Asynchronous Replica Exchange Software for Grid and Heterogeneous Computing.

PubMed

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.

Asynchronous transfer mode link performance over ground networks

NASA Technical Reports Server (NTRS)

Chow, E. T.; Markley, R. W.

1993-01-01

The results of an experiment to determine the feasibility of using asynchronous transfer mode (ATM) technology to support advanced spacecraft missions that require high-rate ground communications and, in particular, full-motion video are reported. Potential nodes in such a ground network include Deep Space Network (DSN) antenna stations, the Jet Propulsion Laboratory, and a set of national and international end users. The experiment simulated a lunar microrover, lunar lander, the DSN ground communications system, and distributed science users. The users were equipped with video-capable workstations. A key feature was an optical fiber link between two high-performance workstations equipped with ATM interfaces. Video was also transmitted through JPL's institutional network to a user 8 km from the experiment. Variations in video depending on the networks and computers were observed, the results are reported.

Asynchronous Video Streaming vs. Synchronous Videoconferencing for Teaching a Pharmacogenetic Pharmacotherapy Course

PubMed Central

2007-01-01

Objectives To compare students' performance and course evaluations for a pharmacogenetic pharmacotherapy course taught by synchronous videoconferencing method via the Internet and for the same course taught via asynchronous video streaming via the Internet. Methods In spring 2005, a pharmacogenetic therapy course was taught to 73 students located on Amarillo, Lubbock, and Dallas campuses using synchronous videoconferencing, and in spring 2006, to 78 students located on the same 3 campuses using asynchronous video streaming. A course evaluation was administered to each group at the end of the courses. Results Students in the asynchronous setting had final course grades of 89% ± 7% compared to the mean final course grade of 87% ± 7% in the synchronous group (p = 0.05). Regardless of which technology was used, average course grades did not differ significantly among the 3 campus sites. Significantly more of the students in the asynchronous setting agreed (57%) with the statement that they could read the lecture notes and absorb the content on their own without attending the class than students in the synchronous class (23%; chi-square test; p < 0.001). Conclusions Students in both asynchronous and synchronous settings performed well. However, students taught using asynchronous videotaped lectures had lower satisfaction with the method of content delivery, and preferred live interactive sessions or a mix of interactive sessions and asynchronous videos over delivery of content using the synchronous or asynchronous method alone. PMID:17429516

Asynchronous Discussion Board Facilitation and Rubric Use in a Blended Learning Environment

ERIC Educational Resources Information Center

Giacumo, Lisa

2012-01-01

The purpose of this study was to investigate the effects of instructor response prompts and rubrics on students' performance in an asynchronous discussion-board assignment, their learning achievement on an objective-type posttest, and their reported satisfaction levels. Researchers who have studied asynchronous computer-mediated student…

Academic Performance, Course Completion Rates, and Student Perception of the Quality and Frequency of Interaction in a Virtual High School

ERIC Educational Resources Information Center

Hawkins, Abigail; Graham, Charles R.; Sudweeks, Richard R.; Barbour, Michael K.

2013-01-01

This study examined the relationship between students' perceptions of teacher-student interaction and academic performance at an asynchronous, self-paced, statewide virtual high school. Academic performance was measured by grade awarded and course completion. There were 2269 students who responded to an 18-item survey designed to measure student…

An epigenetic state associated with areas of gene duplication

PubMed Central

Gimelbrant, Alexander A.; Chess, Andrew

2006-01-01

Asynchronous DNA replication is an epigenetically determined feature found in all cases of monoallelic expression, including genomic imprinting, X-inactivation, and random monoallelic expression of autosomal genes such as immunoglobulins and olfactory receptor genes. Most genes of the latter class were identified in experiments focused on genes functioning in the chemosensory and immune systems. We performed an unbiased survey of asynchronous replication in the mouse genome, excluding known asynchronously replicated genes. Fully 10% (eight of 80) of the genes tested exhibited asynchronous replication. A common feature of the newly identified asynchronously replicated areas is their proximity to areas of tandem gene duplication. Testing of other clustered areas supported the idea that such regions are enriched with asynchronously replicated genes. PMID:16687731

Design Improvements and Analysis of Innovative High-Level Waste Pipeline Unplugging Technologies - 12171

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pribanic, Tomas; Awwad, Amer; Crespo, Jairo

2012-07-01

Transferring high-level waste (HLW) between storage tanks or to treatment facilities is a common practice performed at the Department of Energy (DoE) sites. Changes in the chemical and/or physical properties of the HLW slurry during the transfer process may lead to the formation of blockages inside the pipelines resulting in schedule delays and increased costs. To improve DoE's capabilities in the event of a pipeline plugging incident, FIU has continued to develop two novel unplugging technologies: an asynchronous pulsing system and a peristaltic crawler. The asynchronous pulsing system uses a hydraulic pulse generator to create pressure disturbances at two oppositemore » inlet locations of the pipeline to dislodge blockages by attacking the plug from both sides remotely. The peristaltic crawler is a pneumatic/hydraulic operated crawler that propels itself by a sequence of pressurization/depressurization of cavities (inner tubes). The crawler includes a frontal attachment that has a hydraulically powered unplugging tool. In this paper, details of the asynchronous pulsing system's ability to unplug a pipeline on a small-scale test-bed and results from the experimental testing of the second generation peristaltic crawler are provided. The paper concludes with future improvements for the third generation crawler and a recommended path forward for the asynchronous pulsing testing. (authors)« less

Data-Driven Based Asynchronous Motor Control for Printing Servo Systems

NASA Astrophysics Data System (ADS)

Bian, Min; Guo, Qingyun

Modern digital printing equipment aims to the environmental-friendly industry with high dynamic performances and control precision and low vibration and abrasion. High performance motion control system of printing servo systems was required. Control system of asynchronous motor based on data acquisition was proposed. Iterative learning control (ILC) algorithm was studied. PID control was widely used in the motion control. However, it was sensitive to the disturbances and model parameters variation. The ILC applied the history error data and present control signals to approximate the control signal directly in order to fully track the expect trajectory without the system models and structures. The motor control algorithm based on the ILC and PID was constructed and simulation results were given. The results show that data-driven control method is effective dealing with bounded disturbances for the motion control of printing servo systems.

High-precision shape representation using a neuromorphic vision sensor with synchronous address-event communication interface

NASA Astrophysics Data System (ADS)

Belbachir, A. N.; Hofstätter, M.; Litzenberger, M.; Schön, P.

2009-10-01

A synchronous communication interface for neuromorphic temporal contrast vision sensors is described and evaluated in this paper. This interface has been designed for ultra high-speed synchronous arbitration of a temporal contrast image sensors pixels' data. Enabling high-precision timestamping, this system demonstrates its uniqueness for handling peak data rates and preserving the main advantage of the neuromorphic electronic systems, that is high and accurate temporal resolution. Based on a synchronous arbitration concept, the timestamping has a resolution of 100 ns. Both synchronous and (state-of-the-art) asynchronous arbiters have been implemented in a neuromorphic dual-line vision sensor chip in a standard 0.35 µm CMOS process. The performance analysis of both arbiters and the advantages of the synchronous arbitration over asynchronous arbitration in capturing high-speed objects are discussed in detail.

Surface-distributed low-frequency asynchronous stimulation delays fatigue of stimulated muscles.

PubMed

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

2013-12-01

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

Asynchronous Transfer Mode Quality-of-Service Testing

NASA Technical Reports Server (NTRS)

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).

The Effect of Synchronous and Asynchronous Participation on Students' Performance in Online Accounting Courses

ERIC Educational Resources Information Center

Duncan, Keith; Kenworthy, Amy; McNamara, Ray

2012-01-01

This article examines the relationship between MBA students' performance and participation in two online environments: a synchronous forum (chat room) and an asynchronous forum (discussion board) at an Australian university. The "quality" and "quantity" of students' participation is used to predict their final examination and…

High power-efficient asynchronous SAR ADC for IoT devices

NASA Astrophysics Data System (ADS)

Zhang, Beichen; Yao, Bingbing; Liu, Liyuan; Liu, Jian; Wu, Nanjian

2017-10-01

This paper presents a power-efficient 100-MS/s, 10-bit asynchronous successive approximation register (SAR) ADC. It includes an on-chip reference buffer and the total power dissipation is 6.8 mW. To achieve high performance with high power-efficiency in the proposed ADC, bootstrapped switch, redundancy, set-and-down switching approach, dynamic comparator and dynamic logic techniques are employed. The prototype was fabricated using 65 nm standard CMOS technology. At a 1.2-V supply and 100 MS/s, the ADC achieves an SNDR of 56.2 dB and a SFDR of 65.1 dB. The ADC core consumes only 3.1 mW, resulting in a figure of merit (FOM) of 30.27 fJ/conversionstep and occupies an active area of only 0.009 mm2.

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

NASA Astrophysics Data System (ADS)

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 compose asynchronous GSO workflows. Most importantly, it provides better support for locating and diagnosing potential exceptions.

Forced synchronization and asynchronous quenching in a thermo-acoustic system

NASA Astrophysics Data System (ADS)

Mondal, Sirshendu; Pawar, Samadhan A.; Sujith, Raman

2017-11-01

Forced synchronization, which has been extensively studied in theory and experiments, occurs through two different mechanisms known as phase locking and asynchronous quenching. The latter indicates the suppression of oscillation amplitude. In most practical combustion systems such as gas turbine engines, the main concern is high amplitude pressure oscillations, known as thermo-acoustic instability. Thermo-acoustic instability is undesirable and needs to be suppressed because of its damaging consequences to an engine. In the present study, a systematic experimental investigation of forced synchronization is performed in a prototypical thermo-acoustic system, a Rijke tube, in its limit cycle operation. Further, we show a qualitatively similar behavior using a reduced order model. In the phase locking region, the simultaneous occurrence of synchronization and resonant amplification leads to high amplitude pressure oscillations. However, a reduction in the amplitude of natural oscillations by about 78% of the unforced amplitude is observed when the forcing frequency is far lower than the natural frequency. This shows the possibility of suppression of the oscillation amplitude through asynchronous quenching in thermo-acoustic systems.

Neighbor Discovery Algorithm in Wireless Local Area Networks Using Multi-beam Directional Antennas

NASA Astrophysics Data System (ADS)

Wang, Jin; Peng, Wei; Liu, Song

2017-10-01

Neighbor discovery is an important step for Wireless Local Area Networks (WLAN) and the use of multi-beam directional antennas can greatly improve the network performance. However, most neighbor discovery algorithms in WLAN, based on multi-beam directional antennas, can only work effectively in synchronous system but not in asynchro-nous system. And collisions at AP remain a bottleneck for neighbor discovery. In this paper, we propose two asynchrono-us neighbor discovery algorithms: asynchronous hierarchical scanning (AHS) and asynchronous directional scanning (ADS) algorithm. Both of them are based on three-way handshaking mechanism. AHS and ADS reduce collisions at AP to have a good performance in a hierarchical way and directional way respectively. In the end, the performance of the AHS and ADS are tested on OMNeT++. Moreover, it is analyzed that different application scenarios and the factors how to affect the performance of these algorithms. The simulation results show that AHS is suitable for the densely populated scenes around AP while ADS is suitable for that most of the neighborhood nodes are far from AP.

Distributed Data-aggregation Consensus for Sensor Networks: Relaxation of Consensus Concept and Convergence Property

DTIC Science & Technology

2014-08-01

consensus algorithm called randomized gossip is more suitable [7, 8]. In asynchronous randomized gossip algorithms, pairs of neighboring nodes exchange...messages and perform updates in an asynchronous and unattended manner, and they also 1 The class of broadcast gossip algorithms [9, 10, 11, 12] are...dynamics [2] and asynchronous pairwise randomized gossip [7, 8], broadcast gossip algorithms do not require that nodes know the identities of their

Asynchronous Learning Sources in a High-Tech Organization

ERIC Educational Resources Information Center

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…

Performance evaluation of an asynchronous multisensor track fusion filter

NASA Astrophysics Data System (ADS)

Alouani, Ali T.; Gray, John E.; McCabe, D. H.

2003-08-01

Recently the authors developed a new filter that uses data generated by asynchronous sensors to produce a state estimate that is optimal in the minimum mean square sense. The solution accounts for communications delay between sensors platform and fusion center. It also deals with out of sequence data as well as latent data by processing the information in a batch-like manner. This paper compares, using simulated targets and Monte Carlo simulations, the performance of the filter to the optimal sequential processing approach. It was found that the new asynchronous Multisensor track fusion filter (AMSTFF) performance is identical to that of the extended sequential Kalman filter (SEKF), while the new filter updates its track at a much lower rate than the SEKF.

Telemedicine for children with developmental disabilities: a more effective clinical process than office-based care.

PubMed

Langkamp, Diane L; McManus, Mark D; Blakemore, Susan D

2015-02-01

The literature on the use of telemedicine for children with developmental disabilities (DD) is limited and mostly describes telemedicine being used to link patients with distant subspecialty multidisciplinary care. Parents generally have reported satisfaction with such care and have perceived it to be equally effective as in-person care. Here we report on the use of school-based asynchronous telemedicine to connect children with DD with primary care providers. We developed Tele-Health-Kids, a school-based program using asynchronous telemedicine to connect children with DD with their primary care physician for the care of minor illnesses. We surveyed parents at enrollment and after the child's first telemedicine visit to assess satisfaction. We describe 4 cases that illustrate benefits, particularly for children with DD and challenging behaviors, suggesting that asynchronous telemedicine may actually be superior to traditional in-office visits in some circumstances. Most parents expressed a high level of satisfaction with the program. Benefits identified include decreased stress to the child and the parents as well as increasing the likelihood of a successful medical examination due to greater cooperation by the child. Visits using asynchronous or "store and forward" telemedicine technology may be superior in some situations by allowing the visit to be performed at a pace that can be adjusted to the needs of the child with DD. More research in the use of asynchronous telemedicine for children and youth with DD, particularly for children with DD and challenging behaviors, is needed.

Modeling and Analysis of Mixed Synchronous/Asynchronous Systems

NASA Technical Reports Server (NTRS)

Driscoll, Kevin R.; Madl. Gabor; Hall, Brendan

2012-01-01

Practical safety-critical distributed systems must integrate safety critical and non-critical data in a common platform. Safety critical systems almost always consist of isochronous components that have synchronous or asynchronous interface with other components. Many of these systems also support a mix of synchronous and asynchronous interfaces. This report presents a study on the modeling and analysis of asynchronous, synchronous, and mixed synchronous/asynchronous systems. We build on the SAE Architecture Analysis and Design Language (AADL) to capture architectures for analysis. We present preliminary work targeted to capture mixed low- and high-criticality data, as well as real-time properties in a common Model of Computation (MoC). An abstract, but representative, test specimen system was created as the system to be modeled.

Implementation of a tactical voice/data network over FDDI. [Fiber Distributed Data Interface

NASA Technical Reports Server (NTRS)

Bergman, L. A.; Halloran, F.; Martinez, J.

1988-01-01

An asynchronous high-speed fiber-optic local-area network is described that simultaneously supports packet data traffic with synchronous TI voice traffic over a standard asynchronous FDDI (fiber distributed data interface) token-ring channel. A voice interface module was developed that parses, buffers, and resynchronizes the voice data to the packet network. The technique is general, however, and can be applied to any deterministic class of networks, including multitier backbones. In addition, the higher layer packet data protocols may operate independently of those for the voice, thereby permitting great flexibility in reconfiguring the network. Voice call setup and switching functions are performed external to the network with PABX equipment.

Direct Proof of Endo-Epicardial Asynchrony of the Atrial Wall During Atrial Fibrillation in Humans.

PubMed

de Groot, Natasja; van der Does, Lisette; Yaksh, Ameeta; Lanters, Eva; Teuwen, Christophe; Knops, Paul; van de Woestijne, Pieter; Bekkers, Jos; Kik, Charles; Bogers, Ad; Allessie, Maurits

2016-05-01

The presence of focal fibrillation waves during atrial fibrillation (AF) can, besides ectopic activity, also be explained by asynchronous activation of the atrial endo- and epicardial layer and transmurally propagating fibrillation waves. To provide direct proof of endo-epicardial asynchrony, we performed simultaneous high-resolution mapping of the right atrial endo- and epicardial wall during AF in humans. Intraoperative mapping of the endo- and epicardial right atrial wall was performed during (induced) AF in 10 patients with AF (paroxysmal: n=3; persistent: n=4; and longstanding persistent: n=3) and 4 patients without a history of AF. A clamp made of 2 rectangular 8×16 electrode arrays (interelectrode distance 2 mm) was inserted into the incision in the right atrial appendage. Recordings of 10 seconds of AF were analyzed to determine the incidence of asynchronous endo-epicardial activation times (≥15 ms) of opposite electrodes. Asynchronous endo-epicardial activation ranged between 0.9 and 55.9% without preference for either side. Focal waves appeared equally frequent at endocardium and epicardium (11% versus 13%; ITALIC! P=0.18). Using strict criteria for breakthrough (presence of an opposite wave within 4 mm and ≤14 ms before the origin of the focal wave), the majority (65%) of all focal fibrillation waves could be attributed to endo-epicardial excitation. We provided the first evidence for asynchronous activation of the endo-epicardial wall during AF in humans. Endo-epicardial asynchrony may play a major role in the pathophysiology of AF and may offer an explanation why in some patients therapy fails. © 2016 American Heart Association, Inc.

Parallel tempering simulation of the three-dimensional Edwards-Anderson model with compact asynchronous multispin coding on GPU

NASA Astrophysics Data System (ADS)

Fang, Ye; Feng, Sheng; Tam, Ka-Ming; Yun, Zhifeng; Moreno, Juana; Ramanujam, J.; Jarrell, Mark

2014-10-01

Monte Carlo simulations of the Ising model play an important role in the field of computational statistical physics, and they have revealed many properties of the model over the past few decades. However, the effect of frustration due to random disorder, in particular the possible spin glass phase, remains a crucial but poorly understood problem. One of the obstacles in the Monte Carlo simulation of random frustrated systems is their long relaxation time making an efficient parallel implementation on state-of-the-art computation platforms highly desirable. The Graphics Processing Unit (GPU) is such a platform that provides an opportunity to significantly enhance the computational performance and thus gain new insight into this problem. In this paper, we present optimization and tuning approaches for the CUDA implementation of the spin glass simulation on GPUs. We discuss the integration of various design alternatives, such as GPU kernel construction with minimal communication, memory tiling, and look-up tables. We present a binary data format, Compact Asynchronous Multispin Coding (CAMSC), which provides an additional 28.4% speedup compared with the traditionally used Asynchronous Multispin Coding (AMSC). Our overall design sustains a performance of 33.5 ps per spin flip attempt for simulating the three-dimensional Edwards-Anderson model with parallel tempering, which significantly improves the performance over existing GPU implementations.

Highly Asynchronous VisitOr Queue Graph Toolkit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pearce, R.

2012-10-01

HAVOQGT is a C++ framework that can be used to create highly parallel graph traversal algorithms. The framework stores the graph and algorithmic data structures on external memory that is typically mapped to high performance locally attached NAND FLASH arrays. The framework supports a vertex-centered visitor programming model. The frameworkd has been used to implement breadth first search, connected components, and single source shortest path.

Full-Featured Web Conferencing Systems

ERIC Educational Resources Information Center

Foreman, Joel; Jenkins, Roy

2005-01-01

In order to match the customary strengths of the still dominant face-to-face instructional mode, a high-performance online learning system must employ synchronous as well as asynchronous communications; buttress graphics, animation, and text with live audio and video; and provide many of the features and processes associated with course management…

Method of joint bit rate/modulation format identification and optical performance monitoring using asynchronous delay-tap sampling for radio-over-fiber systems

NASA Astrophysics Data System (ADS)

Guesmi, Latifa; Menif, Mourad

2016-08-01

In the context of carrying a wide variety of modulation formats and data rates for home networks, the study covers the radio-over-fiber (RoF) technology, where the need for an alternative way of management, automated fault diagnosis, and formats identification is expressed. Also, RoF signals in an optical link are impaired by various linear and nonlinear effects including chromatic dispersion, polarization mode dispersion, amplified spontaneous emission noise, and so on. Hence, for this purpose, we investigated the sampling method based on asynchronous delay-tap sampling in conjunction with a cross-correlation function for the joint bit rate/modulation format identification and optical performance monitoring. Three modulation formats with different data rates are used to demonstrate the validity of this technique, where the identification accuracy and the monitoring ranges reached high values.

Asynchronous Assessment in a Large Lecture Marketing Course

ERIC Educational Resources Information Center

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…

Synchronous versus Asynchronous CMC and Transfer to Japanese Oral Performance

ERIC Educational Resources Information Center

Hirotani, Maki

2009-01-01

This study investigated the effects of synchronous and asynchronous CMC (computer-mediated communication)on the development of linguistic features of learners' speech in Japanese. Using learners from fourth-semester Japanese classes, the following research questions were examined: (a) Does CMC have positive effects on the development of oral…

Relationship of Metacognitive Monitoring with Interaction in an Asynchronous Online Discussion Forum

ERIC Educational Resources Information Center

Topcu, Abdullah

2010-01-01

Monitoring one's own performance accurately is essential for information-processing and self-regulation, which are indispensable in an online learning environment. In this article, the effect of metacognitive monitoring (MM) on interaction in an asynchronous online discussion forum was investigated. Transcripts of this forum, which was integrated…

High performance interconnection between high data rate networks

NASA Technical Reports Server (NTRS)

Foudriat, E. C.; Maly, K.; Overstreet, C. M.; Zhang, L.; Sun, W.

1992-01-01

The bridge/gateway system needed to interconnect a wide range of computer networks to support a wide range of user quality-of-service requirements is discussed. The bridge/gateway must handle a wide range of message types including synchronous and asynchronous traffic, large, bursty messages, short, self-contained messages, time critical messages, etc. It is shown that messages can be classified into three basic classes, synchronous and large and small asynchronous messages. The first two require call setup so that packet identification, buffer handling, etc. can be supported in the bridge/gateway. Identification enables resequences in packet size. The third class is for messages which do not require call setup. Resequencing hardware based to handle two types of resequencing problems is presented. The first is for a virtual parallel circuit which can scramble channel bytes. The second system is effective in handling both synchronous and asynchronous traffic between networks with highly differing packet sizes and data rates. The two other major needs for the bridge/gateway are congestion and error control. A dynamic, lossless congestion control scheme which can easily support effective error correction is presented. Results indicate that the congestion control scheme provides close to optimal capacity under congested conditions. Under conditions where error may develop due to intervening networks which are not lossless, intermediate error recovery and correction takes 1/3 less time than equivalent end-to-end error correction under similar conditions.

An Asynchronous Recurrent Network of Cellular Automaton-Based Neurons and Its Reproduction of Spiking Neural Network Activities.

PubMed

Matsubara, Takashi; Torikai, Hiroyuki

2016-04-01

Modeling and implementation approaches for the reproduction of input-output relationships in biological nervous tissues contribute to the development of engineering and clinical applications. However, because of high nonlinearity, the traditional modeling and implementation approaches encounter difficulties in terms of generalization ability (i.e., performance when reproducing an unknown data set) and computational resources (i.e., computation time and circuit elements). To overcome these difficulties, asynchronous cellular automaton-based neuron (ACAN) models, which are described as special kinds of cellular automata that can be implemented as small asynchronous sequential logic circuits have been proposed. This paper presents a novel type of such ACAN and a theoretical analysis of its excitability. This paper also presents a novel network of such neurons, which can mimic input-output relationships of biological and nonlinear ordinary differential equation model neural networks. Numerical analyses confirm that the presented network has a higher generalization ability than other major modeling and implementation approaches. In addition, Field-Programmable Gate Array-implementations confirm that the presented network requires lower computational resources.

Neuromorphic Event-Based 3D Pose Estimation

PubMed Central

Reverter Valeiras, David; Orchard, Garrick; Ieng, Sio-Hoi; Benosman, Ryad B.

2016-01-01

Pose estimation is a fundamental step in many artificial vision tasks. It consists of estimating the 3D pose of an object with respect to a camera from the object's 2D projection. Current state of the art implementations operate on images. These implementations are computationally expensive, especially for real-time applications. Scenes with fast dynamics exceeding 30–60 Hz can rarely be processed in real-time using conventional hardware. This paper presents a new method for event-based 3D object pose estimation, making full use of the high temporal resolution (1 μs) of asynchronous visual events output from a single neuromorphic camera. Given an initial estimate of the pose, each incoming event is used to update the pose by combining both 3D and 2D criteria. We show that the asynchronous high temporal resolution of the neuromorphic camera allows us to solve the problem in an incremental manner, achieving real-time performance at an update rate of several hundreds kHz on a conventional laptop. We show that the high temporal resolution of neuromorphic cameras is a key feature for performing accurate pose estimation. Experiments are provided showing the performance of the algorithm on real data, including fast moving objects, occlusions, and cases where the neuromorphic camera and the object are both in motion. PMID:26834547

At a Distance: A Comparative Study of Distance Delivery Modalities for PhD Nursing Students

ERIC Educational Resources Information Center

Black, Andrew G.

2010-01-01

This study sought to ascertain and compare the attitudes and perceptions of PhD nursing students attending their coursework through synchronous and asynchronous means at two different universities. Many studies have been performed comparing both synchronous videoconferencing and asynchronous online education with the traditional classroom, but no…

Peer Moderation of Asynchronous Online Discussions: An Exploratory Study of Peer E-Moderating Behaviour

ERIC Educational Resources Information Center

Ghadirian, Hajar; Ayub, Ahmad Fauzi Mohd

2017-01-01

This study explored patterns of e-moderating behaviour students performed when they were assigned as peer moderators of asynchronous online discussions in a reciprocal manner. Eighty-four students from an undergraduate blended course were observed during a 7-week-long online discussions. Using quantitative content analysis peer moderators'…

Hydrodynamic advantages of swimming by salp chains.

PubMed

Sutherland, Kelly R; Weihs, Daniel

2017-08-01

Salps are marine invertebrates comprising multiple jet-propelled swimming units during a colonial life-cycle stage. Using theory, we show that asynchronous swimming with multiple pulsed jets yields substantial hydrodynamic benefit due to the production of steady swimming velocities, which limit drag. Laboratory comparisons of swimming kinematics of aggregate salps ( Salpa fusiformis and Weelia cylindrica ) using high-speed video supported that asynchronous swimming by aggregates results in a smoother velocity profile and showed that this smoother velocity profile is the result of uncoordinated, asynchronous swimming by individual zooids. In situ flow visualizations of W. cylindrica swimming wakes revealed that another consequence of asynchronous swimming is that fluid interactions between jet wakes are minimized. Although the advantages of multi-jet propulsion have been mentioned elsewhere, this is the first time that the theory has been quantified and the role of asynchronous swimming verified using experimental data from the laboratory and the field. © 2017 The Author(s).

Asynchronous vibration problem of centrifugal compressor

NASA Technical Reports Server (NTRS)

Fujikawa, T.; Ishiguro, N.; Ito, M.

1980-01-01

An unstable asynchronous vibration problem in a high pressure centrifugal compressor and the remedial actions against it are described. Asynchronous vibration of the compressor took place when the discharge pressure (Pd) was increased, after the rotor was already at full speed. The typical spectral data of the shaft vibration indicate that as the pressure Pd increases, pre-unstable vibration appears and becomes larger, and large unstable asynchronous vibration occurs suddenly (Pd = 5.49MPa). A computer program was used which calculated the logarithmic decrement and the damped natural frequency of the rotor bearing systems. The analysis of the log-decrement is concluded to be effective in preventing unstable vibration in both the design stage and remedial actions.

Application of high performance asynchronous socket communication in power distribution automation

NASA Astrophysics Data System (ADS)

Wang, Ziyu

2017-05-01

With the development of information technology and Internet technology, and the growing demand for electricity, the stability and the reliable operation of power system have been the goal of power grid workers. With the advent of the era of big data, the power data will gradually become an important breakthrough to guarantee the safe and reliable operation of the power grid. So, in the electric power industry, how to efficiently and robustly receive the data transmitted by the data acquisition device, make the power distribution automation system be able to execute scientific decision quickly, which is the pursuit direction in power grid. In this paper, some existing problems in the power system communication are analysed, and with the help of the network technology, a set of solutions called Asynchronous Socket Technology to the problem in network communication which meets the high concurrency and the high throughput is proposed. Besides, the paper also looks forward to the development direction of power distribution automation in the era of big data and artificial intelligence.

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

ERIC Educational Resources Information Center

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…

[Cost-effectiveness of Synchronous vs. Asynchronous Telepsychiatry in Prison Inmates With Depression].

PubMed

Barrera-Valencia, Camilo; Benito-Devia, Alexis Vladimir; Vélez-Álvarez, Consuelo; Figueroa-Barrera, Mario; Franco-Idárraga, Sandra Milena

Telepsychiatry is defined as the use of information and communication technology (ICT) in providing remote psychiatric services. Telepsychiatry is applied using two types of communication: synchronous (real time) and asynchronous (store and forward). To determine the cost-effectiveness of a synchronous and an asynchronous telepsychiatric model in prison inmate patients with symptoms of depression. A cost-effectiveness study was performed on a population consisting of 157 patients from the Establecimiento Penitenciario y Carcelario de Mediana Seguridad de Manizales, Colombia. The sample was determined by applying Zung self-administered surveys for depression (1965) and the Hamilton Depression Rating Scale (HDRS), the latter being the tool used for the comparison. Initial Hamilton score, arrival time, duration of system downtime, and clinical effectiveness variables had normal distributions (P>.05). There were significant differences (P<.001) between care costs for the different models, showing that the mean cost of the asynchronous model is less than synchronous model, and making the asynchronous model more cost-effective. The asynchronous model is the most cost-effective model of telepsychiatry care for patients with depression admitted to a detention centre, according to the results of clinical effectiveness, cost measurement, and patient satisfaction. Copyright © 2016 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

Efficacy of an asynchronous electronic curriculum in emergency medicine education in the United States.

PubMed

Wray, Alisa; Bennett, Kathryn; Boysen-Osborn, Megan; Wiechmann, Warren; Toohey, Shannon

2017-01-01

The aim of this study was to measure the effect of an iPad-based asynchronous curriculum on emergency medicine resident performance on the in-training exam (ITE). We hypothesized that the implementation of an asynchronous curriculum (replacing 1 hour of weekly didactic time) would result in non-inferior ITE scores compared to the historical scores of residents who had participated in the traditional 5-hour weekly didactic curriculum. The study was a retrospective, non-inferiority study. conducted at the University of California, Irvine Emergency Medicine Residency Program. We compared ITE scores from 2012 and 2013, when there were 5 weekly hours of didactic content, with scores from 2014 and 2015, when 1 hour of conference was replaced with asynchro-nous content. Examination results were compared using a non-inferiority data analysis with a 10% margin of difference. Using a non-inferiority test with a 95% confidence interval, there was no difference between the 2 groups (before and after implementation of asynchronous learning), as the confidence interval for the change of the ITE was -3.5 to 2.3 points, whereas the 10% non-inferiority margin was 7.8 points. Replacing 1 hour of didactic conference with asynchronous learning showed no negative impact on resident ITE scores.

Asynchronous decision making in a memorized paddle pressing task

NASA Astrophysics Data System (ADS)

Dankert, James R.; Olson, Byron; Si, Jennie

2008-12-01

This paper presents a method for asynchronous decision making using recorded neural data in a binary decision task. This is a demonstration of a technique for developing motor cortical neural prosthetics that do not rely on external cued timing information. The system presented in this paper uses support vector machines and leaky integrate-and-fire elements to predict directional paddle presses. In addition to the traditional metrics of accuracy, asynchronous systems must also optimize the time needed to make a decision. The system presented is able to predict paddle presses with a median accuracy of 88% and all decisions are made before the time of the actual paddle press. An alternative bit rate measure of performance is defined to show that the system proposed here is able to perform the task with the same efficiency as the rats.

What can neuromorphic event-driven precise timing add to spike-based pattern recognition?

PubMed

Akolkar, Himanshu; Meyer, Cedric; Clady, Zavier; Marre, Olivier; Bartolozzi, Chiara; Panzeri, Stefano; Benosman, Ryad

2015-03-01

This letter introduces a study to precisely measure what an increase in spike timing precision can add to spike-driven pattern recognition algorithms. The concept of generating spikes from images by converting gray levels into spike timings is currently at the basis of almost every spike-based modeling of biological visual systems. The use of images naturally leads to generating incorrect artificial and redundant spike timings and, more important, also contradicts biological findings indicating that visual processing is massively parallel, asynchronous with high temporal resolution. A new concept for acquiring visual information through pixel-individual asynchronous level-crossing sampling has been proposed in a recent generation of asynchronous neuromorphic visual sensors. Unlike conventional cameras, these sensors acquire data not at fixed points in time for the entire array but at fixed amplitude changes of their input, resulting optimally sparse in space and time-pixel individually and precisely timed only if new, (previously unknown) information is available (event based). This letter uses the high temporal resolution spiking output of neuromorphic event-based visual sensors to show that lowering time precision degrades performance on several recognition tasks specifically when reaching the conventional range of machine vision acquisition frequencies (30-60 Hz). The use of information theory to characterize separability between classes for each temporal resolution shows that high temporal acquisition provides up to 70% more information that conventional spikes generated from frame-based acquisition as used in standard artificial vision, thus drastically increasing the separability between classes of objects. Experiments on real data show that the amount of information loss is correlated with temporal precision. Our information-theoretic study highlights the potentials of neuromorphic asynchronous visual sensors for both practical applications and theoretical investigations. Moreover, it suggests that representing visual information as a precise sequence of spike times as reported in the retina offers considerable advantages for neuro-inspired visual computations.

An Examination of Undergraduates' Metacognitive Strategies in Pre-Class Asynchronous Activity in a Flipped Classroom

ERIC Educational Resources Information Center

Yilmaz, Rabia M.; Baydas, Ozlem

2017-01-01

The aim of the study is to examine undergraduate students' awareness of metacognition, the metacognitive strategies they use in their learning and their learning performance in pre-class asynchronous activity in a flipped classroom. The sample consisted of 47 undergraduate students. Eleven students were not included in this study since they did…

Measuring moment-to-moment pilot workload using synchronous presentations of secondary tasks in a motion-base trainer

NASA Technical Reports Server (NTRS)

Bortolussi, Michael R.; Hart, Sandra G.; Shively, Robert J.

1987-01-01

A simulation was conducted to determine whether the sensitivity of secondary task measures of pilot workload could be improved by synchronizing their presentation to the occurrence of specific events or pilot actions. This synchronous method of presentation was compared to the more typical asynchronous method, where secondary task presentations are independent of pilot's flight-related activities. Twelve pilots flew low- and high-difficulty scenarios in a motion-base trainer with and without concurrent secondary tasks (e.g., choice reaction time and time production). The difficulty of each scenario was manipulated by the addition of 21 flight-related tasks superimposed on a standard approach and landing sequence. The insertion of the secondary tasks did not affect primary flight performance. However, secondary task performance did reflect workload differences between scenarios and among flight segments within scenarios, replicating the results of an earlier study in which the secondary tasks were presented asynchronously (Bortolussi et al., 1986).

A simple, effective media access protocol system for integrated, high data rate networks

NASA Technical Reports Server (NTRS)

Foudriat, E. C.; Maly, K.; Overstreet, C. M.; Khanna, S.; Zhang, L.

1992-01-01

The operation and performance of a dual media access protocol for integrated, gigabit networks are described. Unlike other dual protocols, each protocol supports a different class of traffic. The Carrier Sensed Multiple Access-Ring Network (CSMA/RN) protocol and the Circulating Reservation Packet (CRP) protocol support asynchronous and synchronous traffic, respectively. The two protocols operate with minimal impact upon each other. Performance information demonstrates that they support a complete range of integrated traffic loads, do not require call setup/termination or a special node for synchronous traffic control, and provide effective pre-use and recovery. The CRP also provides guaranteed access and fairness control for the asynchronous system. The paper demonstrates that the CSMA-CRP system fulfills many of the requirements for gigabit LAN-MAN networks most effectively and simply. To accomplish this, CSMA-CRP features are compared against similar ring and bus systems, such as Cambridge Fast Ring, Metaring, Cyclic Reservation Multiple Access, and Distributed Dual Queue Data Bus (DQDB).

Implementing asyncronous collective operations in a multi-node processing system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dong; Eisley, Noel A.; Heidelberger, Philip

A method, system, and computer program product are disclosed for implementing an asynchronous collective operation in a multi-node data processing system. In one embodiment, the method comprises sending data to a plurality of nodes in the data processing system, broadcasting a remote get to the plurality of nodes, and using this remote get to implement asynchronous collective operations on the data by the plurality of nodes. In one embodiment, each of the nodes performs only one task in the asynchronous operations, and each nodes sets up a base address table with an entry for a base address of a memorymore » buffer associated with said each node. In another embodiment, each of the nodes performs a plurality of tasks in said collective operations, and each task of each node sets up a base address table with an entry for a base address of a memory buffer associated with the task.« less

A Qualitative Analysis of African American Female High School Graduates' Perceptions of Participating in an Asynchronous Credit Recovery Program

ERIC Educational Resources Information Center

Waters, Eric L.

2010-01-01

Asynchronous online credit recovery programs have been implemented in public schools across the United States for a variety of reasons. In this case, African American female students who are deficient in course credits towards high school graduation have taken advantage of this relatively new e-programming mechanism as a means to capture course…

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

PubMed

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

2011-10-01

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

Exploring the Link between Online Behaviours and Course Performance in Asynchronous Online High School Courses

ERIC Educational Resources Information Center

Lowes, Susan; Lin, Peiyi; Kinghorn, Brian

2015-01-01

As enrolment in online courses has grown and LMS data has become accessible for analysis, researchers have begun to examine the link between in-course behaviours and course outcomes. This paper explores the use of readily available LMS data generated by approximately 700 students enrolled in the 12 online courses offered by Pamoja Education, the…

Designing a Web-Based Asynchronous Innovation/Entrepreneurism Course

ERIC Educational Resources Information Center

Ghandforoush, Parviz

2017-01-01

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

Terahertz cyclotron resonance spectroscopy of an AlGaN/GaN heterostructure using a high-field pulsed magnet and an asynchronous optical sampling technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, B. F., E-mail: Ben.Spencer@manchester.ac.uk; Smith, W. F.; Hibberd, M. T.

2016-05-23

The effective mass, sheet carrier concentration, and mobility of electrons within a two-dimensional electron gas in an AlGaN/GaN heterostructure were determined using a laboratory-based terahertz cyclotron resonance spectrometer. The ability to perform terahertz cyclotron resonance spectroscopy with magnetic fields of up to 31 T was enabled by combining a high-field pulsed magnet with a modified asynchronous optical sampling terahertz detection scheme. This scheme allowed around 100 transmitted terahertz waveforms to be recorded over the 14 ms magnetic field pulse duration. The sheet density and mobility were measured to be 8.0 × 10{sup 12 }cm{sup −2} and 9000 cm{sup 2} V{sup −1} s{sup −1} at 77 K. The in-planemore » electron effective mass at the band edge was determined to be 0.228 ± 0.002m{sub 0}.« less

Minimizing calibration time using inter-subject information of single-trial recognition of error potentials in brain-computer interfaces.

PubMed

Iturrate, Iñaki; Montesano, Luis; Chavarriaga, Ricardo; del R Millán, Jose; Minguez, Javier

2011-01-01

One of the main problems of both synchronous and asynchronous EEG-based BCIs is the need of an initial calibration phase before the system can be used. This phase is necessary due to the high non-stationarity of the EEG, since it changes between sessions and users. The calibration process limits the BCI systems to scenarios where the outputs are very controlled, and makes these systems non-friendly and exhausting for the users. Although it has been studied how to reduce calibration time for asynchronous signals, it is still an open issue for event-related potentials. Here, we propose the minimization of the calibration time on single-trial error potentials by using classifiers based on inter-subject information. The results show that it is possible to have a classifier with a high performance from the beginning of the experiment, and which is able to adapt itself making the calibration phase shorter and transparent to the user.

The Effects on Health Behavior and Health Outcomes of Internet-Based Asynchronous Communication Between Health Providers and Patients With a Chronic Condition: A Systematic Review

PubMed Central

Ros, Wynand JG; Schrijvers, Guus

2014-01-01

Background In support of professional practice, asynchronous communication between the patient and the provider is implemented separately or in combination with Internet-based self-management interventions. This interaction occurs primarily through electronic messaging or discussion boards. There is little evidence as to whether it is a useful tool for chronically ill patients to support their self-management and increase the effectiveness of interventions. Objective The aim of our study was to review the use and usability of patient-provider asynchronous communication for chronically ill patients and the effects of such communication on health behavior, health outcomes, and patient satisfaction. Methods A literature search was performed using PubMed and Embase. The quality of the articles was appraised according to the National Institute for Health and Clinical Excellence (NICE) criteria. The use and usability of the asynchronous communication was analyzed by examining the frequency of use and the number of users of the interventions with asynchronous communication, as well as of separate electronic messaging. The effectiveness of asynchronous communication was analyzed by examining effects on health behavior, health outcomes, and patient satisfaction. Results Patients’ knowledge concerning their chronic condition increased and they seemed to appreciate being able to communicate asynchronously with their providers. They not only had specific questions but also wanted to communicate about feeling ill. A decrease in visits to the physician was shown in two studies (P=.07, P=.07). Increases in self-management/self-efficacy for patients with back pain, dyspnea, and heart failure were found. Positive health outcomes were shown in 12 studies, where the clinical outcomes for diabetic patients (HbA1c level) and for asthmatic patients (forced expiratory volume [FEV]) improved. Physical symptoms improved in five studies. Five studies generated a variety of positive psychosocial outcomes. Conclusions The effect of asynchronous communication is not shown unequivocally in these studies. Patients seem to be interested in using email. Patients are willing to participate and are taking the initiative to discuss health issues with their providers. Additional testing of the effects of asynchronous communication on self-management in chronically ill patients is needed. PMID:24434570

The effects on health behavior and health outcomes of Internet-based asynchronous communication between health providers and patients with a chronic condition: a systematic review.

PubMed

de Jong, Catharina Carolina; Ros, Wynand Jg; Schrijvers, Guus

2014-01-16

In support of professional practice, asynchronous communication between the patient and the provider is implemented separately or in combination with Internet-based self-management interventions. This interaction occurs primarily through electronic messaging or discussion boards. There is little evidence as to whether it is a useful tool for chronically ill patients to support their self-management and increase the effectiveness of interventions. The aim of our study was to review the use and usability of patient-provider asynchronous communication for chronically ill patients and the effects of such communication on health behavior, health outcomes, and patient satisfaction. A literature search was performed using PubMed and Embase. The quality of the articles was appraised according to the National Institute for Health and Clinical Excellence (NICE) criteria. The use and usability of the asynchronous communication was analyzed by examining the frequency of use and the number of users of the interventions with asynchronous communication, as well as of separate electronic messaging. The effectiveness of asynchronous communication was analyzed by examining effects on health behavior, health outcomes, and patient satisfaction. Patients' knowledge concerning their chronic condition increased and they seemed to appreciate being able to communicate asynchronously with their providers. They not only had specific questions but also wanted to communicate about feeling ill. A decrease in visits to the physician was shown in two studies (P=.07, P=.07). Increases in self-management/self-efficacy for patients with back pain, dyspnea, and heart failure were found. Positive health outcomes were shown in 12 studies, where the clinical outcomes for diabetic patients (HbA1c level) and for asthmatic patients (forced expiratory volume [FEV]) improved. Physical symptoms improved in five studies. Five studies generated a variety of positive psychosocial outcomes. The effect of asynchronous communication is not shown unequivocally in these studies. Patients seem to be interested in using email. Patients are willing to participate and are taking the initiative to discuss health issues with their providers. Additional testing of the effects of asynchronous communication on self-management in chronically ill patients is needed.

Overview of AMS (CCSDS Asynchronous Message Service)

NASA Technical Reports Server (NTRS)

Burleigh, Scott

2006-01-01

This viewgraph presentation gives an overview of the Consultative Committee for Space Data Systems (CCSDS) Asynchronous Message Service (AMS). The topics include: 1) Key Features; 2) A single AMS continuum; 3) The AMS Protocol Suite; 4) A multi-continuum venture; 5) Constraining transmissions; 6) Security; 7) Fault Tolerance; 8) Performance of Reference Implementation; 9) AMS vs Multicast (1); 10) AMS vs Multicast (2); 11) RAMS testing exercise; and 12) Results.

Neural timing signal for precise tactile timing judgments

PubMed Central

Watanabe, Junji; Nishida, Shin'ya

2016-01-01

The brain can precisely encode the temporal relationship between tactile inputs. While behavioural studies have demonstrated precise interfinger temporal judgments, the underlying neural mechanism remains unknown. Computationally, two kinds of neural responses can act as the information source. One is the phase-locked response to the phase of relatively slow inputs, and the other is the response to the amplitude change of relatively fast inputs. To isolate the contributions of these components, we measured performance of a synchrony judgment task for sine wave and amplitude-modulation (AM) wave stimuli. The sine wave stimulus was a low-frequency sinusoid, with the phase shifted in the asynchronous stimulus. The AM wave stimulus was a low-frequency sinusoidal AM of a 250-Hz carrier, with only the envelope shifted in the asynchronous stimulus. In the experiment, three stimulus pairs, two synchronous ones and one asynchronous one, were sequentially presented to neighboring fingers, and participants were asked to report which one was the asynchronous pair. We found that the asynchrony of AM waves could be detected as precisely as single impulse pair, with the threshold asynchrony being ∼20 ms. On the other hand, the asynchrony of sine waves could not be detected at all in the range from 5 to 30 Hz. Our results suggest that the timing signal for tactile judgments is provided not by the stimulus phase information but by the envelope of the response of the high-frequency-sensitive Pacini channel (PC), although they do not exclude a possible contribution of the envelope of non-PCs. PMID:26843600

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

PubMed

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%.

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

PubMed Central

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

Research on navigation of satellite constellation based on an asynchronous observation model using X-ray pulsar

NASA Astrophysics Data System (ADS)

Guo, Pengbin; Sun, Jian; Hu, Shuling; Xue, Ju

2018-02-01

Pulsar navigation is a promising navigation method for high-altitude orbit space tasks or deep space exploration. At present, an important reason for restricting the development of pulsar navigation is that navigation accuracy is not high due to the slow update of the measurements. In order to improve the accuracy of pulsar navigation, an asynchronous observation model which can improve the update rate of the measurements is proposed on the basis of satellite constellation which has a broad space for development because of its visibility and reliability. The simulation results show that the asynchronous observation model improves the positioning accuracy by 31.48% and velocity accuracy by 24.75% than that of the synchronous observation model. With the new Doppler effects compensation method in the asynchronous observation model proposed in this paper, the positioning accuracy is improved by 32.27%, and the velocity accuracy is improved by 34.07% than that of the traditional method. The simulation results show that without considering the clock error will result in a filtering divergence.

Asynchronous discrete event schemes for PDEs

NASA Astrophysics Data System (ADS)

Stone, D.; Geiger, S.; Lord, G. J.

2017-08-01

A new class of asynchronous discrete-event simulation schemes for advection-diffusion-reaction equations is introduced, based on the principle of allowing quanta of mass to pass through faces of a (regular, structured) Cartesian finite volume grid. The timescales of these events are linked to the flux on the face. The resulting schemes are self-adaptive, and local in both time and space. Experiments are performed on realistic physical systems related to porous media flow applications, including a large 3D advection diffusion equation and advection diffusion reaction systems. The results are compared to highly accurate reference solutions where the temporal evolution is computed with exponential integrator schemes using the same finite volume discretisation. This allows a reliable estimation of the solution error. Our results indicate a first order convergence of the error as a control parameter is decreased, and we outline a framework for analysis.

Asynchronous BCI control using high-frequency SSVEP.

PubMed

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

2011-07-14

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

An improved asynchronous brain interface: making use of the temporal history of the LF-ASD feature vectors

NASA Astrophysics Data System (ADS)

Bashashati, Ali; Mason, Steve; Ward, Rabab K.; Birch, Gary E.

2006-06-01

The low-frequency asynchronous switch design (LF-ASD) has been introduced as a direct brain interface (BI) for asynchronous control applications. Asynchronous interfaces, as opposed to synchronous interfaces, have the advantage of being operational at all times and not only at specific system-defined periods. This paper modifies the LF-ASD design by incorporating into the system more knowledge about the attempted movements. Specifically, the history of feature values extracted from the EEG signal is used to detect a right index finger movement attempt. Using data collected from individuals with high-level spinal cord injuries and able-bodied subjects, it is shown that the error characteristics of the modified design are significantly better than the previous LF-ASD design. The true positive rate percentage increased by up to 15 which corresponds to 50% improvement when the system is operating with false positive rates in the 1-2% range.

Educational Outcomes of Synchronous and Asynchronous High School Students: A Quantitative Causal-Comparative Study of Online Algebra 1

ERIC Educational Resources Information Center

Berry, Sharon

2017-01-01

This study used a quantitative, causal-comparative design. It compared educational outcome data from online Algebra 1 courses to determine if a significant difference existed between synchronous and asynchronous students for end-of-course grades, state assessments scores, and student perceptions of their course. The study found that synchronous…

Distributed Training for the Reserve Component: Remote Delivery Using Asynchronous Computer Conferencing.

ERIC Educational Resources Information Center

Hahn, H. A.; And Others

The purposes of this research were to evaluate the cost effectiveness of using Asynchronous Computer Conferencing (ACC) and to develop guidelines for effectively conducting high quality military training using ACC. The evaluation used a portion of the Engineer Officer Advanced Course (EOAC) as a test bed. Course materials which taught the same…

Effects of altered auditory feedback across effector systems: production of melodies by keyboard and singing.

PubMed

Pfordresher, Peter Q; Mantell, James T

2012-01-01

We report an experiment that tested whether effects of altered auditory feedback (AAF) during piano performance differ from its effects during singing. These effector systems differ with respect to the mapping between motor gestures and pitch content of auditory feedback. Whereas this action-effect mapping is highly reliable during phonation in any vocal motor task (singing or speaking), mapping between finger movements and pitch occurs only in limited situations, such as piano playing. Effects of AAF in both tasks replicated results previously found for keyboard performance (Pfordresher, 2003), in that asynchronous (delayed) feedback slowed timing whereas alterations to feedback pitch increased error rates, and the effect of asynchronous feedback was similar in magnitude across tasks. However, manipulations of feedback pitch had larger effects on singing than on keyboard production, suggesting effector-specific differences in sensitivity to action-effect mapping with respect to feedback content. These results support the view that disruption from AAF is based on abstract, effector independent, response-effect associations but that the strength of associations differs across effector systems. Copyright © 2011. Published by Elsevier B.V.

XUNET experimental high-speed network testbed CRADA 1136, DOE TTI No. 92-MULT-020-B2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmer, R.E.

1996-04-01

XUNET is a research program with AT&T and other partners to study high-speed wide area communication between local area networks over a backbone using Asynchronous Transfer Mode (ATM) switches. Important goals of the project are to develop software techniques for network control and management, and applications for high-speed networks. The project entails building a testbed between member sites to explore performance issues for mixed network traffic such as congestion control, multimedia communications protocols, segmentation and reassembly of ATM cells, and overall data throughput rates.

Asynchronous signal-dependent non-uniform sampler

NASA Astrophysics Data System (ADS)

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadowski, Greg

In one form, a logic circuit includes an asynchronous logic circuit, a synchronous logic circuit, and an interface circuit coupled between the asynchronous logic circuit and the synchronous logic circuit. The asynchronous logic circuit has a plurality of asynchronous outputs for providing a corresponding plurality of asynchronous signals. The synchronous logic circuit has a plurality of synchronous inputs corresponding to the plurality of asynchronous outputs, a stretch input for receiving a stretch signal, and a clock output for providing a clock signal. The synchronous logic circuit provides the clock signal as a periodic signal but prolongs a predetermined state ofmore » the clock signal while the stretch signal is active. The asynchronous interface detects whether metastability could occur when latching any of the plurality of the asynchronous outputs of the asynchronous logic circuit using said clock signal, and activates the stretch signal while the metastability could occur.« less

Architectures for Cognitive Systems

DTIC Science & Technology

2010-02-01

highly modular many- node chip was designed which addressed power efficiency to the maximum extent possible. Each node contains an Asynchronous Field...optimization to perform complex cognitive computing operations. This project focused on the design of the core and integration across a four node chip . A...follow on project will focus on creating a 3 dimensional stack of chips that is enabled by the low power usage. The chip incorporates structures to

Taming the Wild: A Unified Analysis of Hogwild!-Style Algorithms.

PubMed

De Sa, Christopher; Zhang, Ce; Olukotun, Kunle; Ré, Christopher

2015-12-01

Stochastic gradient descent (SGD) is a ubiquitous algorithm for a variety of machine learning problems. Researchers and industry have developed several techniques to optimize SGD's runtime performance, including asynchronous execution and reduced precision. Our main result is a martingale-based analysis that enables us to capture the rich noise models that may arise from such techniques. Specifically, we use our new analysis in three ways: (1) we derive convergence rates for the convex case (Hogwild!) with relaxed assumptions on the sparsity of the problem; (2) we analyze asynchronous SGD algorithms for non-convex matrix problems including matrix completion; and (3) we design and analyze an asynchronous SGD algorithm, called Buckwild!, that uses lower-precision arithmetic. We show experimentally that our algorithms run efficiently for a variety of problems on modern hardware.

Questions as Indicators of Ocean Literacy: Students' Online Asynchronous Discussion with a Marine Scientist

ERIC Educational Resources Information Center

Fauville, Géraldine

2017-01-01

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

A formal model of asynchronous communication and its use in mechanically verifying a biphase mark protocol

NASA Technical Reports Server (NTRS)

Moore, J. Strother

1992-01-01

In this paper we present a formal model of asynchronous communication as a function in the Boyer-Moore logic. The function transforms the signal stream generated by one processor into the signal stream consumed by an independently clocked processor. This transformation 'blurs' edges and 'dilates' time due to differences in the phases and rates of the two clocks and the communications delay. The model can be used quantitatively to derive concrete performance bounds on asynchronous communications at ISO protocol level 1 (physical level). We develop part of the reusable formal theory that permits the convenient application of the model. We use the theory to show that a biphase mark protocol can be used to send messages of arbitrary length between two asynchronous processors. We study two versions of the protocol, a conventional one which uses cells of size 32 cycles and an unconventional one which uses cells of size 18. We conjecture that the protocol can be proved to work under our model for smaller cell sizes and more divergent clock rates but the proofs would be harder.

Performance Analysis of New Binary User Codes for DS-CDMA Communication

NASA Astrophysics Data System (ADS)

Usha, Kamle; Jaya Sankar, Kottareddygari

2016-03-01

This paper analyzes new binary spreading codes through correlation properties and also presents their performance over additive white Gaussian noise (AWGN) channel. The proposed codes are constructed using gray and inverse gray codes. In this paper, a n-bit gray code appended by its n-bit inverse gray code to construct the 2n-length binary user codes are discussed. Like Walsh codes, these binary user codes are available in sizes of power of two and additionally code sets of length 6 and their even multiples are also available. The simple construction technique and generation of code sets of different sizes are the salient features of the proposed codes. Walsh codes and gold codes are considered for comparison in this paper as these are popularly used for synchronous and asynchronous multi user communications respectively. In the current work the auto and cross correlation properties of the proposed codes are compared with those of Walsh codes and gold codes. Performance of the proposed binary user codes for both synchronous and asynchronous direct sequence CDMA communication over AWGN channel is also discussed in this paper. The proposed binary user codes are found to be suitable for both synchronous and asynchronous DS-CDMA communication.

NULL Convention Floating Point Multiplier

PubMed Central

Ramachandran, Seshasayanan

2015-01-01

Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation. PMID:25879069

NULL convention floating point multiplier.

PubMed

Albert, Anitha Juliette; Ramachandran, Seshasayanan

2015-01-01

Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

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

PubMed

Yuan, Wu-Jie; Zhou, Jian-Fang; Zhou, Changsong

2013-01-01

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 application for examining STDP by measuring neural population activity in a cultured neural network.

Asynchronous Transfer Mode (ATM) Switch Technology and Vendor Survey

NASA Technical Reports Server (NTRS)

Berry, Noemi

1995-01-01

Asynchronous Transfer Mode (ATM) switch and software features are described and compared in order to make switch comparisons meaningful. An ATM switch's performance cannot be measured solely based on its claimed switching capacity; traffic management and congestion control are emerging as the determining factors in an ATM network's ultimate throughput. Non-switch ATM products and experiences with actual installations of ATM networks are described. A compilation of select vendor offerings as of October 1994 is provided in chart form.

Using process groups to implement failure detection in asynchronous environments

NASA Technical Reports Server (NTRS)

Ricciardi, Aleta M.; Birman, Kenneth P.

1991-01-01

Agreement on the membership of a group of processes in a distributed system is a basic problem that arises in a wide range of applications. Such groups occur when a set of processes cooperate to perform some task, share memory, monitor one another, subdivide a computation, and so forth. The group membership problems is discussed as it relates to failure detection in asynchronous, distributed systems. A rigorous, formal specification for group membership is presented under this interpretation. A solution is then presented for this problem.

Effectiveness of an Asynchronous Online Module on University Students' Understanding of the Bohr Model of the Hydrogen Atom

ERIC Educational Resources Information Center

Farina, William J., Jr.; Bodzin, Alec M.

2018-01-01

Web-based learning is a growing field in education, yet empirical research into the design of high quality Web-based university science instruction is scarce. A one-week asynchronous online module on the Bohr Model of the atom was developed and implemented guided by the knowledge integration framework. The unit design aligned with three identified…

Seebeck Coefficient Metrology: Do Contemporary Protocols Measure Up?

NASA Astrophysics Data System (ADS)

Martin, Joshua; Wong-Ng, Winnie; Green, Martin L.

2015-06-01

Comparative measurements of the Seebeck coefficient are challenging due to the diversity of instrumentation and measurement protocols. With the implementation of standardized measurement protocols and the use of Standard Reference Materials (SRMs®), for example, the recently certified National Institute of Standards and Technology (NIST) SRM® 3451 ``Low Temperature Seebeck Coefficient Standard (10-390 K)'', researchers can reliably analyze and compare data, both intra- and inter-laboratory, thereby accelerating the development of more efficient thermoelectric materials and devices. We present a comparative overview of commonly adopted Seebeck coefficient measurement practices. First, we examine the influence of asynchronous temporal and spatial measurement of electric potential and temperature. Temporal asynchronicity introduces error in the absolute Seebeck coefficient of the order of ≈10%, whereas spatial asynchronicity introduces error of the order of a few percent. Second, we examine the influence of poor thermal contact between the measurement probes and the sample. This is especially critical at high temperature, wherein the prevalent mode of measuring surface temperature is facilitated by pressure contact. Each topic will include the comparison of data measured using different measurement techniques and using different probe arrangements. We demonstrate that the probe arrangement is the primary limit to high accuracy, wherein the Seebeck coefficients measured by the 2-probe arrangement and those measured by the 4-probe arrangement diverge with the increase in temperature, approaching ≈14% at 900 K. Using these analyses, we provide recommended measurement protocols to guide members of the thermoelectric materials community in performing more accurate measurements and in evaluating more comprehensive uncertainty limits.

Wireless acoustic modules for real-time data fusion using asynchronous sniper localization algorithms

NASA Astrophysics Data System (ADS)

Hengy, S.; De Mezzo, S.; Duffner, P.; Naz, P.

2012-11-01

The presence of snipers in modern conflicts leads to high insecurity for the soldiers. In order to improve the soldier's protection against this threat, the French German Research Institute of Saint-Louis (ISL) has been conducting studies in the domain of acoustic localization of shots. Mobile antennas mounted on the soldier's helmet were initially used for real-time detection, classification and localization of sniper shots. It showed good performances in land scenarios, but also in urban scenarios if the array was in the shot corridor, meaning that the microphones first detect the direct wave and then the reflections of the Mach and muzzle waves (15% distance estimation error compared to the actual shooter array distance). Fusing data sent by multiple sensor nodes distributed on the field showed some of the limitations of the technologies that have been implemented in ISL's demonstrators. Among others, the determination of the arrays' orientation was not accurate enough, thereby degrading the performance of data fusion. Some new solutions have been developed in the past year in order to obtain better performance for data fusion. Asynchronous localization algorithms have been developed and post-processed on data measured in both free-field and urban environments with acoustic modules on the line of sight of the shooter. These results are presented in the first part of the paper. The impact of GPS position estimation error is also discussed in the article in order to evaluate the possible use of those algorithms for real-time processing using mobile acoustic nodes. In the frame of ISL's transverse project IMOTEP (IMprovement Of optical and acoustical TEchnologies for the Protection), some demonstrators are developed that will allow real-time asynchronous localization of sniper shots. An embedded detection and classification algorithm is implemented on wireless acoustic modules that send the relevant information to a central PC. Data fusion is then processed and the estimated position of the shooter is sent back to the users. A SWIR active imaging system is used for localization refinement. A built-in DSP is related to the detection/classification tasks for each acoustic module. A GPS module is used for time difference of arrival and module's position estimation. Wireless communication is supported using ZigBee technology. These acoustic modules are described in the article and first results of real-time asynchronous sniper localization using those modules are discussed.

Design of resolution/power controllable Asynchronous Sigma-Delta Modulator

NASA Astrophysics Data System (ADS)

Deshmukh, Anita Arvind; Deshmukh, Raghvendra B.

2016-12-01

This paper presents the design of a Programmable Asynchronous Modulator (PAM) with field control of resolution and power. A novel variable hysteresis Schmitt Trigger (ST) is used for external programmability. Asynchronous Sigma-Delta Modulator (ASDM) implementation with external control voltages is proposed to supervise the resolution and power. This architecture with reduced circuit complexity considerably improves the earlier realizations by eliminating multiple current sources as well switched capacitor circuits and results in power saving up to 87 %. Proposed PAM design demonstrates an improved SNDR of 115 dB, DR of 96 dB, and power consumption below 280 μW. It illustrates Effective Number of Bits (ENOB) to 18.81 and Figure of Merit (FoM) to 0.15 fJ/conversion step. Modulator is implemented in Cadence UMC Hspice 0.18 μm CMOS analog technology. Off-chip PAM control for resolution/power performance has potential applications in battery operated ultra low power applications like IoT; where ADC is one of the major power consuming components. It offers the promise for an efficient performance with power saving.

Asynchronous State Estimation for Discrete-Time Switched Complex Networks With Communication Constraints.

PubMed

Zhang, Dan; Wang, Qing-Guo; Srinivasan, Dipti; Li, Hongyi; Yu, Li

2018-05-01

This paper is concerned with the asynchronous state estimation for a class of discrete-time switched complex networks with communication constraints. An asynchronous estimator is designed to overcome the difficulty that each node cannot access to the topology/coupling information. Also, the event-based communication, signal quantization, and the random packet dropout problems are studied due to the limited communication resource. With the help of switched system theory and by resorting to some stochastic system analysis method, a sufficient condition is proposed to guarantee the exponential stability of estimation error system in the mean-square sense and a prescribed performance level is also ensured. The characterization of the desired estimator gains is derived in terms of the solution to a convex optimization problem. Finally, the effectiveness of the proposed design approach is demonstrated by a simulation example.

Toward Active Control of Noise from Hot Supersonic Jets

DTIC Science & Technology

2012-07-24

1.5 heated jet simulated by way of LES. spreading angles of the jet which were determined from prelimi- nary LES computations performed by CRAFT Tech...system allowed time-resolved and high dynamic range measurements to be ob- tained for a heated , supersonic jet. Each component of the system is...independently operated, temporal spacing between frames is variable and can be set in an asynchronous fashion. Such flexibility even allows eight

Effects of synchronous versus asynchronous mode of propulsion on wheelchair basketball sprinting.

PubMed

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

2013-11-01

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

On the Suitability of MPI as a PGAS Runtime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daily, Jeffrey A.; Vishnu, Abhinav; Palmer, Bruce J.

2014-12-18

Partitioned Global Address Space (PGAS) models are emerging as a popular alternative to MPI models for designing scalable applications. At the same time, MPI remains a ubiquitous communication subsystem due to its standardization, high performance, and availability on leading platforms. In this paper, we explore the suitability of using MPI as a scalable PGAS communication subsystem. We focus on the Remote Memory Access (RMA) communication in PGAS models which typically includes {\\em get, put,} and {\\em atomic memory operations}. We perform an in-depth exploration of design alternatives based on MPI. These alternatives include using a semantically-matching interface such as MPI-RMA,more » as well as not-so-intuitive interfaces such as MPI two-sided with a combination of multi-threading and dynamic process management. With an in-depth exploration of these alternatives and their shortcomings, we propose a novel design which is facilitated by the data-centric view in PGAS models. This design leverages a combination of highly tuned MPI two-sided semantics and an automatic, user-transparent split of MPI communicators to provide asynchronous progress. We implement the asynchronous progress ranks approach and other approaches within the Communication Runtime for Exascale which is a communication subsystem for Global Arrays. Our performance evaluation spans pure communication benchmarks, graph community detection and sparse matrix-vector multiplication kernels, and a computational chemistry application. The utility of our proposed PR-based approach is demonstrated by a 2.17x speed-up on 1008 processors over the other MPI-based designs.« less

Software and hardware complex for research and management of the separation process

NASA Astrophysics Data System (ADS)

Borisov, A. P.

2018-01-01

The article is devoted to the development of a program for studying the operation of an asynchronous electric drive using vector-algorithmic switching of windings, as well as the development of a hardware-software complex for controlling parameters and controlling the speed of rotation of an asynchronous electric drive for investigating the operation of a cyclone. To study the operation of an asynchronous electric drive, a method was used in which the average value of flux linkage is found and a method for vector-algorithmic calculation of the power and electromagnetic moment of an asynchronous electric drive feeding from a single-phase network is developed, with vector-algorithmic commutation, and software for calculating parameters. The software part of the complex allows to regulate the speed of rotation of the motor by vector-algorithmic switching of transistors or, using pulse-width modulation (PWM), set any engine speed. Also sensors are connected to the hardware-software complex at the inlet and outlet of the cyclone. The developed cyclone with an inserted complex allows to receive high efficiency of product separation at various entrance speeds. At an inlet air speed of 18 m / s, the cyclone’s maximum efficiency is achieved. For this, it is necessary to provide the rotational speed of an asynchronous electric drive with a frequency of 45 Hz.

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

PubMed

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

2016-04-06

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.

Data Collection for Mobile Group Consumption: An Asynchronous Distributed Approach †

PubMed Central

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

Asynchronous Two-Level Checkpointing Scheme for Large-Scale Adjoints in the Spectral-Element Solver Nek5000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schanen, Michel; Marin, Oana; Zhang, Hong

Adjoints are an important computational tool for large-scale sensitivity evaluation, uncertainty quantification, and derivative-based optimization. An essential component of their performance is the storage/recomputation balance in which efficient checkpointing methods play a key role. We introduce a novel asynchronous two-level adjoint checkpointing scheme for multistep numerical time discretizations targeted at large-scale numerical simulations. The checkpointing scheme combines bandwidth-limited disk checkpointing and binomial memory checkpointing. Based on assumptions about the target petascale systems, which we later demonstrate to be realistic on the IBM Blue Gene/Q system Mira, we create a model of the expected performance of our checkpointing approach and validatemore » it using the highly scalable Navier-Stokes spectralelement solver Nek5000 on small to moderate subsystems of the Mira supercomputer. In turn, this allows us to predict optimal algorithmic choices when using all of Mira. We also demonstrate that two-level checkpointing is significantly superior to single-level checkpointing when adjoining a large number of time integration steps. To our knowledge, this is the first time two-level checkpointing had been designed, implemented, tuned, and demonstrated on fluid dynamics codes at large scale of 50k+ cores.« less

Facilitating preemptive hardware system design using partial reconfiguration techniques.

PubMed

Dondo Gazzano, Julio; Rincon, Fernando; Vaderrama, Carlos; Villanueva, Felix; Caba, Julian; Lopez, Juan Carlos

2014-01-01

In FPGA-based control system design, partial reconfiguration is especially well suited to implement preemptive systems. In real-time systems, the deadline for critical task can compel the preemption of noncritical one. Besides, an asynchronous event can demand immediate attention and, then, force launching a reconfiguration process for high-priority task implementation. If the asynchronous event is previously scheduled, an explicit activation of the reconfiguration process is performed. If the event cannot be previously programmed, such as in dynamically scheduled systems, an implicit activation to the reconfiguration process is demanded. This paper provides a hardware-based approach to explicit and implicit activation of the partial reconfiguration process in dynamically reconfigurable SoCs and includes all the necessary tasks to cope with this issue. Furthermore, the reconfiguration service introduced in this work allows remote invocation of the reconfiguration process and then the remote integration of off-chip components. A model that offers component location transparency is also presented to enhance and facilitate system integration.

Facilitating Preemptive Hardware System Design Using Partial Reconfiguration Techniques

PubMed Central

Rincon, Fernando; Vaderrama, Carlos; Villanueva, Felix; Caba, Julian; Lopez, Juan Carlos

2014-01-01

In FPGA-based control system design, partial reconfiguration is especially well suited to implement preemptive systems. In real-time systems, the deadline for critical task can compel the preemption of noncritical one. Besides, an asynchronous event can demand immediate attention and, then, force launching a reconfiguration process for high-priority task implementation. If the asynchronous event is previously scheduled, an explicit activation of the reconfiguration process is performed. If the event cannot be previously programmed, such as in dynamically scheduled systems, an implicit activation to the reconfiguration process is demanded. This paper provides a hardware-based approach to explicit and implicit activation of the partial reconfiguration process in dynamically reconfigurable SoCs and includes all the necessary tasks to cope with this issue. Furthermore, the reconfiguration service introduced in this work allows remote invocation of the reconfiguration process and then the remote integration of off-chip components. A model that offers component location transparency is also presented to enhance and facilitate system integration. PMID:24672292

Asynchronous RTK precise DGNSS positioning method for deriving a low-latency high-rate output

NASA Astrophysics Data System (ADS)

Liang, Zhang; Hanfeng, Lv; Dingjie, Wang; Yanqing, Hou; Jie, Wu

2015-07-01

Low-latency high-rate (1 Hz) precise real-time kinematic (RTK) can be applied in high-speed scenarios such as aircraft automatic landing, precise agriculture and intelligent vehicle. The classic synchronous RTK (SRTK) precise differential GNSS (DGNSS) positioning technology, however, is not able to obtain a low-latency high-rate output for the rover receiver because of long data link transmission time delays (DLTTD) from the reference receiver. To overcome the long DLTTD, this paper proposes an asynchronous real-time kinematic (ARTK) method using asynchronous observations from two receivers. The asynchronous observation model (AOM) is developed based on undifferenced carrier phase observation equations of the two receivers at different epochs with short baseline. The ephemeris error and atmosphere delay are the possible main error sources on positioning accuracy in this model, and they are analyzed theoretically. In a short DLTTD and during a period of quiet ionosphere activity, the main error sources decreasing positioning accuracy are satellite orbital errors: the "inverted ephemeris error" and the integration of satellite velocity error which increase linearly along with DLTTD. The cycle slip of asynchronous double-differencing carrier phase is detected by TurboEdit method and repaired by the additional ambiguity parameter method. The AOM can deal with synchronous observation model (SOM) and achieve precise positioning solution with synchronous observations as well, since the SOM is only a specific case of AOM. The proposed method not only can reduce the cost of data collection and transmission, but can also support the mobile phone network data link transfer mode for the data of the reference receiver. This method can avoid data synchronizing process besides ambiguity initialization step, which is very convenient for real-time navigation of vehicles. The static and kinematic experiment results show that this method achieves 20 Hz or even higher rate output in real time. The ARTK positioning accuracy is better and more robust than the combination of phase difference over time (PDOT) and SRTK method at a high rate. The ARTK positioning accuracy is equivalent to SRTK solution when the DLTTD is 0.5 s, and centimeter level accuracy can be achieved even when DLTTD is 15 s.

Hatching behavior of eastern long-necked turtles (Chelodina longicollis): The influence of asynchronous environments on embryonic heart rate and phenotype.

PubMed

McGlashan, Jessica K; Loudon, Fiona K; Thompson, Michael B; Spencer, Ricky-John

2015-10-01

Variable temperatures within a nest cause asynchronous development within clutches of freshwater turtle embryos, yet synchronous hatching occurs and is thought to be an important survival strategy for hatchlings. Metabolic compensation and circadian rhythms in heart rates of embryonic turtles indicate the potential of communication between embryos in a nest. Heart rates were used to identify metabolic circadian rhythms in clutches of an Australian freshwater turtle (Chelodina longicollis) and determine whether embryos metabolically compensate and hatch synchronously when incubated in asynchronous environments. The effects of a group environment during incubation on egg development and incubation period were also investigated during the final 3 weeks of development. Chelodina longicollis hatch synchronously and metabolically compensate so that less advanced embryos catch up to more advanced clutch-mates. Heart rates of embryos remained stable from week 4-7 in asynchronous (M=89 bpm) and synchronous (M=92 bpm) groups and declined in the final 2 weeks of incubation (M=72 and 77 bpm). Circadian rhythms were present throughout development and diel heart rates of embryos in asynchronous groups showed less deviation from the mean (M=-0.5 bpm) than synchronous groups (M=-4 bpm). Eggs incubated in groups had a significantly shorter incubation period than eggs incubated individually. Phenotypic traits including size, performance, and growth of all hatchlings were not affected. Egg position within a turtle nest is important for coordinating development throughout incubation and facilitating synchronous hatching. Copyright © 2015 Elsevier Inc. All rights reserved.

The queueing perspective of asynchronous network coding in two-way relay network

NASA Astrophysics Data System (ADS)

Liang, Yaping; Chang, Qing; Li, Xianxu

2018-04-01

Asynchronous network coding (NC) has potential to improve the wireless network performance compared with a routing or the synchronous network coding. Recent researches concentrate on the optimization between throughput/energy consuming and delay with a couple of independent input flow. However, the implementation of NC requires a thorough investigation of its impact on relevant queueing systems where few work focuses on. Moreover, few works study the probability density function (pdf) in network coding scenario. In this paper, the scenario with two independent Poisson input flows and one output flow is considered. The asynchronous NC-based strategy is that a new arrival evicts a head packet holding in its queue when waiting for another packet from the other flow to encode. The pdf for the output flow which contains both coded and uncoded packets is derived. Besides, the statistic characteristics of this strategy are analyzed. These results are verified by numerical simulations.

Supporting Handoff in Asynchronous Collaborative Sensemaking Using Knowledge-Transfer Graphs.

PubMed

Zhao, Jian; Glueck, Michael; Isenberg, Petra; Chevalier, Fanny; Khan, Azam

2018-01-01

During asynchronous collaborative analysis, handoff of partial findings is challenging because externalizations produced by analysts may not adequately communicate their investigative process. To address this challenge, we developed techniques to automatically capture and help encode tacit aspects of the investigative process based on an analyst's interactions, and streamline explicit authoring of handoff annotations. We designed our techniques to mediate awareness of analysis coverage, support explicit communication of progress and uncertainty with annotation, and implicit communication through playback of investigation histories. To evaluate our techniques, we developed an interactive visual analysis system, KTGraph, that supports an asynchronous investigative document analysis task. We conducted a two-phase user study to characterize a set of handoff strategies and to compare investigative performance with and without our techniques. The results suggest that our techniques promote the use of more effective handoff strategies, help increase an awareness of prior investigative process and insights, as well as improve final investigative outcomes.

Regression analysis of sparse asynchronous longitudinal data.

PubMed

Cao, Hongyuan; Zeng, Donglin; Fine, Jason P

2015-09-01

We consider estimation of regression models for sparse asynchronous longitudinal observations, where time-dependent responses and covariates are observed intermittently within subjects. Unlike with synchronous data, where the response and covariates are observed at the same time point, with asynchronous data, the observation times are mismatched. Simple kernel-weighted estimating equations are proposed for generalized linear models with either time invariant or time-dependent coefficients under smoothness assumptions for the covariate processes which are similar to those for synchronous data. For models with either time invariant or time-dependent coefficients, the estimators are consistent and asymptotically normal but converge at slower rates than those achieved with synchronous data. Simulation studies evidence that the methods perform well with realistic sample sizes and may be superior to a naive application of methods for synchronous data based on an ad hoc last value carried forward approach. The practical utility of the methods is illustrated on data from a study on human immunodeficiency virus.

Analysis of backward error recovery for concurrent processes with recovery blocks

NASA Technical Reports Server (NTRS)

Shin, K. G.; Lee, Y. H.

1982-01-01

Three different methods of implementing recovery blocks (RB's). These are the asynchronous, synchronous, and the pseudo recovery point implementations. Pseudo recovery points so that unbounded rollback may be avoided while maintaining process autonomy are proposed. Probabilistic models for analyzing these three methods under standard assumptions in computer performance analysis, i.e., exponential distributions for related random variables were developed. The interval between two successive recovery lines for asynchronous RB's mean loss in computation power for the synchronized method, and additional overhead and rollback distance in case PRP's are used were estimated.

Rapid Feedforward Inhibition and Asynchronous Excitation Regulate Granule Cell Activity in the Mammalian Main Olfactory Bulb

PubMed Central

Burton, Shawn D.

2015-01-01

Granule cell-mediated inhibition is critical to patterning principal neuron activity in the olfactory bulb, and perturbation of synaptic input to granule cells significantly alters olfactory-guided behavior. Despite the critical role of granule cells in olfaction, little is known about how sensory input recruits granule cells. Here, we combined whole-cell patch-clamp electrophysiology in acute mouse olfactory bulb slices with biophysical multicompartmental modeling to investigate the synaptic basis of granule cell recruitment. Physiological activation of sensory afferents within single glomeruli evoked diverse modes of granule cell activity, including subthreshold depolarization, spikelets, and suprathreshold responses with widely distributed spike latencies. The generation of these diverse activity modes depended, in part, on the asynchronous time course of synaptic excitation onto granule cells, which lasted several hundred milliseconds. In addition to asynchronous excitation, each granule cell also received synchronous feedforward inhibition. This inhibition targeted both proximal somatodendritic and distal apical dendritic domains of granule cells, was reliably recruited across sniff rhythms, and scaled in strength with excitation as more glomeruli were activated. Feedforward inhibition onto granule cells originated from deep short-axon cells, which responded to glomerular activation with highly reliable, short-latency firing consistent with tufted cell-mediated excitation. Simulations showed that feedforward inhibition interacts with asynchronous excitation to broaden granule cell spike latency distributions and significantly attenuates granule cell depolarization within local subcellular compartments. Collectively, our results thus identify feedforward inhibition onto granule cells as a core feature of olfactory bulb circuitry and establish asynchronous excitation and feedforward inhibition as critical regulators of granule cell activity. SIGNIFICANCE STATEMENT Inhibitory granule cells are involved critically in shaping odor-evoked principal neuron activity in the mammalian olfactory bulb, yet little is known about how sensory input activates granule cells. Here, we show that sensory input to the olfactory bulb evokes a barrage of asynchronous synaptic excitation and highly reliable, short-latency synaptic inhibition onto granule cells via a disynaptic feedforward inhibitory circuit involving deep short-axon cells. Feedforward inhibition attenuates local depolarization within granule cell dendritic branches, interacts with asynchronous excitation to suppress granule cell spike-timing precision, and scales in strength with excitation across different levels of sensory input to normalize granule cell firing rates. PMID:26490853

Process membership in asynchronous environments

NASA Technical Reports Server (NTRS)

Ricciardi, Aleta M.; Birman, Kenneth P.

1993-01-01

The development of reliable distributed software is simplified by the ability to assume a fail-stop failure model. The emulation of such a model in an asynchronous distributed environment is discussed. The solution proposed, called Strong-GMP, can be supported through a highly efficient protocol, and was implemented as part of a distributed systems software project at Cornell University. The precise definition of the problem, the protocol, correctness proofs, and an analysis of costs are addressed.

Testing and Performance Analysis of the Multichannel Error Correction Code Decoder

NASA Technical Reports Server (NTRS)

Soni, Nitin J.

1996-01-01

This report provides the test results and performance analysis of the multichannel error correction code decoder (MED) system for a regenerative satellite with asynchronous, frequency-division multiple access (FDMA) uplink channels. It discusses the system performance relative to various critical parameters: the coding length, data pattern, unique word value, unique word threshold, and adjacent-channel interference. Testing was performed under laboratory conditions and used a computer control interface with specifically developed control software to vary these parameters. Needed technologies - the high-speed Bose Chaudhuri-Hocquenghem (BCH) codec from Harris Corporation and the TRW multichannel demultiplexer/demodulator (MCDD) - were fully integrated into the mesh very small aperture terminal (VSAT) onboard processing architecture and were demonstrated.

Intelligent neuroprocessors for in-situ launch vehicle propulsion systems health management

NASA Technical Reports Server (NTRS)

Gulati, S.; Tawel, R.; Thakoor, A. P.

1993-01-01

Efficacy of existing on-board propulsion systems health management systems (HMS) are severely impacted by computational limitations (e.g., low sampling rates); paradigmatic limitations (e.g., low-fidelity logic/parameter redlining only, false alarms due to noisy/corrupted sensor signatures, preprogrammed diagnostics only); and telemetry bandwidth limitations on space/ground interactions. Ultra-compact/light, adaptive neural networks with massively parallel, asynchronous, fast reconfigurable and fault-tolerant information processing properties have already demonstrated significant potential for inflight diagnostic analyses and resource allocation with reduced ground dependence. In particular, they can automatically exploit correlation effects across multiple sensor streams (plume analyzer, flow meters, vibration detectors, etc.) so as to detect anomaly signatures that cannot be determined from the exploitation of single sensor. Furthermore, neural networks have already demonstrated the potential for impacting real-time fault recovery in vehicle subsystems by adaptively regulating combustion mixture/power subsystems and optimizing resource utilization under degraded conditions. A class of high-performance neuroprocessors, developed at JPL, that have demonstrated potential for next-generation HMS for a family of space transportation vehicles envisioned for the next few decades, including HLLV, NLS, and space shuttle is presented. Of fundamental interest are intelligent neuroprocessors for real-time plume analysis, optimizing combustion mixture-ratio, and feedback to hydraulic, pneumatic control systems. This class includes concurrently asynchronous reprogrammable, nonvolatile, analog neural processors with high speed, high bandwidth electronic/optical I/O interfaced, with special emphasis on NASA's unique requirements in terms of performance, reliability, ultra-high density ultra-compactness, ultra-light weight devices, radiation hardened devices, power stringency, and long life terms.

Asynchronous hatching and food limitation: A test of Lack's hypothesis

USGS Publications Warehouse

Skagen, Susan Knight

1988-01-01

Lack's (1954, 1968) hypothesis that asynchronous hatching of altricial birds is an adaptive response to unpredictable food shortages during the breeding season was examined in the highly granivorous Zebra Finch (Poephila guttata). I compared growth and survival of nestlings in asynchronous and artificially created synchronous broods reared under food-limited and food-abundant conditions in an aviary. I also examined the role of parental experience on survival and growth of nestlings.There was no differential mortality of Zebra Finch nestlings due to either asynchrony or food abundance. Young in abundant food treatments grew more rapidly, however, than those in food-restricted treatments. Heaviest Zebra Finch nestlings in a brood grew more quickly than their lightest siblings when food was limited, supporting Lack's hypothesis. Further, differential survival of light and heavy siblings occurred when food was abundant, suggesting that asynchronous hatching can be maladaptive under some ecological conditions. Nestlings reared by inexperienced parents suffered greater mortality and slower growth when food was abundant than nestlings raised by experienced parents. Prefledging mass was correlated with size at adulthood

FBMC receiver for multi-user asynchronous transmission on fragmented spectrum

NASA Astrophysics Data System (ADS)

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.

Acceptability of an Asynchronous Learning Forum on Mobile Devices

ERIC Educational Resources Information Center

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…

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

ERIC Educational Resources Information Center

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…

An Analysis of Performance Enhancement Techniques for Overset Grid Applications

NASA Technical Reports Server (NTRS)

Djomehri, J. J.; Biswas, R.; Potsdam, M.; Strawn, R. C.; Biegel, Bryan (Technical Monitor)

2002-01-01

The overset grid methodology has significantly reduced time-to-solution of high-fidelity computational fluid dynamics (CFD) simulations about complex aerospace configurations. The solution process resolves the geometrical complexity of the problem domain by using separately generated but overlapping structured discretization grids that periodically exchange information through interpolation. However, high performance computations of such large-scale realistic applications must be handled efficiently on state-of-the-art parallel supercomputers. This paper analyzes the effects of various performance enhancement techniques on the parallel efficiency of an overset grid Navier-Stokes CFD application running on an SGI Origin2000 machine. Specifically, the role of asynchronous communication, grid splitting, and grid grouping strategies are presented and discussed. Results indicate that performance depends critically on the level of latency hiding and the quality of load balancing across the processors.

Pharmacists' perception of synchronous versus asynchronous distance learning for continuing education programs.

PubMed

Buxton, Eric C

2014-02-12

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

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

PubMed Central

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. Methods. An 8-lecture series of online presentations on the topic of new drug therapies was offered to pharmacists in synchronous and asynchronous webinar formats. Participants completed a 50-question online survey at the end of the program series to evaluate their perceptions of the distance learning experience. Results. Eighty-two participants completed the survey instrument (41 participants from the live webinar series and 41 participants from the asynchronous webinar series.) Responses indicated that while both groups were satisfied with the program content, the asynchronous group showed greater satisfaction with many aspects of the learning environment. Conclusion. The synchronous and asynchronous webinar participants responded positively regarding the quality of the programming and the method of delivery, but asynchronous participants rated their experience more positively overall. PMID:24558276

Comparing the force ripple during asynchronous and conventional stimulation.

PubMed

Downey, Ryan J; Tate, Mark; Kawai, Hiroyuki; Dixon, Warren E

2014-10-01

Asynchronous stimulation has been shown to reduce fatigue during electrical stimulation; however, it may also exhibit a force ripple. We quantified the ripple during asynchronous and conventional single-channel transcutaneous stimulation across a range of stimulation frequencies. The ripple was measured during 5 asynchronous stimulation protocols, 2 conventional stimulation protocols, and 3 volitional contractions in 12 healthy individuals. Conventional 40 Hz and asynchronous 16 Hz stimulation were found to induce contractions that were as smooth as volitional contractions. Asynchronous 8, 10, and 12 Hz stimulation induced contractions with significant ripple. Lower stimulation frequencies can reduce fatigue; however, they may also lead to increased ripple. Future efforts should study the relationship between force ripple and the smoothness of the evoked movements in addition to the relationship between stimulation frequency and NMES-induced fatigue to elucidate an optimal stimulation frequency for asynchronous stimulation. © 2014 Wiley Periodicals, Inc.

Synchronous Office Hours in an Asynchronous Course: Making the Connection

ERIC Educational Resources Information Center

Gibbons-Kunka, Beatrice

2017-01-01

The notion of synchronous office hours in an asynchronous course seems counterintuitive. After all, one of the tenets of asynchronous education is to not require students to be online and participating at any time during the course. Having taught higher education online asynchronous courses for twenty years, the researcher experimented with online…

A simple highly efficient non invasive EMG-based HMI.

PubMed

Vitiello, N; Olcese, U; Oddo, C M; Carpaneto, J; Micera, S; Carrozza, M C; Dario, P

2006-01-01

Muscle activity recorded non-invasively is sufficient to control a mobile robot if it is used in combination with an algorithm for its asynchronous analysis. In this paper, we show that several subjects successfully can control the movements of a robot in a structured environment made up of six rooms by contracting two different muscles using a simple algorithm. After a small training period, subjects were able to control the robot with performances comparable to those achieved manually controlling the robot.

Pseudo Asynchronous Level Crossing adc for ecg Signal Acquisition.

PubMed

Marisa, T; Niederhauser, T; Haeberlin, A; Wildhaber, R A; Vogel, R; Goette, J; Jacomet, M

2017-02-07

A new pseudo asynchronous level crossing analogue-to-digital converter (adc) architecture targeted for low-power, implantable, long-term biomedical sensing applications is presented. In contrast to most of the existing asynchronous level crossing adc designs, the proposed design has no digital-to-analogue converter (dac) and no continuous time comparators. Instead, the proposed architecture uses an analogue memory cell and dynamic comparators. The architecture retains the signal activity dependent sampling operation by generating events only when the input signal is changing. The architecture offers the advantages of smaller chip area, energy saving and fewer analogue system components. Beside lower energy consumption the use of dynamic comparators results in a more robust performance in noise conditions. Moreover, dynamic comparators make interfacing the asynchronous level crossing system to synchronous processing blocks simpler. The proposed adc was implemented in [Formula: see text] complementary metal-oxide-semiconductor (cmos) technology, the hardware occupies a chip area of 0.0372 mm 2 and operates from a supply voltage of [Formula: see text] to [Formula: see text]. The adc's power consumption is as low as 0.6 μW with signal bandwidth from [Formula: see text] to [Formula: see text] and achieves an equivalent number of bits (enob) of up to 8 bits.

Effect of music-movement synchrony on exercise oxygen consumption.

PubMed

Bacon, C J; Myers, T R; Karageorghis, C I

2012-08-01

Past research indicates that endurance is improved when exercise movements are synchronised with a musical beat, however it is unclear whether such benefits are associated with reduced metabolic cost. We compared oxygen consumption (.VO2) and related physiological effects of exercise conducted synchronously and asynchronously with music. Three music tracks, each recorded at three different tempi (123, 130, and 137 beats.min-1), accompanied cycle ergometry at 65 pedal revolutions.min-1. Thus three randomly-assigned experimental conditions were administered: slow tempo asynchronous, synchronous, and fast tempo asynchronous. Exercise response of .VO2, HR, and ratings of perceived exertion (RPE), to each condition was monitored in 10 untrained male participants aged 21.7±0.8 years (mean±SD) who cycled for 12 min at 70% maximal heart rate (HR). Mean .VO2 differed among conditions (P=0.008), being lower in the synchronous (1.80±0.22 L.min-1) compared to the slow tempo asynchronous condition (1.94±0.21 L.min-1; P<0.05). There was no difference in HR or RPE among conditions, although HR showed a similar trend to .VO2. The present results indicate that exercise is more efficient when performed synchronously with music than when musical tempo is slightly slower than the rate of cyclical movement.

A Phenomenological Synapse Model for Asynchronous Neurotransmitter Release

PubMed Central

Wang, Tao; Yin, Luping; Zou, Xiaolong; Shu, Yousheng; Rasch, Malte J.; Wu, Si

2016-01-01

Neurons communicate with each other via synapses. Action potentials cause release of neurotransmitters at the axon terminal. Typically, this neurotransmitter release is tightly time-locked to the arrival of an action potential and is thus called synchronous release. However, neurotransmitter release is stochastic and the rate of release of small quanta of neurotransmitters can be considerably elevated even long after the ceasing of spiking activity, leading to asynchronous release of neurotransmitters. Such asynchronous release varies for tissue and neuron types and has been shown recently to be pronounced in fast-spiking neurons. Notably, it was found that asynchronous release is enhanced in human epileptic tissue implicating a possibly important role in generating abnormal neural activity. Current neural network models for simulating and studying neural activity virtually only consider synchronous release and ignore asynchronous transmitter release. Here, we develop a phenomenological model for asynchronous neurotransmitter release, which, on one hand, captures the fundamental features of the asynchronous release process, and, on the other hand, is simple enough to be incorporated in large-size network simulations. Our proposed model is based on the well-known equations for short-term dynamical synaptic interactions and includes an additional stochastic term for modeling asynchronous release. We use experimental data obtained from inhibitory fast-spiking synapses of human epileptic tissue to fit the model parameters, and demonstrate that our model reproduces the characteristics of realistic asynchronous transmitter release. PMID:26834617

Experience with synchronous and asynchronous digital control systems

NASA Technical Reports Server (NTRS)

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.

Regression analysis of sparse asynchronous longitudinal data

PubMed Central

Cao, Hongyuan; Zeng, Donglin; Fine, Jason P.

2015-01-01

Summary We consider estimation of regression models for sparse asynchronous longitudinal observations, where time-dependent responses and covariates are observed intermittently within subjects. Unlike with synchronous data, where the response and covariates are observed at the same time point, with asynchronous data, the observation times are mismatched. Simple kernel-weighted estimating equations are proposed for generalized linear models with either time invariant or time-dependent coefficients under smoothness assumptions for the covariate processes which are similar to those for synchronous data. For models with either time invariant or time-dependent coefficients, the estimators are consistent and asymptotically normal but converge at slower rates than those achieved with synchronous data. Simulation studies evidence that the methods perform well with realistic sample sizes and may be superior to a naive application of methods for synchronous data based on an ad hoc last value carried forward approach. The practical utility of the methods is illustrated on data from a study on human immunodeficiency virus. PMID:26568699

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

PubMed

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

2018-02-01

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

The potential of high intensity focused ultrasound (HIFU) combine phase-sensitive optical coherence tomography (PhS-OCT) for diseases diagnosis, treatment and monitoring

NASA Astrophysics Data System (ADS)

Zhou, Kanheng; Wang, Yan; Feng, Kairui; Li, Chunhui; Huang, Zhihong

2018-02-01

HIFU is a truly noninvasive, acoustic therapeutic technique that utilizes high intensity acoustic field in the focus to kill the targeted tissue for disease treatment purpose. The mechanical properties of targeted tissue changes before and after treatment, and this change can be accurately detected by shear wave elastography. Hence, shear wave elastography is usually used for monitoring HIFU treatment asynchronously. To improve the low spatial resolution in ultrasound shear wave elastography, and to perform diseases diagnosis, treatment and monitoring in the same system, a new setup that combines HIFU and PhS-OCT system was proposed in this study. This proposed setup could do 1) HIFU treatment when the transducer works at high energy level, 2) ultrasound induced shear wave optical coherence elastography for HIFU treatment asynchronous monitoring when the transducer works at low energy level. Ex-vivo bovine liver tissue was treated at the same energy level for different time (0s, 1s, 5s, 9s) in this research. Elastography was performed on the lesion area of the sample after HIFU treatment, and the elastogram was reconstructed by the time of flight time method. The elastogram results clearly show the boundary of HIFU lesion area and surrounding normal tissue, even for 1s treatment time. And the average elasticity of the lesion grows linearly as the treatment time increases. Combined with OCT needle probe, the proposed method has a large potential not only to be used for superficial diseases treatment, but also to be used for high-precision-demanded diseases treatment, e.g. nervous disease treatment.

Patterns and Perceptions of Asynchronous Video Discussion in a Graduate Health Sciences Course.

PubMed

Cummins, Mollie; Rajan, Naresh Sundar; Hodge, Chad; Gouripeddi, Ramkiran

2016-12-01

Studies of graduate online education indicate a need for increased interaction among students and faculty. However, it can be challenging to foster a high level of scholarly interaction and engagement in fully online courses. The objective of this study was to evaluate student perceptions and participation patterns related to online, asynchronous video discussion in a graduate health sciences course. An asynchronous video discussion was piloted in a 2014 interprofessional informatics course and students were subsequently surveyed to determine their perceptions of this approach. Participation patterns were analyzed using descriptive statistics and social network analysis. The results indicate broad and inclusive interaction among students and faculty, with discussion characteristics perceived as equivalent to, or better than, traditional classroom discussion. The quality of student participation was high, and students spent additional time researching and preparing their contributions. This format for a seminar-style discussion holds good potential for effective teaching and learning in online graduate-level health courses and supports the development of students' critical thinking and scholarly communication skills. [J Nurs Educ. 2016;55(12):706-710.]. Copyright 2016, SLACK Incorporated.

mdtmFTP and its evaluation on ESNET SDN testbed

DOE PAGES

Zhang, Liang; Wu, Wenji; DeMar, Phil; ...

2017-04-21

In this paper, to address the high-performance challenges of data transfer in the big data era, we are developing and implementing mdtmFTP: a high-performance data transfer tool for big data. mdtmFTP has four salient features. First, it adopts an I/O centric architecture to execute data transfer tasks. Second, it more efficiently utilizes the underlying multicore platform through optimized thread scheduling. Third, it implements a large virtual file mechanism to address the lots-of-small-files (LOSF) problem. In conclusion, mdtmFTP integrates multiple optimization mechanisms, including–zero copy, asynchronous I/O, pipelining, batch processing, and pre-allocated buffer pools–to enhance performance. mdtmFTP has been extensively tested andmore » evaluated within the ESNET 100G testbed. Evaluations show that mdtmFTP can achieve higher performance than existing data transfer tools, such as GridFTP, FDT, and BBCP.« less

Electrical Design and Evaluation of Asynchronous Serial Bus Communication Network of 48 Sensor Platform LSIs with Single-Ended I/O for Integrated MEMS-LSI Sensors.

PubMed

Shao, Chenzhong; Tanaka, Shuji; Nakayama, Takahiro; Hata, Yoshiyuki; Muroyama, Masanori

2018-01-15

For installing many sensors in a limited space with a limited computing resource, the digitization of the sensor output at the site of sensation has advantages such as a small amount of wiring, low signal interference and high scalability. For this purpose, we have developed a dedicated Complementary Metal-Oxide-Semiconductor (CMOS) Large-Scale Integration (LSI) (referred to as "sensor platform LSI") for bus-networked Micro-Electro-Mechanical-Systems (MEMS)-LSI integrated sensors. In this LSI, collision avoidance, adaptation and event-driven functions are simply implemented to relieve data collision and congestion in asynchronous serial bus communication. In this study, we developed a network system with 48 sensor platform LSIs based on Printed Circuit Board (PCB) in a backbone bus topology with the bus length being 2.4 m. We evaluated the serial communication performance when 48 LSIs operated simultaneously with the adaptation function. The number of data packets received from each LSI was almost identical, and the average sampling frequency of 384 capacitance channels (eight for each LSI) was 73.66 Hz.

Hybrid optical CDMA-FSO communications network under spatially correlated gamma-gamma scintillation.

PubMed

Jurado-Navas, Antonio; Raddo, Thiago R; Garrido-Balsells, José María; Borges, Ben-Hur V; Olmos, Juan José Vegas; Monroy, Idelfonso Tafur

2016-07-25

In this paper, we propose a new hybrid network solution based on asynchronous optical code-division multiple-access (OCDMA) and free-space optical (FSO) technologies for last-mile access networks, where fiber deployment is impractical. The architecture of the proposed hybrid OCDMA-FSO network is thoroughly described. The users access the network in a fully asynchronous manner by means of assigned fast frequency hopping (FFH)-based codes. In the FSO receiver, an equal gain-combining technique is employed along with intensity modulation and direct detection. New analytical formalisms for evaluating the average bit error rate (ABER) performance are also proposed. These formalisms, based on the spatially correlated gamma-gamma statistical model, are derived considering three distinct scenarios, namely, uncorrelated, totally correlated, and partially correlated channels. Numerical results show that users can successfully achieve error-free ABER levels for the three scenarios considered as long as forward error correction (FEC) algorithms are employed. Therefore, OCDMA-FSO networks can be a prospective alternative to deliver high-speed communication services to access networks with deficient fiber infrastructure.

3D Hybrid Simulations of Interactions of High-Velocity Plasmoids with Obstacles

NASA Astrophysics Data System (ADS)

Omelchenko, Y. A.; Weber, T. E.; Smith, R. J.

2015-11-01

Interactions of fast plasma streams and objects with magnetic obstacles (dipoles, mirrors, etc) lie at the core of many space and laboratory plasma phenomena ranging from magnetoshells and solar wind interactions with planetary magnetospheres to compact fusion plasmas (spheromaks and FRCs) to astrophysics-in-lab experiments. Properly modeling ion kinetic, finite-Larmor radius and Hall effects is essential for describing large-scale plasma dynamics, turbulence and heating in complex magnetic field geometries. Using an asynchronous parallel hybrid code, HYPERS, we conduct 3D hybrid (particle-in-cell ion, fluid electron) simulations of such interactions under realistic conditions that include magnetic flux coils, ion-ion collisions and the Chodura resistivity. HYPERS does not step simulation variables synchronously in time but instead performs time integration by executing asynchronous discrete events: updates of particles and fields carried out as frequently as dictated by local physical time scales. Simulations are compared with data from the MSX experiment which studies the physics of magnetized collisionless shocks through the acceleration and subsequent stagnation of FRC plasmoids against a strong magnetic mirror and flux-conserving boundary.

Designing Asynchronous Communication Tools for Optimization of Patient-Clinician Coordination

PubMed Central

Eschler, Jordan; Liu, Leslie S.; Vizer, Lisa M.; McClure, Jennifer B.; Lozano, Paula; Pratt, Wanda; Ralston, James D.

2015-01-01

Asynchronous communication outside the clinical setting has both enriched and complicated patient-clinician interactions. Many patients can now interact with a patient portal 24 hours a day, asking questions of their clinicians via secure message, checking lab results, ordering medication refills, or making appointments. However, the mode of communication (asynchronous) and the nature of the interaction (lacking tone or body language) strip valuable information from each side of patient-clinician asynchronous communication. Using interviews with 34 individuals who actively manage a chronic illness of their own, or for a child or partner, we elicited narratives about patients’ experiences and expectations for using asynchronous communication to address medical issues with their clinicians. Based on these perspectives, we present opportunities for designing asynchronous communication tools to better facilitate understanding of and coordination around care activities between patients and clinicians. PMID:26958188

A Motion-Based Feature for Event-Based Pattern Recognition

PubMed Central

Clady, Xavier; Maro, Jean-Matthieu; Barré, Sébastien; Benosman, Ryad B.

2017-01-01

This paper introduces an event-based luminance-free feature from the output of asynchronous event-based neuromorphic retinas. The feature consists in mapping the distribution of the optical flow along the contours of the moving objects in the visual scene into a matrix. 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. The optical flow is computed at each event, and is integrated locally or globally in a speed and direction coordinate frame based grid, using speed-tuned temporal kernels. The latter ensures that the resulting feature equitably represents the distribution of the normal motion along the current moving edges, whatever their respective dynamics. The usefulness and the generality of the proposed feature are demonstrated in pattern recognition applications: local corner detection and global gesture recognition. PMID:28101001

Programs as Polypeptides.

PubMed

Williams, Lance R

2016-01-01

Object-oriented combinator chemistry (OOCC) is an artificial chemistry with composition devices borrowed from object-oriented and functional programming languages. Actors in OOCC are embedded in space and subject to diffusion; since they are neither created nor destroyed, their mass is conserved. Actors use programs constructed from combinators to asynchronously update their own states and the states of other actors in their neighborhoods. The fact that programs and combinators are themselves reified as actors makes it possible to build programs that build programs from combinators of a few primitive types using asynchronous spatial processes that resemble chemistry as much as computation. To demonstrate this, OOCC is used to define a parallel, asynchronous, spatially distributed self-replicating system modeled in part on the living cell. Since interactions among its parts result in the construction of more of these same parts, the system is strongly constructive. The system's high normalized complexity is contrasted with that of a simple composome.

Building asynchronous geospatial processing workflows with web services

NASA Astrophysics Data System (ADS)

Zhao, Peisheng; Di, Liping; Yu, Genong

2012-02-01

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

Asynchronous, Decentralized DS-CDMA Using Feedback-Controlled Spreading Sequences for Time-Dispersive Channels

NASA Astrophysics Data System (ADS)

Miyatake, Teruhiko; Chiba, Kazuki; Hamamura, Masanori; Tachikawa, Shin'ichi

We propose a novel asynchronous direct-sequence codedivision multiple access (DS-CDMA) using feedback-controlled spreading sequences (FCSSs) (FCSS/DS-CDMA). At the receiver of FCSS/DS-CDMA, the code-orthogonalizing filter (COF) produces a spreading sequence, and the receiver returns the spreading sequence to the transmitter. Then the transmitter uses the spreading sequence as its updated version. The performance of FCSS/DS-CDMA is evaluated over time-dispersive channels. The results indicate that FCSS/DS-CDMA greatly suppresses both the intersymbol interference (ISI) and multiple access interference (MAI) over time-invariant channels. FCSS/DS-CDMA is applicable to the decentralized multiple access.

Critical Literacy Performances in Online Literature Discussions

ERIC Educational Resources Information Center

Forest, Danielle E.; Kimmel, Sue C.

2016-01-01

In today's media-laden environment, the ability to read text from a critical literacy perspective is imperative, particularly for librarians who influence children's reading choices and behaviors. This study examines the critical literacy performances of students in an online, asynchronous, graduate-level children's literature course using a…

A robust low-rate coding scheme for packet video

NASA Technical Reports Server (NTRS)

Chen, Y. C.; Sayood, Khalid; Nelson, D. J.; Arikan, E. (Editor)

1991-01-01

Due to the rapidly evolving field of image processing and networking, video information promises to be an important part of telecommunication systems. Although up to now video transmission has been transported mainly over circuit-switched networks, it is likely that packet-switched networks will dominate the communication world in the near future. Asynchronous transfer mode (ATM) techniques in broadband-ISDN can provide a flexible, independent and high performance environment for video communication. For this paper, the network simulator was used only as a channel in this simulation. Mixture blocking coding with progressive transmission (MBCPT) has been investigated for use over packet networks and has been found to provide high compression rate with good visual performance, robustness to packet loss, tractable integration with network mechanics and simplicity in parallel implementation.

Dynamic Performance of a Back-to-Back HVDC Station Based on Voltage Source Converters

NASA Astrophysics Data System (ADS)

Khatir, Mohamed; Zidi, Sid-Ahmed; Hadjeri, Samir; Fellah, Mohammed-Karim

2010-01-01

The recent developments in semiconductors and control equipment have made the voltage source converter based high voltage direct current (VSC-HVDC) feasible. This new DC transmission is known as "HVDC Light or "HVDC Plus by leading vendors. Due to the use of VSC technology and pulse width modulation (PWM) the VSC-HVDC has a number of potential advantages as compared with classic HVDC. In this paper, the scenario of back-to-back VSC-HVDC link connecting two adjacent asynchronous AC networks is studied. Control strategy is implemented and its dynamic performances during disturbances are investigated in MATLAB/Simulink program. The simulation results have shown good performance of the proposed system under balanced and unbalanced fault conditions.

Synchronization of Hierarchical Time-Varying Neural Networks Based on Asynchronous and Intermittent Sampled-Data Control.

PubMed

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

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

Digital Synchronizer without Metastability

NASA Technical Reports Server (NTRS)

Simle, Robert M.; Cavazos, Jose A.

2009-01-01

A proposed design for a digital synchronizing circuit would eliminate metastability that plagues flip-flop circuits in digital input/output interfaces. This metastability is associated with sampling, by use of flip-flops, of an external signal that is asynchronous with a clock signal that drives the flip-flops: it is a temporary flip-flop failure that can occur when a rising or falling edge of an asynchronous signal occurs during the setup and/or hold time of a flip-flop. The proposed design calls for (1) use of a clock frequency greater than the frequency of the asynchronous signal, (2) use of flip-flop asynchronous preset or clear signals for the asynchronous input, (3) use of a clock asynchronous recovery delay with pulse width discriminator, and (4) tying the data inputs to constant logic levels to obtain (5) two half-rate synchronous partial signals - one for the falling and one for the rising edge. Inasmuch as the flip-flop data inputs would be permanently tied to constant logic levels, setup and hold times would not be violated. The half-rate partial signals would be recombined to construct a signal that would replicate the original asynchronous signal at its original rate but would be synchronous with the clock signal.

SEU Performance of TAG Based Flip Flops

NASA Technical Reports Server (NTRS)

Shuler, Robert L.; Kouba, Coy; O'Neill, Patrick M.

2005-01-01

We describe heavy ion test results for two new SEU tolerant latches based on transition nand gates, one for single rail asynchronous and the other for dual rail synchronous designs, implemented in AMI 0.5microprocess.

A novel comparator featured with input data characteristic

NASA Astrophysics Data System (ADS)

Jiang, Xiaobo; Ye, Desheng; Xu, Xiangmin; Zheng, Shuai

2016-03-01

Two types of low-power asynchronous comparators featured with input data statistical characteristic are proposed in this article. The asynchronous ripple comparator stops comparing at the first unequal bit but delivers the result to the least significant bit. The pre-stop asynchronous comparator can completely stop comparing and obtain results immediately. The proposed and contrastive comparators were implemented in SMIC 0.18 μm process with different bit widths. Simulation shows that the proposed pre-stop asynchronous comparator features the lowest power consumption, shortest average propagation delay and highest area efficiency among the comparators. Data path of low-density parity check decoder using the proposed pre-stop asynchronous comparators are most power efficient compared with other data paths with synthesised, clock gating and bitwise competition logic comparators.

Interactional Coherence in Asynchronous Learning Networks: A Rhetorical Approach

ERIC Educational Resources Information Center

Potter, Andrew

2008-01-01

Numerous studies have affirmed the value of asynchronous online communication as a learning resource. Several investigations, however, have indicated that discussions in asynchronous environments are often neither interactive nor coherent. The research reported sought to develop an enhanced understanding of interactional coherence, argumentation,…

Continuous EEG signal analysis for asynchronous BCI application.

PubMed

Hsu, Wei-Yen

2011-08-01

In this study, we propose a two-stage recognition system for continuous analysis of electroencephalogram (EEG) signals. An independent component analysis (ICA) and correlation coefficient are used to automatically eliminate the electrooculography (EOG) artifacts. Based on the continuous wavelet transform (CWT) and Student's two-sample t-statistics, active segment selection then detects the location of active segment in the time-frequency domain. Next, multiresolution fractal feature vectors (MFFVs) are extracted with the proposed modified fractal dimension from wavelet data. Finally, the support vector machine (SVM) is adopted for the robust classification of MFFVs. The EEG signals are continuously analyzed in 1-s segments, and every 0.5 second moves forward to simulate asynchronous BCI works in the two-stage recognition architecture. The segment is first recognized as lifted or not in the first stage, and then is classified as left or right finger lifting at stage two if the segment is recognized as lifting in the first stage. Several statistical analyses are used to evaluate the performance of the proposed system. The results indicate that it is a promising system in the applications of asynchronous BCI work.

Experience with synchronous and asynchronous digital control systems. [for flight

NASA Technical Reports Server (NTRS)

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

Control of an electrical prosthesis with an SSVEP-based BCI.

PubMed

Müller-Putz, Gernot R; Pfurtscheller, Gert

2008-01-01

Brain-computer interfaces (BCIs) are systems that establish a direct connection between the human brain and a computer, thus providing an additional communication channel. They are used in a broad field of applications nowadays. One important issue is the control of neuroprosthetic devices for the restoration of the grasp function in spinal-cord-injured people. In this communication, an asynchronous (self-paced) four-class BCI based on steady-state visual evoked potentials (SSVEPs) was used to control a two-axes electrical hand prosthesis. During training, four healthy participants reached an online classification accuracy between 44% and 88%. Controlling the prosthetic hand asynchronously, the participants reached a performance of 75.5 to 217.5 s to copy a series of movements, whereas the fastest possible duration determined by the setup was 64 s. The number of false negative (FN) decisions varied from 0 to 10 (the maximal possible decisions were 34). It can be stated that the SSVEP-based BCI, operating in an asynchronous mode, is feasible for the control of neuroprosthetic devices with the flickering lights mounted on its surface.

Collective network for computer structures

DOEpatents

Blumrich, Matthias A; Coteus, Paul W; Chen, Dong; Gara, Alan; Giampapa, Mark E; Heidelberger, Philip; Hoenicke, Dirk; Takken, Todd E; Steinmacher-Burow, Burkhard D; Vranas, Pavlos M

2014-01-07

A system and method for enabling high-speed, low-latency global collective communications among interconnected processing nodes. The global collective network optimally enables collective reduction operations to be performed during parallel algorithm operations executing in a computer structure having a plurality of the interconnected processing nodes. Router devices are included that interconnect the nodes of the network via links to facilitate performance of low-latency global processing operations at nodes of the virtual network. The global collective network may be configured to provide global barrier and interrupt functionality in asynchronous or synchronized manner. When implemented in a massively-parallel supercomputing structure, the global collective network is physically and logically partitionable according to the needs of a processing algorithm.

Collective network for computer structures

DOEpatents

Blumrich, Matthias A [Ridgefield, CT; Coteus, Paul W [Yorktown Heights, NY; Chen, Dong [Croton On Hudson, NY; Gara, Alan [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Hoenicke, Dirk [Ossining, NY; Takken, Todd E [Brewster, NY; Steinmacher-Burow, Burkhard D [Wernau, DE; Vranas, Pavlos M [Bedford Hills, NY

2011-08-16

A system and method for enabling high-speed, low-latency global collective communications among interconnected processing nodes. The global collective network optimally enables collective reduction operations to be performed during parallel algorithm operations executing in a computer structure having a plurality of the interconnected processing nodes. Router devices ate included that interconnect the nodes of the network via links to facilitate performance of low-latency global processing operations at nodes of the virtual network and class structures. The global collective network may be configured to provide global barrier and interrupt functionality in asynchronous or synchronized manner. When implemented in a massively-parallel supercomputing structure, the global collective network is physically and logically partitionable according to needs of a processing algorithm.

Decentralized Quasi-Newton Methods

NASA Astrophysics Data System (ADS)

Eisen, Mark; Mokhtari, Aryan; Ribeiro, Alejandro

2017-05-01

We introduce the decentralized Broyden-Fletcher-Goldfarb-Shanno (D-BFGS) method as a variation of the BFGS quasi-Newton method for solving decentralized optimization problems. The D-BFGS method is of interest in problems that are not well conditioned, making first order decentralized methods ineffective, and in which second order information is not readily available, making second order decentralized methods impossible. D-BFGS is a fully distributed algorithm in which nodes approximate curvature information of themselves and their neighbors through the satisfaction of a secant condition. We additionally provide a formulation of the algorithm in asynchronous settings. Convergence of D-BFGS is established formally in both the synchronous and asynchronous settings and strong performance advantages relative to first order methods are shown numerically.

Labeled Postings for Asynchronous Interaction

ERIC Educational Resources Information Center

ChanLin, Lih-Juan; Chen, Yong-Ting; Chan, Kung-Chi

2009-01-01

The Internet promotes computer-mediated communications, and so asynchronous learning network systems permit more flexibility in time, space, and interaction than synchronous mode of learning. The key point of asynchronous learning is the materials for web-aided teaching and the flow of knowledge. This research focuses on improving online…

An Asynchronous Augmentation to Traditional Course Delivery.

ERIC Educational Resources Information Center

Wolverton, Marvin L.; Wolverton, Mimi

Asynchronous augmentation facilitates distributed learning, which relies heavily on technology and self-learning. This paper reports the results of delivering a real estate principles course using an asynchronous course delivery format. It highlights one of many ways to enhance learning using technology, and it provides information concerning how…

A Taxonomy of Learning through Asynchronous Discussion

ERIC Educational Resources Information Center

Knowlton, Dave S.

2005-01-01

This article presents a five-tiered taxonomy that describes the nature of participation in, and learning through, asynchronous discussion. The taxonomy is framed by a constructivist view of asynchronous discussion. The five tiers of the taxonomy include the following: (a) passive participation, (b) developmental participation, (c) generative…

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

ERIC Educational Resources Information Center

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…

When the rhythm disappears and the mind keeps dancing: sustained effects of attentional entrainment.

PubMed

Trapp, Sabrina; Havlicek, Ondrej; Schirmer, Annett; Keller, Peter E

2018-01-17

Research has demonstrated that the human cognitive system allocates attention most efficiently to a stimulus that occurs in synchrony with an established rhythmic background. However, our environment is dynamic and constantly changing. What happens when rhythms to which our cognitive system adapted disappear? We addressed this question using a visual categorization task comprising emotional and neutral faces. The task was split into three blocks of which the first and the last were completed in silence. The second block was accompanied by an acoustic background rhythm that, for one group of participants, was synchronous with face presentations, and for another group was asynchronous. Irrespective of group, performance improved with background stimulation. Importantly, improved performance extended into the third silent block for the synchronous, but not for the asynchronous group. These data suggest that attentional entrainment resulting from rhythmic environmental regularities disintegrates only gradually after the regularities disappear.

Asynchronous multilevel adaptive methods for solving partial differential equations on multiprocessors - Performance results

NASA Technical Reports Server (NTRS)

Mccormick, S.; Quinlan, D.

1989-01-01

The fast adaptive composite grid method (FAC) is an algorithm that uses various levels of uniform grids (global and local) to provide adaptive resolution and fast solution of PDEs. Like all such methods, it offers parallelism by using possibly many disconnected patches per level, but is hindered by the need to handle these levels sequentially. The finest levels must therefore wait for processing to be essentially completed on all the coarser ones. A recently developed asynchronous version of FAC, called AFAC, completely eliminates this bottleneck to parallelism. This paper describes timing results for AFAC, coupled with a simple load balancing scheme, applied to the solution of elliptic PDEs on an Intel iPSC hypercube. These tests include performance of certain processes necessary in adaptive methods, including moving grids and changing refinement. A companion paper reports on numerical and analytical results for estimating convergence factors of AFAC applied to very large scale examples.

Performance study for a set of BLUE based Filters applied to amplitude estimation using as a reference the single photoelectron signal of the ν-Angra Experiment

NASA Astrophysics Data System (ADS)

Souza, D. M.; Costa, I. A.; Nóbrega, R. A.

2017-10-01

This document presents a detailed study of the performance of a set of digital filters whose implementations are based on the best linear unbiased estimator theory interpreted as a constrained optimization problem that could be relaxed depending on the input signal characteristics. This approach has been employed by a number of recent particle physics experiments for measuring the energy of particle events interacting with their detectors. The considered filters have been designed to measure the peak amplitude of signals produced by their detectors based on the digitized version of such signals. This study provides a clear understanding of the characteristics of those filters in the context of particle physics and, additionally, it proposes a phase related constraint based on the second derivative of the Taylor expansion in order to make the estimator less sensitive to phase variation (phase between the analog signal shaping and its sampled version), which is stronger in asynchronous experiments. The asynchronous detector developed by the ν-Angra Collaboration is used as the basis for this work. Nevertheless, the proposed analysis goes beyond, considering a wide range of conditions related to signal parameters such as pedestal, phase, sampling rate, amplitude resolution, noise and pile-up; therefore crossing the bounds of the ν-Angra Experiment to make it interesting and useful for different asynchronous and even synchronous experiments.

Performance measurements of the first RAID prototype

NASA Technical Reports Server (NTRS)

Chervenak, Ann L.

1990-01-01

The performance is examined of Redundant Arrays of Inexpensive Disks (RAID) the First, a prototype disk array. A hierarchy of bottlenecks was discovered in the system that limit overall performance. The most serious is the memory system contention on the Sun 4/280 host CPU, which limits array bandwidth to 2.3 MBytes/sec. The array performs more successfully on small random operations, achieving nearly 300 I/Os per second before the Sun 4/280 becomes CPU limited. Other bottlenecks in the system are the VME backplane, bandwidth on the disk controller, and overheads associated with the SCSI protocol. All are examined in detail. The main conclusion is that to achieve the potential bandwidth of arrays, more powerful CPU's alone will not suffice. Just as important are adequate host memory bandwidth and support for high bandwidth on disk controllers. Current disk controllers are more often designed to achieve large numbers of small random operations, rather than high bandwidth. Operating systems also need to change to support high bandwidth from disk arrays. In particular, they should transfer data in larger blocks, and should support asynchronous I/O to improve sequential write performance.

When big brother is watching: goal orientation shapes reactions to electronic monitoring during online training.

PubMed

Watson, Aaron M; Foster Thompson, Lori; Rudolph, Jane V; Whelan, Thomas J; Behrend, Tara S; Gissel, Amanda L

2013-07-01

Web-based training is frequently used by organizations as a convenient and low-cost way to teach employees new knowledge and skills. As web-based training is typically unproctored, employees may be held accountable to the organization by computer software that monitors their behaviors. The current study examines how the introduction of electronic performance monitoring may provoke negative emotional reactions and decrease learning among certain types of e-learners. Through motivated action theory and trait activation theory, we examine the role of performance goal orientation when e-learners are exposed to asynchronous and synchronous monitoring. We show that some e-learners are more susceptible than others to evaluation apprehension when they perceive their activities are being monitored electronically. Specifically, e-learners higher in avoid performance goal orientation exhibited increased evaluation apprehension if they believed asynchronous monitoring was present, and they showed decreased skill attainment as a result. E-learners higher on prove performance goal orientation showed greater evaluation apprehension if they believed real-time monitoring was occurring, resulting in decreased skill attainment. PsycINFO Database Record (c) 2013 APA, all rights reserved.

No Need for Templates in the Auditory Enhancement Effect

PubMed Central

Carcagno, Samuele; Semal, Catherine; Demany, Laurent

2013-01-01

The audibility of a target tone in a multitone background masker is enhanced by the presentation of a precursor sound consisting of the masker alone. There is evidence that precursor-induced neural adaptation plays a role in this perceptual enhancement. However, the precursor may also be strategically used by listeners as a spectral template of the following masker to better segregate it from the target. In the present study, we tested this hypothesis by measuring the audibility of a target tone in a multitone masker after the presentation of precursors which, in some conditions, were made dissimilar to the masker by gating their components asynchronously. The precursor and the following sound were presented either to the same ear or to opposite ears. In either case, we found no significant difference in the amount of enhancement produced by synchronous and asynchronous precursors. In a second experiment, listeners had to judge whether a synchronous multitone complex contained exactly the same tones as a preceding precursor complex or had one tone less. In this experiment, listeners performed significantly better with synchronous than with asynchronous precursors, showing that asynchronous precursors were poorer perceptual templates of the synchronous multitone complexes. Overall, our findings indicate that precursor-induced auditory enhancement cannot be fully explained by the strategic use of the precursor as a template of the following masker. Our results are consistent with an explanation of enhancement based on selective neural adaptation taking place at a central locus of the auditory system. PMID:23826348

No Need for Templates in the Auditory Enhancement Effect.

PubMed

Carcagno, Samuele; Semal, Catherine; Demany, Laurent

2013-01-01

The audibility of a target tone in a multitone background masker is enhanced by the presentation of a precursor sound consisting of the masker alone. There is evidence that precursor-induced neural adaptation plays a role in this perceptual enhancement. However, the precursor may also be strategically used by listeners as a spectral template of the following masker to better segregate it from the target. In the present study, we tested this hypothesis by measuring the audibility of a target tone in a multitone masker after the presentation of precursors which, in some conditions, were made dissimilar to the masker by gating their components asynchronously. The precursor and the following sound were presented either to the same ear or to opposite ears. In either case, we found no significant difference in the amount of enhancement produced by synchronous and asynchronous precursors. In a second experiment, listeners had to judge whether a synchronous multitone complex contained exactly the same tones as a preceding precursor complex or had one tone less. In this experiment, listeners performed significantly better with synchronous than with asynchronous precursors, showing that asynchronous precursors were poorer perceptual templates of the synchronous multitone complexes. Overall, our findings indicate that precursor-induced auditory enhancement cannot be fully explained by the strategic use of the precursor as a template of the following masker. Our results are consistent with an explanation of enhancement based on selective neural adaptation taking place at a central locus of the auditory system.

Actively Engaging Students in Asynchronous Online Classes. IDEA Paper #64

ERIC Educational Resources Information Center

Riggs, Shannon A.; Linder, Kathryn E.

2016-01-01

Active learning activities and pedagogical strategies can look different in online learning environments, particularly in asynchronous courses when students are not interacting with the instructor, or with each other, in real time. This paper suggests a three-pronged approach for conceptualizing active learning in the online asynchronous class:…

Exploring Asynchronous and Synchronous Tool Use in Online Courses

ERIC Educational Resources Information Center

Oztok, Murat; Zingaro, Daniel; Brett, Clare; Hewitt, Jim

2013-01-01

While the independent contributions of synchronous and asynchronous interaction in online learning are clear, comparatively less is known about the pedagogical consequences of using both modes in the same environment. In this study, we examine relationships between students' use of asynchronous discussion forums and synchronous private messages…

Teaching Presence and Communication Timeliness in Asynchronous Online Courses

ERIC Educational Resources Information Center

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.…

Two Studies Examining Argumentation in Asynchronous Computer Mediated Communication

ERIC Educational Resources Information Center

Joiner, Richard; Jones, Sarah; Doherty, John

2008-01-01

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

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

ERIC Educational Resources Information Center

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…

Designing Asynchronous, Text-Based Computer Conferences: Ten Research-Based Suggestions

ERIC Educational Resources Information Center

Choitz, Paul; Lee, Doris

2006-01-01

Asynchronous computer conferencing refers to the use of computer software and a network enabling participants to post messages that allow discourse to continue even though interactions may be extended over days and weeks. Asynchronous conferences are time-independent, adapting to multiple time zones and learner schedules. Such activities as…

Asynchronous Learning Forums for Business Acculturation

ERIC Educational Resources Information Center

Pence, Christine Cope; Wulf, Catharina

2009-01-01

The use of IT as a facilitator for student collaboration in higher business education has grown rapidly since 2000. Asynchronous discussion forums are used abundantly for collaborative training purposes and for teaching students business-relevant tools for their future careers. This article presents an analysis of the asynchronous discussion forum…

Comparing face-to-face, synchronous, and asynchronous learning: postgraduate dental resident preferences.

PubMed

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

2014-06-01

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

Asynchronous glimpsing of speech: Spread of masking and task set-size

PubMed Central

Ozmeral, Erol J.; Buss, Emily; Hall, Joseph W.

2012-01-01

Howard-Jones and Rosen [(1993). J. Acoust. Soc. Am. 93, 2915–2922] investigated the ability to integrate glimpses of speech that are separated in time and frequency using a “checkerboard” masker, with asynchronous amplitude modulation (AM) across frequency. Asynchronous glimpsing was demonstrated only for spectrally wide frequency bands. It is possible that the reduced evidence of spectro-temporal integration with narrower bands was due to spread of masking at the periphery. The present study tested this hypothesis with a dichotic condition, in which the even- and odd-numbered bands of the target speech and asynchronous AM masker were presented to opposite ears, minimizing the deleterious effects of masking spread. For closed-set consonant recognition, thresholds were 5.1–8.5 dB better for dichotic than for monotic asynchronous AM conditions. Results were similar for closed-set word recognition, but for open-set word recognition the benefit of dichotic presentation was more modest and level dependent, consistent with the effects of spread of masking being level dependent. There was greater evidence of asynchronous glimpsing in the open-set than closed-set tasks. Presenting stimuli dichotically supported asynchronous glimpsing with narrower frequency bands than previously shown, though the magnitude of glimpsing was reduced for narrower bandwidths even in some dichotic conditions. PMID:22894234

Asynchronous vs didactic education: it's too early to throw in the towel on tradition.

PubMed

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

2013-08-08

Asynchronous, computer based instruction is cost effective, allows self-directed pacing and review, and addresses preferences of millennial learners. Current research suggests there is no significant difference in learning compared to traditional classroom instruction. Data are limited for novice learners in emergency medicine. The objective of this study was to compare asynchronous, computer-based instruction with traditional didactics for senior medical students during a week-long intensive course in acute care. We hypothesized both modalities would be equivalent. This was a prospective observational quasi-experimental study of 4th year medical students who were novice learners with minimal prior exposure to curricular elements. We assessed baseline knowledge with an objective pre-test. The curriculum was delivered in either traditional lecture format (shock, acute abdomen, dyspnea, field trauma) or via asynchronous, computer-based modules (chest pain, EKG interpretation, pain management, trauma). An interactive review covering all topics was followed by a post-test. Knowledge retention was measured after 10 weeks. Pre and post-test items were written by a panel of medical educators and validated with a reference group of learners. Mean scores were analyzed using dependent t-test and attitudes were assessed by a 5-point Likert scale. 44 of 48 students completed the protocol. Students initially acquired more knowledge from didactic education as demonstrated by mean gain scores (didactic: 28.39% ± 18.06; asynchronous 9.93% ± 23.22). Mean difference between didactic and asynchronous = 18.45% with 95% CI [10.40 to 26.50]; p = 0.0001. Retention testing demonstrated similar knowledge attrition: mean gain scores -14.94% (didactic); -17.61% (asynchronous), which was not significantly different: 2.68% ± 20.85, 95% CI [-3.66 to 9.02], p = 0.399. The attitudinal survey revealed that 60.4% of students believed the asynchronous modules were educational and 95.8% enjoyed the flexibility of the method. 39.6% of students preferred asynchronous education for required didactics; 37.5% were neutral; 23% preferred traditional lectures. Asynchronous, computer-based instruction was not equivalent to traditional didactics for novice learners of acute care topics. Interactive, standard didactic education was valuable. Retention rates were similar between instructional methods. Students had mixed attitudes toward asynchronous learning but enjoyed the flexibility. We urge caution in trading in traditional didactic lectures in favor of asynchronous education for novice learners in acute care.

Pronuclear synchronization and nuclear morphology of mature and in vitro matured oocytes in the rat: an ultrastructural study.

PubMed

Cincik, M; Baykal, B; Zeteroglu, S; Onalan, G; Ceyhan, S T; Ergur, R

2005-01-01

The objective of this study was to evaluate synchronous and asynchronous pronucleus (PN) formation and the related patterns of juxtapositional nucleolus (n) formation in immature (prophase I [PI] and metaphase I [MI]) and mature (metaphase II [MII]) oocytes after fertilization, both ultrastructurally and at the level of light microscope. A single dose of 15 IU gonadotrophin was injected subcutaneously to twenty four 26-wk-old, female Wistar rats to induce ovulation. Human chorionic gonadotrophin (4 IU) was administered 40 h later, and after 4-6 h the ovaries were dissected, and the oocytes were aspirated. A total of 214 rat oocytes were classified according to a maturation index as follows: group I, 80 PI oocytes; group II, 50 MI oocytes; and group III, 84 MII oocytes. Immature oocytes were in vitro matured for 18-36 h. Spermatozoa were acquired by microepididymal sperm aspiration and processed using swim-up technique. Intracytoplasmic sperm injection was performed on mature oocytes after 2 h of incubation and on in vitro matured (IVM) oocytes 4 h after maturation. Pronuclear synchronization [both pronucleases (PNs) centrally located, equal sized, with equal numbers and sizes of juxtapositional nucleoli (Nn)] was observed in fertilized oocytes. Asynchronous PN formation (diversity between male and female PNs, related to dimensions, localization, and the number of Nn) in groups I, II, and III was found in 75, 86, and 47% of preembryos, respectively. There was a significant difference of synchronous pronuclear formation between mature and IVM oocytes (P < 0.05). In IVM oocytes, asynchronous PN formation is high, and juxtapositional pronucleolar patterns are observed to be low by transmission electron microscope (TEM).

Gigabit Ethernet: A Technical Assessment.

ERIC Educational Resources Information Center

Axner, David

1997-01-01

Describes gigabit ethernet for LAN (local area network) technology that will expand ethernet bandwidth. Technical details are discussed, including protocol stacks, optical fiber, deployment strategy for performance improvement, ATM (Asynchronous Transfer Mode), real-time protocol, reserve reservation protocol, and standards. (LRW)

Electrical Design and Evaluation of Asynchronous Serial Bus Communication Network of 48 Sensor Platform LSIs with Single-Ended I/O for Integrated MEMS-LSI Sensors

PubMed Central

Shao, Chenzhong; Tanaka, Shuji; Nakayama, Takahiro; Hata, Yoshiyuki

2018-01-01

For installing many sensors in a limited space with a limited computing resource, the digitization of the sensor output at the site of sensation has advantages such as a small amount of wiring, low signal interference and high scalability. For this purpose, we have developed a dedicated Complementary Metal-Oxide-Semiconductor (CMOS) Large-Scale Integration (LSI) (referred to as “sensor platform LSI”) for bus-networked Micro-Electro-Mechanical-Systems (MEMS)-LSI integrated sensors. In this LSI, collision avoidance, adaptation and event-driven functions are simply implemented to relieve data collision and congestion in asynchronous serial bus communication. In this study, we developed a network system with 48 sensor platform LSIs based on Printed Circuit Board (PCB) in a backbone bus topology with the bus length being 2.4 m. We evaluated the serial communication performance when 48 LSIs operated simultaneously with the adaptation function. The number of data packets received from each LSI was almost identical, and the average sampling frequency of 384 capacitance channels (eight for each LSI) was 73.66 Hz. PMID:29342923

MPEG-2 Over Asynchronous Transfer Mode (ATM) Over Satellite Quality of Service (QoS) Experiments: Laboratory Tests

NASA Technical Reports Server (NTRS)

Ivancic, William D.; Frantz, Brian D.; Spells, Marcus J.

1998-01-01

Asynchronous transfer mode (ATM) quality of service (QoS) experiments were performed 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 transmit high-quality multimedia information by using the ATM protocol. The detailed test plan and test configuration are described herein as are the test results. MPEG-2 transport streams were baselined in an errored environment, followed by a series of tests using, MPEG-2 over ATM. Errors were created both digitally as well as in an IF link by using a satellite modem and commercial gaussian noise test set for two different MPEG-2 decoder implementations. The results show that ITU-T Recommendation 1.356 Class 1, stringent ATM applications will require better link quality than currently specified; in particular, cell loss ratios of better than 1.0 x 10(exp -8) and cell error ratios of better than 1.0 x 10(exp -7) are needed. These tests were conducted at the NASA Lewis Research Center in support of satellite-ATM interoperability research.

ASP-based method for the enumeration of attractors in non-deterministic synchronous and asynchronous multi-valued networks.

PubMed

Ben Abdallah, Emna; Folschette, Maxime; Roux, Olivier; Magnin, Morgan

2017-01-01

This paper addresses the problem of finding attractors in biological regulatory networks. We focus here on non-deterministic synchronous and asynchronous multi-valued networks, modeled using automata networks (AN). AN is a general and well-suited formalism to study complex interactions between different components (genes, proteins,...). An attractor is a minimal trap domain, that is, a part of the state-transition graph that cannot be escaped. Such structures are terminal components of the dynamics and take the form of steady states (singleton) or complex compositions of cycles (non-singleton). Studying the effect of a disease or a mutation on an organism requires finding the attractors in the model to understand the long-term behaviors. We present a computational logical method based on answer set programming (ASP) to identify all attractors. Performed without any network reduction, the method can be applied on any dynamical semantics. In this paper, we present the two most widespread non-deterministic semantics: the asynchronous and the synchronous updating modes. The logical approach goes through a complete enumeration of the states of the network in order to find the attractors without the necessity to construct the whole state-transition graph. We realize extensive computational experiments which show good performance and fit the expected theoretical results in the literature. The originality of our approach lies on the exhaustive enumeration of all possible (sets of) states verifying the properties of an attractor thanks to the use of ASP. Our method is applied to non-deterministic semantics in two different schemes (asynchronous and synchronous). The merits of our methods are illustrated by applying them to biological examples of various sizes and comparing the results with some existing approaches. It turns out that our approach succeeds to exhaustively enumerate on a desktop computer, in a large model (100 components), all existing attractors up to a given size (20 states). This size is only limited by memory and computation time.

Fostering Critical Reflection in a Computer-Based, Asynchronously Delivered Diversity Training Course

ERIC Educational Resources Information Center

Givhan, Shawn T.

2013-01-01

This dissertation study chronicles the creation of a computer-based, asynchronously delivered diversity training course for a state agency. The course format enabled efficient delivery of a mandatory curriculum to the Massachusetts Department of State Police workforce. However, the asynchronous format posed a challenge to achieving the learning…

Anonymity and Motivation in Asynchronous Discussions and L2 Vocabulary Learning

ERIC Educational Resources Information Center

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…

Exploring the Effect of Scripted Roles on Cognitive Presence in Asynchronous Online Discussions

ERIC Educational Resources Information Center

Olesova, Larisa; Slavin, Margaret; Lim, Jieun

2016-01-01

The purpose of this study was to identify the effect of scripted roles on students' level of cognitive presence in asynchronous online threaded discussions. A quantitative content analysis was used to investigate: (1) what level of cognitive presence is achieved by students' assigned roles in asynchronous online discussions; (2) differences…

A Multi-Perspective Investigation into Learners' Interaction in Asynchronous Computer-Mediated Communication (CMC)

ERIC Educational Resources Information Center

Çardak, Çigdem Suzan

2016-01-01

This article focusses on graduate level students' interactions during asynchronous CMC activities of an online course about the teaching profession in Turkey. The instructor of the course designed and facilitated a semester-long asynchronous CMC on forum discussions, and investigated the interaction of learners in multiple perspectives: learners'…

The Negotiation Model in Asynchronous Computer-Mediated Communication (CMC): Negotiation in Task-Based Email Exchanges

ERIC Educational Resources Information Center

Kitade, Keiko

2006-01-01

Based on recent studies, computer-mediated communication (CMC) has been considered a tool to aid in language learning on account of its distinctive interactional features. However, most studies have referred to "synchronous" CMC and neglected to investigate how "asynchronous" CMC contributes to language learning. Asynchronous CMC possesses…

Integrating the Intangibles into Asynchronous Online Instruction: Strategies for Improving Interaction and Social Presence

ERIC Educational Resources Information Center

McGuire, Beverley Foulks

2016-01-01

This paper considers how instructors of asynchronous online courses in the Humanities might integrate intangibles associated with face-to-face instruction into their online environments. It presents a case study of asynchronous online instruction in a philosophy and religion department at a midsize public university in the southeastern United…

Postgraduate Students' Knowledge Construction during Asynchronous Computer Conferences in a Blended Learning Environment: A Malaysian Experience

ERIC Educational Resources Information Center

Kian-Sam, Hong; Lee, Julia Ai Cheng

2008-01-01

Blended learning, using e-learning tools to supplement existing on campus learning, often incorporates asynchronous computer conferencing as a means of augmenting knowledge construction among students. This case study reports findings about levels of knowledge construction amongst adult postgraduate students in six asynchronous computer…

Asynchronous reference frame agreement in a quantum network

NASA Astrophysics Data System (ADS)

Islam, Tanvirul; Wehner, Stephanie

2016-03-01

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

The Rubber Hand Illusion: Feeling of Ownership and Proprioceptive Drift Do Not Go Hand in Hand

PubMed Central

Rohde, Marieke; Di Luca, Massimiliano; Ernst, Marc O.

2011-01-01

In the Rubber Hand Illusion, the feeling of ownership of a rubber hand displaced from a participant's real occluded hand is evoked by synchronously stroking both hands with paintbrushes. A change of perceived finger location towards the rubber hand (proprioceptive drift) has been reported to correlate with this illusion. To measure the time course of proprioceptive drift during the Rubber Hand Illusion, we regularly interrupted stroking (performed by robot arms) to measure perceived finger location. Measurements were made by projecting a probe dot into the field of view (using a semi-transparent mirror) and asking participants if the dot is to the left or to the right of their invisible hand (Experiment 1) or to adjust the position of the dot to that of their invisible hand (Experiment 2). We varied both the measurement frequency (every 10 s, 40 s, 120 s) and the mode of stroking (synchronous, asynchronous, just vision). Surprisingly, with frequent measurements, proprioceptive drift occurs not only in the synchronous stroking condition but also in the two control conditions (asynchronous stroking, just vision). Proprioceptive drift in the synchronous stroking condition is never higher than in the just vision condition. Only continuous exposure to asynchronous stroking prevents proprioceptive drift and thus replicates the differences in drift reported in the literature. By contrast, complementary subjective ratings (questionnaire) show that the feeling of ownership requires synchronous stroking and is not present in the asynchronous stroking condition. Thus, subjective ratings and drift are dissociated. We conclude that different mechanisms of multisensory integration are responsible for proprioceptive drift and the feeling of ownership. Proprioceptive drift relies on visuoproprioceptive integration alone, a process that is inhibited by asynchronous stroking, the most common control condition in Rubber Hand Illusion experiments. This dissociation implies that conclusions about feelings of ownership cannot be drawn from measuring proprioceptive drift alone. PMID:21738756

Pediatric emergency medicine asynchronous e-learning: a multicenter randomized controlled Solomon four-group study.

PubMed

Chang, Todd P; Pham, Phung K; Sobolewski, Brad; Doughty, Cara B; Jamal, Nazreen; Kwan, Karen Y; Little, Kim; Brenkert, Timothy E; Mathison, David J

2014-08-01

Asynchronous e-learning allows for targeted teaching, particularly advantageous when bedside and didactic education is insufficient. An asynchronous e-learning curriculum has not been studied across multiple centers in the context of a clinical rotation. We hypothesize that an asynchronous e-learning curriculum during the pediatric emergency medicine (EM) rotation improves medical knowledge among residents and students across multiple participating centers. Trainees on pediatric EM rotations at four large pediatric centers from 2012 to 2013 were randomized in a Solomon four-group design. The experimental arms received an asynchronous e-learning curriculum consisting of nine Web-based, interactive, peer-reviewed Flash/HTML5 modules. Postrotation testing and in-training examination (ITE) scores quantified improvements in knowledge. A 2 × 2 analysis of covariance (ANCOVA) tested interaction and main effects, and Pearson's correlation tested associations between module usage, scores, and ITE scores. A total of 256 of 458 participants completed all study elements; 104 had access to asynchronous e-learning modules, and 152 were controls who used the current education standards. No pretest sensitization was found (p = 0.75). Use of asynchronous e-learning modules was associated with an improvement in posttest scores (p < 0.001), from a mean score of 18.45 (95% confidence interval [CI] = 17.92 to 18.98) to 21.30 (95% CI = 20.69 to 21.91), a large effect (partial η(2) = 0.19). Posttest scores correlated with ITE scores (r(2) = 0.14, p < 0.001) among pediatric residents. Asynchronous e-learning is an effective educational tool to improve knowledge in a clinical rotation. Web-based asynchronous e-learning is a promising modality to standardize education among multiple institutions with common curricula, particularly in clinical rotations where scheduling difficulties, seasonality, and variable experiences limit in-hospital learning. © 2014 by the Society for Academic Emergency Medicine.

Modeling and Analysis of Asynchronous Systems Using SAL and Hybrid SAL

NASA Technical Reports Server (NTRS)

Tiwari, Ashish; Dutertre, Bruno

2013-01-01

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

Detection of Failure in Asynchronous Motor Using Soft Computing Method

NASA Astrophysics Data System (ADS)

Vinoth Kumar, K.; Sony, Kevin; Achenkunju John, Alan; Kuriakose, Anto; John, Ano P.

2018-04-01

This paper investigates the stator short winding failure of asynchronous motor also their effects on motor current spectrums. A fuzzy logic approach i.e., model based technique possibly will help to detect the asynchronous motor failure. Actually, fuzzy logic similar to humanoid intelligent methods besides expected linguistic empowering inferences through vague statistics. The dynamic model is technologically advanced for asynchronous motor by means of fuzzy logic classifier towards investigate the stator inter turn failure in addition open phase failure. A hardware implementation was carried out with LabVIEW for the online-monitoring of faults.

Asynchronous discrete control of continuous processes

NASA Astrophysics Data System (ADS)

Kaliski, M. E.; Johnson, T. L.

1984-07-01

The research during this second contract year continued to deal with the development of sound theoretical models for asynchronous systems. Two criteria served to shape the research pursued: the first, that the developed models extend and generalize previously developed research for synchronous discrete control; the second, that the models explicitly address the question of how to incorporate system transition times into themselves. The following sections of this report concisely delineate this year's work. Our original proposal for this research identified four general tasks of investigation: (1.1) Analysis of Qualitative Properties of Asynchronous Hybrid Systems; (1.2) Acceptance and Control for Asynchronous Hybrid Systems.

Distance Learning.

ERIC Educational Resources Information Center

Orey, Michael; Koenecke, Lynne; Snider, Richard C.; Perkins, Ross A.; Holmes, Glen A.; Lockee, Barbara B.; Moller, Leslie A.; Harvey, Douglas; Downs, Margaret; Godshalk, Veronica M.

2003-01-01

Contains four articles covering trends and issues on distance learning including: the experience of two learners learning via the Internet; a systematic approach to determining the scalability of a distance education program; identifying factors that affect learning community development and performance in asynchronous distance education; and…

Combining Live Video and Audio Broadcasting, Synchronous Chat, and Asynchronous Open Forum Discussions in Distance Education

ERIC Educational Resources Information Center

Teng, Tian-Lih; Taveras, Marypat

2004-01-01

This article outlines the evolution of a unique distance education program that began as a hybrid--combining face-to-face instruction with asynchronous online teaching--and evolved to become an innovative combination of synchronous education using live streaming video, audio, and chat over the Internet, blended with asynchronous online discussions…

The Development, Validity, and Reliability of Communication Satisfaction in an Online Asynchronous Discussion Scale

ERIC Educational Resources Information Center

Hung, Min-Ling; Chou, Chien

2014-01-01

The purpose of this study was to identify dimensions of students' communication satisfaction in an asynchronous discussion forum. An asynchronous discussion may be defined as text-based human-to-human communication via computer networks that provides a platform for the participants to interact with one another to exchange ideas, insights, and…

Web-based Cases in Teaching and Learning - the Quality of Discussions and a Stage of Perspective Taking in Asynchronous Communication.

ERIC Educational Resources Information Center

Jarvela, Sanna; Hakkinen, Paivi

2002-01-01

Examines the quality of asynchronous interaction in Web-based conferencing among preservice teachers. The study combines asynchronous conferencing with peer and mentor collaboration to electronically apprentice student learning. Results point out different levels of Web-based discussion: higher-level, progressive, and lower-level discussion. A…

On the utility of threads for data parallel programming

NASA Technical Reports Server (NTRS)

Fahringer, Thomas; Haines, Matthew; Mehrotra, Piyush

1995-01-01

Threads provide a useful programming model for asynchronous behavior because of their ability to encapsulate units of work that can then be scheduled for execution at runtime, based on the dynamic state of a system. Recently, the threaded model has been applied to the domain of data parallel scientific codes, and initial reports indicate that the threaded model can produce performance gains over non-threaded approaches, primarily through the use of overlapping useful computation with communication latency. However, overlapping computation with communication is possible without the benefit of threads if the communication system supports asynchronous primitives, and this comparison has not been made in previous papers. This paper provides a critical look at the utility of lightweight threads as applied to data parallel scientific programming.

Three-dimensional particle tracking velocimetry using dynamic vision sensors

NASA Astrophysics Data System (ADS)

Borer, D.; Delbruck, T.; Rösgen, T.

2017-12-01

A fast-flow visualization method is presented based on tracking neutrally buoyant soap bubbles with a set of neuromorphic cameras. The "dynamic vision sensors" register only the changes in brightness with very low latency, capturing fast processes at a low data rate. The data consist of a stream of asynchronous events, each encoding the corresponding pixel position, the time instant of the event and the sign of the change in logarithmic intensity. The work uses three such synchronized cameras to perform 3D particle tracking in a medium sized wind tunnel. The data analysis relies on Kalman filters to associate the asynchronous events with individual tracers and to reconstruct the three-dimensional path and velocity based on calibrated sensor information.

Decentralized automatic generation control of interconnected power systems incorporating asynchronous tie-lines.

PubMed

Ibraheem; Hasan, Naimul; Hussein, Arkan Ahmed

2014-01-01

This Paper presents the design of decentralized automatic generation controller for an interconnected power system using PID, Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The designed controllers are tested on identical two-area interconnected power systems consisting of thermal power plants. The area interconnections between two areas are considered as (i) AC tie-line only (ii) Asynchronous tie-line. The dynamic response analysis is carried out for 1% load perturbation. The performance of the intelligent controllers based on GA and PSO has been compared with the conventional PID controller. The investigations of the system dynamic responses reveal that PSO has the better dynamic response result as compared with PID and GA controller for both type of area interconnection.

Asynchronous vs didactic education: it’s too early to throw in the towel on tradition

PubMed Central

2013-01-01

Background Asynchronous, computer based instruction is cost effective, allows self-directed pacing and review, and addresses preferences of millennial learners. Current research suggests there is no significant difference in learning compared to traditional classroom instruction. Data are limited for novice learners in emergency medicine. The objective of this study was to compare asynchronous, computer-based instruction with traditional didactics for senior medical students during a week-long intensive course in acute care. We hypothesized both modalities would be equivalent. Methods This was a prospective observational quasi-experimental study of 4th year medical students who were novice learners with minimal prior exposure to curricular elements. We assessed baseline knowledge with an objective pre-test. The curriculum was delivered in either traditional lecture format (shock, acute abdomen, dyspnea, field trauma) or via asynchronous, computer-based modules (chest pain, EKG interpretation, pain management, trauma). An interactive review covering all topics was followed by a post-test. Knowledge retention was measured after 10 weeks. Pre and post-test items were written by a panel of medical educators and validated with a reference group of learners. Mean scores were analyzed using dependent t-test and attitudes were assessed by a 5-point Likert scale. Results 44 of 48 students completed the protocol. Students initially acquired more knowledge from didactic education as demonstrated by mean gain scores (didactic: 28.39% ± 18.06; asynchronous 9.93% ± 23.22). Mean difference between didactic and asynchronous = 18.45% with 95% CI [10.40 to 26.50]; p = 0.0001. Retention testing demonstrated similar knowledge attrition: mean gain scores −14.94% (didactic); -17.61% (asynchronous), which was not significantly different: 2.68% ± 20.85, 95% CI [−3.66 to 9.02], p = 0.399. The attitudinal survey revealed that 60.4% of students believed the asynchronous modules were educational and 95.8% enjoyed the flexibility of the method. 39.6% of students preferred asynchronous education for required didactics; 37.5% were neutral; 23% preferred traditional lectures. Conclusions Asynchronous, computer-based instruction was not equivalent to traditional didactics for novice learners of acute care topics. Interactive, standard didactic education was valuable. Retention rates were similar between instructional methods. Students had mixed attitudes toward asynchronous learning but enjoyed the flexibility. We urge caution in trading in traditional didactic lectures in favor of asynchronous education for novice learners in acute care. PMID:23927420

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

PubMed

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

2016-08-01

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

Calibration of asynchronous smart phone cameras from moving objects

NASA Astrophysics Data System (ADS)

Hagen, Oksana; Istenič, Klemen; Bharti, Vibhav; Dhali, Maruf Ahmed; Barmaimon, Daniel; Houssineau, Jérémie; Clark, Daniel

2015-04-01

Calibrating multiple cameras is a fundamental prerequisite for many Computer Vision applications. Typically this involves using a pair of identical synchronized industrial or high-end consumer cameras. This paper considers an application on a pair of low-cost portable cameras with different parameters that are found in smart phones. This paper addresses the issues of acquisition, detection of moving objects, dynamic camera registration and tracking of arbitrary number of targets. The acquisition of data is performed using two standard smart phone cameras and later processed using detections of moving objects in the scene. The registration of cameras onto the same world reference frame is performed using a recently developed method for camera calibration using a disparity space parameterisation and the single-cluster PHD filter.

Astronaut Office Scheduling System Software

NASA Technical Reports Server (NTRS)

Brown, Estevancio

2010-01-01

AOSS is a highly efficient scheduling application that uses various tools to schedule astronauts weekly appointment information. This program represents an integration of many technologies into a single application to facilitate schedule sharing and management. It is a Windows-based application developed in Visual Basic. Because the NASA standard office automation load environment is Microsoft-based, Visual Basic provides AO SS developers with the ability to interact with Windows collaboration components by accessing objects models from applications like Outlook and Excel. This also gives developers the ability to create newly customizable components that perform specialized tasks pertaining to scheduling reporting inside the application. With this capability, AOSS can perform various asynchronous tasks, such as gathering/ sending/ managing astronauts schedule information directly to their Outlook calendars at any time.

Moderating influence of dominant attentional style and exercise intensity on responses to asynchronous music.

PubMed

Hutchinson, Jasmin C; Karageorghis, Costas I

2013-12-01

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

Homoclinic behaviors and chaotic motions of double layered viscoelastic nanoplates based on nonlocal theory and extended Melnikov method.

PubMed

Wang, Yu; Li, Feng-Ming; Wang, Yi-Ze

2015-06-01

The nonlinear dynamical equations are established for the double layered viscoelastic nanoplates (DLNP) subjected to in-plane excitation based on the nonlocal theory and von Kármán large deformation theory. The extended high dimensional homoclinic Melnikov method is employed to study the homoclinic phenomena and chaotic motions for the parametrically excited DLNP system. The criteria for the homoclinic transverse intersection for both the asynchronous and synchronous buckling cases are proposed. Lyapunov exponents and phase portraits are obtained to verify the Melnikov-type analysis. The influences of structural parameters on the transverse homoclinic orbits and homoclinic bifurcation sets are discussed for the two buckling cases. Some novel phenomena are observed in the investigation. It should be noticed that the nonlocal effect on the homoclinic behaviors and chaotic motions is quite remarkable. Hence, the small scale effect should be taken into account for homoclinic and chaotic analysis for nanostructures. It is significant that the nonlocal effect on the homoclinic phenomena for the asynchronous buckling case is quite different from that for the synchronous buckling case. Moreover, due to the van der Walls interaction between the layers, the nonlocal effect on the homoclinic behaviors and chaotic motions for high order mode is rather tiny under the asynchronous buckling condition.

Homoclinic behaviors and chaotic motions of double layered viscoelastic nanoplates based on nonlocal theory and extended Melnikov method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yu; Wang, Yi-Ze; Li, Feng-Ming, E-mail: fmli@bjut.edu.cn

2015-06-15

The nonlinear dynamical equations are established for the double layered viscoelastic nanoplates (DLNP) subjected to in-plane excitation based on the nonlocal theory and von Kármán large deformation theory. The extended high dimensional homoclinic Melnikov method is employed to study the homoclinic phenomena and chaotic motions for the parametrically excited DLNP system. The criteria for the homoclinic transverse intersection for both the asynchronous and synchronous buckling cases are proposed. Lyapunov exponents and phase portraits are obtained to verify the Melnikov-type analysis. The influences of structural parameters on the transverse homoclinic orbits and homoclinic bifurcation sets are discussed for the two bucklingmore » cases. Some novel phenomena are observed in the investigation. It should be noticed that the nonlocal effect on the homoclinic behaviors and chaotic motions is quite remarkable. Hence, the small scale effect should be taken into account for homoclinic and chaotic analysis for nanostructures. It is significant that the nonlocal effect on the homoclinic phenomena for the asynchronous buckling case is quite different from that for the synchronous buckling case. Moreover, due to the van der Walls interaction between the layers, the nonlocal effect on the homoclinic behaviors and chaotic motions for high order mode is rather tiny under the asynchronous buckling condition.« less

A wavelet approach to binary blackholes with asynchronous multitasking

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Improvements of the ALICE HLT data transport framework for LHC Run 2

NASA Astrophysics Data System (ADS)

Rohr, David; Krzwicki, Mikolaj; Engel, Heiko; Lehrbach, Johannes; Lindenstruth, Volker; ALICE Collaboration

2017-10-01

The ALICE HLT uses a data transport framework based on the publisher- subscriber message principle, which transparently handles the communication between processing components over the network and between processing components on the same node via shared memory with a zero copy approach. We present an analysis of the performance in terms of maximum achievable data rates and event rates as well as processing capabilities during Run 1 and Run 2. Based on this analysis, we present new optimizations we have developed for ALICE in Run 2. These include support for asynchronous transport via Zero-MQ which enables loops in the reconstruction chain graph and which is used to ship QA histograms to DQM. We have added asynchronous processing capabilities in order to support long-running tasks besides the event-synchronous reconstruction tasks in normal HLT operation. These asynchronous components run in an isolated process such that the HLT as a whole is resilient even to fatal errors in these asynchronous components. In this way, we can ensure that new developments cannot break data taking. On top of that, we have tuned the processing chain to cope with the higher event and data rates expected from the new TPC readout electronics (RCU2) and we have improved the configuration procedure and the startup time in order to increase the time where ALICE can take physics data. We analyze the maximum achievable data processing rates taking into account processing capabilities of CPUs and GPUs, buffer sizes, network bandwidth, the incoming links from the detectors, and the outgoing links to data acquisition.

Merging the Forces of Asynchronous Tutoring and Synchronous Conferencing: A Qualitative Study of Arab ESL Academic Writers Using E-Tutoring

ERIC Educational Resources Information Center

Alqadoumi, Omar Mohamed

2012-01-01

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

Differences in Electronic Exchanges in Synchronous and Asynchronous Computer-Mediated Communication: The Effect of Culture as a Mediating Variable

ERIC Educational Resources Information Center

Angeli, Charoula; Schwartz, Neil H.

2016-01-01

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

Localized radio frequency communication using asynchronous transfer mode protocol

DOEpatents

Witzke, Edward L [Edgewood, NM; Robertson, Perry J [Albuquerque, NM; Pierson, Lyndon G [Albuquerque, NM

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.

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

PubMed

Huang, Yuecheng; Cheng, Wuyi; Luo, Sida; Luo, Yun; Ma, Chengchen; He, Tailin

2016-01-01

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

Policing the Information Highway.

ERIC Educational Resources Information Center

McClure, Ben

1996-01-01

Although broadband Asynchronous Transfer Mode (ATM) can deliver much greater amounts of information than narrow-band Integrated Services Digital Networks (ISDN), in reality bottlenecks place severe constraints on its performance. This article discusses shortfalls in Internet services, technology and user behavior, and describes efforts in the…

Performance of asynchronous transfer mode (ATM) local area and wide area networks for medical imaging transmission in clinical environment.

PubMed

Huang, H K; Wong, A W; Zhu, X

1997-01-01

Asynchronous transfer mode (ATM) technology emerges as a leading candidate for medical image transmission in both local area network (LAN) and wide area network (WAN) applications. This paper describes the performance of an ATM LAN and WAN network at the University of California, San Francisco. The measurements were obtained using an intensive care unit (ICU) server connecting to four image workstations (WS) at four different locations of a hospital-integrated picture archiving and communication system (HI-PACS) in a daily regular clinical environment. Four types of performance were evaluated: magnetic disk-to-disk, disk-to-redundant array of inexpensive disks (RAID), RAID-to-memory, and memory-to-memory. Results demonstrate that the transmission rate between two workstations can reach 5-6 Mbytes/s from RAID-to-memory, and 8-10 Mbytes/s from memory-to-memory. When the server has to send images to all four workstations simultaneously, the transmission rate to each WS is about 4 Mbytes/s. Both situations are adequate for radiologic image communications for picture archiving and communication systems (PACS) and teleradiology applications.

Compression of digital images over local area networks. Appendix 1: Item 3. M.S. Thesis

NASA Technical Reports Server (NTRS)

Gorjala, Bhargavi

1991-01-01

Differential Pulse Code Modulation (DPCM) has been used with speech for many years. It has not been as successful for images because of poor edge performance. The only corruption in DPC is quantizer error but this corruption becomes quite large in the region of an edge because of the abrupt changes in the statistics of the signal. We introduce two improved DPCM schemes; Edge correcting DPCM and Edge Preservation Differential Coding. These two coding schemes will detect the edges and take action to correct them. In an Edge Correcting scheme, the quantizer error for an edge is encoded using a recursive quantizer with entropy coding and sent to the receiver as side information. In an Edge Preserving scheme, when the quantizer input falls in the overload region, the quantizer error is encoded and sent to the receiver repeatedly until the quantizer input falls in the inner levels. Therefore these coding schemes increase the bit rate in the region of an edge and require variable rate channels. We implement these two variable rate coding schemes on a token wing network. Timed token protocol supports two classes of messages; asynchronous and synchronous. The synchronous class provides a pre-allocated bandwidth and guaranteed response time. The remaining bandwidth is dynamically allocated to the asynchronous class. The Edge Correcting DPCM is simulated by considering the edge information under the asynchronous class. For the simulation of the Edge Preserving scheme, the amount of information sent each time is fixed, but the length of the packet or the bit rate for that packet is chosen depending on the availability capacity. The performance of the network, and the performance of the image coding algorithms, is studied.

RootJS: Node.js Bindings for ROOT 6

NASA Astrophysics Data System (ADS)

Beffart, Theo; Früh, Maximilian; Haas, Christoph; Rajgopal, Sachin; Schwabe, Jonas; Wolff, Christoph; Szuba, Marek

2017-10-01

We present rootJS, an interface making it possible to seamlessly integrate ROOT 6 into applications written for Node.js, the JavaScript runtime platform increasingly commonly used to create high-performance Web applications. ROOT features can be called both directly from Node.js code and by JIT-compiling C++ macros. All rootJS methods are invoked asynchronously and support callback functions, allowing non-blocking operation of Node.js applications using them. Last but not least, our bindings have been designed to platform-independent and should therefore work on all systems supporting both ROOT 6 and Node.js. Thanks to rootJS it is now possible to create ROOT-aware Web applications taking full advantage of the high performance and extensive capabilities of Node.js. Examples include platforms for the quality assurance of acquired, reconstructed or simulated data, book-keeping and e-log systems, and even Web browser-based data visualisation and analysis.

Left bundle branch block, an old-new entity.

PubMed

Breithardt, Günter; Breithardt, Ole-Alexander

2012-04-01

Left bundle branch block (LBBB) is generally associated with a poorer prognosis in comparison to normal intraventricular conduction, but also in comparison to right bundle branch block which is generally considered to be benign in the absence of an underlying cardiac disorder like congenital heart disease. LBBB may be the first manifestation of a more diffuse myocardial disease. The typical surface ECG feature of LBBB is a prolongation of QRS above 0.11 s in combination with a delay of the intrinsic deflection in leads V5 and V6 of more than 60 ms and no septal q waves in leads I, V5, and V6 due to the abnormal septal activation from right to left. LBBB may induce abnormalities in left ventricular performance due to abnormal asynchronous contraction patterns which can be compensated by biventricular pacing (resynchronization therapy). Asynchronous electrical activation of the ventricles causes regional differences in workload which may lead to asymmetric hypertrophy and left ventricular dilatation, especially due to increased wall mass in late-activated regions, which may aggravate preexisting left ventricular pumping performance or even induce it. Of special interest are patients with LBBB and normal left ventricular dimensions and normal ejection fraction at rest but who may present with an abnormal increase in pulmonary artery pressure during exercise, production of lactate during high-rate pacing, signs of ischemia on myocardial scintigrams (but no coronary artery narrowing), and abnormal ultrastructural findings on myocardial biopsy. For this entity, the term latent cardiomyopathy had been suggested previously.

Performance Enhancement Strategies for Multi-Block Overset Grid CFD Applications

NASA Technical Reports Server (NTRS)

Djomehri, M. Jahed; Biswas, Rupak

2003-01-01

The overset grid methodology has significantly reduced time-to-solution of highfidelity computational fluid dynamics (CFD) simulations about complex aerospace configurations. The solution process resolves the geometrical complexity of the problem domain by using separately generated but overlapping structured discretization grids that periodically exchange information through interpolation. However, high performance computations of such large-scale realistic applications must be handled efficiently on state-of-the-art parallel supercomputers. This paper analyzes the effects of various performance enhancement strategies on the parallel efficiency of an overset grid Navier-Stokes CFD application running on an SGI Origin2000 machinc. Specifically, the role of asynchronous communication, grid splitting, and grid grouping strategies are presented and discussed. Details of a sophisticated graph partitioning technique for grid grouping are also provided. Results indicate that performance depends critically on the level of latency hiding and the quality of load balancing across the processors.

Barrier-breaking performance for industrial problems on the CRAY C916

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graffunder, S.K.

1993-12-31

Nine applications, including third-party codes, were submitted to the Gordon Bell Prize committee showing the CRAY C916 supercomputer providing record-breaking time to solution for industrial problems in several disciplines. Performance was obtained by balancing raw hardware speed; effective use of large, real, shared memory; compiler vectorization and autotasking; hand optimization; asynchronous I/O techniques; and new algorithms. The highest GFLOPS performance for the submissions was 11.1 GFLOPS out of a peak advertised performance of 16 GFLOPS for the CRAY C916 system. One program achieved a 15.45 speedup from the compiler with just two hand-inserted directives to scope variables properly for themore » mathematical library. New I/O techniques hide tens of gigabytes of I/O behind parallel computations. Finally, new iterative solver algorithms have demonstrated times to solution on 1 CPU as high as 70 times faster than the best direct solvers.« less

A Parallel Particle Swarm Optimization Algorithm Accelerated by Asynchronous Evaluations

NASA Technical Reports Server (NTRS)

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.

Illinois High School Principals' Perceptions of Alternative Learning Environments

ERIC Educational Resources Information Center

Carlton, Lawrence W.

2009-01-01

This study examined Illinois high school principals' perceptions of the growth, quality, advantages and disadvantages of alternative learning environments. In this study, alternative learning environments involved the use of both synchronous and asynchronous modes of communication for course delivery. Synchronous modes of instructional delivery…

Issues in ATM Support of High-Performance, Geographically Distributed Computing

NASA Technical Reports Server (NTRS)

Claus, Russell W.; Dowd, Patrick W.; Srinidhi, Saragur M.; Blade, Eric D.G

1995-01-01

This report experimentally assesses the effect of the underlying network in a cluster-based computing environment. The assessment is quantified by application-level benchmarking, process-level communication, and network file input/output. Two testbeds were considered, one small cluster of Sun workstations and another large cluster composed of 32 high-end IBM RS/6000 platforms. The clusters had Ethernet, fiber distributed data interface (FDDI), Fibre Channel, and asynchronous transfer mode (ATM) network interface cards installed, providing the same processors and operating system for the entire suite of experiments. The primary goal of this report is to assess the suitability of an ATM-based, local-area network to support interprocess communication and remote file input/output systems for distributed computing.

The analysis of the quality of the frequency control of induction motor carried out on the basis of the processes in the rotor circuit

NASA Astrophysics Data System (ADS)

Kodkin, V. L.; Anikin, A. S.; Baldenkov, A. A.

2018-01-01

The results of researches of asynchronous electric drives with the frequency control which are carried out for the purpose of establishment of causes and effect relationships between a control method, the implementable standard frequency converter of the Schneider Electric company (ATV-71, ATV-32) and its efficiency are given in article. Tests with asynchronous motors with wound rotor were for the first time carried out. It allowed registering during the experiments the instantaneous values not only the stator currents, but also rotor currents. Authors for the first time applied spectrum analysis of stator and rotor currents, it showed that «sensorless vector» control leads to origin of high-frequency harmonicas with the considerable amplitude and, as a result of they are non-sinusoidal of the created torque and inefficiency of the electric drive. The accelerations that are carried out during the researches to 94, 157 and 251 Rad/s confirmed this feature of vector control that appears incapable to linearize the asynchronous electric drive as it was supposed authors of a method. These results do not contradict theoretical provisions if not to neglect assumptions which usually become in case of an output of the equations of vector control. Unfortunately, the modern researchers do not subject these assumptions to doubts. Continued studies make it possible to create an effective frequency management of asynchronous electric drives required for current technology.

Optimization of parameters of special asynchronous electric drives

NASA Astrophysics Data System (ADS)

Karandey, V. Yu; Popov, B. K.; Popova, O. B.; Afanasyev, V. L.

2018-03-01

The article considers the solution of the problem of parameters optimization of special asynchronous electric drives. The solution of the problem will allow one to project and create special asynchronous electric drives for various industries. The created types of electric drives will have optimum mass-dimensional and power parameters. It will allow one to realize and fulfill the set characteristics of management of technological processes with optimum level of expenses of electric energy, time of completing the process or other set parameters. The received decision allows one not only to solve a certain optimizing problem, but also to construct dependences between the optimized parameters of special asynchronous electric drives, for example, with the change of power, current in a winding of the stator or rotor, induction in a gap or steel of magnetic conductors and other parameters. On the constructed dependences, it is possible to choose necessary optimum values of parameters of special asynchronous electric drives and their components without carrying out repeated calculations.

Tensor Algebra Library for NVidia Graphics Processing Units

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liakh, Dmitry

This is a general purpose math library implementing basic tensor algebra operations on NVidia GPU accelerators. This software is a tensor algebra library that can perform basic tensor algebra operations, including tensor contractions, tensor products, tensor additions, etc., on NVidia GPU accelerators, asynchronously with respect to the CPU host. It supports a simultaneous use of multiple NVidia GPUs. Each asynchronous API function returns a handle which can later be used for querying the completion of the corresponding tensor algebra operation on a specific GPU. The tensors participating in a particular tensor operation are assumed to be stored in local RAMmore » of a node or GPU RAM. The main research area where this library can be utilized is the quantum many-body theory (e.g., in electronic structure theory).« less

Frog: Asynchronous Graph Processing on GPU with Hybrid Coloring Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Xuanhua; Luo, Xuan; Liang, Junling

GPUs have been increasingly used to accelerate graph processing for complicated computational problems regarding graph theory. Many parallel graph algorithms adopt the asynchronous computing model to accelerate the iterative convergence. Unfortunately, the consistent asynchronous computing requires locking or atomic operations, leading to significant penalties/overheads when implemented on GPUs. As such, coloring algorithm is adopted to separate the vertices with potential updating conflicts, guaranteeing the consistency/correctness of the parallel processing. Common coloring algorithms, however, may suffer from low parallelism because of a large number of colors generally required for processing a large-scale graph with billions of vertices. We propose a light-weightmore » asynchronous processing framework called Frog with a preprocessing/hybrid coloring model. The fundamental idea is based on Pareto principle (or 80-20 rule) about coloring algorithms as we observed through masses of realworld graph coloring cases. We find that a majority of vertices (about 80%) are colored with only a few colors, such that they can be read and updated in a very high degree of parallelism without violating the sequential consistency. Accordingly, our solution separates the processing of the vertices based on the distribution of colors. In this work, we mainly answer three questions: (1) how to partition the vertices in a sparse graph with maximized parallelism, (2) how to process large-scale graphs that cannot fit into GPU memory, and (3) how to reduce the overhead of data transfers on PCIe while processing each partition. We conduct experiments on real-world data (Amazon, DBLP, YouTube, RoadNet-CA, WikiTalk and Twitter) to evaluate our approach and make comparisons with well-known non-preprocessed (such as Totem, Medusa, MapGraph and Gunrock) and preprocessed (Cusha) approaches, by testing four classical algorithms (BFS, PageRank, SSSP and CC). On all the tested applications and datasets, Frog is able to significantly outperform existing GPU-based graph processing systems except Gunrock and MapGraph. MapGraph gets better performance than Frog when running BFS on RoadNet-CA. The comparison between Gunrock and Frog is inconclusive. Frog can outperform Gunrock more than 1.04X when running PageRank and SSSP, while the advantage of Frog is not obvious when running BFS and CC on some datasets especially for RoadNet-CA.« less

Asynchronous Communication of TLNS3DMB Boundary Exchange

NASA Technical Reports Server (NTRS)

Hammond, Dana P.

1997-01-01

This paper describes the recognition of implicit serialization due to coarse-grain, synchronous communication and demonstrates the conversion to asynchronous communication for the exchange of boundary condition information in the Thin-Layer Navier Stokes 3-Dimensional Multi Block (TLNS3DMB) code. The implementation details of using asynchronous communication is provided including buffer allocation, message identification, and barrier control. The IBM SP2 was used for the tests presented.

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

PubMed Central

Huang, Yuecheng; Cheng, Wuyi; Luo, Sida; Luo, Yun; Ma, Chengchen; He, Tailin

2016-01-01

The features of the asynchronous correlation between accident indices and the factors that influence accidents can provide an effective reference for warnings of coal mining accidents. However, what are the features of this correlation? To answer this question, data from the China coal price index and the number of deaths from coal mining accidents were selected as the sample data. The fluctuation modes of the asynchronous correlation between the two data sets were defined according to the asynchronous correlation coefficients, symbolization, and sliding windows. We then built several directed and weighted network models, within which the fluctuation modes and the transformations between modes were represented by nodes and edges. Then, the features of the asynchronous correlation between these two variables could be studied from a perspective of network topology. We found that the correlation between the price index and the accidental deaths was asynchronous and fluctuating. Certain aspects, such as the key fluctuation modes, the subgroups characteristics, the transmission medium, the periodicity and transmission path length in the network, were analyzed by using complex network theory, analytical methods and spectral analysis method. These results provide a scientific reference for generating warnings for coal mining accidents based on economic indices. PMID:27902748

Quinoa - Adaptive Computational Fluid Dynamics, 0.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakosi, Jozsef; Gonzalez, Francisco; Rogers, Brandon

Quinoa is a set of computational tools that enables research and numerical analysis in fluid dynamics. At this time it remains a test-bed to experiment with various algorithms using fully asynchronous runtime systems. Currently, Quinoa consists of the following tools: (1) Walker, a numerical integrator for systems of stochastic differential equations in time. It is a mathematical tool to analyze and design the behavior of stochastic differential equations. It allows the estimation of arbitrary coupled statistics and probability density functions and is currently used for the design of statistical moment approximations for multiple mixing materials in variable-density turbulence. (2) Inciter,more » an overdecomposition-aware finite element field solver for partial differential equations using 3D unstructured grids. Inciter is used to research asynchronous mesh-based algorithms and to experiment with coupling asynchronous to bulk-synchronous parallel code. Two planned new features of Inciter, compared to the previous release (LA-CC-16-015), to be implemented in 2017, are (a) a simple Navier-Stokes solver for ideal single-material compressible gases, and (b) solution-adaptive mesh refinement (AMR), which enables dynamically concentrating compute resources to regions with interesting physics. Using the NS-AMR problem we plan to explore how to scale such high-load-imbalance simulations, representative of large production multiphysics codes, to very large problems on very large computers using an asynchronous runtime system. (3) RNGTest, a test harness to subject random number generators to stringent statistical tests enabling quantitative ranking with respect to their quality and computational cost. (4) UnitTest, a unit test harness, running hundreds of tests per second, capable of testing serial, synchronous, and asynchronous functions. (5) MeshConv, a mesh file converter that can be used to convert 3D tetrahedron meshes from and to either of the following formats: Gmsh, (http://www.geuz.org/gmsh), Netgen, (http://sourceforge.net/apps/mediawiki/netgen-mesher), ExodusII, (http://sourceforge.net/projects/exodusii), HyperMesh, (http://www.altairhyperworks.com/product/HyperMesh).« less

Distributed Large Data-Object Environments: End-to-End Performance Analysis of High Speed Distributed Storage Systems in Wide Area ATM Networks

NASA Technical Reports Server (NTRS)

Johnston, William; Tierney, Brian; Lee, Jason; Hoo, Gary; Thompson, Mary

1996-01-01

We have developed and deployed a distributed-parallel storage system (DPSS) in several high speed asynchronous transfer mode (ATM) wide area networks (WAN) testbeds to support several different types of data-intensive applications. Architecturally, the DPSS is a network striped disk array, but is fairly unique in that its implementation allows applications complete freedom to determine optimal data layout, replication and/or coding redundancy strategy, security policy, and dynamic reconfiguration. In conjunction with the DPSS, we have developed a 'top-to-bottom, end-to-end' performance monitoring and analysis methodology that has allowed us to characterize all aspects of the DPSS operating in high speed ATM networks. In particular, we have run a variety of performance monitoring experiments involving the DPSS in the MAGIC testbed, which is a large scale, high speed, ATM network and we describe our experience using the monitoring methodology to identify and correct problems that limit the performance of high speed distributed applications. Finally, the DPSS is part of an overall architecture for using high speed, WAN's for enabling the routine, location independent use of large data-objects. Since this is part of the motivation for a distributed storage system, we describe this architecture.

ATM: Restructing Learning for Deaf Students.

ERIC Educational Resources Information Center

Keefe, Barbara; Stockford, David

Governor Baxter School for the Deaf is one of six Maine pilot sites chosen by NYNEX to showcase asynchronous transfer mode (ATM) technology. ATM is a network connection that allows high bandwidth transmission of data, voice, and video. Its high speed capability allows for high quality two-way full-motion video, which is especially beneficial to a…

Asynchronous networks: modularization of dynamics theorem

NASA Astrophysics Data System (ADS)

Bick, Christian; Field, Michael

2017-02-01

Building on the first part of this paper, we develop the theory of functional asynchronous networks. We show that a large class of functional asynchronous networks can be (uniquely) represented as feedforward networks connecting events or dynamical modules. For these networks we can give a complete description of the network function in terms of the function of the events comprising the network: the modularization of dynamics theorem. We give examples to illustrate the main results.

Simulating fail-stop in asynchronous distributed systems

NASA Technical Reports Server (NTRS)

Sabel, Laura; Marzullo, Keith

1994-01-01

The fail-stop failure model appears frequently in the distributed systems literature. However, in an asynchronous distributed system, the fail-stop model cannot be implemented. In particular, it is impossible to reliably detect crash failures in an asynchronous system. In this paper, we show that it is possible to specify and implement a failure model that is indistinguishable from the fail-stop model from the point of view of any process within an asynchronous system. We give necessary conditions for a failure model to be indistinguishable from the fail-stop model, and derive lower bounds on the amount of process replication needed to implement such a failure model. We present a simple one-round protocol for implementing one such failure model, which we call simulated fail-stop.

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

PubMed Central

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

High-speed network for delivery of education-on-demand

NASA Astrophysics Data System (ADS)

Cordero, Carlos; Harris, Dale; Hsieh, Jeff

1996-03-01

A project to investigate the feasibility of delivering on-demand distance education to the desktop, known as the Asynchronous Distance Education ProjecT (ADEPT), is presently being carried out. A set of Stanford engineering classes is digitized on PC, Macintosh, and UNIX platforms, and is made available on servers. Students on campus and in industry may then access class material on these servers via local and metropolitan area networks. Students can download class video and audio, encoded in QuickTimeTM and Show-Me TVTM formats, via file-transfer protocol or the World Wide Web. Alternatively, they may stream a vector-quantized version of the class directly from a server for real-time playback. Students may also download PostscriptTM and Adobe AcrobatTM versions of class notes. Off-campus students may connect to ADEPT servers via the internet, the Silicon Valley Test Track (SVTT), or the Bay-Area Gigabit Network (BAGNet). The SVTT and BAGNet are high-speed metropolitan-area networks, spanning the Bay Area, which provide IP access over asynchronous transfer mode (ATM). Student interaction is encouraged through news groups, electronic mailing lists, and an ADEPT home page. Issues related to having multiple platforms and interoperability are examined in this paper. The ramifications of providing a reliable service are discussed. System performance and the parameters that affect it are then described. Finally, future work on expanding ATM access, real-time delivery of classes, and enhanced student interaction is described.

Dual-balanced detection scheme with optical hard-limiters in an optical code division multiple access system

NASA Astrophysics Data System (ADS)

Liu, Maw-Yang; Hsu, Yi-Kai

2017-03-01

Three-arm dual-balanced detection scheme is studied in an optical code division multiple access system. As the MAI and beat noise are the main deleterious source of system performance, we utilize optical hard-limiters to alleviate such channel impairment. In addition, once the channel condition is improved effectively, the proposed two-dimensional error correction code can remarkably enhance the system performance. In our proposed scheme, the optimal thresholds of optical hard-limiters and decision circuitry are fixed, and they will not change with other system parameters. Our proposed scheme can accommodate a large number of users simultaneously and is suitable for burst traffic with asynchronous transmission. Therefore, it is highly recommended as the platform for broadband optical access network.

An efficient micro control unit with a reconfigurable filter design for wireless body sensor networks (WBSNs).

PubMed

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

2012-11-22

In this paper, a low-cost, low-power and high performance micro control unit (MCU) core is proposed for wireless body sensor networks (WBSNs). It consists of an asynchronous interface, a register bank, a reconfigurable filter, a slop-feature forecast, a lossless data encoder, an error correct coding (ECC) encoder, a UART interface, a power management (PWM), and a multi-sensor controller. To improve the system performance and expansion abilities, the asynchronous interface is added for handling signal exchanges between different clock domains. To eliminate the noise of various bio-signals, the reconfigurable filter is created to provide the functions of average, binomial and sharpen filters. The slop-feature forecast and the lossless data encoder is proposed to reduce the data of various biomedical signals for transmission. Furthermore, the ECC encoder is added to improve the reliability for the wireless transmission and the UART interface is employed the proposed design to be compatible with wireless devices. For long-term healthcare monitoring application, a power management technique is developed for reducing the power consumption of the WBSN system. In addition, the proposed design can be operated with four different bio-sensors simultaneously. The proposed design was successfully tested with a FPGA verification board. The VLSI architecture of this work contains 7.67-K gate counts and consumes the power of 5.8 mW or 1.9 mW at 100 MHz or 133 MHz processing rate using a TSMC 0.18 μm or 0.13 μm CMOS process. Compared with previous techniques, this design achieves higher performance, more functions, more flexibility and higher compatibility than other micro controller designs.

Distance Synchronous Information Systems Course Delivery

ERIC Educational Resources Information Center

Peslak, Alan R.; Lewis, Griffith R.; Aebli, Fred

2014-01-01

Teaching computer information systems via distance education is a challenge for both student and faculty. Much research work has been performed on methods of teaching via distance education. Today we are faced with a variety of options for course delivery. Asynchronous delivery via online or lesson instruction still remains most common. But…

Case Study: eCoaching in a Corporate Environment

ERIC Educational Resources Information Center

Warner, Teri L. C.

2012-01-01

This qualitative particularistic case study was an exploration and evaluation of an online, asynchronous, non-human coaching system called an "eCoaching system." Developed by the researcher, the eCoaching system combined performance coaching with the latest technologies in eLearning. The coaching was based on the appreciative inquiry approach, and…

Enhancing the Internet of Things Architecture with Flow Semantics

ERIC Educational Resources Information Center

DeSerranno, Allen Ronald

2017-01-01

Internet of Things ("IoT") systems are complex, asynchronous solutions often comprised of various software and hardware components developed in isolation of each other. These components function with different degrees of reliability and performance over an inherently unreliable network, the Internet. Many IoT systems are developed within…

Creating an Organic Knowledge-Building Environment within an Asynchronous Distributed Learning Context.

ERIC Educational Resources Information Center

Moller, Leslie; Prestera, Gustavo E.; Harvey, Douglas; Downs-Keller, Margaret; McCausland, Jo-Ann

2002-01-01

Discusses organic architecture and suggests that learning environments should be designed and constructed using an organic approach, so that learning is not viewed as a distinct human activity but incorporated into everyday performance. Highlights include an organic knowledge-building model; information objects; scaffolding; discourse action…

Asynchronous automated electronic laboratory result notifications: a systematic review.

PubMed

Slovis, Benjamin H; Nahass, Thomas A; Salmasian, Hojjat; Kuperman, Gilad; Vawdrey, David K

2017-11-01

To systematically review the literature pertaining to asynchronous automated electronic notifications of laboratory results to clinicians. PubMed, Web of Science, and the Cochrane Collaboration were queried for studies pertaining to automated electronic notifications of laboratory results. A title review was performed on the primary results, with a further abstract review and full review to produce the final set of included articles. The full review included 34 articles, representing 19 institutions. Of these, 19 reported implementation and design of systems, 11 reported quasi-experimental studies, 3 reported a randomized controlled trial, and 1 was a meta-analysis. Twenty-seven articles included alerts of critical results, while 5 focused on urgent notifications and 2 on elective notifications. There was considerable variability in clinical setting, system implementation, and results presented. Several asynchronous automated electronic notification systems for laboratory results have been evaluated, most from >10 years ago. Further research on the effect of notifications on clinicians as well as the use of modern electronic health records and new methods of notification is warranted to determine their effects on workflow and clinical outcomes. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Asynchronous timing and Doppler recovery in DSP based DPSK modems for fixed and mobile satellite applications

NASA Astrophysics Data System (ADS)

Koblents, B.; Belanger, M.; Woods, D.; McLane, P. J.

While conventional analog modems employ some kind of clock wave regenerator circuit for synchronous timing recovery, in sampled modem receivers the timing is recovered asynchronously to the incoming data stream, with no adjustment being made to the input sampling rate. All timing corrections are accomplished by digital operations on the sampled data stream, and timing recovery is asynchronous with the uncontrolled, input A/D system. A good timing error measurement algorithm is a zero crossing tracker proposed by Gardner. Digital, speech rate (2400 - 4800 bps) M-PSK modem receivers employing Gardner's zero crossing tracker were implemented and tested and found to achieve BER performance very close to theoretical values on the AWGN channel. Nyguist pulse shaped modem systems with excess bandwidth factors ranging from 100 to 60 percent were considered. We can show that for any symmetric M-PSK signal set Gardner's NDA algorithm is free of pattern jitter for any carrier phase offset for rectangular pulses and for Nyquist pulses having 100 percent excess bandwidth. Also, the Nyquist pulse shaped system is studied on the mobile satellite channel, where Doppler shifts and multipath fading degrade the pi/4-DQPSK signal. Two simple modifications to Gardner's zero crossing tracker enable it to remain useful in the presence of multipath fading.

Asynchronous timing and Doppler recovery in DSP based DPSK modems for fixed and mobile satellite applications

NASA Technical Reports Server (NTRS)

Koblents, B.; Belanger, M.; Woods, D.; Mclane, P. J.

1993-01-01

While conventional analog modems employ some kind of clock wave regenerator circuit for synchronous timing recovery, in sampled modem receivers the timing is recovered asynchronously to the incoming data stream, with no adjustment being made to the input sampling rate. All timing corrections are accomplished by digital operations on the sampled data stream, and timing recovery is asynchronous with the uncontrolled, input A/D system. A good timing error measurement algorithm is a zero crossing tracker proposed by Gardner. Digital, speech rate (2400 - 4800 bps) M-PSK modem receivers employing Gardner's zero crossing tracker were implemented and tested and found to achieve BER performance very close to theoretical values on the AWGN channel. Nyguist pulse shaped modem systems with excess bandwidth factors ranging from 100 to 60 percent were considered. We can show that for any symmetric M-PSK signal set Gardner's NDA algorithm is free of pattern jitter for any carrier phase offset for rectangular pulses and for Nyquist pulses having 100 percent excess bandwidth. Also, the Nyquist pulse shaped system is studied on the mobile satellite channel, where Doppler shifts and multipath fading degrade the pi/4-DQPSK signal. Two simple modifications to Gardner's zero crossing tracker enable it to remain useful in the presence of multipath fading.

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

NASA Astrophysics Data System (ADS)

Yi, Ting-Hua; Li, Hong-Nan; Zhang, Xu-Dong

2012-12-01

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.

Interference tables: a useful model for interference analysis in asynchronous multicarrier transmission

NASA Astrophysics Data System (ADS)

Medjahdi, Yahia; Terré, Michel; Ruyet, Didier Le; Roviras, Daniel

2014-12-01

In this paper, we investigate the impact of timing asynchronism on the performance of multicarrier techniques in a spectrum coexistence context. Two multicarrier schemes are considered: cyclic prefix-based orthogonal frequency division multiplexing (CP-OFDM) with a rectangular pulse shape and filter bank-based multicarrier (FBMC) with physical layer for dynamic spectrum access and cognitive radio (PHYDYAS) and isotropic orthogonal transform algorithm (IOTA) waveforms. First, we present the general concept of the so-called power spectral density (PSD)-based interference tables which are commonly used for multicarrier interference characterization in spectrum sharing context. After highlighting the limits of this approach, we propose a new family of interference tables called `instantaneous interference tables'. The proposed tables give the interference power caused by a given interfering subcarrier on a victim one, not only as a function of the spectral distance separating both subcarriers but also with respect to the timing misalignment between the subcarrier holders. In contrast to the PSD-based interference tables, the accuracy of the proposed tables has been validated through different simulation results. Furthermore, due to the better frequency localization of both PHYDYAS and IOTA waveforms, FBMC technique is demonstrated to be more robust to timing asynchronism compared to OFDM one. Such a result makes FBMC a potential candidate for the physical layer of future cognitive radio systems.

Asynchronous collision integrators: Explicit treatment of unilateral contact with friction and nodal restraints

PubMed Central

Wolff, Sebastian; Bucher, Christian

2013-01-01

This article presents asynchronous collision integrators and a simple asynchronous method treating nodal restraints. Asynchronous discretizations allow individual time step sizes for each spatial region, improving the efficiency of explicit time stepping for finite element meshes with heterogeneous element sizes. The article first introduces asynchronous variational integration being expressed by drift and kick operators. Linear nodal restraint conditions are solved by a simple projection of the forces that is shown to be equivalent to RATTLE. Unilateral contact is solved by an asynchronous variant of decomposition contact response. Therein, velocities are modified avoiding penetrations. Although decomposition contact response is solving a large system of linear equations (being critical for the numerical efficiency of explicit time stepping schemes) and is needing special treatment regarding overconstraint and linear dependency of the contact constraints (for example from double-sided node-to-surface contact or self-contact), the asynchronous strategy handles these situations efficiently and robust. Only a single constraint involving a very small number of degrees of freedom is considered at once leading to a very efficient solution. The treatment of friction is exemplified for the Coulomb model. Special care needs the contact of nodes that are subject to restraints. Together with the aforementioned projection for restraints, a novel efficient solution scheme can be presented. The collision integrator does not influence the critical time step. Hence, the time step can be chosen independently from the underlying time-stepping scheme. The time step may be fixed or time-adaptive. New demands on global collision detection are discussed exemplified by position codes and node-to-segment integration. Numerical examples illustrate convergence and efficiency of the new contact algorithm. Copyright © 2013 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons, Ltd. PMID:23970806

Within-female plasticity in sex allocation is associated with a behavioural polyphenism in house wrens.

PubMed

Bowers, E K; Thompson, C F; Sakaluk, S K

2016-03-01

Sex allocation theory assumes individual plasticity in maternal strategies, but few studies have investigated within-individual changes across environments. In house wrens, differences between nests in the degree of hatching synchrony of eggs represent a behavioural polyphenism in females, and its expression varies with seasonal changes in the environment. Between-nest differences in hatching asynchrony also create different environments for offspring, and sons are more strongly affected than daughters by sibling competition when hatching occurs asynchronously over several days. Here, we examined variation in hatching asynchrony and sex allocation, and its consequences for offspring fitness. The number and condition of fledglings declined seasonally, and the frequency of asynchronous hatching increased. In broods hatched asynchronously, sons, which are over-represented in the earlier-laid eggs, were in better condition than daughters, which are over-represented in the later-laid eggs. Nonetheless, asynchronous broods were more productive later within seasons. The proportion of sons in asynchronous broods increased seasonally, whereas there was a seasonal increase in the production of daughters by mothers hatching their eggs synchronously, which was characterized by within-female changes in offspring sex and not by sex-biased mortality. As adults, sons from asynchronous broods were in better condition and produced more broods of their own than males from synchronous broods, and both males and females from asynchronous broods had higher lifetime reproductive success than those from synchronous broods. In conclusion, hatching patterns are under maternal control, representing distinct strategies for allocating offspring within broods, and are associated with offspring sex ratios and differences in offspring reproductive success. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Distance Learning for Special Populations

ERIC Educational Resources Information Center

Bates, Rodger A.

2012-01-01

Distance education strategies for remotely deployed, highly mobile, or institutionalized populations are reviewed and critiqued. Specifically, asynchronous, offline responses for special military units, Native Americans on remote reservations, prison populations and other geographically, temporally or technologically isolated niche populations are…

Observations and temporal model of a honeybee's hairy tongue in microfluid transport

NASA Astrophysics Data System (ADS)

Zhao, Chenjia; Wu, Jianing; Yan, Shaoze

2015-11-01

Nectarivorous insects are endowed with specific mouthparts, which provide an inspiration for the design of micropumps. We combined the postmortem examination and high-speed imaging to observe the kinematics of the honeybee's tongue. We found an asynchronization between the tongue movement and the glossa hair erection. We propose a physical model to describe the feeding process considering the trade-off between nectar-intake volume and energy consumption. This asynchronization is validated to be effective in maximizing the nectar-intake amount by theoretically figuring out the optimal moment when the glossal hairs began to erect. Our results reveal that the honeybee not only develops a subtle tongue with erectable glossal hairs but also preforms a highly evolved scheduled coordination between tongue movements and hair erection, which could serve as valuable models for developing miniature pumps that are both extendable and have dynamic surfaces.

High-fidelity entanglement swapping and generation of three-qubit GHZ state using asynchronous telecom photon pair sources.

PubMed

Tsujimoto, Yoshiaki; Tanaka, Motoki; Iwasaki, Nobuo; Ikuta, Rikizo; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki

2018-01-23

We experimentally demonstrate a high-fidelity entanglement swapping and a generation of the Greenberger-Horne-Zeilinger (GHZ) state using polarization-entangled photon pairs at telecommunication wavelength produced by spontaneous parametric down conversion with continuous-wave pump light. While spatially separated sources asynchronously emit photon pairs, the time-resolved photon detection guarantees the temporal indistinguishability of photons without active timing synchronizations of pump lasers and/or adjustment of optical paths. In the experiment, photons are sufficiently narrowed by fiber-based Bragg gratings with the central wavelengths of 1541 nm & 1580 nm, and detected by superconducting nanowire single-photon detectors with low timing jitters. The observed fidelities of the final states for entanglement swapping and the generated three-qubit state were 0.84 ± 0.04 and 0.70 ± 0.05, respectively.

Effectiveness of an Asynchronous Online Module on University Students' Understanding of the Bohr Model of the Hydrogen Atom

NASA Astrophysics Data System (ADS)

Farina, William J.; Bodzin, Alec M.

2017-12-01

Web-based learning is a growing field in education, yet empirical research into the design of high quality Web-based university science instruction is scarce. A one-week asynchronous online module on the Bohr Model of the atom was developed and implemented guided by the knowledge integration framework. The unit design aligned with three identified metaprinciples of science learning: making science accessible, making thinking visible, and promoting autonomy. Students in an introductory chemistry course at a large east coast university completed either an online module or traditional classroom instruction. Data from 99 students were analyzed and results showed significant knowledge growth in both online and traditional formats. For the online learning group, findings revealed positive student perceptions of their learning experiences, highly positive feedback for online science learning, and an interest amongst students to learn chemistry within an online environment.

On the asynchronization of hemispheric high-latitude solar activity

NASA Astrophysics Data System (ADS)

Li, K. J.; Gao, P. X.; Zhan, L. S.; Shi, X. J.; Zhu, W. W.

2008-11-01

The monthly mean numbers of polar faculae in the time interval of 1951 August to 1998 December, from observations of the National Astronomical Observatory of Japan are used to investigate the reasons which mathematically result in the asynchronization of high-latitude solar activity between the northern and southern hemispheres. It is found that the monthly mean numbers of polar faculae in the northern hemisphere three months lead those in the southern one, which should mathematically lead to phase asynchrony of the hemispheric polar-facula activity but with a slight effect. The Schwabe period length for the polar-facula activity in one hemisphere obviously differs from that in the other, which should also lead to phase asynchrony of the hemispheric polar-facula activity. It is the low-frequency components of the hemispheric polar-facula activity in period scales around the Schwabe cycle that are responsible for its strong phase synchronization. In the high-frequency components, there is a strong phase mixing, which should also lead to phase asynchrony of the hemispheric polar-facula activity.

A Binary Array Asynchronous Sorting Algorithm with Using Petri Nets

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

Asynchronous machine rotor speed estimation using a tabulated numerical approach

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

High-throughput GPU-based LDPC decoding

NASA Astrophysics Data System (ADS)

Chang, Yang-Lang; Chang, Cheng-Chun; Huang, Min-Yu; Huang, Bormin

2010-08-01

Low-density parity-check (LDPC) code is a linear block code known to approach the Shannon limit via the iterative sum-product algorithm. LDPC codes have been adopted in most current communication systems such as DVB-S2, WiMAX, WI-FI and 10GBASE-T. LDPC for the needs of reliable and flexible communication links for a wide variety of communication standards and configurations have inspired the demand for high-performance and flexibility computing. Accordingly, finding a fast and reconfigurable developing platform for designing the high-throughput LDPC decoder has become important especially for rapidly changing communication standards and configurations. In this paper, a new graphic-processing-unit (GPU) LDPC decoding platform with the asynchronous data transfer is proposed to realize this practical implementation. Experimental results showed that the proposed GPU-based decoder achieved 271x speedup compared to its CPU-based counterpart. It can serve as a high-throughput LDPC decoder.

Asynchronous marine-terrestrial signals of the last deglacial warming in East Asia associated with low- and high-latitude climate changes.

PubMed

Xu, Deke; Lu, Houyuan; Wu, Naiqin; Liu, Zhenxia; Li, Tiegang; Shen, Caiming; Wang, Luo

2013-06-11

A high-resolution multiproxy record, including pollen, foraminifera, and alkenone paleothermometry, obtained from a single core (DG9603) from the Okinawa Trough, East China Sea (ECS), provided unambiguous evidence for asynchronous climate change between the land and ocean over the past 40 ka. On land, the deglacial stage was characterized by rapid warming, as reflected by paleovegetation, and it began ca. 15 kaBP, consistent with the timing of the last deglacial warming in Greenland. However, sea surface temperature estimates from foraminifera and alkenone paleothermometry increased around 20-19 kaBP, as in the Western Pacific Warm Pool (WPWP). Sea surface temperatures in the Okinawa Trough were influenced mainly by heat transport from the tropical western Pacific Ocean by the Kuroshio Current, but the epicontinental vegetation of the ECS was influenced by atmospheric circulation linked to the northern high-latitude climate. Asynchronous terrestrial and marine signals of the last deglacial warming in East Asia were thus clearly related to ocean currents and atmospheric circulation. We argue that (i) early warming seawater of the WPWP, driven by low-latitude insolation and trade winds, moved northward via the Kuroshio Current and triggered marine warming along the ECS around 20-19 kaBP similar to that in the WPWP, and (ii) an almost complete shutdown of the Atlantic Meridional Overturning Circulation ca. 18-15 kaBP was associated with cold Heinrich stadial-1 and delayed terrestrial warming during the last deglacial warming until ca. 15 kaBP at northern high latitudes, and hence in East Asia. Terrestrial deglacial warming therefore lagged behind marine changes by ca. 3-4 ka.

Asynchronous marine-terrestrial signals of the last deglacial warming in East Asia associated with low- and high-latitude climate changes

PubMed Central

Xu, Deke; Lu, Houyuan; Wu, Naiqin; Liu, Zhenxia; Li, Tiegang; Shen, Caiming; Wang, Luo

2013-01-01

A high-resolution multiproxy record, including pollen, foraminifera, and alkenone paleothermometry, obtained from a single core (DG9603) from the Okinawa Trough, East China Sea (ECS), provided unambiguous evidence for asynchronous climate change between the land and ocean over the past 40 ka. On land, the deglacial stage was characterized by rapid warming, as reflected by paleovegetation, and it began ca. 15 kaBP, consistent with the timing of the last deglacial warming in Greenland. However, sea surface temperature estimates from foraminifera and alkenone paleothermometry increased around 20–19 kaBP, as in the Western Pacific Warm Pool (WPWP). Sea surface temperatures in the Okinawa Trough were influenced mainly by heat transport from the tropical western Pacific Ocean by the Kuroshio Current, but the epicontinental vegetation of the ECS was influenced by atmospheric circulation linked to the northern high-latitude climate. Asynchronous terrestrial and marine signals of the last deglacial warming in East Asia were thus clearly related to ocean currents and atmospheric circulation. We argue that (i) early warming seawater of the WPWP, driven by low-latitude insolation and trade winds, moved northward via the Kuroshio Current and triggered marine warming along the ECS around 20–19 kaBP similar to that in the WPWP, and (ii) an almost complete shutdown of the Atlantic Meridional Overturning Circulation ca. 18–15 kaBP was associated with cold Heinrich stadial-1 and delayed terrestrial warming during the last deglacial warming until ca. 15 kaBP at northern high latitudes, and hence in East Asia. Terrestrial deglacial warming therefore lagged behind marine changes by ca. 3–4 ka. PMID:23720306

Multiuser receiver for DS-CDMA signals in multipath channels: an enhanced multisurface method.

PubMed

Mahendra, Chetan; Puthusserypady, Sadasivan

2006-11-01

This paper deals with the problem of multiuser detection in direct-sequence code-division multiple-access (DS-CDMA) systems in multipath environments. The existing multiuser detectors can be divided into two categories: (1) low-complexity poor-performance linear detectors and (2) high-complexity good-performance nonlinear detectors. In particular, in channels where the orthogonality of the code sequences is destroyed by multipath, detectors with linear complexity perform much worse than the nonlinear detectors. In this paper, we propose an enhanced multisurface method (EMSM) for multiuser detection in multipath channels. EMSM is an intermediate piecewise linear detection scheme with a run-time complexity linear in the number of users. Its bit error rate performance is compared with existing linear detectors, a nonlinear radial basis function detector trained by the new support vector learning algorithm, and Verdu's optimal detector. Simulations in multipath channels, for both synchronous and asynchronous cases, indicate that it always outperforms all other linear detectors, performing nearly as well as nonlinear detectors.

Exploring Use of the Coordinate Response Measure in a Multitalker Babble Paradigm

PubMed Central

Kidd, Gary R.; Fogerty, Daniel

2017-01-01

Purpose Three experiments examined the use of competing coordinate response measure (CRM) sentences as a multitalker babble. Method In Experiment I, young adults with normal hearing listened to a CRM target sentence in the presence of 2, 4, or 6 competing CRM sentences with synchronous or asynchronous onsets. In Experiment II, the condition with 6 competing sentences was explored further. Three stimulus conditions (6 talkers saying same sentence, 1 talker producing 6 different sentences, and 6 talkers each saying a different sentence) were evaluated with different methods of presentation. Experiment III examined the performance of older adults with hearing impairment in a subset of conditions from Experiment II. Results In Experiment I, performance declined with increasing numbers of talkers and improved with asynchronous sentence onsets. Experiment II identified conditions under which an increase in the number of talkers led to better performance. In Experiment III, the relative effects of the number of talkers, messages, and onset asynchrony were the same for young and older listeners. Conclusions Multitalker babble composed of CRM sentences has masking properties similar to other types of multitalker babble. However, when the number of different talkers and messages are varied independently, performance is best with more talkers and fewer messages. PMID:28249093

Performance, throughput, and cost of in-home training for the Army Reserve: Using asynchronous computer conferencing as an alternative to resident training

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hahn, H.A.; Ashworth, R.L. Jr.; Phelps, R.H.

1990-01-01

Asynchronous computer conferencing (ACC) was investigated as an alternative to resident training for the Army Reserve Component (RC). Specifically, the goals were to (1) evaluate the performance and throughput of ACC as compared with traditional Resident School instruction and (2) determine the cost-effectiveness of developing and implementing ACC. Fourteen RC students took a module of the Army Engineer Officer Advanced Course (EOAC) via ACC. Course topics included Army doctrine, technical engineering subjects, leadership, and presentation skills. Resident content was adapted for presentation via ACC. The programs of instruction for ACC and the equivalent resident course were identical; only the mediamore » used for presentation were changed. Performance on tests, homework, and practical exercises; self-assessments of learning; throughput; and cost data wee the measures of interest. Comparison data were collected on RC students taking the course in residence. Results indicated that there were no performance differences between the two groups. Students taking the course via ACC perceived greater learning benefit than did students taking the course in residence. Resident throughput was superior to ACC throughput, both in terms of numbers of students completing and time to complete the course. In spite of this fact, however, ACC was more cost-effective than resident training.« less

Interpolation algorithm for asynchronous ADC-data

NASA Astrophysics Data System (ADS)

Bramburger, Stefan; Zinke, Benny; Killat, Dirk

2017-09-01

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

Application of intelligent soft start in asynchronous motor

NASA Astrophysics Data System (ADS)

Du, Xue; Ye, Ying; Wang, Yuelong; Peng, Lei; Zhang, Suying

2018-05-01

The starting way of three phase asynchronous motor has full voltage start and step-down start. Direct starting brings large current impact, causing excessive local temperature to the power grid and larger starting torque will also impact the motor equipment and affect the service life of the motor. Aim at the problem of large current and torque caused by start-up, an intelligent soft starter is proposed. Through the application of intelligent soft start on asynchronous motor, highlights its application advantage in motor control.

Research on TCP/IP network communication based on Node.js

NASA Astrophysics Data System (ADS)

Huang, Jing; Cai, Lixiong

2018-04-01

In the face of big data, long connection and high synchronization, TCP/IP network communication will cause performance bottlenecks due to its blocking multi-threading service model. This paper presents a method of TCP/IP network communication protocol based on Node.js. On the basis of analyzing the characteristics of Node.js architecture and asynchronous non-blocking I/O model, the principle of its efficiency is discussed, and then compare and analyze the network communication model of TCP/IP protocol to expound the reasons why TCP/IP protocol stack is widely used in network communication. Finally, according to the large data and high concurrency in the large-scale grape growing environment monitoring process, a TCP server design based on Node.js is completed. The results show that the example runs stably and efficiently.

Pteros 2.0: Evolution of the fast parallel molecular analysis library for C++ and python.

PubMed

Yesylevskyy, Semen O

2015-07-15

Pteros is the high-performance open-source library for molecular modeling and analysis of molecular dynamics trajectories. Starting from version 2.0 Pteros is available for C++ and Python programming languages with very similar interfaces. This makes it suitable for writing complex reusable programs in C++ and simple interactive scripts in Python alike. New version improves the facilities for asynchronous trajectory reading and parallel execution of analysis tasks by introducing analysis plugins which could be written in either C++ or Python in completely uniform way. The high level of abstraction provided by analysis plugins greatly simplifies prototyping and implementation of complex analysis algorithms. Pteros is available for free under Artistic License from http://sourceforge.net/projects/pteros/. © 2015 Wiley Periodicals, Inc.

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

NASA Astrophysics Data System (ADS)

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.

Videoconferencing Comes of Age.

ERIC Educational Resources Information Center

Bosak, Steve

2000-01-01

Hundreds of districts are using high-speed videoconferencing for distance learning and resource sharing, inservice training, and districtwide meetings. Speed matters. Districts will need either Ethernet or ATM (asynchronous transfer mode) forms of wide-area networks to connect schools and offices. (MLH)

Temporal prediction abilities are mediated by motor effector and rhythmic expertise.

PubMed

Manning, Fiona C; Harris, Jennifer; Schutz, Michael

2017-03-01

Motor synchronization is a critical part of musical performance and listening. Recently, motor control research has described how movements that contain more available degrees of freedom are more accurately timed. Previously, we demonstrated that stick tapping improves perception in a timing detection task, where percussionists greatly outperformed non-percussionists only when tapping along. Since most synchronization studies implement finger tapping to examine simple motor synchronization, here we completed a similar task where percussionists and non-percussionists synchronized using finger tapping; movement with fewer degrees of freedom than stick tapping. Percussionists and non-percussionists listened to an isochronous beat sequence and identified the timing of a probe tone. On half of the trials, they tapped along with their index finger, and on the other half of the trials, they listened without moving prior to making timing judgments. We found that both groups benefited from tapping overall. Interestingly, percussionists performed only marginally better than did non-percussionists when finger tapping and no different when listening alone, differing from past studies reporting highly superior timing abilities in percussionists. Additionally, we found that percussionist finger tapping was less variable and less asynchronous than was non-percussionist tapping. Moreover, in both groups finger tapping was more variable and more asynchronous than stick tapping in our previous study. This study demonstrates that the motor effector implemented in tapping studies affects not only synchronization abilities, but also subsequent prediction abilities. We discuss these findings in light of effector-specific training and degrees of freedom in motor timing, both of which impact timing abilities to different extents.

Enabling technologies for millimeter-wave radio-over-fiber systems in next generation heterogeneous mobile access networks

NASA Astrophysics Data System (ADS)

Zhang, Junwen; Yu, Jianjun; Wang, Jing; Xu, Mu; Cheng, Lin; Lu, Feng; Shen, Shuyi; Yan, Yan; Cho, Hyunwoo; Guidotti, Daniel; Chang, Gee-kung

2017-01-01

Fifth-generation (5G) wireless access network promises to support higher access data rate with more than 1,000 times capacity with respect to current long-term evolution (LTE) systems. New radio-access-technologies (RATs) based on higher carrier frequencies to millimeter-wave (MMW) radio-over-fiber, and carrier-aggregation (CA) using multi-band resources are intensively studied to support the high data rate access and effectively use of frequency resources in heterogeneous mobile network (Het-Net). In this paper, we investigate several enabling technologies for MMW RoF systems in 5G Het-Net. Efficient mobile fronthaul (MFH) solutions for 5G centralized radio access network (C-RAN) and beyond are proposed, analyzed and experimentally demonstrated based on the analog scheme. Digital predistortion based on memory polynomial for analog MFH linearization are presented with improved EVM performances and receiver sensitivity. We also propose and experimentally demonstrate a novel inter-/intra- RAT CA scheme for 5G Het- Net. The real-time standard 4G-LTE signal is carrier-aggregated with three broadband 60GHz MMW signals based on proposed optical-domain band-mapping method. RATs based on new waveforms have also been studied here to achieve higher spectral-efficiency (SE) in asynchronous environments. Full-duplex asynchronous quasi-gapless carrier aggregation scheme for MMW ROF inter-/intra-RAT based on the FBMC is also presented with 4G-LTE signals. Compared with OFDM-based signals with large guard-bands, FBMC achieves higher spectral-efficiency with better EVM performance at less received power and smaller guard-bands.

Collaboration Levels in Asynchronous Discussion Forums: A Social Network Analysis Approach

ERIC Educational Resources Information Center

Luhrs, Cecilia; McAnally-Salas, Lewis

2016-01-01

Computer Supported Collaborative Learning literature relates high levels of collaboration to enhanced learning outcomes. However, an agreement on what is considered a high level of collaboration is unclear, especially if a qualitative approach is taken. This study describes how methods of Social Network Analysis were used to design a collaboration…

THE RHIC SEQUENCER.

DOE Office of Scientific and Technical Information (OSTI.GOV)

VAN ZEIJTS,J.; DOTTAVIO,T.; FRAK,B.

The Relativistic Heavy Ion Collider (RHIC) has a high level asynchronous time-line driven by a controlling program called the ''Sequencer''. Most high-level magnet and beam related issues are orchestrated by this system. The system also plays an important task in coordinated data acquisition and saving. We present the program, operator interface, operational impact and experience.

Elements of Satisfactory Online Asynchronous Teacher Behaviour in Higher Education

ERIC Educational Resources Information Center

Smits, Anneke; Voogt, Joke

2017-01-01

In this study, differences were analysed between two groups of online teachers in a Master of Special Educational Needs program. One group scored high on student satisfaction and the second group received low student satisfaction ratings. Findings indicate that high satisfaction is associated with relatively long and pedagogically complex messages…

Adaptive Game Based Learning Using Brain Measures for Attention--Some Explorations

ERIC Educational Resources Information Center

van der Pal, Jelke; Roos, Christopher; Sewnath, Ghanshaam; Rosheuvel, Christian

2016-01-01

The prospective use of low fidelity simulation and gaming in aviation training is high, and may facilitate individual, personal training needs in usually asynchronous training setting. Without direct feedback from, or intervention by, an instructor, adaptivity of the training environment is in high demand to ensure training sessions maintain an…

Task Virtuality and Its Effect on Student Project Team Effectiveness

ERIC Educational Resources Information Center

Pineda, Rodley C.

2015-01-01

This study explores the extent to which students in colocated teams use synchronous and asynchronous computer-mediated communication channels (task virtuality) and how this use affects their perceptions of the team's performance, their satisfaction with the team, and the learning they derive from the process. Survey results show that different…

Visual tracking using neuromorphic asynchronous event-based cameras.

PubMed

Ni, Zhenjiang; Ieng, Sio-Hoi; Posch, Christoph; Régnier, Stéphane; Benosman, Ryad

2015-04-01

This letter presents a novel computationally efficient and robust pattern tracking method based on a time-encoded, frame-free visual data. Recent interdisciplinary developments, combining inputs from engineering and biology, have yielded a novel type of camera that encodes visual information into a continuous stream of asynchronous, temporal events. These events encode temporal contrast and intensity locally in space and time. We show that the sparse yet accurately timed information is well suited as a computational input for object tracking. In this letter, visual data processing is performed for each incoming event at the time it arrives. The method provides a continuous and iterative estimation of the geometric transformation between the model and the events representing the tracked object. It can handle isometry, similarities, and affine distortions and allows for unprecedented real-time performance at equivalent frame rates in the kilohertz range on a standard PC. Furthermore, by using the dimension of time that is currently underexploited by most artificial vision systems, the method we present is able to solve ambiguous cases of object occlusions that classical frame-based techniques handle poorly.

Determination of power and moment on shaft of special asynchronous electric drives

NASA Astrophysics Data System (ADS)

Karandey, V. Yu; Popov, B. K.; Popova, O. B.; Afanasyev, V. L.

2018-03-01

In the article, questions and tasks of determination of power and the moment on a shaft of special asynchronous electric drives are considered. Use of special asynchronous electric drives in mechanical engineering and other industries is relevant. The considered types of electric drives possess the improved mass-dimensional indicators in comparison with singleengine systems. Also these types of electric drives have constructive advantages; the improved characteristics allow one to realize the technological process. But creation and design of new electric drives demands adjustment of existing or development of new methods and approaches of calculation of parameters. Determination of power and the moment on a shaft of special asynchronous electric drives is the main objective during design of electric drives. This task has been solved based on a method of electromechanical transformation of energy.

Distributed asynchronous microprocessor architectures in fault tolerant integrated flight systems

NASA Technical Reports Server (NTRS)

Dunn, W. R.

1983-01-01

The paper discusses the implementation of fault tolerant digital flight control and navigation systems for rotorcraft application. It is shown that in implementing fault tolerance at the systems level using advanced LSI/VLSI technology, aircraft physical layout and flight systems requirements tend to define a system architecture of distributed, asynchronous microprocessors in which fault tolerance can be achieved locally through hardware redundancy and/or globally through application of analytical redundancy. The effects of asynchronism on the execution of dynamic flight software is discussed. It is shown that if the asynchronous microprocessors have knowledge of time, these errors can be significantly reduced through appropiate modifications of the flight software. Finally, the papear extends previous work to show that through the combined use of time referencing and stable flight algorithms, individual microprocessors can be configured to autonomously tolerate intermittent faults.

The Design of Finite State Machine for Asynchronous Replication Protocol

NASA Astrophysics Data System (ADS)

Wang, Yanlong; Li, Zhanhuai; Lin, Wei; Hei, Minglei; Hao, Jianhua

Data replication is a key way to design a disaster tolerance system and to achieve reliability and availability. It is difficult for a replication protocol to deal with the diverse and complex environment. This means that data is less well replicated than it ought to be. To reduce data loss and to optimize replication protocols, we (1) present a finite state machine, (2) run it to manage an asynchronous replication protocol and (3) report a simple evaluation of the asynchronous replication protocol based on our state machine. It's proved that our state machine is applicable to guarantee the asynchronous replication protocol running in the proper state to the largest extent in the event of various possible events. It also can helpful to build up replication-based disaster tolerance systems to ensure the business continuity.

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

NASA Technical Reports Server (NTRS)

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.

An accurate evaluation of the performance of asynchronous DS-CDMA systems with zero-correlation-zone coding in Rayleigh fading

NASA Astrophysics Data System (ADS)

Walker, Ernest; Chen, Xinjia; Cooper, Reginald L.

2010-04-01

An arbitrarily accurate approach is used to determine the bit-error rate (BER) performance for generalized asynchronous DS-CDMA systems, in Gaussian noise with Raleigh fading. In this paper, and the sequel, new theoretical work has been contributed which substantially enhances existing performance analysis formulations. Major contributions include: substantial computational complexity reduction, including a priori BER accuracy bounding; an analytical approach that facilitates performance evaluation for systems with arbitrary spectral spreading distributions, with non-uniform transmission delay distributions. Using prior results, augmented by these enhancements, a generalized DS-CDMA system model is constructed and used to evaluated the BER performance, in a variety of scenarios. In this paper, the generalized system modeling was used to evaluate the performance of both Walsh- Hadamard (WH) and Walsh-Hadamard-seeded zero-correlation-zone (WH-ZCZ) coding. The selection of these codes was informed by the observation that WH codes contain N spectral spreading values (0 to N - 1), one for each code sequence; while WH-ZCZ codes contain only two spectral spreading values (N/2 - 1,N/2); where N is the sequence length in chips. Since these codes span the spectral spreading range for DS-CDMA coding, by invoking an induction argument, the generalization of the system model is sufficiently supported. The results in this paper, and the sequel, support the claim that an arbitrary accurate performance analysis for DS-CDMA systems can be evaluated over the full range of binary coding, with minimal computational complexity.

Data flow language and interpreter for a reconfigurable distributed data processor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurt, A.D.; Heath, J.R.

1982-01-01

An analytic language and an interpreter whereby an applications data flow graph may serve as an input to a reconfigurable distributed data processor is proposed. The architecture considered consists of a number of loosely coupled computing elements (CES) which may be linked to data and file memories through fully nonblocking interconnect networks. The real-time performance of such an architecture depends upon its ability to alter its topology in response to changes in application, asynchronous data rates and faults. Such a data flow language enhances the versatility of a reconfigurable architecture by allowing the user to specify the machine's topology atmore » a very high level. 11 references.« less

CIFO 3.0

NASA Technical Reports Server (NTRS)

Rogers, Pat

1992-01-01

The Ada Runtime Environment Working Group has, since 1985, developed and published the Catalog of Interface Features and Options (CFIO) for Ada runtime environments. These interfaces, expressed in legal Ada, provide 'hooks' into the runtime system to export both functionality and enhanced performance beyond that of 'vanilla' Ada implementations. Such enhancements include high- and low-level scheduling control, asynchronous communications facilities, predictable storage management facilities, and fast interrupt response. CIFO 3.0 represents the latest release, which incorporates the efforts of the European real time community as well as new interfaces and expansions of previous catalog entries. This presentation will give both an overview of the Catalog's contents and an 'insider's' view of the Catalog as a whole.

Digital Self-Interference Cancellation for Asynchronous In-Band Full-Duplex Underwater Acoustic Communication.

PubMed

Qiao, Gang; Gan, Shuwei; Liu, Songzuo; Ma, Lu; Sun, Zongxin

2018-05-24

To improve the throughput of underwater acoustic (UWA) networking, the In-band full-duplex (IBFD) communication is one of the most vital pieces of research. The major drawback of IBFD-UWA communication is Self-Interference (SI). This paper presents a digital SI cancellation algorithm for asynchronous IBFD-UWA communication system. We focus on two issues: one is asynchronous communication dissimilar to IBFD radio communication, the other is nonlinear distortion caused by power amplifier (PA). First, we discuss asynchronous IBFD-UWA signal model with the nonlinear distortion of PA. Then, we design a scheme for asynchronous IBFD-UWA communication utilizing the non-overlapping region between SI and intended signal to estimate the nonlinear SI channel. To cancel the nonlinear distortion caused by PA, we propose an Over-Parameterization based Recursive Least Squares (RLS) algorithm (OPRLS) to estimate the nonlinear SI channel. Furthermore, we present the OPRLS with a sparse constraint to estimate the SI channel, which reduces the requirement of the length of the non-overlapping region. Finally, we verify our concept through simulation and the pool experiment. Results demonstrate that the proposed digital SI cancellation scheme can cancel SI efficiently.

A massively asynchronous, parallel brain.

PubMed

Zeki, Semir

2015-05-19

Whether the visual brain uses a parallel or a serial, hierarchical, strategy to process visual signals, the end result appears to be that different attributes of the visual scene are perceived asynchronously--with colour leading form (orientation) by 40 ms and direction of motion by about 80 ms. Whatever the neural root of this asynchrony, it creates a problem that has not been properly addressed, namely how visual attributes that are perceived asynchronously over brief time windows after stimulus onset are bound together in the longer term to give us a unified experience of the visual world, in which all attributes are apparently seen in perfect registration. In this review, I suggest that there is no central neural clock in the (visual) brain that synchronizes the activity of different processing systems. More likely, activity in each of the parallel processing-perceptual systems of the visual brain is reset independently, making of the brain a massively asynchronous organ, just like the new generation of more efficient computers promise to be. Given the asynchronous operations of the brain, it is likely that the results of activities in the different processing-perceptual systems are not bound by physiological interactions between cells in the specialized visual areas, but post-perceptually, outside the visual brain.

Exploring Gigabyte Datasets in Real Time: Architectures, Interfaces and Time-Critical Design

NASA Technical Reports Server (NTRS)

Bryson, Steve; Gerald-Yamasaki, Michael (Technical Monitor)

1998-01-01

Architectures and Interfaces: The implications of real-time interaction on software architecture design: decoupling of interaction/graphics and computation into asynchronous processes. The performance requirements of graphics and computation for interaction. Time management in such an architecture. Examples of how visualization algorithms must be modified for high performance. Brief survey of interaction techniques and design, including direct manipulation and manipulation via widgets. talk discusses how human factors considerations drove the design and implementation of the virtual wind tunnel. Time-Critical Design: A survey of time-critical techniques for both computation and rendering. Emphasis on the assignment of a time budget to both the overall visualization environment and to each individual visualization technique in the environment. The estimation of the benefit and cost of an individual technique. Examples of the modification of visualization algorithms to allow time-critical control.

Scalable asynchronous execution of cellular automata

NASA Astrophysics Data System (ADS)

Folino, Gianluigi; Giordano, Andrea; Mastroianni, Carlo

2016-10-01

The performance and scalability of cellular automata, when executed on parallel/distributed machines, are limited by the necessity of synchronizing all the nodes at each time step, i.e., a node can execute only after the execution of the previous step at all the other nodes. However, these synchronization requirements can be relaxed: a node can execute one step after synchronizing only with the adjacent nodes. In this fashion, different nodes can execute different time steps. This can be a notable advantageous in many novel and increasingly popular applications of cellular automata, such as smart city applications, simulation of natural phenomena, etc., in which the execution times can be different and variable, due to the heterogeneity of machines and/or data and/or executed functions. Indeed, a longer execution time at a node does not slow down the execution at all the other nodes but only at the neighboring nodes. This is particularly advantageous when the nodes that act as bottlenecks vary during the application execution. The goal of the paper is to analyze the benefits that can be achieved with the described asynchronous implementation of cellular automata, when compared to the classical all-to-all synchronization pattern. The performance and scalability have been evaluated through a Petri net model, as this model is very useful to represent the synchronization barrier among nodes. We examined the usual case in which the territory is partitioned into a number of regions, and the computation associated with a region is assigned to a computing node. We considered both the cases of mono-dimensional and two-dimensional partitioning. The results show that the advantage obtained through the asynchronous execution, when compared to the all-to-all synchronous approach is notable, and it can be as large as 90% in terms of speedup.

"Power-on resets" in cardiac implantable electronic devices during magnetic resonance imaging.

PubMed

Higgins, John V; Sheldon, Seth H; Watson, Robert E; Dalzell, Connie; Acker, Nancy; Cha, Yong-Mei; Asirvatham, Samuel J; Kapa, Suraj; Felmlee, Joel P; Friedman, Paul A

2015-03-01

Magnetic resonance imaging (MRI) has been safely performed in some patients with cardiac implantable electronic devices (CIEDs) under careful monitoring and prespecified conditions. Pacemaker-dependent patients are often excluded, partly because of the potential for "power-on reset" (PoR), which can lead to a change from asynchronous to inhibited pacing with consequent inhibition of pacing due to electromagnetic interference during MRI. The purpose of this study was to review risk factors for PoR during MRI. A prospective study was performed between January 2008 and May 2013 in patients with CIEDs undergoing clinically indicated MRI. Eligible patients were not pacemaker dependent. Devices were interrogated before and after MRI, programmed to an asynchronous mode or an inhibition mode with tachyarrhythmia therapies turned off, and reprogrammed to their original settings after MRI. MRI scans (n = 256) were performed in 198 patients with non-MRI-conditional CIEDs between 2008 and 2013 (median age 66 years; interquartile range 57-77 years; 59% men). PoR occurred during 9 MRI scans (3.5%) in 8 patients. PoR was more frequent with Medtronic devices than with other generator brands (n = 9/139 vs 0/117 [6% vs 0%]; P = .005). Devices with PoR were all released before 2002 and were implanted from 1999 to 2004. Effects of PoR included a decrease in heart rate during MRI (n = 4) and transient anomalous battery life indication (n = 1). All devices functioned normally after MRI. PoR occurs infrequently but can cause deleterious changes in pacing mode and heart rate. MRI should not be performed in pacemaker-dependent patients with older at-risk generators. Continuous monitoring during MRI is essential because unrecognized PoR may inhibit pacing or accelerate battery depletion due to high pacing output. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Scenario Decomposition for 0-1 Stochastic Programs: Improvements and Asynchronous Implementation

DOE PAGES

Ryan, Kevin; Rajan, Deepak; Ahmed, Shabbir

2016-05-01

We recently proposed scenario decomposition algorithm for stochastic 0-1 programs finds an optimal solution by evaluating and removing individual solutions that are discovered by solving scenario subproblems. In our work, we develop an asynchronous, distributed implementation of the algorithm which has computational advantages over existing synchronous implementations of the algorithm. Improvements to both the synchronous and asynchronous algorithm are proposed. We also test the results on well known stochastic 0-1 programs from the SIPLIB test library and is able to solve one previously unsolved instance from the test set.

Finite-time synchronization of uncertain coupled switched neural networks under asynchronous switching.

PubMed

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

2017-01-01

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

Interaction between the Stress Phase Angle (SPA) and the Oscillatory Shear Index (OSI) Affects Endothelial Cell Gene Expression.

PubMed

Amaya, Ronny; Cancel, Limary M; Tarbell, John M

2016-01-01

Hemodynamic forces play an important role in the non-uniform distribution of atherosclerotic lesions. Endothelial cells are exposed simultaneously to fluid wall shear stress (WSS) and solid circumferential stress (CS). Due to variations in impedance (global factors) and geometric complexities (local factors) in the arterial circulation a time lag arises between these two forces that can be characterized by the temporal phase angle between CS and WSS (stress phase angle-SPA). Asynchronous flows (SPA close to -180°) that are most prominent in coronary arteries have been associated with localization of atherosclerosis. Reversing oscillatory flows characterized by an oscillatory shear index (OSI) that is great than zero are also associated with atherosclerosis localization. In this study we examined the relationship between asynchronous flows and reversing flows in altering the expression of 37 genes relevant to atherosclerosis development. In the case of reversing oscillatory flow, we observed that the asynchronous condition upregulated 8 genes compared to synchronous hemodynamics, most of them proatherogenic. Upregulation of the pro-inflammatory transcription factor NFκB p65 was confirmed by western blot, and nuclear translocation of NFκB p65 was confirmed by immunofluorescence staining. A comparative study between non-reversing flow and reversing flow found that in the case of synchronous hemodynamics, reversing flow altered the expression of 11 genes, while in the case of asynchronous hemodynamics, reversing flow altered the expression of 17 genes. Reversing flow significantly upregulated protein expression of NFκB p65 for both synchronous and asynchronous conditions. Nuclear translocation of NFκB p65 was confirmed for synchronous and asynchronous conditions in the presence of flow reversal. These data suggest that asynchronous hemodynamics and reversing flow can elicit proatherogenic responses in endothelial cells compared to synchronous hemodynamics without shear stress reversal, indicating that SPA as well as reversal flow (OSI) are important parameters characterizing arterial susceptibility to disease.

Interaction between the Stress Phase Angle (SPA) and the Oscillatory Shear Index (OSI) Affects Endothelial Cell Gene Expression

PubMed Central

Amaya, Ronny; Cancel, Limary M.; Tarbell, John M.

2016-01-01

Hemodynamic forces play an important role in the non-uniform distribution of atherosclerotic lesions. Endothelial cells are exposed simultaneously to fluid wall shear stress (WSS) and solid circumferential stress (CS). Due to variations in impedance (global factors) and geometric complexities (local factors) in the arterial circulation a time lag arises between these two forces that can be characterized by the temporal phase angle between CS and WSS (stress phase angle–SPA). Asynchronous flows (SPA close to -180°) that are most prominent in coronary arteries have been associated with localization of atherosclerosis. Reversing oscillatory flows characterized by an oscillatory shear index (OSI) that is great than zero are also associated with atherosclerosis localization. In this study we examined the relationship between asynchronous flows and reversing flows in altering the expression of 37 genes relevant to atherosclerosis development. In the case of reversing oscillatory flow, we observed that the asynchronous condition upregulated 8 genes compared to synchronous hemodynamics, most of them proatherogenic. Upregulation of the pro-inflammatory transcription factor NFκB p65 was confirmed by western blot, and nuclear translocation of NFκB p65 was confirmed by immunofluorescence staining. A comparative study between non-reversing flow and reversing flow found that in the case of synchronous hemodynamics, reversing flow altered the expression of 11 genes, while in the case of asynchronous hemodynamics, reversing flow altered the expression of 17 genes. Reversing flow significantly upregulated protein expression of NFκB p65 for both synchronous and asynchronous conditions. Nuclear translocation of NFκB p65 was confirmed for synchronous and asynchronous conditions in the presence of flow reversal. These data suggest that asynchronous hemodynamics and reversing flow can elicit proatherogenic responses in endothelial cells compared to synchronous hemodynamics without shear stress reversal, indicating that SPA as well as reversal flow (OSI) are important parameters characterizing arterial susceptibility to disease. PMID:27846267

Predictability in cellular automata.

PubMed

Agapie, Alexandru; Andreica, Anca; Chira, Camelia; Giuclea, Marius

2014-01-01

Modelled as finite homogeneous Markov chains, probabilistic cellular automata with local transition probabilities in (0, 1) always posses a stationary distribution. This result alone is not very helpful when it comes to predicting the final configuration; one needs also a formula connecting the probabilities in the stationary distribution to some intrinsic feature of the lattice configuration. Previous results on the asynchronous cellular automata have showed that such feature really exists. It is the number of zero-one borders within the automaton's binary configuration. An exponential formula in the number of zero-one borders has been proved for the 1-D, 2-D and 3-D asynchronous automata with neighborhood three, five and seven, respectively. We perform computer experiments on a synchronous cellular automaton to check whether the empirical distribution obeys also that theoretical formula. The numerical results indicate a perfect fit for neighbourhood three and five, which opens the way for a rigorous proof of the formula in this new, synchronous case.

A Required Online Course with a Public Health Focus for Third Professional Year Pharmacy Students.

PubMed

King, Amber E; Egras, Amy M

2015-06-25

To design, deliver, and evaluate the impact of a required course on student knowledge acquisition and ability to evaluate contemporary public health issues. A 2-credit course was implemented using asynchronous, online delivery. Learning activities included literature retrieval and assessment, analytic writing, quizzes, and creation of a group wiki evaluating a current public health issue. Course topics included health care reform, social determinants of health, health disparities, evidence-based medicine, end-of-life care, patient safety, and research ethics. Strong student performance on assessments indicated an ability to use higher-order cognitive domains. Online delivery provided students with the flexibility to complete assignments at their convenience, allowed participation by all students, and encouraged self-directed learning. Completion of a required, online, asynchronous course with a public health focus allowed pharmacy students to increase their knowledge of and ability to evaluate contemporary ethical, social, cultural, and governmental issues affecting pharmacy practice.

Rapid temporal recalibration is unique to audiovisual stimuli.

PubMed

Van der Burg, Erik; Orchard-Mills, Emily; Alais, David

2015-01-01

Following prolonged exposure to asynchronous multisensory signals, the brain adapts to reduce the perceived asynchrony. Here, in three separate experiments, participants performed a synchrony judgment task on audiovisual, audiotactile or visuotactile stimuli and we used inter-trial analyses to examine whether temporal recalibration occurs rapidly on the basis of a single asynchronous trial. Even though all combinations used the same subjects, task and design, temporal recalibration occurred for audiovisual stimuli (i.e., the point of subjective simultaneity depended on the preceding trial's modality order), but none occurred when the same auditory or visual event was combined with a tactile event. Contrary to findings from prolonged adaptation studies showing recalibration for all three combinations, we show that rapid, inter-trial recalibration is unique to audiovisual stimuli. We conclude that recalibration occurs at two different timescales for audiovisual stimuli (fast and slow), but only on a slow timescale for audiotactile and visuotactile stimuli.

Comparison of bio-hydrogen production yield capacity between asynchronous and simultaneous saccharification and fermentation processes from agricultural residue by mixed anaerobic cultures.

PubMed

Li, Yameng; Zhang, Zhiping; Zhu, Shengnan; Zhang, Huan; Zhang, Yang; Zhang, Tian; Zhang, Quanguo

2018-01-01

Taken common agricultural residues as substrate, dark fermentation bio-hydrogen yield capacity from asynchronous saccharification and fermentation (ASF) and simultaneous saccharification and fermentation (SSF) was investigated. The highest hydrogen yield of 472.75mL was achieved with corncob using ASF. Hydrogen yield from corn straw, rice straw, corncob and sorghum stalk by SSF were 20.54%,10.31%,13.99% and 5.92% higher than ASF, respectively. The experimental data fitted well to the modified Gompertz model. SSF offered a distinct advantage over ASF with respect to reducing overall process time (60h of SSF, 108h of ASF). Meanwhile, SSF performed better than SSF with respect to shortening the lag-stage. The major metabolites of anaerobic fermentation hydrogen production by ASF and SSF were butyric acid and acetic acid. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrical engineering unit for the reactive power control of the load bus at the voltage instability

NASA Astrophysics Data System (ADS)

Kotenev, A. V.; Kotenev, V. I.; Kochetkov, V. V.; Elkin, D. A.

2018-01-01

For the purpose of reactive power control error reduction and decrease of the voltage sags in the electric power system caused by the asynchronous motors started the mathematical model of the load bus was developed. The model was built up of the sub-models of the following elements: a transformer, a transmission line, a synchronous and an asynchronous loads and a capacitor bank load, and represents the automatic reactive power control system taking into account electromagnetic processes of the asynchronous motors started and reactive power changing of the electric power system elements caused by the voltage fluctuation. The active power/time and reactive power/time characteristics based on the recommended procedure of the equivalent electric circuit parameters calculation were obtained. The derived automatic reactive power control system was shown to eliminate the voltage sags in the electric power system caused by the asynchronous motors started.

PsychVACS: a system for asynchronous telepsychiatry.

PubMed

Odor, Alberto; Yellowlees, Peter; Hilty, Donald; Parish, Michelle Burke; Nafiz, Najia; Iosif, Ana-Maria

2011-05-01

To describe the technical development of an asynchronous telepsychiatry application, the Psychiatric Video Archiving and Communication System. A client-server application was developed in Visual Basic.Net with Microsoft(®) SQL database as the backend. It includes the capability of storing video-recorded psychiatric interviews and manages the workflow of the system with automated messaging. Psychiatric Video Archiving and Communication System has been used to conduct the first ever series of asynchronous telepsychiatry consultations worldwide. A review of the software application and the process as part of this project has led to a number of improvements that are being implemented in the next version, which is being written in Java. This is the first description of the use of video recorded data in an asynchronous telemedicine application. Primary care providers and consulting psychiatrists have found it easy to work with and a valuable resource to increase the availability of psychiatric consultation in remote rural locations.

Access to Specialized Care Through Telemedicine in Limited-Resource Country: Initial 1,065 Teleconsultations in Albania.

PubMed

Latifi, Rifat; Gunn, Jayleen K L; Bakiu, Evis; Boci, Arian; Dasho, Erion; Olldashi, Fatos; Pipero, Pellumb; Stroster, John A; Qesteri, Orland; Kucani, Julian; Sulo, Ardi; Oshafi, Manjola; Osmani, Kalterina L; Dogjani, Agron; Doarn, Charles R; Shatri, Zhaneta; Kociraj, Agim; Merrell, Ronald C

2016-12-01

To analyze the initial experience of the nationwide clinical telemedicine program of Albania, as a model of implementation of telemedicine using "Initiate-Build-Operate-Transfer" strategy. This was a retrospective study of prospectively collected data from teleconsultations in Albania between January 1, 2014 and August 26, 2015, delivered synchronously, asynchronously, or a combination of both methods. Patient's demographics, mode of consultation, clinical specialty, hospitals providing referral and consultation, time from initial call to completion of consultation, and patient disposition following teleconsultation were analyzed. Challenges of the newly created program have been identified and analyzed as well. There were 1,065 teleconsultations performed altogether during the study period. Ninety-one patients with autism managed via telemedicine were not included in this analysis and will be reported separately. Of 974 teleconsults, the majority were for radiology, neurotrauma, and stroke (55%, 16%, and 10% respectively). Asynchronous technology accounted for nearly two-thirds of all teleconsultations (63.7%), followed by combined (24.3%), and then synchronous (12.0%). Of 974 cases, only 20.0% of patients in 2014 and 22.72% of patients in 2015 were transferred to a tertiary hospital. A majority (98.5%) of all teleconsultations were conducted within the country itself. The Integrated Telemedicine and e-Health program of Albania has become a useful tool to improve access to high-quality healthcare, particularly in high demanding specialty disciplines. A number of challenges were identified and these should serve as lessons for other countries in their quest to establish nationwide telemedicine programs.

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

PubMed Central

Wagener, Johannes; Spjuth, Ola; Willighagen, Egon L; Wikberg, Jarl ES

2009-01-01

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. PMID:19732427

Reverse engineering a gene network using an asynchronous parallel evolution strategy

PubMed Central

2010-01-01

Background The use of reverse engineering methods to infer gene regulatory networks by fitting mathematical models to gene expression data is becoming increasingly popular and successful. However, increasing model complexity means that more powerful global optimisation techniques are required for model fitting. The parallel Lam Simulated Annealing (pLSA) algorithm has been used in such approaches, but recent research has shown that island Evolutionary Strategies can produce faster, more reliable results. However, no parallel island Evolutionary Strategy (piES) has yet been demonstrated to be effective for this task. Results Here, we present synchronous and asynchronous versions of the piES algorithm, and apply them to a real reverse engineering problem: inferring parameters in the gap gene network. We find that the asynchronous piES exhibits very little communication overhead, and shows significant speed-up for up to 50 nodes: the piES running on 50 nodes is nearly 10 times faster than the best serial algorithm. We compare the asynchronous piES to pLSA on the same test problem, measuring the time required to reach particular levels of residual error, and show that it shows much faster convergence than pLSA across all optimisation conditions tested. Conclusions Our results demonstrate that the piES is consistently faster and more reliable than the pLSA algorithm on this problem, and scales better with increasing numbers of nodes. In addition, the piES is especially well suited to further improvements and adaptations: Firstly, the algorithm's fast initial descent speed and high reliability make it a good candidate for being used as part of a global/local search hybrid algorithm. Secondly, it has the potential to be used as part of a hierarchical evolutionary algorithm, which takes advantage of modern multi-core computing architectures. PMID:20196855

Multiple asynchronous stimulus- and task-dependent hierarchies (STDH) within the visual brain's parallel processing systems.

PubMed

Zeki, Semir

2016-10-01

Results from a variety of sources, some many years old, lead ineluctably to a re-appraisal of the twin strategies of hierarchical and parallel processing used by the brain to construct an image of the visual world. Contrary to common supposition, there are at least three 'feed-forward' anatomical hierarchies that reach the primary visual cortex (V1) and the specialized visual areas outside it, in parallel. These anatomical hierarchies do not conform to the temporal order with which visual signals reach the specialized visual areas through V1. Furthermore, neither the anatomical hierarchies nor the temporal order of activation through V1 predict the perceptual hierarchies. The latter shows that we see (and become aware of) different visual attributes at different times, with colour leading form (orientation) and directional visual motion, even though signals from fast-moving, high-contrast stimuli are among the earliest to reach the visual cortex (of area V5). Parallel processing, on the other hand, is much more ubiquitous than commonly supposed but is subject to a barely noticed but fundamental aspect of brain operations, namely that different parallel systems operate asynchronously with respect to each other and reach perceptual endpoints at different times. This re-assessment leads to the conclusion that the visual brain is constituted of multiple, parallel and asynchronously operating task- and stimulus-dependent hierarchies (STDH); which of these parallel anatomical hierarchies have temporal and perceptual precedence at any given moment is stimulus and task related, and dependent on the visual brain's ability to undertake multiple operations asynchronously. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Pulvinar thalamic nucleus allows for asynchronous spike propagation through the cortex

PubMed Central

Cortes, Nelson; van Vreeswijk, Carl

2015-01-01

We create two multilayered feedforward networks composed of excitatory and inhibitory integrate-and-fire neurons in the balanced state to investigate the role of cortico-pulvino-cortical connections. The first network consists of ten feedforward levels where a Poisson spike train with varying firing rate is applied as an input in layer one. Although the balanced state partially avoids spike synchronization during the transmission, the average firing-rate in the last layer either decays or saturates depending on the feedforward pathway gain. The last layer activity is almost independent of the input even for a carefully chosen intermediate gain. Adding connections to the feedforward pathway by a nine areas Pulvinar structure improves the firing-rate propagation to become almost linear among layers. Incoming strong pulvinar spikes balance the low feedforward gain to have a unit input-output relation in the last layer. Pulvinar neurons evoke a bimodal activity depending on the magnitude input: synchronized spike bursts between 20 and 80 Hz and an asynchronous activity for very both low and high frequency inputs. In the first regime, spikes of last feedforward layer neurons are asynchronous with weak, low frequency, oscillations in the rate. Here, the uncorrelated incoming feedforward pathway washes out the synchronized thalamic bursts. In the second regime, spikes in the whole network are asynchronous. As the number of cortical layers increases, long-range pulvinar connections can link directly two or more cortical stages avoiding their either saturation or gradual activity falling. The Pulvinar acts as a shortcut that supplies the input-output firing-rate relationship of two separated cortical areas without changing the strength of connections in the feedforward pathway. PMID:26042026

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

PubMed

Wagener, Johannes; Spjuth, Ola; Willighagen, Egon L; Wikberg, Jarl E S

2009-09-04

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. 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. 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.

Tactile stimulation and hemispheric asymmetries modulate auditory perception and neural responses in primary auditory cortex.

PubMed

Hoefer, M; Tyll, S; Kanowski, M; Brosch, M; Schoenfeld, M A; Heinze, H-J; Noesselt, T

2013-10-01

Although multisensory integration has been an important area of recent research, most studies focused on audiovisual integration. Importantly, however, the combination of audition and touch can guide our behavior as effectively which we studied here using psychophysics and functional magnetic resonance imaging (fMRI). We tested whether task-irrelevant tactile stimuli would enhance auditory detection, and whether hemispheric asymmetries would modulate these audiotactile benefits using lateralized sounds. Spatially aligned task-irrelevant tactile stimuli could occur either synchronously or asynchronously with the sounds. Auditory detection was enhanced by non-informative synchronous and asynchronous tactile stimuli, if presented on the left side. Elevated fMRI-signals to left-sided synchronous bimodal stimulation were found in primary auditory cortex (A1). Adjacent regions (planum temporale, PT) expressed enhanced BOLD-responses for synchronous and asynchronous left-sided bimodal conditions. Additional connectivity analyses seeded in right-hemispheric A1 and PT for both bimodal conditions showed enhanced connectivity with right-hemispheric thalamic, somatosensory and multisensory areas that scaled with subjects' performance. Our results indicate that functional asymmetries interact with audiotactile interplay which can be observed for left-lateralized stimulation in the right hemisphere. There, audiotactile interplay recruits a functional network of unisensory cortices, and the strength of these functional network connections is directly related to subjects' perceptual sensitivity. Copyright © 2013 Elsevier Inc. All rights reserved.

Pattern of online communication in teaching a blended oral surgery course.

PubMed

Marei, H F; Al-Khalifa, K S

2016-11-01

To explore the factors that might affect the patterns of interaction amongst dental students that can be found in asynchronous online discussion fora. It is a qualitative study that involved the participation of 71 dental students (42 male and 29 female) who belong to one academic year. Students were participated in asynchronous online discussion fora as a part of a blended oral surgery course that involved both face-to-face lecture and an online learning environment using the Blackboard learning management system. Qualitative analysis of students' pattern of discussion was performed using Transcript Analysis Tool. The total number of postings was 410. Sixty-seven of 71 students participated in the discussion by writing posts, whereas all of the students had accessed all of the postings. A positive correlation between imposing vertical questions and the number of non-referential and referential statements was observed. Regarding horizontal questions, a positive correlation was observed with the number of referential statements, whilst there was a negative correlation with the number of non-referential statements. Asynchronous online discussion fora that are integrated as a part of a whole pedagogical practice may provide an opportunity for promoting learning, especially when consideration is given to the structure of problems, timely feedback by tutors and supportive strategies within the discussion threads. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A Communication Perspective on Sexual Harassment: Affiliative Nonverbal Behaviors in Asynchronous Relationships.

ERIC Educational Resources Information Center

Hickson, Mark, III; And Others

1991-01-01

Develops a communication perspective on sexual harassment in asynchronous relationships. Presents a six-step process model to predict private harassing behavior among faculty members in higher education. Makes suggestions for prevention of sexual harassment. (SR)

Development of a high capacity bubble domain memory element and related epitaxial garnet materials for application in spacecraft data recorders. Item 1: Development of a high capacity memory element

NASA Technical Reports Server (NTRS)

Besser, P. J.

1977-01-01

Several versions of the 100K bit chip, which is configured as a single serial loop, were designed, fabricated and evaluated. Design and process modifications were introduced into each succeeding version to increase device performance and yield. At an intrinsic field rate of 150 KHz the final design operates from -10 C to +60 C with typical bias margins of 12 and 8 percent, respectively, for continuous operation. Asynchronous operation with first bit detection on start-up produces essentially the same margins over the temperature range. Cost projections made from fabrication yield runs on the 100K bit devices indicate that the memory element cost will be less than 10 millicents/bit in volume production.

Latency Hiding in Dynamic Partitioning and Load Balancing of Grid Computing Applications

NASA Technical Reports Server (NTRS)

Das, Sajal K.; Harvey, Daniel J.; Biswas, Rupak

2001-01-01

The Information Power Grid (IPG) concept developed by NASA is aimed to provide a metacomputing platform for large-scale distributed computations, by hiding the intricacies of highly heterogeneous environment and yet maintaining adequate security. In this paper, we propose a latency-tolerant partitioning scheme that dynamically balances processor workloads on the.IPG, and minimizes data movement and runtime communication. By simulating an unsteady adaptive mesh application on a wide area network, we study the performance of our load balancer under the Globus environment. The number of IPG nodes, the number of processors per node, and the interconnected speeds are parameterized to derive conditions under which the IPG would be suitable for parallel distributed processing of such applications. Experimental results demonstrate that effective solution are achieved when the IPG nodes are connected by a high-speed asynchronous interconnection network.

High engagement, high quality: A guiding framework for developing empirically informed asynchronous e-learning programs for health professional educators.

PubMed

Sinclair, Peter M; Levett-Jones, Tracey; Morris, Amanda; Carter, Ben; Bennett, Paul N; Kable, Ashley

2017-03-01

E-learning involves the transfer of skills and knowledge via technology so that learners can access meaningful and authentic educational materials. While learner engagement is important, in the context of healthcare education, pedagogy must not be sacrificed for edu-tainment style instructional design. Consequently, health professional educators need to be competent in the use of current web-based educational technologies so that learners are able to access relevant and engaging e-learning materials without restriction. The increasing popularity of asynchronous e-learning programs developed for use outside of formal education institutions has made this need more relevant. In these contexts, educators must balance design and functionality to deliver relevant, cost-effective, sustainable, and accessible programs that overcome scheduling and geographic barriers for learners. This paper presents 10 guiding design principles and their application in the development of an e-learning program for general practice nurses focused on behavior change. Consideration of these principles will assist educators to develop high quality, pedagogically sound, engaging, and interactive e-learning resources. © 2017 John Wiley & Sons Australia, Ltd.

Hybrid WDM/OCDMA for next generation access network

NASA Astrophysics Data System (ADS)

Wang, Xu; Wada, Naoya; Miyazaki, T.; Cincotti, G.; Kitayama, Ken-ichi

2007-11-01

Hybrid wavelength division multiplexing/optical code division multiple access (WDM/OCDMA) passive optical network (PON), where asynchronous OCDMA traffic transmits over WDM network, can be one potential candidate for gigabit-symmetric fiber-to-the-home (FTTH) services. In a cost-effective WDM/OCDMA network, a large scale multi-port encoder/decoder can be employed in the central office, and a low cost encoder/decoder will be used in optical network unit (ONU). The WDM/OCDMA system could be one promising solution to the symmetric high capacity access network with high spectral efficiency, cost effective, good flexibility and enhanced security. Asynchronous WDM/OCDMA systems have been experimentally demonstrated using superstructured fiber Bragg gratings (SSFBG) and muti-port OCDMA en/decoders. The total throughput has reached above Tera-bit/s with spectral efficiency of about 0.41. The key enabling techniques include ultra-long SSFBG, multi-port E/D with high power contrast ratio, optical thresholding, differential phase shift keying modulation with balanced detection, forward error correction, and etc. Using multi-level modulation formats to carry multi-bit information with single pulse, the total capacity and spectral efficiency could be further enhanced.

Comparaison de méthodes d'identification des paramètres d'une machine asynchrone

NASA Astrophysics Data System (ADS)

Bellaaj-Mrabet, N.; Jelassi, K.

1998-07-01

Interests, in Genetic Algorithms (G.A.) expands rapidly. This paper consists initially to apply G.A. for identifying induction motor parameters. Next, we compare the performances with classical methods like Maximum Likelihood and classical electrotechnical methods. These methods are applied on three induction motors of different powers to compare results following a set of criteria. Les algorithmes génétiques sont des méthodes adaptatives de plus en plus utilisée pour la résolution de certains problèmes d'optimisation. Le présent travail consiste d'une part, à mettre en œuvre un A.G sur des problèmes d'identification des machines électriques, et d'autre part à comparer ses performances avec les méthodes classiques tels que la méthode du maximum de vraisemblance et la méthode électrotechnique basée sur des essais à vides et en court-circuit. Ces méthodes sont appliquées sur des machines asynchrones de différentes puissances. Les résultats obtenus sont comparés selon certains critères, permettant de conclure sur la validité et la performance de chaque méthode.

Asynchronous Laser Transponders for Precise Interplanetary Ranging and Time Transfer

NASA Technical Reports Server (NTRS)

Degnan, John J.; Smith, David E. (Technical Monitor)

2001-01-01

The feasibility of a two-way asynchronous (i.e. independently firing) interplanetary laser transponder pair, capable of decimeter ranging and subnanosecond time transfer from Earth to a spacecraft anywhere within the inner Solar System, is discussed. In the Introduction, we briefly discuss the current state-of-the-art in Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) which use single-ended range measurements to a passive optical reflector, and the limitations of this approach in ranging beyond the Moon to the planets. In Section 2 of this paper, we describe two types of transponders (echo and asynchronous), introduce the transponder link equation and the concept of "balanced" transponders, describe how range and time can be transferred between terminals, and preview the potential advantages of photon counting asynchronous transponders for interplanetary applications. In Section 3, we discuss and provide mathematical models for the various sources of noise in an interplanetary transponder link including planetary albedo, solar or lunar illumination of the local atmosphere, and laser backscatter off the local atmosphere. In Section 4, we introduce the key engineering elements of an interplanetary laser transponder and develop an operational scenario for the acquisition and tracking of the opposite terminal. In Section 5, we use the theoretical models of th previous sections to perform an Earth-Mars link analysis over a full synodic period of 780 days under the simplifying assumption of coaxial, coplanar, circular orbits. We demonstrate that, using slightly modified versions of existing space and ground based laser systems, an Earth-Mars transponder link is not only feasible but quite robust. We also demonstrate through analysis the advantages and feasibility of compact, low output power (<300 mW photon-counting transponders using NASA's developmental SLR2000 satellite laser ranging system as the Earth terminal. Section 6 provides a summary of the results and some concluding remarks regarding future applications.

Masked and unmasked error-related potentials during continuous control and feedback

NASA Astrophysics Data System (ADS)

Lopes Dias, Catarina; Sburlea, Andreea I.; Müller-Putz, Gernot R.

2018-06-01

The detection of error-related potentials (ErrPs) in tasks with discrete feedback is well established in the brain–computer interface (BCI) field. However, the decoding of ErrPs in tasks with continuous feedback is still in its early stages. Objective. We developed a task in which subjects have continuous control of a cursor’s position by means of a joystick. The cursor’s position was shown to the participants in two different modalities of continuous feedback: normal and jittered. The jittered feedback was created to mimic the instability that could exist if participants controlled the trajectory directly with brain signals. Approach. This paper studies the electroencephalographic (EEG)—measurable signatures caused by a loss of control over the cursor’s trajectory, causing a target miss. Main results. In both feedback modalities, time-locked potentials revealed the typical frontal-central components of error-related potentials. Errors occurring during the jittered feedback (masked errors) were delayed in comparison to errors occurring during normal feedback (unmasked errors). Masked errors displayed lower peak amplitudes than unmasked errors. Time-locked classification analysis allowed a good distinction between correct and error classes (average Cohen-, average TPR  =  81.8% and average TNR  =  96.4%). Time-locked classification analysis between masked error and unmasked error classes revealed results at chance level (average Cohen-, average TPR  =  60.9% and average TNR  =  58.3%). Afterwards, we performed asynchronous detection of ErrPs, combining both masked and unmasked trials. The asynchronous detection of ErrPs in a simulated online scenario resulted in an average TNR of 84.0% and in an average TPR of 64.9%. Significance. The time-locked classification results suggest that the masked and unmasked errors were indistinguishable in terms of classification. The asynchronous classification results suggest that the feedback modality did not hinder the asynchronous detection of ErrPs.

Student Satisfaction with Asynchronous Learning

ERIC Educational Resources Information Center

Dziuban, Charles; Moskal, Patsy; Brophy, Jay; Shea, Peter

2007-01-01

The authors discuss elements that potentially impact student satisfaction with asynchronous learning: the media culture, digital, personal and mobile technologies, student learning preferences, pedagogy, complexities of measurement, and the digital generation. They describe a pilot study to identify the underlying dimensions of student…

An exploration of teaching presence in online interprofessional education facilitation.

PubMed

Evans, Sherryn Maree; Ward, Catherine; Reeves, Scott

2017-07-01

Although the prevalence of online asynchronous interprofessional education (IPE) has increased in the last decade, little is known about the processes of facilitation in this environment. The teaching presence element of the Community of Inquiry Framework offers an approach to analyze the contributions of online facilitators, however, to date it has only been used on a limited basis in health professions education literature. Using an exploratory case study design, we explored the types of contributions made by IPE facilitators to asynchronous interprofessional team discussions by applying the notion of teaching presence. Using a purposeful sampling approach, we analyzed 14 facilitators' contributions to asynchronous team discussion boards in an online IPE course. We analyzed data using directed content analysis based on the key indicators of teaching presence. The online IPE facilitators undertook the three critical pedagogical functions identified in teaching presence: facilitating discourse, direct instruction, and instructional design and organization. While our data fitted well with a number of key activities embedded in these three functions, further modification of the teaching presence concept was needed to describe our facilitators' teaching presence. This study provides an initial insight into the key elements of online asynchronous IPE facilitation. Further research is required to continue to illuminate the complexity of online asynchronous IPE facilitation.

Rock Hill Business, Education, and Community Online Network.

ERIC Educational Resources Information Center

Broyles, Alan

The Business, Education & Community On-line Network (BEACON) is designed to support development and implementation of demonstration applications operating in an asynchronous transfer mode (ATM) fiber optic network environment. Initial origination and destination sites include high schools and universities around Rock Hill (South Carolina). The…

Online Calibration of the TPC Drift Time in the ALICE High Level Trigger

NASA Astrophysics Data System (ADS)

Rohr, David; Krzewicki, Mikolaj; Zampolli, Chiara; Wiechula, Jens; Gorbunov, Sergey; Chauvin, Alex; Vorobyev, Ivan; Weber, Steffen; Schweda, Kai; Lindenstruth, Volker

2017-06-01

A Large Ion Collider Experiment (ALICE) is one of the four major experiments at the Large Hadron Collider (LHC) at CERN. The high level trigger (HLT) is a compute cluster, which reconstructs collisions as recorded by the ALICE detector in real-time. It employs a custom online data-transport framework to distribute data and workload among the compute nodes. ALICE employs subdetectors that are sensitive to environmental conditions such as pressure and temperature, e.g., the time projection chamber (TPC). A precise reconstruction of particle trajectories requires calibration of these detectors. Performing calibration in real time in the HLT improves the online reconstructions and renders certain offline calibration steps obsolete speeding up offline physics analysis. For LHC Run 3, starting in 2020 when data reduction will rely on reconstructed data, online calibration becomes a necessity. Reconstructed particle trajectories build the basis for the calibration making a fast online-tracking mandatory. The main detectors used for this purpose are the TPC and Inner Tracking System. Reconstructing the trajectories in the TPC is the most compute-intense step. We present several improvements to the ALICE HLT developed to facilitate online calibration. The main new development for online calibration is a wrapper that can run ALICE offline analysis and calibration tasks inside the HLT. In addition, we have added asynchronous processing capabilities to support long-running calibration tasks in the HLT framework, which runs event-synchronously otherwise. In order to improve the resiliency, an isolated process performs the asynchronous operations such that even a fatal error does not disturb data taking. We have complemented the original loop-free HLT chain with ZeroMQ data-transfer components. The ZeroMQ components facilitate a feedback loop that inserts the calibration result created at the end of the chain back into tracking components at the beginning of the chain, after a short delay. All these new features are implemented in a general way, such that they have use-cases aside from online calibration. In order to gather sufficient statistics for the calibration, the asynchronous calibration component must process enough events per time interval. Since the calibration is valid only for a certain time period, the delay until the feedback loop provides updated calibration data must not be too long. A first full-scale test of the online calibration functionality was performed during 2015 heavy-ion run under real conditions. Since then, online calibration is enabled and benchmarked in 2016 proton-proton data taking. We present a timing analysis of this first online-calibration test, which concludes that the HLT is capable of online TPC drift time calibration fast enough to calibrate the tracking via the feedback loop. We compare the calibration results with the offline calibration and present a comparison of the residuals of the TPC cluster coordinates with respect to offline reconstruction.

Learning Objects and Gerontology

ERIC Educational Resources Information Center

Weinreich, Donna M.; Tompkins, Catherine J.

2006-01-01

Virtual AGE (vAGE) is an asynchronous educational environment that utilizes learning objects focused on gerontology and a learning anytime/anywhere philosophy. This paper discusses the benefits of asynchronous instruction and the process of creating learning objects. Learning objects are "small, reusable chunks of instructional media" Wiley…

Redundant Asynchronous Microprocessor System

NASA Technical Reports Server (NTRS)

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.

On a model of three-dimensional bursting and its parallel implementation

NASA Astrophysics Data System (ADS)

Tabik, S.; Romero, L. F.; Garzón, E. M.; Ramos, J. I.

2008-04-01

A mathematical model for the simulation of three-dimensional bursting phenomena and its parallel implementation are presented. The model consists of four nonlinearly coupled partial differential equations that include fast and slow variables, and exhibits bursting in the absence of diffusion. The differential equations have been discretized by means of a second-order accurate in both space and time, linearly-implicit finite difference method in equally-spaced grids. The resulting system of linear algebraic equations at each time level has been solved by means of the Preconditioned Conjugate Gradient (PCG) method. Three different parallel implementations of the proposed mathematical model have been developed; two of these implementations, i.e., the MPI and the PETSc codes, are based on a message passing paradigm, while the third one, i.e., the OpenMP code, is based on a shared space address paradigm. These three implementations are evaluated on two current high performance parallel architectures, i.e., a dual-processor cluster and a Shared Distributed Memory (SDM) system. A novel representation of the results that emphasizes the most relevant factors that affect the performance of the paralled implementations, is proposed. The comparative analysis of the computational results shows that the MPI and the OpenMP implementations are about twice more efficient than the PETSc code on the SDM system. It is also shown that, for the conditions reported here, the nonlinear dynamics of the three-dimensional bursting phenomena exhibits three stages characterized by asynchronous, synchronous and then asynchronous oscillations, before a quiescent state is reached. It is also shown that the fast system reaches steady state in much less time than the slow variables.

A comparison of classroom and online asynchronous problem-based learning for students undertaking statistics training as part of a Public Health Masters degree.

PubMed

de Jong, N; Verstegen, D M L; Tan, F E S; O'Connor, S J

2013-05-01

This case-study compared traditional, face-to-face classroom-based teaching with asynchronous online learning and teaching methods in two sets of students undertaking a problem-based learning module in the multilevel and exploratory factor analysis of longitudinal data as part of a Masters degree in Public Health at Maastricht University. Students were allocated to one of the two study variants on the basis of their enrolment status as full-time or part-time students. Full-time students (n = 11) followed the classroom-based variant and part-time students (n = 12) followed the online asynchronous variant which included video recorded lectures and a series of asynchronous online group or individual SPSS activities with synchronous tutor feedback. A validated student motivation questionnaire was administered to both groups of students at the start of the study and a second questionnaire was administered at the end of the module. This elicited data about student satisfaction with the module content, teaching and learning methods, and tutor feedback. The module coordinator and problem-based learning tutor were also interviewed about their experience of delivering the experimental online variant and asked to evaluate its success in relation to student attainment of the module's learning outcomes. Student examination results were also compared between the two groups. Asynchronous online teaching and learning methods proved to be an acceptable alternative to classroom-based teaching for both students and staff. Educational outcomes were similar for both groups, but importantly, there was no evidence that the asynchronous online delivery of module content disadvantaged part-time students in comparison to their full-time counterparts.

A Taxonomy of Asynchronous Instructional Video Styles

ERIC Educational Resources Information Center

Chorianopoulos, Konstantinos

2018-01-01

Many educational organizations are employing instructional videos in their pedagogy, but there is a limited understanding of the possible video formats. In practice, the presentation format of instructional videos ranges from direct recording of classroom teaching with a stationary camera, or screencasts with voiceover, to highly elaborate video…

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

PubMed

Lew, Edward K; Nordquist, Erik K

2016-01-01

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. The goal was to evaluate effectiveness, participation, and preference for this mode of learning. 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. 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. 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.

Adaptive digital beamforming for a CDMA mobile communications payload

NASA Technical Reports Server (NTRS)

Munoz-Garcia, Samuel G.; Ruiz, Javier Benedicto

1993-01-01

In recent years, Spread-Spectrum Code Division Multiple Access (CDMA) has become a very popular access scheme for mobile communications due to a variety of reasons: excellent performance in multipath environments, high scope for frequency reuse, graceful degradation near saturation, etc. In this way, a CDMA system can support simultaneous digital communication among a large community of relatively uncoordinated users sharing a given frequency band. Nevertheless, there are also important problems associated with the use of CDMA. First, in a conventional CDMA scheme, the signature sequences of asynchronous users are not orthogonal and, as the number of active users increases, the self-noise generated by the mutual interference between users considerably degrades the performance, particularly in the return link. Furthermore, when there is a large disparity in received powers - due to differences in slant range or atmospheric attenuation - the non-zero cross-correlation between the signals gives rise to the so-called near-far problem. This leads to an inefficient utilization of the satellite resources and, consequently, to a drastic reduction in capacity. Several techniques were proposed to overcome this problem, such as Synchronized CDMA - in which the signature sequences of the different users are quasi-orthogonal - and power control. At the expense of increased network complexity and user coordination, these techniques enable the system capacity to be restored by equitably sharing the satellite resources among the users. An alternative solution is presented based upon the use of time-reference adaptive digital beamforming on board the satellite. This technique enables a high number of independently steered beams to be generated from a single phased array antenna, which automatically track the desired user signal and null the unwanted interference source. In order to use a time-reference adaptive antenna in a communications system, the main challenge is to obtain a reference signal highly correlated with the desired user signal and uncorrelated with the interferences. CDMA lends itself very easily to the generation of such a reference signal, thanks to the a priori knowledge of the user's signature sequence. First, the integration of an adaptive antenna in an asynchronous CDMA system is analyzed. The adaptive antenna system can provide increased interference rejection - much higher than that afforded by the code alone - and, since CDMA is mainly interference limited, any reduction in interference converts directly and linearly into an increase in capacity. Analyses and computer simulations are presented that show how an asynchronous CDMA system incorporating adaptive beamforming can provide at least as much capacity as a synchronous system. More importantly, the proposed concept allows the near-far effect to be mitigated without requiring a tight coordination of the users in terms of transmitted power control or network synchronization. The system is extremely robust to the near-far effect because the signals reaching the satellite from directions other than that of the desired user - which are likely to have different power levels - are adaptively canceled by the antenna. Finally, a payload architecture is presented that illustrates the practical implementation of this concept. This digital payload architecture demonstrates that with the advent of high performance CMOS digital processing, the on-board implementation of complex DSP techniques - in particular Digital Beamforming - has become possible, being most attractive for Mobile Satellite Communications.

Adaptive digital beamforming for a CDMA mobile communications payload

NASA Astrophysics Data System (ADS)

Munoz-Garcia, Samuel G.; Ruiz, Javier Benedicto

In recent years, Spread-Spectrum Code Division Multiple Access (CDMA) has become a very popular access scheme for mobile communications due to a variety of reasons: excellent performance in multipath environments, high scope for frequency reuse, graceful degradation near saturation, etc. In this way, a CDMA system can support simultaneous digital communication among a large community of relatively uncoordinated users sharing a given frequency band. Nevertheless, there are also important problems associated with the use of CDMA. First, in a conventional CDMA scheme, the signature sequences of asynchronous users are not orthogonal and, as the number of active users increases, the self-noise generated by the mutual interference between users considerably degrades the performance, particularly in the return link. Furthermore, when there is a large disparity in received powers - due to differences in slant range or atmospheric attenuation - the non-zero cross-correlation between the signals gives rise to the so-called near-far problem. This leads to an inefficient utilization of the satellite resources and, consequently, to a drastic reduction in capacity. Several techniques were proposed to overcome this problem, such as Synchronized CDMA - in which the signature sequences of the different users are quasi-orthogonal - and power control. At the expense of increased network complexity and user coordination, these techniques enable the system capacity to be restored by equitably sharing the satellite resources among the users. An alternative solution is presented based upon the use of time-reference adaptive digital beamforming on board the satellite. This technique enables a high number of independently steered beams to be generated from a single phased array antenna, which automatically track the desired user signal and null the unwanted interference source. In order to use a time-reference adaptive antenna in a communications system, the main challenge is to obtain a reference signal highly correlated with the desired user signal and uncorrelated with the interferences. CDMA lends itself very easily to the generation of such a reference signal, thanks to the a priori knowledge of the user's signature sequence. First, the integration of an adaptive antenna in an asynchronous CDMA system is analyzed. The adaptive antenna system can provide increased interference rejection - much higher than that afforded by the code alone - and, since CDMA is mainly interference limited, any reduction in interference converts directly and linearly into an increase in capacity. Analyses and computer simulations are presented that show how an asynchronous CDMA system incorporating adaptive beamforming can provide at least as much capacity as a synchronous system. More importantly, the proposed concept allows the near-far effect to be mitigated without requiring a tight coordination of the users in terms of transmitted power control or network synchronization. The system is extremely robust to the near-far effect because the signals reaching the satellite from directions other than that of the desired user - which are likely to have different power levels - are adaptively canceled by the antenna. Finally, a payload architecture is presented that illustrates the practical implementation of this concept.

Data Capture Technique for High Speed Signaling

DOEpatents

Barrett, Wayne Melvin; Chen, Dong; Coteus, Paul William; Gara, Alan Gene; Jackson, Rory; Kopcsay, Gerard Vincent; Nathanson, Ben Jesse; Vranas, Paylos Michael; Takken, Todd E.

2008-08-26

A data capture technique for high speed signaling to allow for optimal sampling of an asynchronous data stream. This technique allows for extremely high data rates and does not require that a clock be sent with the data as is done in source synchronous systems. The present invention also provides a hardware mechanism for automatically adjusting transmission delays for optimal two-bit simultaneous bi-directional (SiBiDi) signaling.

Innovative Methods for Providing Instruction to Distance Students Using Technology.

ERIC Educational Resources Information Center

Pival, Paul R.; Tunon, Johanna

2001-01-01

Examines three innovative methods tried at Nova Southeastern University for providing quality bibliographic instruction to distance students: one synchronous, one asynchronous, and one that combined features from both synchronous and asynchronous methods of delivering instruction. Topics include compressed video, collaborative groupware, streaming…

Miscellany of Students' Satisfaction in an Asynchronous Learning Environment

ERIC Educational Resources Information Center

Larbi-Siaw, Otu; Owusu-Agyeman, Yaw

2017-01-01

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

Developing asynchronous online interprofessional education.

PubMed

Sanborn, Heidi

2016-09-01

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

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

PubMed

Zhou, Keming; Cherra, Salvatore J; Goncharov, Alexandr; Jin, Yishi

2017-05-09

Excitation-inhibition imbalance in neural networks is widely linked to neurological and neuropsychiatric disorders. However, how genetic factors alter neuronal activity, leading to excitation-inhibition imbalance, remains unclear. Here, using the C. elegans locomotor circuit, we examine how altering neuronal activity for varying time periods affects synaptic release pattern and animal behavior. We show that while short-duration activation of excitatory cholinergic neurons elicits a reversible enhancement of presynaptic strength, persistent activation results to asynchronous and reduced cholinergic drive, inducing imbalance between endogenous excitation and inhibition. We find that the neuronal calcium sensor protein NCS-2 is required for asynchronous cholinergic release in an activity-dependent manner and dampens excitability of inhibitory neurons non-cell autonomously. The function of NCS-2 requires its Ca 2+ binding and membrane association domains. These results reveal a synaptic mechanism implicating asynchronous release in regulation of excitation-inhibition balance. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Asynchronous and synchronous dual-wavelength pulse generation in a passively mode-locked fiber laser with a mode-locker.

PubMed

Hu, Guoqing; Pan, Yingling; Zhao, Xin; Yin, Siyao; Zhang, Meng; Zheng, Zheng

2017-12-01

The evolution from asynchronous to synchronous dual-wavelength pulse generation in a passively mode-locked fiber laser is experimentally investigated by tailoring the intracavity dispersion. Through tuning the intracavity-loss-dependent gain profile and the birefringence-induced filter effect, asynchronous dual-wavelength soliton pulses can be generated until the intracavity anomalous dispersion is reduced to ∼8  fs/nm. The transition from asynchronous to synchronous pulse generation is then observed at an elevated pump power in the presence of residual anomalous dispersion, and it is shown that pulses are temporally synchronized at the mode-locker in the cavity. Spectral sidelobes are observed and could be attributed to the four-wave-mixing effect between dual-wavelength pulses at the carbon nanotube mode-locker. These results could provide further insight into the design and realization of such dual-wavelength ultrafast lasers for different applications such as dual-comb metrology as well as better understanding of the inter-pulse interactions in such dual-comb lasers.

Bonsai: an event-based framework for processing and controlling data streams

PubMed Central

Lopes, Gonçalo; Bonacchi, Niccolò; Frazão, João; Neto, Joana P.; Atallah, Bassam V.; Soares, Sofia; Moreira, Luís; Matias, Sara; Itskov, Pavel M.; Correia, Patrícia A.; Medina, Roberto E.; Calcaterra, Lorenza; Dreosti, Elena; Paton, Joseph J.; Kampff, Adam R.

2015-01-01

The design of modern scientific experiments requires the control and monitoring of many different data streams. However, the serial execution of programming instructions in a computer makes it a challenge to develop software that can deal with the asynchronous, parallel nature of scientific data. Here we present Bonsai, a modular, high-performance, open-source visual programming framework for the acquisition and online processing of data streams. We describe Bonsai's core principles and architecture and demonstrate how it allows for the rapid and flexible prototyping of integrated experimental designs in neuroscience. We specifically highlight some applications that require the combination of many different hardware and software components, including video tracking of behavior, electrophysiology and closed-loop control of stimulation. PMID:25904861

Fiber optic cable-based high-resolution, long-distance VGA extenders

NASA Astrophysics Data System (ADS)

Rhee, Jin-Geun; Lee, Iksoo; Kim, Heejoon; Kim, Sungjoon; Koh, Yeon-Wan; Kim, Hoik; Lim, Jiseok; Kim, Chur; Kim, Jungwon

2013-02-01

Remote transfer of high-resolution video information finds more applications in detached display applications for large facilities such as theaters, sports complex, airports, and security facilities. Active optical cables (AOCs) provide a promising approach for enhancing both the transmittable resolution and distance that standard copper-based cables cannot reach. In addition to the standard digital formats such as HDMI, the high-resolution, long-distance transfer of VGA format signals is important for applications where high-resolution analog video ports should be also supported, such as military/defense applications and high-resolution video camera links. In this presentation we present the development of a compressionless, high-resolution (up to WUXGA, 1920x1200), long-distance (up to 2 km) VGA extenders based on serialized technique. We employed asynchronous serial transmission and clock regeneration techniques, which enables lower cost implementation of VGA extenders by removing the necessity for clock transmission and large memory at the receiver. Two 3.125-Gbps transceivers are used in parallel to meet the required maximum video data rate of 6.25 Gbps. As the data are transmitted asynchronously, 24-bit pixel clock time stamp is employed to regenerate video pixel clock accurately at the receiver side. In parallel to the video information, stereo audio and RS-232 control signals are transmitted as well.

Learning and Skills Development in a Virtual Class of Educommunication Based on Educational Proposals and Interactions

ERIC Educational Resources Information Center

Bohorquez Sotelo, Maria Cristina; Rodriguez Mendoza, Brigitte Julieth; Vega, Sandra Milena; Roja Higuera, Naydu Shirley; Barbosa Gomez, Luisa Fernanda

2016-01-01

In the present paper we describe the analysis of qualitative and quantitative data from asynchronous learning networks, the virtual forums that take place in VirtualNet 2.0, the platform of the University Manuela Beltran (UMB), inside the course of Educommunication, from the master of Digital technologies applied to education. Here, we performed a…

Style Matching or Ability Building? An Empirical Study on FD Learners' Learning in Well-Structured and Ill-Structured Asynchronous Online Learning Environments

ERIC Educational Resources Information Center

Zheng, Robert Z.; Flygare, Jill A.; Dahl, Laura B.

2009-01-01

The present study investigated (1) the impact of cognitive styles on learner performance in well-structured and ill-structured learning, and (2) scaffolding as a cognitive tool to improve learners' cognitive abilities, especially field dependent (FD) learners' ability to thrive in an ill-structured learning environment. Two experiments were…

The VIRI (Virtual, Interactive, Real-Time, Instructor-Led) Classroom: The Impact of Blended Synchronous Online Courses on Student Performance, Engagement, and Satisfaction

ERIC Educational Resources Information Center

Francescucci, Anthony; Foster, Mary

2013-01-01

Previous research on blended course offerings focuses on the addition of asynchronous online content to an existing course. While some explore synchronous communication, few control for differences between treatment groups. This study investigates the impact of teaching a blended course, using a virtual, interactive, real-time, instructor-led…

Maximizing the Use of a Web-Based Soils Module: Targeting Diverse Populations

ERIC Educational Resources Information Center

Lippert, Robert

2006-01-01

This article deals with an on-line soils module project. The two goals for this part of the project were to determine if an on-line soils module could be successfully used for asynchronous instruction of two diverse populations and to determine which demographic factors are related to test performance. The module was presented to an eighth-grade…

Optimizing symmetry-based recoupling sequences in solid-state NMR by pulse-transient compensation and asynchronous implementation

NASA Astrophysics Data System (ADS)

Hellwagner, Johannes; Sharma, Kshama; Tan, Kong Ooi; Wittmann, Johannes J.; Meier, Beat H.; Madhu, P. K.; Ernst, Matthias

2017-06-01

Pulse imperfections like pulse transients and radio-frequency field maladjustment or inhomogeneity are the main sources of performance degradation and limited reproducibility in solid-state nuclear magnetic resonance experiments. We quantitatively analyze the influence of such imperfections on the performance of symmetry-based pulse sequences and describe how they can be compensated. Based on a triple-mode Floquet analysis, we develop a theoretical description of symmetry-based dipolar recoupling sequences, in particular, R2 6411, calculating first- and second-order effective Hamiltonians using real pulse shapes. We discuss the various origins of effective fields, namely, pulse transients, deviation from the ideal flip angle, and fictitious fields, and develop strategies to counteract them for the restoration of full transfer efficiency. We compare experimental applications of transient-compensated pulses and an asynchronous implementation of the sequence to a supercycle, SR26, which is known to be efficient in compensating higher-order error terms. We are able to show the superiority of R26 compared to the supercycle, SR26, given the ability to reduce experimental error on the pulse sequence by pulse-transient compensation and a complete theoretical understanding of the sequence.

Global tree network for computing structures enabling global processing operations

DOEpatents

Blumrich; Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Hoenicke, Dirk; Steinmacher-Burow, Burkhard D.; Takken, Todd E.; Vranas, Pavlos M.

2010-01-19

A system and method for enabling high-speed, low-latency global tree network communications among processing nodes interconnected according to a tree network structure. The global tree network enables collective reduction operations to be performed during parallel algorithm operations executing in a computer structure having a plurality of the interconnected processing nodes. Router devices are included that interconnect the nodes of the tree via links to facilitate performance of low-latency global processing operations at nodes of the virtual tree and sub-tree structures. The global operations performed include one or more of: broadcast operations downstream from a root node to leaf nodes of a virtual tree, reduction operations upstream from leaf nodes to the root node in the virtual tree, and point-to-point message passing from any node to the root node. The global tree network is configurable to provide global barrier and interrupt functionality in asynchronous or synchronized manner, and, is physically and logically partitionable.

Primordial oscillations in life: Direct observation of glycolytic oscillations in individual HeLa cervical cancer cells

NASA Astrophysics Data System (ADS)

Amemiya, Takashi; Shibata, Kenichi; Itoh, Yoshihiro; Itoh, Kiminori; Watanabe, Masatoshi; Yamaguchi, Tomohiko

2017-10-01

We report the first direct observation of glycolytic oscillations in HeLa cervical cancer cells, which we regard as primordial oscillations preserved in living cells. HeLa cells starved of glucose or both glucose and serum exhibited glycolytic oscillations in nicotinamide adenine dinucleotide (NADH), exhibiting asynchronous intercellular behaviors. Also found were spatially homogeneous and inhomogeneous intracellular NADH oscillations in the individual cells. Our results demonstrate that starved HeLa cells may be induced to exhibit glycolytic oscillations by either high-uptake of glucose or the enhancement of a glycolytic pathway (Crabtree effect or the Warburg effect), or both. Their asynchronous collective behaviors in the oscillations were probably due to a weak intercellular coupling. Elucidation of the relationship between the mechanism of glycolytic dynamics in cancer cells and their pathophysiological characteristics remains a challenge in future.

Asynchronous updates can promote the evolution of cooperation on multiplex networks

NASA Astrophysics Data System (ADS)

Allen, James M.; Hoyle, Rebecca B.

2017-04-01

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

Control strategy for a variable-speed wind energy conversion system

NASA Technical Reports Server (NTRS)

Jacob, A.; Veillette, D.; Rajagopalan, V.

1979-01-01

A control concept for a variable-speed wind energy conversion system is proposed, for which a self-exited asynchronous cage generator is used along with a system of thyristor converters. The control loops are the following: (1) regulation of the entrainment speed as function of available mechanical energy by acting on the resistance couple of the asynchronous generator; (2) control of electric power delivered to the asynchronous machine, functioning as a motor, for start-up of the vertical axis wind converter; and (3) limitation of the slip value, and by consequence, of the induction currents in the presence of sudden variations of input parameters.

False lock performance in polarity-type Costas receivers in the presence of periodic data patterns

NASA Technical Reports Server (NTRS)

Wang, James June-Ming; Lai, Dennis Teng-Tsun; Heng, Veronica Siang-Gek; Godfrey, Robert D.

1987-01-01

The authors address the false-lock performance of receivers which use polarity-type Costas loops for the carrier recovery of unbalanced quadrature phase-shift keyed (QPSK), asynchronous QPSK or binary PSK (BPSK) signals in the presence of periodic data patterns. The potential false-lock frequencies are first identified. Expressions for both true-lock and false-lock components are also derived, thereby allowing numerical evaluation of various key parameters for cases of practical interest.

CAMAC: A Unique Application with a Pocket Terminal.

DTIC Science & Technology

1982-09-16

POCKET TERMINAL S. PERFORMING ORG. REPORT NUMSIER I. AUTWOR(o) S. CONTRACT OR GRANT NUMU41’e() A.D. Elmond S. PERFORMING ORGANIZATION NAME AND ADORIESS 10...port of any CAMAC crate. In addition to being a maintenance device, the HHTT is a " smart " device that can control operations in a CAMAC crate. The...system LSI 11/23 microprocessor through an Asynchronous Serial Port (ASP) interface module. This ASP interface consists of: 1) Crystal Clock 2) MIK -Bus

Virtual Mentorship Network to Address the Rural Shortage of Mental Health Providers.

PubMed

Keeler, Heidi; Sjuts, Tara; Niitsu, Kosuke; Watanabe-Galloway, Shinobu; Mackie, Paul Force-Emery; Liu, Howard

2018-06-01

The process of identifying effective responses to the challenges of placing and retaining a rural behavioral health workforce remains elusive. The Virtual Mentorship Network was developed to test the feasibility of using distance technology to connect rural students interested in mental health careers with mentors. In Year 1, college and high school students were virtually mentored using a near-peer approach both live and asynchronously as a cohort over 7 months. In Year 2, college students only were virtually intensely mentored live over 1 month. High school students were asynchronously provided with informational videos produced by mentors. Program benefits were measured using the Mentoring Functions Questionnaire, and an activity satisfaction survey captured student response to the content and delivery methods. Retrospective analysis of Years 1 and 2 mentoring and satisfaction variables mean differences was performed and overall feasibility assessed. Mentoring Functions Questionnaire scores, overall interaction, and reported satisfaction significantly improved in Year 2 over Year 1. These data suggest that distance mentoring is a feasible option, but that the near-peer benefits of virtually mentoring high school and college students together are overshadowed by different mentoring needs expressed for each group. High school students expressed needs for basic information about career possibilities, whereas college student needs are specific to achieving career goals. Shorter mentoring sessions may be more sustainable long-term and focus limited mentoring resources. This project may serve as a professional pipeline model for others who face a critical shortage of mental health providers. This article is part of a supplement entitled The Behavioral Health Workforce: Planning, Practice, and Preparation, which is sponsored by the Substance Abuse and Mental Health Services Administration and the Health Resources and Services Administration of the U.S. Department of Health and Human Services. Copyright © 2018 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Asynchronous versus Synchronous Learning in Pharmacy Education

ERIC Educational Resources Information Center

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

2013-01-01

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

Knowledge Building in Asynchronous Discussion Groups: Going Beyond Quantitative Analysis

ERIC Educational Resources Information Center

Schrire, Sarah

2006-01-01

This contribution examines the methodological challenges involved in defining the collaborative knowledge-building processes occurring in asynchronous discussion and proposes an approach that could advance understanding of these processes. The written protocols that are available to the analyst provide an exact record of the instructional…

Creating and Nurturing Distributed Asynchronous Learning Environments.

ERIC Educational Resources Information Center

Kochtanek, Thomas R.; Hein, Karen K.

2000-01-01

Describes the evolution of a university course from a face-to-face experience to a Web-based asynchronous learning environment. Topics include cognition and learning; distance learning and distributed learning; student learning communities and the traditional classroom; the future as it relates to education and technology; collaborative student…

Learning about the Literacy Development of English Language Learners in Asynchronous Online Discussions

ERIC Educational Resources Information Center

De Oliveira, Luciana C.; Olesova, Larisa

2013-01-01

This study examined asynchronous online discussions in the online course "English Language Development" to identify themes related to participants' learning about the language and literacy development of English Language Learners when they facilitated online discussions to determine whether the participants developed sufficient…

Creating Asynchronous Online Learning Communities

ERIC Educational Resources Information Center

Kerr, Crystal

2009-01-01

This research project examined how to develop and sustain online, asynchronous learning communities in continuous intake, distance education environments for learners in grades 7 through 10. The study is an action research project that is based upon in-depth, qualitative data. Interviews were conducted with distance education teachers,…

Enhancement of increments in spectral amplitude: further evidence for a mechanism based on central adaptation.

PubMed

Carcagno, Samuele; Semal, Catherine; Demany, Laurent

2013-01-01

The threshold for detecting a tone in a multitone masker is lower when the masker-plus-signal stimulus is preceded by a copy of the masker. One potential explanation of this "enhancement" phenomenon is that the -precursor stimulus acts as a "template" of the subsequent masker, thus helping listeners to segregate the signal from the masker. To assess this idea, we measured enhancement for precursors that were perceptually similar to the masker and for precursors that were made dissimilar to the masker by gating their components asynchronously. We found that the two types of precursor produced similar amounts of enhancement. This was true not only when the precursor and the subsequent test stimulus were presented to the same ear but also when they were presented to opposite ears. In a second experiment, we checked that the precursors with asynchronously gated components were perceptually poor templates of the subsequent maskers. Listeners now had to discriminate between test stimuli -containing the same components as the precursor and test stimuli containing all but one of the precursor components. We found that in this experimental situation, where enhancement could play no role, gating the precursor components asynchronously disrupted performance. Overall, our results are inconsistent with the hypothesis that precursors producing enhancement are beneficial because they are used as perceptual templates of the masker. Our results are instead consistent with an -explanation of enhancement based on selective neural adaptation taking place at a central locus of the auditory system.

Feature Representations for Neuromorphic Audio Spike Streams.

PubMed

Anumula, Jithendar; Neil, Daniel; Delbruck, Tobi; Liu, Shih-Chii

2018-01-01

Event-driven neuromorphic spiking sensors such as the silicon retina and the silicon cochlea encode the external sensory stimuli as asynchronous streams of spikes across different channels or pixels. Combining state-of-art deep neural networks with the asynchronous outputs of these sensors has produced encouraging results on some datasets but remains challenging. While the lack of effective spiking networks to process the spike streams is one reason, the other reason is that the pre-processing methods required to convert the spike streams to frame-based features needed for the deep networks still require further investigation. This work investigates the effectiveness of synchronous and asynchronous frame-based features generated using spike count and constant event binning in combination with the use of a recurrent neural network for solving a classification task using N-TIDIGITS18 dataset. This spike-based dataset consists of recordings from the Dynamic Audio Sensor, a spiking silicon cochlea sensor, in response to the TIDIGITS audio dataset. We also propose a new pre-processing method which applies an exponential kernel on the output cochlea spikes so that the interspike timing information is better preserved. The results from the N-TIDIGITS18 dataset show that the exponential features perform better than the spike count features, with over 91% accuracy on the digit classification task. This accuracy corresponds to an improvement of at least 2.5% over the use of spike count features, establishing a new state of the art for this dataset.

Feature Representations for Neuromorphic Audio Spike Streams

PubMed Central

Anumula, Jithendar; Neil, Daniel; Delbruck, Tobi; Liu, Shih-Chii

2018-01-01

Event-driven neuromorphic spiking sensors such as the silicon retina and the silicon cochlea encode the external sensory stimuli as asynchronous streams of spikes across different channels or pixels. Combining state-of-art deep neural networks with the asynchronous outputs of these sensors has produced encouraging results on some datasets but remains challenging. While the lack of effective spiking networks to process the spike streams is one reason, the other reason is that the pre-processing methods required to convert the spike streams to frame-based features needed for the deep networks still require further investigation. This work investigates the effectiveness of synchronous and asynchronous frame-based features generated using spike count and constant event binning in combination with the use of a recurrent neural network for solving a classification task using N-TIDIGITS18 dataset. This spike-based dataset consists of recordings from the Dynamic Audio Sensor, a spiking silicon cochlea sensor, in response to the TIDIGITS audio dataset. We also propose a new pre-processing method which applies an exponential kernel on the output cochlea spikes so that the interspike timing information is better preserved. The results from the N-TIDIGITS18 dataset show that the exponential features perform better than the spike count features, with over 91% accuracy on the digit classification task. This accuracy corresponds to an improvement of at least 2.5% over the use of spike count features, establishing a new state of the art for this dataset. PMID:29479300

Skype Synchronous Interaction Effectiveness in a Quantitative Management Science Course

ERIC Educational Resources Information Center

Strang, Kenneth David

2012-01-01

An experiment compared asynchronous versus synchronous instruction in an online quantitative course. Mann-Whitney U-tests, correlation, analysis of variance, t tests, and multivariate analysis of covariance (MANCOVA) were utilized to test the hypothesis that more high-quality online experiential learning interactions would increase grade.…

Asynchronous Visualization of Spatiotemporal Information for Multiple Moving Targets

ERIC Educational Resources Information Center

Wang, Huadong

2013-01-01

In the modern information age, the quantity and complexity of spatiotemporal data is increasing both rapidly and continuously. Sensor systems with multiple feeds that gather multidimensional spatiotemporal data will result in information clusters and overload, as well as a high cognitive load for users of these systems. To meet future…

The Necessity of Real-Time: Fact and Fiction in Digital Reference Systems.

ERIC Educational Resources Information Center

Lankes, R. David; Shostack, Pauline

2002-01-01

Discussion of digital reference services and the use of real-time versus asynchronous services such as email focuses on data from the AskERIC digital reference service to demonstrate that asynchronous services are not only useful but may have greater utility than real-time systems. (Author/LRW)

Positioning (Mis)Aligned: The (Un)Making of Intercultural Asynchronous Computer-Mediated Communication

ERIC Educational Resources Information Center

Wu, Zhiwei

2018-01-01

Framed from positioning theory and dynamic systems theory, the paper reports on a naturalistic study involving four Chinese participants and their American peers in an intercultural asynchronous computer-mediated communication (ACMC) activity. Based on the moment-by-moment analysis and triangulation of forum posts, reflective essays, and…

Automated Feedback as a Convergence Tool

ERIC Educational Resources Information Center

Chenoweth, Tim; Corral, Karen; Scott, Kit

2016-01-01

This study evaluates two content delivery options for teaching a programming language to determine whether an asynchronous format can achieve the same learning efficacy as a traditional lecture (face-to-face) format. We use media synchronicity theory as a guide to choose media capabilities to incorporate into an asynchronous tutorial used…

Principles for Effective Asynchronous Online Instruction in Religious Studies

ERIC Educational Resources Information Center

McGuire, Beverley

2017-01-01

Asynchronous online instruction has become increasingly popular in the field of religious studies. However, despite voluminous research on online learning in general and numerous articles on online theological instruction, there has been little discussion of how to effectively design and deliver online undergraduate courses in religious studies.…

Investigating Asynchronous Online Communication: A Connected Stance Revealed

ERIC Educational Resources Information Center

Wegmann, Susan J.; McCauley, Joyce K.

2014-01-01

This research project explores the effects of altering the structure of discussion board formats to increase students' engagement and participation. This paper will present the findings of a two-university, two-class research project in which asynchronous discussion board entries were analyzed for substance. By using oral discourse analysis…

Theoretically Based Pedagogical Strategies Leading to Deep Learning in Asynchronous Online Gerontology Courses

ERIC Educational Resources Information Center

Majeski, Robin; Stover, Merrily

2007-01-01

Online learning has enjoyed increasing popularity in gerontology. This paper presents instructional strategies grounded in Fink's (2003) theory of significant learning designed for the completely asynchronous online gerontology classroom. It links these components with the development of mastery learning goals and provides specific guidelines for…

Developing a Successful Asynchronous Online Extension Program for Forest Landowners

ERIC Educational Resources Information Center

Zobrist, Kevin W.

2014-01-01

Asynchronous online Extension classes can reach a wide audience, is convenient for the learner, and minimizes ongoing demands on instructor time. However, producing such classes takes significant effort up front. Advance planning and good communication with contributors are essential to success. Considerations include delivery platforms, content…

Cultural Influences on Chinese Students' Asynchronous Online Learning in a Canadian University

ERIC Educational Resources Information Center

Zhao, Naxin; McDougall, Douglas

2008-01-01

This study explored six Chinese graduate students' asynchronous online learning in a large urban Canadian university. Individual interviews in Mandarin elicited their perceptions of online learning, their participation in it, and the cultural factors that influenced their experiences. In general, the participants had a positive attitude towards…

Language Use in Asynchronous Computer-Mediated Communication in Taiwan

ERIC Educational Resources Information Center

Huang, Daphne Li-jung

2009-01-01

This paper describes how Chinese-English bilinguals in Taiwan use their languages in asynchronous computer-mediated communication, specifically, via Bulletin Board System (BBS) and email. The main data includes two types: emails collected from a social network and postings collected from two BBS websites. By examining patterns of language choice…

Students' Use of Asynchronous Discussions for Academic Discourse Socialization

ERIC Educational Resources Information Center

Beckett, Gulbahar H.; Amaro-Jimenez, Carla; Beckett, Kelvin S.

2010-01-01

Our universities are becoming increasingly diverse at the same time as online asynchronous discussions (OADs) are emerging as the most important forum for computer mediated communication (CMC) in distance education. But there is shortage of studies that explore how graduate students from different ethnic, linguistic and cultural backgrounds use…

Effects of Belongingness and Synchronicity on Face-to-Face and Computer-Mediated Online Cooperative Pedagogy

ERIC Educational Resources Information Center

Saltarelli, Andrew John

2012-01-01

Previous research suggests asynchronous online computer-mediated communication (CMC) has deleterious effects on certain cooperative learning pedagogies (e.g., constructive controversy), but the processes underlying this effect and how it may be ameliorated remain unclear. This study tests whether asynchronous CMC thwarts belongingness needs…

A Group Intelligence-Based Asynchronous Argumentation Learning-Assistance Platform

ERIC Educational Resources Information Center

Huang, Chenn-Jung; Chang, Shun-Chih; Chen, Heng-Ming; Tseng, Jhe-Hao; Chien, Sheng-Yuan

2016-01-01

Structured argumentation support environments have been built and used in scientific discourse in the literature. However, to the best our knowledge, there is no research work in the literature examining whether student's knowledge has grown during learning activities with asynchronous argumentation. In this work, an intelligent computer-supported…

Participation, Interaction and Social Presence: An Exploratory Study of Collaboration in Online Peer Review Groups

ERIC Educational Resources Information Center

Zhao, Huahui; Sullivan, Kirk P. H.; Mellenius, Ingmarie

2014-01-01

A key reason for using asynchronous computer conferencing in instruction is its potential for supporting collaborative learning. However, few studies have examined collaboration in computer conferencing. This study examined collaboration in six peer review groups within an asynchronous computer conferencing. Eighteen tertiary students participated…

Asynchronous Group Review of EFL Writing: Interactions and Text Revisions

ERIC Educational Resources Information Center

Saeed, Murad Abdu; Ghazali, Kamila

2017-01-01

The current paper reports an empirical study of asynchronous online group review of argumentative essays among nine English as foreign language (EFL) Arab university learners joining English in their first, second, and third years at the institution. In investigating online interactions, commenting patterns, and how the students facilitate text…

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

ERIC Educational Resources Information Center

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…

A Coding Scheme to Analyse the Online Asynchronous Discussion Forums of University Students

ERIC Educational Resources Information Center

Biasutti, Michele

2017-01-01

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

Using Computer-Mediated Communication to Establish Social and Supportive Environments in Teacher Education

ERIC Educational Resources Information Center

Arnold, Nike; Ducate, Lara; Lomicka, Lara; Lord, Gillian

2005-01-01

This article examines social presence in virtual asynchronous learning communities among foreign language teachers. We present the findings of two studies investigating cross-institutional asynchronous forums created to engage participants in online dialogues regarding their foreign language teacher preparation experiences in and out of the…

Adding the Human Touch to Asynchronous Online Learning

ERIC Educational Resources Information Center

Glenn, Cynthia Wheatley

2018-01-01

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

Increasing Student Engagement Using Asynchronous Learning

ERIC Educational Resources Information Center

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…

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

NASA Astrophysics Data System (ADS)

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.

Command and Control Common Semantic Core Required to Enable Net-centric Operations

DTIC Science & Technology

2008-05-20

automated processing capability. A former US Marine Corps component C4 director during Operation Iraqi Freedom identified the problems of 1) uncertainty...interoperability improvements to warfighter community processes, thanks to ubiquitous automated processing , are likely high and somewhat easier to quantify. A...synchronized with the actions of other partners / warfare communities. This requires high- quality information, rapid sharing and automated processing – which

Predictability in Cellular Automata

PubMed Central

Agapie, Alexandru; Andreica, Anca; Chira, Camelia; Giuclea, Marius

2014-01-01

Modelled as finite homogeneous Markov chains, probabilistic cellular automata with local transition probabilities in (0, 1) always posses a stationary distribution. This result alone is not very helpful when it comes to predicting the final configuration; one needs also a formula connecting the probabilities in the stationary distribution to some intrinsic feature of the lattice configuration. Previous results on the asynchronous cellular automata have showed that such feature really exists. It is the number of zero-one borders within the automaton's binary configuration. An exponential formula in the number of zero-one borders has been proved for the 1-D, 2-D and 3-D asynchronous automata with neighborhood three, five and seven, respectively. We perform computer experiments on a synchronous cellular automaton to check whether the empirical distribution obeys also that theoretical formula. The numerical results indicate a perfect fit for neighbourhood three and five, which opens the way for a rigorous proof of the formula in this new, synchronous case. PMID:25271778

Exploring Asynchronous Many-Task Runtime Systems toward Extreme Scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knight, Samuel; Baker, Gavin Matthew; Gamell, Marc

2015-10-01

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

Asynchronous Processing of a Constellation of Geostationary and Polar-Orbiting Satellites for Fire Detection and Smoke Estimation

NASA Astrophysics Data System (ADS)

Hyer, E. J.; Peterson, D. A.; Curtis, C. A.; Schmidt, C. C.; Hoffman, J.; Prins, E. M.

2014-12-01

The Fire Locating and Monitoring of Burning Emissions (FLAMBE) system converts satellite observations of thermally anomalous pixels into spatially and temporally continuous estimates of smoke release from open biomass burning. This system currently processes data from a constellation of 5 geostationary and 2 polar-orbiting sensors. Additional sensors, including NPP VIIRS and the imager on the Korea COMS-1 geostationary satellite, will soon be added. This constellation experiences schedule changes and outages of various durations, making the set of available scenes for fire detection highly variable on an hourly and daily basis. Adding to the complexity, the latency of the satellite data is variable between and within sensors. FLAMBE shares with many fire detection systems the goal of detecting as many fires as possible as early as possible, but the FLAMBE system must also produce a consistent estimate of smoke production with minimal artifacts from the changing constellation. To achieve this, NRL has developed a system of asynchronous processing and cross-calibration that permits satellite data to be used as it arrives, while preserving the consistency of the smoke emission estimates. This talk describes the asynchronous data ingest methodology, including latency statistics for the constellation. We also provide an overview and show results from the system we have developed to normalize multi-sensor fire detection for consistency.

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

NASA Astrophysics Data System (ADS)

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].

Emotional first aid for a suicide crisis: comparison between Telephonic hotline and internet.

PubMed

Gilat, Itzhak; Shahar, Golan

2007-01-01

The telephone and the internet have become popular sources of psychological help in various types of distress, including a suicide crisis. To gain more insight into the unique features of these media, we compared characteristics of calls to three technologically mediated sources of help that are part of the volunteer-based Israeli Association for Emotional First Aid (ERAN): Telephonic hotline (n = 4426), personal chat (n = 373) and an asynchronous online support group (n = 954). Threats of suicide were much more frequent among participants in the asynchronous support group than the telephone and personal chat. These findings encourage further research into suicide-related interpersonal exchanges in asynchronous online support groups.

Asynchronous emergence by loggerhead turtle (Caretta caretta) hatchlings

NASA Astrophysics Data System (ADS)

Houghton, J. D. R.; Hays, G. C.

2001-03-01

For many decades it has been accepted that marine turtle hatchlings from the same nest generally emerge from the sand together. However, for loggerhead turtles (Caretta caretta) nesting on the Greek Island of Kefalonia, a more asynchronous pattern of emergence has been documented. By placing temperature loggers at the top and bottom of nests laid on Kefalonia during 1998, we examined whether this asynchronous emergence was related to the thermal conditions within nests. Pronounced thermal variation existed not only between, but also within, individual nests. These within-nest temperature differences were related to the patterns of hatchling emergence, with hatchlings from nests displaying large thermal ranges emerging over a longer time-scale than those characterised by more uniform temperatures.

Asynchronous, macrotasked relaxation strategies for the solution of viscous, hypersonic flows

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.

1991-01-01

A point-implicit, asynchronous macrotasked relaxation of the steady, thin-layer, Navier-Stokes equations is presented. The method employs multidirectional, single-level storage Gauss-Seidel relaxation sweeps, which effectively communicate perturbations across the entire domain in 2n sweeps, where n is the dimension of the domain. In order to enhance convergence the application of relaxation factors to specific components of the Jacobian is examined using a stability analysis of the advection and diffusion equations. Attention is also given to the complications associated with asynchronous multitasking. Solutions are generated for hypersonic flows over blunt bodies in two and three dimensions with chemical reactions, utilizing single-tasked and multitasked relaxation strategies.

Performance analysis of Integrated Communication and Control System networks

NASA Technical Reports Server (NTRS)

Halevi, Y.; Ray, A.

1990-01-01

This paper presents statistical analysis of delays in Integrated Communication and Control System (ICCS) networks that are based on asynchronous time-division multiplexing. The models are obtained in closed form for analyzing control systems with randomly varying delays. The results of this research are applicable to ICCS design for complex dynamical processes like advanced aircraft and spacecraft, autonomous manufacturing plants, and chemical and processing plants.

Fault-tolerant reactor protection system

DOEpatents

Gaubatz, Donald C.

1997-01-01

A reactor protection system having four divisions, with quad redundant sensors for each scram parameter providing input to four independent microprocessor-based electronic chassis. Each electronic chassis acquires the scram parameter data from its own sensor, digitizes the information, and then transmits the sensor reading to the other three electronic chassis via optical fibers. To increase system availability and reduce false scrams, the reactor protection system employs two levels of voting on a need for reactor scram. The electronic chassis perform software divisional data processing, vote 2/3 with spare based upon information from all four sensors, and send the divisional scram signals to the hardware logic panel, which performs a 2/4 division vote on whether or not to initiate a reactor scram. Each chassis makes a divisional scram decision based on data from all sensors. Each division performs independently of the others (asynchronous operation). All communications between the divisions are asynchronous. Each chassis substitutes its own spare sensor reading in the 2/3 vote if a sensor reading from one of the other chassis is faulty or missing. Therefore the presence of at least two valid sensor readings in excess of a set point is required before terminating the output to the hardware logic of a scram inhibition signal even when one of the four sensors is faulty or when one of the divisions is out of service.

Fault-tolerant reactor protection system

DOEpatents

Gaubatz, D.C.

1997-04-15

A reactor protection system is disclosed having four divisions, with quad redundant sensors for each scram parameter providing input to four independent microprocessor-based electronic chassis. Each electronic chassis acquires the scram parameter data from its own sensor, digitizes the information, and then transmits the sensor reading to the other three electronic chassis via optical fibers. To increase system availability and reduce false scrams, the reactor protection system employs two levels of voting on a need for reactor scram. The electronic chassis perform software divisional data processing, vote 2/3 with spare based upon information from all four sensors, and send the divisional scram signals to the hardware logic panel, which performs a 2/4 division vote on whether or not to initiate a reactor scram. Each chassis makes a divisional scram decision based on data from all sensors. Each division performs independently of the others (asynchronous operation). All communications between the divisions are asynchronous. Each chassis substitutes its own spare sensor reading in the 2/3 vote if a sensor reading from one of the other chassis is faulty or missing. Therefore the presence of at least two valid sensor readings in excess of a set point is required before terminating the output to the hardware logic of a scram inhibition signal even when one of the four sensors is faulty or when one of the divisions is out of service. 16 figs.

Student Outcomes Associated with Use of Asynchronous Online Discussion Forums in Gross Anatomy Teaching

ERIC Educational Resources Information Center

Green, Rodney A.; Hughes, Diane L.

2013-01-01

Asynchronous online discussion forums are increasingly common in blended learning environments but the relationship to student learning outcomes has not been reported for anatomy teaching. Forums were monitored in two multicampus anatomy courses; an introductory first year course and a second year physiotherapy-specific course. The forums are…

Students' Desired and Experienced Levels of Connectivity to an Asynchronous, Online, Distance Degree Program

ERIC Educational Resources Information Center

Schroeder, Shawnda; Baker, Mary; Terras, Katherine; Mahar, Patti; Chiasson, Kari

2016-01-01

This study examined graduate students' desired and experienced levels of connectivity in an online, asynchronous distance degree program. Connectivity was conceptualized as the students' feelings of community and involvement, not their level of access to the Internet. Graduate students enrolled in a distance degree program were surveyed on both…

Three Interaction Patterns on Asynchronous Online Discussion Behaviours: A Methodological Comparison

ERIC Educational Resources Information Center

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

2017-01-01

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

Microbial infection affects egg viability and incubation behavior in a tropical passerine.

Treesearch

Mark I. Cook; Steven R. Beissinger; Gary A. Toranzos; Roberto A. Arendt Rodriguez

2004-01-01

Many avian species initiate incubation before clutch completion, which causes eggs to hatch asynchronously. This influences brood competitive dynamics and often results in nestling mortality. The prevailing hypotheses contend that parents incubate early because asynchronous hatching provides fitness benefits to parents or surviving offspring. An alternative idea is...

FIFO Buffer for Asynchronous Data Streams

NASA Technical Reports Server (NTRS)

Bascle, K. P.

1985-01-01

Variable-rate, asynchronous data signals from up to four measuring instruments or other sources combined in first-in/first-out (FIFO) buffer for transmission on single channel. Constructed in complementary metal-oxide-semiconductor (CMOS) logic, buffer consumes low power (only 125 mW at 5V) and conforms to aerospace standards of reliability and maintainability.

Critical Thinking in Asynchronous Online Discussion: An Investigation of Student Facilitation Techniques

ERIC Educational Resources Information Center

Lim, Sze Chung Raymond; Cheung, Wing Sum; Hew, Khe Foon

2011-01-01

Background: In the last decade, asynchronous online discussion forums have become a primary focus of many educational researchers. Some advocates believed that the process of typing out messages in itself can promote in-depth critical thinking skills. Nevertheless, empirical research has not provided much support for this claim in natural…

Interaction and Cognition in Asynchronous Computer Conferencing

ERIC Educational Resources Information Center

Schrire, Sarah

2004-01-01

This paper is based on a multiple-case study of the learning process in three asynchronous computer conferences. The conferences were part of the distance learning component in doctoral degree courses in computing technology in education offered at an American university. The conferences were analyzed from a number of perspectives, the emphasis in…

Socially Shared Metacognitive Regulation in Asynchronous CSCL in Science: Functions, Evolution and Participation

ERIC Educational Resources Information Center

Iiskala, Tuike; Volet, Simone; Lehtinen, Erno; Vauras, Marja

2015-01-01

The significance of socially shared metacognitive regulation (SSMR) in collaborative learning is gaining momentum. To date, however, there is still a paucity of research of how SSMR is manifested in asynchronous computer-supported collaborative learning (CSCL), and hardly any systematic investigation of SSMR's functions and evolution across…

The Effects of Self-Generated Synchronous and Asynchronous Visual Speech Feedback on Overt Stuttering Frequency

ERIC Educational Resources Information Center

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

2009-01-01

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

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

ERIC Educational Resources Information Center

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…

Asynchronous Education: A Blueprint for the Future of Adult Learning.

ERIC Educational Resources Information Center

Krueger, Lyle L.; Porter, Cyndi Wilson; Burke, Daniel

While the distance learning curriculum at Lakeland College (Wisconsin) began 20 years ago, the idea for Lakeland Online was conceived about two and one-half years ago. A variety of delivery modes were considered before discovering Convene software. Since the communication process enabled by the Convene software is asynchronous and requires only a…

Synchronous and Asynchronous Communication in Distance Learning: A Review of the Literature

ERIC Educational Resources Information Center

Watts, Lynette

2016-01-01

Distance learning is commonplace in higher education, with increasing numbers of students enjoying the flexibility e-learning provides. Keeping students connected with peers and instructors has been a challenge with e-learning, but as technology has advanced, the methods by which educators keep students engaged, synchronously and asynchronously,…

Evaluating the Quality of Interaction in Asynchronous Discussion Forums in Fully Online Courses

ERIC Educational Resources Information Center

Nandi, Dip; Hamilton, Margaret; Harland, James

2012-01-01

Fully online courses are becoming progressively more popular because of their "anytime anywhere" learning flexibility. One of the ways students interact with each other and with the instructors within fully online learning environments is via asynchronous discussion forums. However, student engagement in online discussion forums does not…

Real-Time Implementation of an Asynchronous Vision-Based Target Tracking System for an Unmanned Aerial Vehicle

DTIC Science & Technology

2007-06-01

Chin Khoon Quek. “Vision Based Control and Target Range Estimation for Small Unmanned Aerial Vehicle.” Master’s Thesis, Naval Postgraduate School...December 2005. [6] Kwee Chye Yap. “Incorporating Target Mensuration System for Target Motion Estimation Along a Road Using Asynchronous Filter

Reflections of Students in Their Use of Asynchronous Online Seminars

ERIC Educational Resources Information Center

Groves, Mark; O'Donoghue, John

2009-01-01

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

Using Asynchronous Electronic Surveys to Help In-Class Revision: A Case Study

ERIC Educational Resources Information Center

Tong, Vincent C. H.

2012-01-01

Synchronous e-voting systems (commonly known as "clickers") have become increasingly popular as they can be used to enhance interactivity in lectures. Asynchronous electronic surveys (AESs), unlike these voting system, usually serve as a method of gathering feedback before or after teaching sessions. This paper describes and evaluates a project…

Argumentation in a Multi Party Asynchronous Computer Mediated Conference: A Generic Analysis

ERIC Educational Resources Information Center

Coffin, Caroline; Painter, Clare; Hewings, Ann

2005-01-01

This paper draws on systemic functional linguistic genre analysis to illuminate the way in which post graduate applied linguistics students structure their argumentation within a multi party asynchronous computer mediated conference. Two conference discussions within the same postgraduate course are compared in order to reveal the way in which…

The Socratic Dialogue in Asynchronous Online Discussions: Is Constructivism Redundant?

ERIC Educational Resources Information Center

Kingsley, Paul

2011-01-01

Purpose: This paper aims to examine Socratic dialogue in asynchronous online discussions in relation to constructivism. The links between theory and practice in teaching are to be discussed whilst tracing the origins of Socratic dialogue and recent trends and use of seminar in research based institutions. Design/methodology/approach: Many online…

Asynchronous Online Peer Assistance: Telephone Messages of Encouragement in Post Licensure Nursing Programs

ERIC Educational Resources Information Center

Melrose, Sherri; Swettenham, Steve

2012-01-01

Peer assistance activities can strengthen online learning environments. And yet, like other professional adult learners, working post licensure nurses attending university part time to upgrade their credentials may have limited interest in student-to-student interaction. Some intentionally choose asynchronous self-paced courses so they can work on…

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

ERIC Educational Resources Information Center

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…

Scaffolding Collaborative Argumentation in Asynchronous Discussions with Message Constraints and Message Labels

ERIC Educational Resources Information Center

Jeong, Allan; Joung, Sunyoung

2007-01-01

This study examined the effects of message constraints and labels on collaborative argumentation in asynchronous online discussions. Thirty-eight undergraduate students in an introductory educational technology course were assigned to one of three groups. In one group, students posted specific types of messages using a prescribed set of message…

Flipping the Online Classroom with Web 2.0: The Asynchronous Workshop

ERIC Educational Resources Information Center

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…

Asynchronous CMC, Collaboration and the Development of Critical Thinking in a Graduate Seminar in Applied Linguistics

ERIC Educational Resources Information Center

Abrams, Zsuzsanna I.

2005-01-01

A primary objective of graduate education, and often promoted by peer collaboration tasks, is the development of critical thinking skills. The present study compares how graduate students enrolled in a qualitative research design course in applied linguistics utilized asynchronous computer-mediated communication (ACMC) and face-to-face…

Asynchronous Computer-Mediated Corrective Feedback and the Correct Use of Prepositions: Is It Really Effective?

ERIC Educational Resources Information Center

Hosseini, Seyyed Behrooz

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…

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

ERIC Educational Resources Information Center

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…

Superconducting magnetic energy storage for asynchronous electrical systems

DOEpatents

Boenig, H.J.

1984-05-16

It is an object of the present invention to provide superconducting magnetic energy storage for a plurality of asynchronous electrical systems. It is a further object of the present invention to provide load leveling and stability improvement in a plurality of independent ac systems using a single superconducting magnetic energy storage coil.

Factors Affecting Pre-Service Teachers' Participation in Asynchronous Discussion: The Case of Iran

ERIC Educational Resources Information Center

Ebrahimi, Alice; Faghih, Esmail; Marandi, Seyyedeh Susan

2016-01-01

This study reports on a qualitative small-scale exploratory study which examined the factors influencing 32 Iranian pre-service language teachers' participation in online asynchronous text-based discussion forums. By adopting a multiple case study design and analysing data gathered through semi-structured interviews and participants' online…

A Dynamic Analysis of the Interplay between Asynchronous and Synchronous Communication in Online Learning: The Impact of Motivation

ERIC Educational Resources Information Center

Giesbers, B.; Rienties, B.; Tempelaar, D.; Gijselaers, W.

2014-01-01

With the increased affordances of synchronous communication tools, more opportunities for online learning to resemble face-to-face settings have recently become available. However, synchronous communication does not afford as much time for reflection as asynchronous communication. Therefore, a combination of synchronous and asynchronous…

An Investigation of Assessment and Feedback Practices in Fully Asynchronous Online Undergraduate Mathematics Courses

ERIC Educational Resources Information Center

Trenholm, Sven; Alcock, Lara; Robinson, Carol

2015-01-01

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…

An Integrated Approach to Preempt Cheating on Asynchronous, Objective, Online Assessments in Graduate Business Classes

ERIC Educational Resources Information Center

Sullivan, Daniel P.

2016-01-01

Cheating, left untended, erodes the validity of evaluation and, ultimately, corrupts the legitimacy of a course. We profile an approach to manage, with an eye toward preempting, cheating on asynchronous, objective, online quizzes. This approach taps various technological and social solutions to academic dishonesty, integrating them into a…

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

ERIC Educational Resources Information Center

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…

Students' Learning in Asynchronous Discussion Forums: A Meta-Analysis

ERIC Educational Resources Information Center

Martono, Fkipuntan; Salam, Urai

2017-01-01

Asynchronous discussion forums are among the most preferred tools chosen to foster learning opportunities and knowledge construction. To reveal the cognitive engagement evidenced in the transcripts of the discussion forums, this study presents 51 papers. 17 papers reported research on students' attitude toward the use of ICT for learning, 16…

Student Moderators in Asynchronous Online Discussion: A Question of Questions

ERIC Educational Resources Information Center

Zingaro, Daniel

2012-01-01

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

Content Analysis Coding Schemes for Online Asynchronous Discussion

ERIC Educational Resources Information Center

Weltzer-Ward, Lisa

2011-01-01

Purpose: Researchers commonly utilize coding-based analysis of classroom asynchronous discussion contributions as part of studies of online learning and instruction. However, this analysis is inconsistent from study to study with over 50 coding schemes and procedures applied in the last eight years. The aim of this article is to provide a basis…

Does the Medium Dictate the Message? Cultivating E-Communication in an Asynchronous Environment.

ERIC Educational Resources Information Center

Kiernan, Mary; Thomas, Pete; Woodroffe, Mark

Virtual learning environments (VLEs) are often perceived by education establishments as an opportunity to widen access without traditional overheads. An integral part of most VLEs is asynchronous computer conferencing and on-line moderators must help students migrate quickly to the new virtual environment to minimize learning disruption. This…

An Investigation of Student Practices in Asynchronous Computer Conferencing Courses

ERIC Educational Resources Information Center

Peters, Vanessa L.; Hewitt, Jim

2010-01-01

This study investigated the online practices of students enrolled in graduate-level distance education courses. Using interviews and a questionnaire as data sources, the study sought to: (a) identify common practices that students adopt in asynchronous discussions, and (b) gain an understanding of why students adopt them. An analysis of the data…

Asynchronous Replication and Autosome-Pair Non-Equivalence in Human Embryonic Stem Cells

PubMed Central

Dutta, Devkanya; Ensminger, Alexander W.; Zucker, Jacob P.; Chess, Andrew

2009-01-01

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. PMID:19325893

Air Temperature Distribution Measurement Using Asynchronous-Type Sound Probe

NASA Astrophysics Data System (ADS)

Katano, Yosuke; Wakatsuki, Naoto; Mizutani, Koichi

2009-07-01

In conventional temperature measurement using a sound probe, the operation beginnings of two acoustic sensors must be completely synchronized to measure time of flight (TOF), tf, because the precision of synchronization determines TOF measurement accuracy. A wireless local area network (LAN) is convenient for constructing a sensing grid; however, it causes a fluctuation in the delay of millisecond order. Therefore, it cannot provide sufficient precision for synchronizing acoustic sensors. In previous studies, synchronization was achieved by a trigger line using a coaxial cable; however, the cable reduces the flexibility of a wireless sensing grid especially in larger-scale measurement. In this study, an asynchronous-type sound probe is devised to compensate for the effect of the delay of millisecond order caused by the network. The validity of the probe was examined, and the air temperature distribution was measured using this means. A matrix method is employed to obtain the distribution. Similar results were observed using both asynchronous-type sound probes and thermocouples. This shows the validity of the use of a sensing grid with an asynchronous-type sound probe for temperature distribution measurement even if the trigger line is omitted.

Modulation and synchronization technique for MF-TDMA system

NASA Technical Reports Server (NTRS)

Faris, Faris; Inukai, Thomas; Sayegh, Soheil

1994-01-01

This report addresses modulation and synchronization techniques for a multi-frequency time division multiple access (MF-TDMA) system with onboard baseband processing. The types of synchronization techniques analyzed are asynchronous (conventional) TDMA, preambleless asynchronous TDMA, bit synchronous timing with a preamble, and preambleless bit synchronous timing. Among these alternatives, preambleless bit synchronous timing simplifies onboard multicarrier demultiplexer/demodulator designs (about 2:1 reduction in mass and power), requires smaller onboard buffers (10:1 to approximately 3:1 reduction in size), and provides better frame efficiency as well as lower onboard processing delay. Analysis and computer simulation illustrate that this technique can support a bit rate of up to 10 Mbit/s (or higher) with proper selection of design parameters. High bit rate transmission may require Doppler compensation and multiple phase error measurements. The recommended modulation technique for bit synchronous timing is coherent QPSK with differential encoding for the uplink and coherent QPSK for the downlink.

A Primer for Telemetry Interfacing in Accordance with NASA Standards Using Low Cost FPGAs

NASA Astrophysics Data System (ADS)

McCoy, Jake; Schultz, Ted; Tutt, James; Rogers, Thomas; Miles, Drew; McEntaffer, Randall

2016-03-01

Photon counting detector systems on sounding rocket payloads often require interfacing asynchronous outputs with a synchronously clocked telemetry (TM) stream. Though this can be handled with an on-board computer, there are several low cost alternatives including custom hardware, microcontrollers and field-programmable gate arrays (FPGAs). This paper outlines how a TM interface (TMIF) for detectors on a sounding rocket with asynchronous parallel digital output can be implemented using low cost FPGAs and minimal custom hardware. Low power consumption and high speed FPGAs are available as commercial off-the-shelf (COTS) products and can be used to develop the main component of the TMIF. Then, only a small amount of additional hardware is required for signal buffering and level translating. This paper also discusses how this system can be tested with a simulated TM chain in the small laboratory setting using FPGAs and COTS specialized data acquisition products.

Dump system concepts for the Future Circular Collider

NASA Astrophysics Data System (ADS)

Bartmann, W.; Atanasov, M.; Barnes, M. J.; Borburgh, J.; Burkart, F.; Goddard, B.; Kramer, T.; Lechner, A.; Ull, A. Sanz; Schmidt, R.; Stoel, L. S.; Ostojic, R.; Rodziewicz, J.; van Trappen, P.; Barna, D.

2017-03-01

The Future Circular Collider (FCC-hh) beam dump system must provide a safe and reliable extraction and dilution of the stored beam onto a dump absorber. Energy deposition studies show that damage limits of presently used absorber materials will already be reached for single bunches at 50 TeV. A fast field rise of the extraction kicker is required in order to sufficiently separate swept single bunches on the extraction protection absorbers in case of an asynchronous beam dump. In line with this demand is the proposal of a highly segmented extraction kicker system which allows for accepting a single kicker switch erratic and thus, significantly reduces the probability of an asynchronous beam dump. Superconducting septa are foreseen to limit the overall system length and power consumption. Two extraction system concepts are presented and evaluated regarding overall system length, energy deposition on absorbers, hardware requirements, radiation issues, and layout flexibility.

An assessment of initial body size in loggerhead sea turtle (Caretta caretta) hatchlings in Turkey.

PubMed

Ozdemir, Adem; Ilgaz, Cetin; Kumlutaş, Yusuf; Durmuş, Salih Hakan; Kaska, Yakup; Türkozan, Oğuz

2007-04-01

Eggs, hatchlings, and adult loggerhead turtles, and incubation durations of clutches, were measured on three Turkish beaches (Dalyan, Fethiye and Göksu Delta), and some physical features of nests were compared. These features were not statistically different among the beaches, except for nest depth and distance to the high water mark. There was a positive relationship between hatchling mass and egg size. The carapace length of hatchlings was correlated with both egg diameter and incubation duration. The duration of asynchronous emergence of hatchlings on Fethiye beach was slightly longer than on the other two beaches, and the size of hatchlings decreased as asynchronous emergence proceeded. Of the hatchlings that emerged first, those that died were significantly smaller in SCL and mass than those that lived. These results suggest that smaller hatchlings may not be vigorous enough to emerge earlier from nests, and that they may be less fit.

Exploring Online Asynchronous Counseling With Tobacco Treatment Specialists in the QUIT-PRIMO and National Dental PBRN HI-QUIT Studies: Who Uses It and What Do They Say?

PubMed

Williams, Jessica H; DeLaughter, Kathryn; Volkman, Julie E; Sadasivam, Rajani S; Ray, Midge N; Gilbert, Gregg H; Houston, Thomas K

2018-06-01

To describe the content of messages sent by smokers through asynchronous counseling within a Web-based smoking cessation intervention. Qualitative. National community-based setting of patients who had been engaged by the medical or dental practices at which they attended or via Google advertisements. Adults older than 19 years who were current smokers and interested in quitting. Participants throughout the United States referred to a Web-based cessation intervention by their medical or dental provider or by clicking on a Google advertisement. We conducted a qualitative review of 742 asynchronous counseling messages sent by 270 Web site users. Messages were reviewed, analyzed, and organized into qualitative themes by the investigative team. The asynchronous counseling feature of the intervention was used most frequently by smokers who were white (87%), female (67%), aged 45 to 54 (32%), and who had at least some college-level education (70%). Qualitative analysis yielded 7 basic themes-Talk about the Process of Quitting, Barriers to Quitting, Reasons to Quit, Quit History, Support and Strategies for Quitting, Quitting with Medication, and Quit Progress. The most common theme was Support and Strategies for Quitting with 255 references among all messages. We found rich communication across the spectrum of the quit process, from persons preparing to quit to those who had successfully quit. Asynchronous smoking cessation counseling provides a promising means of social support for smokers during the quit process.

Online Dynamic Asynchronous Audit Strategy for Reflexivity in the Qualitative Paradigm

ERIC Educational Resources Information Center

LaBanca, Frank

2011-01-01

The trustworthiness of a qualitative study can be increased by maintaining high credibility and objectivity. Of utmost importance to these factors is the reflexivity of the researcher. Standard journaling techniques are frequently used to maintain an audit trail and document tentative interpretations of a study. One of the major limitations to…

Asynchronous development of Honey Bee host and Varroa destructor (Mesostigmata: Varroidae) influences reproductive potential of mites

USDA-ARS?s Scientific Manuscript database

A high proportion of non-reproductive (NR) Varroa destructor, is commonly observed in honey bee colonies displaying the Varroa sensitive hygienic trait (VSH). These studies were conducted to determine the influence of brood removal and subsequent host re-invasion of Varroa mites on mite reproduction...

Developing Community and Building Knowledge Online Using a Virtual Reality Environment and Student-Created Videos

ERIC Educational Resources Information Center

O'Connor, Eileen A.

2018-01-01

Within an online science teacher education course, an important although secondary goal was to prepare students for a high-stakes licensure portfolio at some time after course completion. Thus, various communication technologies including synchronous virtual reality meetings and asynchronous student self-created video commentaries were interwoven…

Alternative majority-voting methods for real-time computing systems

NASA Technical Reports Server (NTRS)

Shin, Kang G.; Dolter, James W.

1989-01-01

Two techniques that provide a compromise between the high time overhead in maintaining synchronous voting and the difficulty of combining results in asynchronous voting are proposed. These techniques are specifically suited for real-time applications with a single-source/single-sink structure that need instantaneous error masking. They provide a compromise between a tightly synchronized system in which the synchronization overhead can be quite high, and an asynchronous system which lacks suitable algorithms for combining the output data. Both quorum-majority voting (QMV) and compare-majority voting (CMV) are most applicable to distributed real-time systems with single-source/single-sink tasks. All real-time systems eventually have to resolve their outputs into a single action at some stage. The development of the advanced information processing system (AIPS) and other similar systems serve to emphasize the importance of these techniques. Time bounds suggest that it is possible to reduce the overhead for quorum-majority voting to below that for synchronous voting. All the bounds assume that the computation phase is nonpreemptive and that there is no multitasking.

Enhancing the Simulation Speed of Sensor Network Applications by Asynchronization of Interrupt Service Routines

PubMed Central

Joe, Hyunwoo; Woo, Duk-Kyun; Kim, Hyungshin

2013-01-01

Sensor network simulations require high fidelity and timing accuracy to be used as an implementation and evaluation tool. The cycle-accurate and instruction-level simulator is the known solution for these purposes. However, this type of simulation incurs a high computation cost since it has to model not only the instruction level behavior but also the synchronization between multiple sensors for their causality. This paper presents a novel technique that exploits asynchronous simulations of interrupt service routines (ISR). We can avoid the synchronization overheads when the interrupt service routines are simulated without preemption. If the causality errors occur, we devise a rollback procedure to restore the original synchronized simulation. This concept can be extended to any instruction-level sensor network simulator. Evaluation results show our method can enhance the simulation speed up to 52% in the case of our experiments. For applications with longer interrupt service routines and smaller number of preemptions, the speedup becomes greater. In addition, our simulator is 2 to 11 times faster than the well-known sensor network simulator. PMID:23966200

Area/latency optimized early output asynchronous full adders and relative-timed ripple carry adders.

PubMed

Balasubramanian, P; Yamashita, S

2016-01-01

This article presents two area/latency optimized gate level asynchronous full adder designs which correspond to early output logic. The proposed full adders are constructed using the delay-insensitive dual-rail code and adhere to the four-phase return-to-zero handshaking. For an asynchronous ripple carry adder (RCA) constructed using the proposed early output full adders, the relative-timing assumption becomes necessary and the inherent advantages of the relative-timed RCA are: (1) computation with valid inputs, i.e., forward latency is data-dependent, and (2) computation with spacer inputs involves a bare minimum constant reverse latency of just one full adder delay, thus resulting in the optimal cycle time. With respect to different 32-bit RCA implementations, and in comparison with the optimized strong-indication, weak-indication, and early output full adder designs, one of the proposed early output full adders achieves respective reductions in latency by 67.8, 12.3 and 6.1 %, while the other proposed early output full adder achieves corresponding reductions in area by 32.6, 24.6 and 6.9 %, with practically no power penalty. Further, the proposed early output full adders based asynchronous RCAs enable minimum reductions in cycle time by 83.4, 15, and 8.8 % when considering carry-propagation over the entire RCA width of 32-bits, and maximum reductions in cycle time by 97.5, 27.4, and 22.4 % for the consideration of a typical carry chain length of 4 full adder stages, when compared to the least of the cycle time estimates of various strong-indication, weak-indication, and early output asynchronous RCAs of similar size. All the asynchronous full adders and RCAs were realized using standard cells in a semi-custom design fashion based on a 32/28 nm CMOS process technology.

Refining an Asynchronous Telerehabilitation Platform for Speech-Language Pathology: Engaging End-Users in the Process

PubMed Central

Hill, Annie J.; Breslin, Hugh M.

2016-01-01

Asynchronous telerehabilitation in which computer-based interventions are remotely monitored and adapted offline is an emerging service delivery model in the rehabilitation of communication disorders. The asynchronous nature of this model may hold a benefit over its synchronous counterpart by eliminating scheduling issues and thus improving efficiency in a healthcare landscape of constrained resource allocation. The design of asynchronous telerehabilitation platforms should therefore ensure efficiency and flexibility. The authors have been engaged in a program of research to develop and evaluate an asynchronous telerehabilitation platform for use in speech-language pathology. eSALT is a novel asynchronous telerehabilitation platform in which clinicians design and individualize therapy tasks for transfer to a client's mobile device. An inbuilt telerehabilitation module allows for remote monitoring and updating of tasks. This paper introduces eSALT and reports outcomes from an usability study that considered the needs of two end-user groups, people with aphasia and clinicians, in the on-going refinement of eSALT. In the study participants with aphasia were paired with clinicians who used eSALT to design and customize therapy tasks. After training on the mobile device the participants engaged in therapy at home for a period of 3 weeks, while clinicians remotely monitored and updated tasks. Following the home trial, participants, and clinicians engaged in semi-structured interviews and completed surveys on the usability of eSALT and their satisfaction with the platform. Content analysis of data involving five participants and three clinicians revealed a number of usability themes including ease of use, user support, satisfaction, limitations, and potential improvements. These findings were translated into a number of refinements of the eSALT platform including the development of a client interface for use on the Apple iPad®, greater variety in feedback options to both the participant and clinician, automatic transfer of results to the clinician, and expansion of the task template list. This research highlights the importance of including end-users in the process of technology refinement, in order to ensure effective and efficient use of the technology. Future directions for research are discussed including clinical trials in which the effectiveness of and adherence to intervention protocols using asynchronous telerehabilitation are examined. PMID:28066211

Cascaded VLSI neural network architecture for on-line learning

NASA Technical Reports Server (NTRS)

Thakoor, Anilkumar P. (Inventor); Duong, Tuan A. (Inventor); Daud, Taher (Inventor)

1992-01-01

High-speed, analog, fully-parallel, and asynchronous building blocks are cascaded for larger sizes and enhanced resolution. A hardware compatible algorithm permits hardware-in-the-loop learning despite limited weight resolution. A computation intensive feature classification application was demonstrated with this flexible hardware and new algorithm at high speed. This result indicates that these building block chips can be embedded as an application specific coprocessor for solving real world problems at extremely high data rates.

Cascaded VLSI neural network architecture for on-line learning

NASA Technical Reports Server (NTRS)

Duong, Tuan A. (Inventor); Daud, Taher (Inventor); Thakoor, Anilkumar P. (Inventor)

1995-01-01

High-speed, analog, fully-parallel and asynchronous building blocks are cascaded for larger sizes and enhanced resolution. A hardware-compatible algorithm permits hardware-in-the-loop learning despite limited weight resolution. A comparison-intensive feature classification application has been demonstrated with this flexible hardware and new algorithm at high speed. This result indicates that these building block chips can be embedded as application-specific-coprocessors for solving real-world problems at extremely high data rates.

Current Saturation Avoidance with Real-Time Control using DPCS

NASA Astrophysics Data System (ADS)

Ferrara, M.; Hutchinson, I.; Wolfe, S.; Stillerman, J.; Fredian, T.

2008-11-01

Tokamak ohmic-transformer and equilibrium-field coils need to be able to operate near their maximum current capabilities. However if they reach their upper limit during high-performance discharges or in the presence of a strong off-normal event, shape control is compromised, and instability, even plasma disruptions can result. On Alcator C-Mod we designed and tested an anti-saturation routine which detects the impending saturation of OH and EF currents and interpolates to a neighboring safe equilibrium in real-time. The routine was implemented with a multi-processor, multi-time-scale control scheme, which is based on a master process and multiple asynchronous slave processes. The scheme is general and can be used for any computationally-intensive algorithm. USDoE award DE- FC02-99ER545512.

A fiber optic tactical voice/data network based on FDDI

NASA Technical Reports Server (NTRS)

Bergman, L. A.; Hartmayer, R.; Marelid, S.; Wu, W. H.; Edgar, G.; Cassell, P.; Mancini, R.; Kiernicki, J.; Paul, L. J.; Jeng, J.

1988-01-01

An asynchronous high-speed fiber optic local area network is described that supports ordinary data packet traffic simultaneously with synchronous Tl voice traffic over a common FDDI token ring channel. A voice interface module was developed that parses, buffers, and resynchronizes the voice data to the packet network. The technique is general, however, and can be applied to any deterministic class of networks, including multi-tier backbones. A conventional single token access protocol was employed at the lowest layer, with fixed packet sizes for voice and variable for data. In addition, the higher layer packet data protocols are allowed to operate independently of those for the voice thereby permitting great flexibility in reconfiguring the network. Voice call setup and switching functions were performed external to the network with PABX equipment.

Ultrascalable petaflop parallel supercomputer

DOEpatents

Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton On Hudson, NY; Chiu, George [Cross River, NY; Cipolla, Thomas M [Katonah, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Hall, Shawn [Pleasantville, NY; Haring, Rudolf A [Cortlandt Manor, NY; Heidelberger, Philip [Cortlandt Manor, NY; Kopcsay, Gerard V [Yorktown Heights, NY; Ohmacht, Martin [Yorktown Heights, NY; Salapura, Valentina [Chappaqua, NY; Sugavanam, Krishnan [Mahopac, NY; Takken, Todd [Brewster, NY

2010-07-20

A massively parallel supercomputer of petaOPS-scale includes node architectures based upon System-On-a-Chip technology, where each processing node comprises a single Application Specific Integrated Circuit (ASIC) having up to four processing elements. The ASIC nodes are interconnected by multiple independent networks that optimally maximize the throughput of packet communications between nodes with minimal latency. The multiple networks may include three high-speed networks for parallel algorithm message passing including a Torus, collective network, and a Global Asynchronous network that provides global barrier and notification functions. These multiple independent networks may be collaboratively or independently utilized according to the needs or phases of an algorithm for optimizing algorithm processing performance. The use of a DMA engine is provided to facilitate message passing among the nodes without the expenditure of processing resources at the node.

EXpectation Propagation LOgistic REgRession (EXPLORER): Distributed Privacy-Preserving Online Model Learning

PubMed Central

Wang, Shuang; Jiang, Xiaoqian; Wu, Yuan; Cui, Lijuan; Cheng, Samuel; Ohno-Machado, Lucila

2013-01-01

We developed an EXpectation Propagation LOgistic REgRession (EXPLORER) model for distributed privacy-preserving online learning. The proposed framework provides a high level guarantee for protecting sensitive information, since the information exchanged between the server and the client is the encrypted posterior distribution of coefficients. Through experimental results, EXPLORER shows the same performance (e.g., discrimination, calibration, feature selection etc.) as the traditional frequentist Logistic Regression model, but provides more flexibility in model updating. That is, EXPLORER can be updated one point at a time rather than having to retrain the entire data set when new observations are recorded. The proposed EXPLORER supports asynchronized communication, which relieves the participants from coordinating with one another, and prevents service breakdown from the absence of participants or interrupted communications. PMID:23562651

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

ERIC Educational Resources Information Center

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

2014-01-01

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

Online-BSEE (Online Bachelor of Science in Electrical Engineering): An Asynchronous Online Electrical Engineering Degree Program with Laboratory

ERIC Educational Resources Information Center

Tang, Wendy; Westgate, Charles; Liu, Pao-Lo; Gouzman, Michael

2014-01-01

The Online Bachelor of Science in Electrical Engineering is a collaborative effort among three University Centers at SUNY (State University of New York), namely Stony Brook, Binghamton, and Buffalo. The program delivers the complete electrical engineering curriculum at the bachelor level to students online and asynchronously. Students, however,…

Reversible logic gates on Physarum Polycephalum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schumann, Andrew

2015-03-10

In this paper, we consider possibilities how to implement asynchronous sequential logic gates and quantum-style reversible logic gates on Physarum polycephalum motions. We show that in asynchronous sequential logic gates we can erase information because of uncertainty in the direction of plasmodium propagation. Therefore quantum-style reversible logic gates are more preferable for designing logic circuits on Physarum polycephalum.

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

ERIC Educational Resources Information Center

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…

A Comparison of Asynchronous Online Text-Based Lectures and Synchronous Interactive Web Conferencing Lectures

ERIC Educational Resources Information Center

Skylar, Ashley Ann

2009-01-01

Online learning environments are more prevalent in teacher education than ever before. In 2009, many instructors are attempting to emulate traditional instructional methods in the online learning environment as much as possible. Online courses are separated into two categories, (1) asynchronous; and (2) synchronous, depending on the nature of the…

The Effectiveness of Synchronous and Asynchronous Written Corrective Feedback on Grammatical Accuracy in a Computer-Mediated Environment

ERIC Educational Resources Information Center

Shintani, Natsuko; Aubrey, Scott

2016-01-01

This study extends research on written corrective feedback (CF) by investigating how timing of CF affects grammar acquisition. Specifically, it examined the relative effects of synchronous and asynchronous CF on the accurate use of the hypothetical conditional structure. Participants were 68 intermediate-level students of English at a university…

Microanalytic Case studies of Individual Participation Patterns in an Asynchronous Online Discussion in an Undergraduate Blended Course

ERIC Educational Resources Information Center

Wise, Alyssa Friend; Perera, Nishan; Hsiao, Ying-Ting; Speer, Jennifer; Marbouti, Farshid

2012-01-01

This study presents three case studies of students' participation patterns in an online discussion to address the gap in our current understanding of how "individuals" experience asynchronous learning environments. Cases were constructed via microanalysis of log-file data, post contents, and the evolving discussion structure. The first student was…

Collaborative Learning Processes in an Asynchronous Environment: An Analysis through Discourse and Social Networks

ERIC Educational Resources Information Center

Tirado, Ramon; Aguaded, Ignacio; Hernando, Angel

2011-01-01

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

Asynchronous Online Access as an Accommodation on Students with Learning Disabilities and/or Attention-Deficit Hyperactivity Disorders in Postsecondary STEM Courses

ERIC Educational Resources Information Center

Graves, Laura; Asunda, Paul A.; Plant, Stacey J.; Goad, Chester

2011-01-01

The purpose of this study was to investigate whether asynchronous online access of course recordings was beneficial to students with learning disabilities (LD) and/or Attention Deficit/Hyperactivity Disorder (ADHD) enrolled in science, technology, engineering, and mathematics (STEM) courses. Data were collected through semi-structured interviews…

Digging beneath the Surface: Analyzing the Complexity of Instructors' Participation in Asynchronous Discussion

ERIC Educational Resources Information Center

Clarke, Lane Whitney; Bartholomew, Audrey

2014-01-01

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

Writer L1/L2 Status and Asynchronous Online Writing Center Feedback: Consultant Response Patterns

ERIC Educational Resources Information Center

Weirick, Joshua; Davis, Tracy; Lawson, Daniel

2017-01-01

This case study examines the differences in comments offered by asynchronous online writing center consultants to L1 and L2 speakers and examines the potential disconnects in consultant perceptions of their practice. The researchers collected and coded sample papers and interviewed participants to contextualize data from the quantitative portion…

Reconceptualising Moderation in Asynchronous Online Discussions Using Grounded Theory

ERIC Educational Resources Information Center

Vlachopoulos, Panos; Cowan, John

2010-01-01

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

Exploring Singapore Primary School Students' Perceptions of Chinese Asynchronous Online Discussions

ERIC Educational Resources Information Center

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

2008-01-01

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

Synchronous and Asynchronous Text-Based CMC in Educational Contexts: A Review of Recent Research

ERIC Educational Resources Information Center

Johnson, Genevieve, Marie

2006-01-01

This paper presents a review of recent research that examines the relative instructional utility of text-based synchronous and asynchronous computer-mediated communication (CMC). As a mechanism for limiting the number of studies reviewed as well as controlling for emergent technologies, only research published since 2000 was reviewed. The goal was…

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

ERIC Educational Resources Information Center

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…

Interaction and Critical Inquiry in Asynchronous Computer-Mediated Conferencing: A Research Agenda

ERIC Educational Resources Information Center

Hopkins, Joseph; Gibson, Will; Ros i. Sole, Cristina; Savvides, Nicola; Starkey, Hugh

2008-01-01

This paper reviews research on learner and tutor interaction in asynchronous computer-mediated (ACM) conferences used in distance learning. The authors note claims made for the potential of ACM conferences to promote higher-order critical inquiry and the social construction of knowledge, and argue that there is a general lack of evidence regarding…

Analysis of an Asynchronous Online Discussion as a Supportive Model for Peer Collaboration and Reflection in Teacher Education

ERIC Educational Resources Information Center

Plešec Gasparic, Romina; Pecar, Mojca

2016-01-01

Professional development of future teachers is based on connecting theory and practice with the aim of supporting and developing critical, independent, responsible decision-making and active teaching. With this aim we designed a blended learning environment with an asynchronous online discussion, enabling collaboration and reflection even when…

Comparing Face-To-Face and Asynchronous Online Communication as Mechanisms for Critical Reflective Dialogue

ERIC Educational Resources Information Center

Salter, Susan; Douglas, Tracy; Kember, David

2017-01-01

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

Using Asynchronous Video to Achieve Instructor Immediacy and Closeness in Online Classes: Experiences from Three Cases

ERIC Educational Resources Information Center

Griffiths, Michael; Graham, Charles

2010-01-01

This research sought to understand the experiences of students and instructors with asynchronous video (video-mail) using webcams in three online sections of teacher education classes at Brigham Young University. We examined the experiences of students through scores and comments posted in student ratings surveys, and the experiences of…

Toward Personal and Emotional Connectivity in Mobile Higher Education through Asynchronous Formative Audio Feedback

ERIC Educational Resources Information Center

Rasi, Päivi; Vuojärvi, Hanna

2018-01-01

This study aims to develop asynchronous formative audio feedback practices for mobile learning in higher education settings. The development was conducted in keeping with the principles of design-based research. The research activities focused on an inter-university online course, within which the use of instructor audio feedback was tested,…

Asynchronous online foresight panels: the case of wildfire management

Treesearch

David N. Bengston; Robert L. Olson

2015-01-01

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

Effects of Synchronous and Asynchronous Computer-Mediated Communication (CMC) Oral Conversations on English Language Learners' Discourse Functions

ERIC Educational Resources Information Center

AbuSeileek, Ali Farhan; Qatawneh, Khaleel

2013-01-01

This study aimed to explore the effects of synchronous and asynchronous computer mediated communication (CMC) oral discussions on question types and strategies used by English as a Foreign Language (EFL) learners. The participants were randomly assigned to two treatment conditions/groups; the first group used synchronous CMC, while the second…

Introducing Group-Based Asynchronous Learning to Business Education. Reflections on Effective Course Design and Delivery

ERIC Educational Resources Information Center

Walker, Richard; Arnold, Ivo

2004-01-01

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

Student Perceptions of Asynchronous Multimodal Instructor Feedback: A Multiple Case Study

ERIC Educational Resources Information Center

Lenards, Nishele Dyan

2017-01-01

Student dissatisfaction has been a problem in higher education with regard to the provision of assessment-related feedback. Due to the distant nature of online learning, instructors are faced with many challenges in delivering quality feedback because the communication is asynchronous and lacks social cues that are present in a F2F environment.…

Students' Perceptions of Online Discussions, Participation and E-Moderation Behaviours in Peer-Moderated Asynchronous Online Discussions

ERIC Educational Resources Information Center

Ghadirian, Hajar; Fauzi Mohd Ayub, Ahmad; Salehi, Keyvan

2018-01-01

The aim of this study was to investigate the relationships between students' perceptions of online discussions, participation and e-moderation behaviours in peer-moderated asynchronous online discussions. Using survey data, the learning system's activity log and discussion transcripts, the authors analysed how 84 learners' perceptions of online…

Three-Dimensional Temperature Field Simulation for the Rotor of an Asynchronous Motor

ERIC Educational Resources Information Center

Wang, Yanwu; Fan, Chunli; Yang, Li; Sun, Fengrui

2010-01-01

A three-dimensional heat transfer model is built according to the rotor structure of an asynchronous motor, and three-dimensional temperature fields of the rotor under different working conditions, such as the unloaded, rated loaded and that with broken rotor bars, are studied based on the finite element numerical method and experiments. The…

Bully Proofing Your Twice-Exceptional Child

ERIC Educational Resources Information Center

Mohammed, Amra

2018-01-01

Twice-exceptional (2E) students are those who demonstrate a gift or talent in one or more areas and have a disability in another area. One identifying characteristic of 2E children is asynchronous development, or the display of unusual talent or maturity in one or more areas alongside a struggle to develop in other areas. Asynchronous development…

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

ERIC Educational Resources Information Center

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,…

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

ERIC Educational Resources Information Center

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 [subscript…

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

ERIC Educational Resources Information Center

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…

Computer-Mediated Synchronous and Asynchronous Corrective Feedback Provided by Trainee Teachers to Learners of French: A Preliminary Study

ERIC Educational Resources Information Center

Vidal, Julie; Thouësny, Sylvie

2015-01-01

In this paper, we investigate whether trainee teachers' practices, with respect to multimodal feedback, differ from current research, and to what extent it may affect students' language development. More specifically, the goal of the present study is threefold: (1) it observes how trainee teachers responded, whether synchronously, asynchronously,…

Beyond Social Presence: Facelessness and the Ethics of Asynchronous Online Education

ERIC Educational Resources Information Center

Rose, Ellen

2017-01-01

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

Exploring Change in Graduate Students' Perceptions of Web-Based Education throughout an Asynchronous Course

ERIC Educational Resources Information Center

Timotheou, Maria Mama

2017-01-01

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

Distributed Teaching Presence and Communicative Patterns in Asynchronous Learning: Name versus Reply Networks

ERIC Educational Resources Information Center

Engel, Anna; Coll, Cesar; Bustos, Alfonso

2013-01-01

This work explores some methodological challenges in the application of Social Network Analysis (SNA) to the study of "Asynchronous Learning Networks" (ALN). Our interest in the SNA is situated within the framework of the study of Distributed Teaching Presence (DTP), understood as the exercise of educational influence, through a multi-method…

Cyber Asynchronous versus Blended Cyber Approach in Distance English Learning

ERIC Educational Resources Information Center

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…

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

ERIC Educational Resources Information Center

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…

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

ERIC Educational Resources Information Center

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…

A Survey of Factors Contributing to Learners' "Listening" Behaviors in Asynchronous Online Discussions

ERIC Educational Resources Information Center

Wise, Alyssa Friend; Marbouti, Farshid; Hsiao, Ying-Ting; Hausknecht, Simone

2012-01-01

Sixty-seven undergraduates taking either a Blended Business Course (BBC) or an Online Education Course (OEC) were surveyed about factors influencing their "listening" behaviors in asynchronous online course discussions. These are the ways they attend to the posts made by others: which posts they open, how they engage with open posts, and…

Reflective Outcomes of Convergent and Divergent Group Tasking in the Online Learning Environment

ERIC Educational Resources Information Center

Hawkes, Mark

2007-01-01

Using collaborative critical reflection as an index, this study examines the asynchronous and face-to-face discourse of 28 suburban Chicago elementary teachers developing problem based learning (PBL) curriculum. Statistical analysis of the corpus produced by the 2 mediums shows that the asynchronous online network emerges as the medium of choice…

The Effects of Computer-Mediated Synchronous and Asynchronous Direct Corrective Feedback on Writing: A Case Study

ERIC Educational Resources Information Center

Shintani, Natsuko

2016-01-01

This case study investigated the characteristics of computer-mediated synchronous corrective feedback (SCF, provided while students wrote) and asynchronous corrective feedback (ACF, provided after students had finished writing) in an EFL writing task. The task, designed to elicit the use of the hypothetical conditional, was completed by two…

Live Synchronous Web Meetings in Asynchronous Online Courses: Reconceptualizing Virtual Office Hours

ERIC Educational Resources Information Center

Lowenthal, Patrick R.; Snelson, Chareen; Dunlap, Joanna C.

2017-01-01

Most online courses rely solely on asynchronous text-based online communication. This type of communication can foster anytime, anywhere reflection, critical thinking, and deep learning. However, it can also frustrate participants because of the lack of spontaneity and visual cues and the time it takes for conversations to develop and feedback to…

Use of a Post-Asynchronous Online Discussion Assessment to Enhance Student Critical Thinking

ERIC Educational Resources Information Center

Klisc, Chris; McGill, Tanya; Hobbs, Valerie

2017-01-01

Asynchronous online discussion (AOD) is used in many tertiary education courses, and assessing it has been shown to enhance critical thinking outcomes. There has, however, been debate on what should be assessed and how the assessment should be implemented. The most common form of assessment involves grading the individual discussion contributions,…

Asynchronous Cooperative e-Learning System and Its Evaluation

NASA Astrophysics Data System (ADS)

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.

Psychophysiological effects of synchronous versus asynchronous music during cycling.

PubMed

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

2014-02-01

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

Benefits and Limitations of Online Instruction in Natural Science Undergraduate Liberal Arts Courses

NASA Astrophysics Data System (ADS)

Liddicoat, Joseph; Roberts, Godfrey; Liddicoat, Kendra; Porzecanski, Ana Luz; Mendez, Martin; McMullen, David

2013-04-01

Online courses in the Natural Sciences are taught three ways at New York University to undergraduate students majoring in the liberal arts and professional programs - synchronous courses in which students communicate online with the instructor and classmates in real time, asynchronous courses when faculty present course material for students to access and learn at their leisure, and hybrid or blended courses when part is taught asynchronously and part is taught face-to-face in a classroom with all students present. We have done online courses each way - Global Ecology (synchronous); Stars, Planets, and Life (synchronous and asynchronous); Darwin to DNA: An Overview of Evolution (asynchronous); Biodiversity Conservation (asynchronous); and Biology of Hunger and Population (blended). We will present the advantages and challenges we experienced teaching courses online in this fashion. Besides the advantages listed in the description for this session, another can be programmed learning that allows a set of sequential steps or a more complex branching of steps that allows students to repeat lessons multiple times to master the material. And from an academic standpoint, course content and assessment can be standardized, making it possible for each student to learn the same material. Challenges include resistance to online learning by a host of stakeholders who might be educators, students, parents, and the community. Equally challenging might be the readiness of instructors and students to teach and learn online. Student integrity issues such as plagiarism and cheating are a concern in a course taught online (Thormann and Zimmerman, 2012), so we will discuss our strategies to mitigate them.

Instructional WebBoard Strategies in Secondary Education and University Teaching.

ERIC Educational Resources Information Center

Siegle, Del; Ward, Layne; McCoach, D. Betsy

The nature of student participation with WebBoard, an electronic bulletin board system that can be used for synchronous and asynchronous discussions among participants, was studied in an action research project in two settings. In one, 67 and 59 high school students of Japanese participated in a course using WebBoard. The number of times students…

Communication, Community, and Disconnection: Pre-Service Teachers in Virtual School Field Experiences

ERIC Educational Resources Information Center

Wilkens, Christian; Eckdahl, Kelli; Morone, Mike; Cook, Vicki; Giblin, Thomas; Coon, Joshua

2014-01-01

This study examined the experiences of 11 graduate-level pre-service teachers completing Virtual School Field Experiences (VSFEs) with cooperating teachers in fully online, asynchronous high school courses in New York State. The VSFEs included a 7-week online teacher training course, and a 7-week online field experience. Pre-service teachers…