和异步框架的研究,对多种异步技术进行了详细的阐述和比较,并对不同需求下对各类技术的优劣进行了说明。最后设计并实现了ActionPot框架,该框架有着较好的易用性和扩展性。

  14. Simultaneous and independent optical impairments monitoring using singular spectrum analysis of asynchronously sampled signal amplitudes

    Science.gov (United States)

    Guesmi, Latifa; Menif, Mourad

    2015-09-01

    Optical performance monitoring (OPM) becomes an inviting topic in high speed optical communication networks. In this paper, a novel technique of OPM based on a new elaborated computation approach of singular spectrum analysis (SSA) for time series prediction is presented. Indeed, various optical impairments among chromatic dispersion (CD), polarization mode dispersion (PMD) and amplified spontaneous emission (ASE) noise are a major factors limiting quality of transmission data in the systems with data rates lager than 40 Gbit/s. This technique proposed an independent and simultaneous multi-impairments monitoring, where we used SSA of time series analysis and forecasting. It has proven their usefulness in the temporal analysis of short and noisy time series in several fields, that it is based on the singular value decomposition (SVD). Also, advanced optical modulation formats (100 Gbit/s non-return-to zero dual-polarization quadrature phase shift keying (NRZ-DP-QPSK) and 160 Gbit/s DP-16 quadrature amplitude modulation (DP-16QAM)) offering high spectral efficiencies have been successfully employed by analyzing their asynchronously sampled amplitude. The simulated results proved that our method is efficient on CD, first-order PMD, Q-factor and OSNR monitoring, which enabled large monitoring ranges, the CD in the range of 170-1700 ps/nm.Km and 170-1110 ps/nm.Km for 100 Gbit/s NRZ-DP-QPSK and 160 Gbit/s DP-16QAM respectively, and also the DGD up to 20 ps is monitored. We could accurately monitor the OSNR in the range of 10-40 dB with monitoring error remains less than 1 dB in the presence of large accumulated CD.

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

    Directory of Open Access Journals (Sweden)

    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

  16. Radiation Survival in Synchronous and Asynchronous Chinese Hamster Cells In Vitro

    International Nuclear Information System (INIS)

    Synchronized mammalian cells enable radiation responses to be examined as a function of the position of the cell within its generation cycle. However, synchrony techniques are limited by the random distribution of generation rates in cell populations and, because of the techniques employed, stages such as G2 and mitosis are difficult to examine. Superposing on the mitotic selection technique high-specific- activity tritiated thymidine to inactivate resistant S cells enables the average sensitivity of G2 and mitotic cells to be established. The changes in sensitivity during the cell cycle for Chinese hamster cells are considerable, at least as great as the effect of the presence or absence of oxygen. G2 and mitosis are the most sensitive cells, followed by G1, early S and finally late S cells as the most resistant. With this data the response of an asynchronous population can be estimated and compared with experimental data. Calculation and experiment agree well. The selection + tritiated thymidine technique is still limited in resolution to a one-hour period. Experiments varying the interval between irradiation and selection indicate that there is, very probably, a brief phase more sensitive than the average in the selected mitotic population which should be examined further. Experiments with Janus (fission) neutrons indicate that the changes in response during the cell cycle are smaller than for X-rays and the shapes of the survival curves are different. The RBE of these neutrons is shown to vary with both dose level and position in the cell cycle. (author)

  17. Asynchronous changes in vegetation, runoff and erosion in the nile river watershed during the holocene.

    Directory of Open Access Journals (Sweden)

    Cécile L Blanchet

    Full Text Available The termination of the African Humid Period in northeastern Africa during the early Holocene was marked by the southward migration of the rain belt and the disappearance of the Green Sahara. This interval of drastic environmental changes was also marked by the initiation of food production by North African hunter-gatherer populations and thus provides critical information on human-environment relationships. However, existing records of regional climatic and environmental changes exhibit large differences in timing and modes of the wet/dry transition at the end of the African Humid Period. Here we present independent records of changes in river runoff, vegetation and erosion in the Nile River watershed during the Holocene obtained from a unique sedimentary sequence on the Nile River fan using organic and inorganic proxy data. This high-resolution reconstruction allows to examine the phase relationship between the changes of these three parameters and provides a detailed picture of the environmental conditions during the Paleolithic/Neolithic transition. The data show that river runoff decreased gradually during the wet/arid transition at the end of the AHP whereas rapid shifts of vegetation and erosion occurred earlier between 8.7 and ∼6 ka BP. These asynchronous changes are compared to other regional records and provide new insights into the threshold responses of the environment to climatic changes. Our record demonstrates that the degradation of the environment in northeastern Africa was more abrupt and occurred earlier than previously thought and may have accelerated the process of domestication in order to secure sustainable food resources for the Neolithic African populations.

  18. Multi-Threshold NULL Convention Logic (MTNCL: An Ultra-Low Power Asynchronous Circuit Design Methodology

    Directory of Open Access Journals (Sweden)

    Liang Zhou

    2015-05-01

    Full Text Available This paper develops an ultra-low power asynchronous circuit design methodology, called Multi-Threshold NULL Convention Logic (MTNCL, also known as Sleep Convention Logic (SCL, which combines Multi-Threshold CMOS (MTCMOS with NULL Convention Logic (NCL, to yield significant power reduction without any of the drawbacks of applying MTCMOS to synchronous circuits. In contrast to other power reduction techniques that usually result in large area overhead, MTNCL circuits are actually smaller than their original NCL versions. MTNCL utilizes high-Vt transistors to gate power and ground of a low-Vt logic block to provide for both fast switching and very low leakage power when idle. To demonstrate the advantages of MTNCL, a number of 32-bit IEEE single-precision floating-point co-processors were designed for comparison using the 1.2 V IBM 8RF-LM 130 nm CMOS process: original NCL, MTNCL with just combinational logic (C/L slept, Bit-Wise MTNCL (BWMTNCL, MTNCL with C/L and completion logic slept, MTNCL with C/L, completion logic, and registers slept, MTNCL with Safe Sleep architecture, and synchronous MTCMOS. These designs are compared in terms of throughput, area, dynamic energy, and idle power, showing the tradeoffs between the various MTNCL architectures, and that the best MTNCL design is much better than the original NCL design in all aspects, and much better than the synchronous MTCMOS design in terms of area, energy per operation, and idle power, although the synchronous design can operate faster.

  19. A multi-threaded approach to using asynchronous C libraries with Java

    Science.gov (United States)

    Gates, John; Deich, William

    2014-07-01

    It is very common to write device drivers and code that access low level operation system functions in C or C+ +. There are also many powerful C and C++ libraries available for a variety of tasks. Java is a programming language that is meant to be system independent and is arguably much simpler to code than C/C++. However, Java has minimal support for talking to native libraries, which results in interesting challenges when using C/C++ libraries with Java code. Part of the problem is that Java's standard mechanism for communicating with C libraries, Java Native Interface, requires a significant amount of effort to do fairly simple things, such as copy structure data from C to a class in Java. This is largely solved by using the Java Native Access Library, which provides a reasonable way of transferring data between C structures and Java classes and calling C functions from Java. A more serious issue is that there is no mechanism for a C/C++ library loaded by a Java program to call a Java function in the Java program, as this is a major issue with any library that uses callback functions. A solution to this problem was found using a moderate amount of C code and multiple threads in Java. The Keck Task Language API (KTL) is used as a primary means of inter-process communication at Keck and Lick Observatory. KTL is implemented in a series or C libraries and uses callback functions for asynchronous communication. It is a good demonstration of how to use a C library within a Java program.

  20. A bio-inspired asynchronous skin system for crack detection applications

    International Nuclear Information System (INIS)

    In many applications of structural health monitoring (SHM) it is imperative or advantageous to have large sensor arrays in order to properly sense the state of health of the structure. Typically these sensor networks are implemented by placing a large number of sensors over a structure and running individual cables from each sensor back to a central measurement station. Data is then collected from each sensor on the network at a constant sampling rate regardless of the current timescales at which events are acting on the structure. These conventional SHM sensor networks have a number of shortfalls. They tend to have a large number of cables that can represent a single point of failure for each sensor as well as add significant weight and installation costs. The constant sampling rate associated with each sensor very quickly leads to large amounts of data that must be analyzed, stored, and possibly transmitted to a remote user. This leads to increased demands on power consumption, bandwidth, and size. It also taxes our current techniques for managing large amounts of data. For the last decade the goal of the SHM community has been to endow structures with the functionality of a biological nervous system. Despite this goal the community has predominantly ignored the biological nervous system as inspiration for building structural nervous systems, choosing instead to focus on experimental mechanics and simulation techniques. In this work we explore the use of a novel, bio-inspired, SHM skin. This skin makes use of distributed computing and asynchronous communication techniques to alleviate the scale of the data management challenge as well as reduce power. The system also periodically sends a ‘heat beat’ signal to provide state-of-health updates. This conductive skin was implemented using conductive ink resistors as well as with graphene-oxide capacitors. (paper)