scholarly journals Xenomai-based multiple-process system, for real-time data acquisition and graphical display control

2017 ◽  
Author(s):  
Hadrien Caron ◽  
Pierre Pouget
Keyword(s):  
Real Time ◽  
Open Source Software ◽  
Time Data ◽  
Graphical Displays ◽  
Real World Setting ◽  
Process System ◽  
Multiple Process ◽  
Hard Real Time ◽  
Millisecond Accuracy ◽  
Display Control

AbstractTo elicit complex and rich graphical displays, and record neuronal phenomena ofinterest while all simultaneously being capable to interact in a closed-loop with external devises is a challenging task to all neurophysiologists. To facilitate this process, we have developed an Open-Source software system using a single computer running a well established Linux architecture (Ubuntu) associated to a kernel duo providing hard real-time support (Xenomai). We show that a single computer using our API is capable, for any tasks that require OpenGL displaying, to acheive millisecond accuracy programmed events. In this report, we describe the design of our system, benchmark and its performance in a real-world setting, and describe some key features.

A Novel Crash Recovery Scheme for Distributed Real-Time Databases

2009 ◽  
pp. 769-787
Author(s):  
Yingyuan Xiao
Keyword(s):  
Real Time ◽  
Agile Manufacturing ◽  
Database System ◽  
Main Memory ◽  
Information Support ◽  
Timing Constraints ◽  
Time Data ◽  
Main Memory Database ◽  
Distributed Database System ◽  
Hard Real Time

Recently, the demand for real-time data services has been increasing (Aslinger & Son, 2005). Many applications such as online stock trading, agile manufacturing, traffic control, target tracking, network management, and so forth, require the support of a distributed real-time database system (DRTDBS). Typically, these applications need predictable response time, and they often have to process various kinds of queries in a timely fashion. A DRTDBS is defined as a distributed database system within which transactions and data have timing characteristics or explicit timing constraints and system correctness that depend not only on the logic results but also on the time at which the logic results are produced. Similar to conventional real-time systems, transactions in DRTDBSs are usually associated with timing constraints. On the other hand, a DRTDBS must maintain databases for useful information, support the manipulation of the databases, and process transactions. Timing constraints of transactions in a DRTDBS are typically specified in the form of deadlines that require a transaction to be completed by a specified time. For soft realtime transactions, failure to meet a deadline can cause the results to lose their value, and for firm or hard real-time transactions, a result produced too late may be useless or harmful. DRTDBSs often process both temporal data that lose validity after their period of validity and persistent data that remain valid regardless of time. In order to meet the timing constraints of transactions and data, DRTDBSs usually adopt main memory database (MMDB) as their ground support. In an MMDB, “working copy” of a database is placed in the main memory, and a “secondary copy” of the database on disks serves as backup. Data I/O can be eliminated during a transaction execution by adopting an MMDB so that a substantial performance improvement can be achieved. We define a DRTDBS integrating MMDB as a distributed real-time main memory database system (DRTMMDBS).

SoftPLC-Based Control

2012 ◽  
pp. 440-463 ◽  
Author(s):  
Stefano Scanzio
Keyword(s):  
Open Source ◽  
Control Systems ◽  
Real Time ◽  
Open Source Software ◽  
Industrial Ethernet ◽  
Programmable Logic ◽  
Programmable Logic Controllers ◽  
Hard Real Time ◽  
Logic Controllers

Nowadays, most control systems are based on programmable logic controllers (PLCs) and on commercial programs, but the use of conventional PCs is becoming an increasing by popularity and competitive alternative. After an introduction that underlines the positive and negative aspects of both solutions, EtherCAT, a hard real-time industrial Ethernet protocol that allows the use of both conventional PCs and open-source software, is analyzed. Two different EtherCAT master implementations are compared, which are based on a commercial and on a open-source software, respectively. In order to highlight differences and provide a short reference, a simple example was implemented in the two environments.

scholarly journals Development and implementation of real-time data acquisition systems for fusion devices with Open Source software

2010 ◽  
Vol 85 (3-4) ◽  
pp. 378-382 ◽  
Author(s):  
M. Zilker ◽  
K. Behler ◽  
T. Bluhm ◽  
P. Heimann ◽  
Ch. Hennig ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Open Source ◽  
Real Time ◽  
Open Source Software ◽  
Time Data ◽  
Data Acquisition Systems ◽  
Real Time Data

scholarly journals Status of Earthquake Early Warning in Switzerland

2021 ◽  
Vol 9 ◽  
Author(s):  
Frédérick Massin ◽  
John Clinton ◽  
Maren Böse
Keyword(s):  
Real Time ◽  
Open Source Software ◽  
Early Warning ◽  
Seismic Network ◽  
Earthquake Early Warning ◽  
Fault Rupture ◽  
Time Data ◽  
Origin Time ◽  
P Waves ◽  
Finite Fault

The Swiss Seismological Service (SED) at ETH has been developing methods and open-source software for Earthquake Early Warning (EEW) for more than a decade and has been using SeisComP for earthquake monitoring since 2012. The SED has built a comprehensive set of SeisComP modules that can provide EEW solutions in a quick and transparent manner by any seismic service operating SeisComP. To date, implementations of the Virtual Seismologist (VS) and Finite-Fault Rupture Detector (FinDer) EEW algorithms are available. VS provides rapid EEW magnitudes building on existing SeisComP detection and location modules for point-source origins. FinDer matches growing patterns of observed high-frequency seismic acceleration amplitudes with modeled templates to identify rupture extent, and hence can infer on-going finite-fault rupture in real-time. Together these methods can provide EEW for all event dimensions from moderate to great, if a high quality, EEW-ready, seismic network is available. In this paper, we benchmark the performance of this SeisComP-based EEW system using recent seismicity in Switzerland. Both algorithms are observed to be similarly fast and can often produce first EEW alerts within 4–6 s of origin time. In real time performance, the median delay for the first VS alert is 8.7 s after origin time (56 earthquakes since 2014, from M2.7 to M4.6), and 7 s for FinDer (10 earthquakes since 2017, from M2.7 to M4.3). The median value for the travel time of the P waves from event origin to the fourth station accounts for 3.5 s of delay; with an additional 1.4 s for real-time data sample delays. We demonstrate that operating two independent algorithms provides redundancy and tolerance to failures of a single algorithm. This is documented with the case of a moderate M3.9 event that occured seconds after a quarry blast, where picks from both events produced a 4 s delay in the pick-based VS, while FinDer performed as expected. Operating on the Swiss Seismic Network, that is being continuously optimised for EEW, the SED-ETHZ SeisComP EEW system is achieving performance that is comparable to operational EEW systems around the world.

Use of open source software for hard real-time experiments

2004 ◽  
Author(s):  
R. Ostrovrsnik ◽  
A. Hace ◽  
M. Terbuc
Keyword(s):  
Open Source ◽  
Real Time ◽  
Open Source Software ◽  
Hard Real Time

Ambulatory Assessment

2009 ◽  
Vol 14 (2) ◽  
pp. 109-119 ◽  
Author(s):  
Ulrich W. Ebner-Priemer ◽  
Timothy J. Trull
Keyword(s):  
Real Time ◽  
Clinical Psychology ◽  
Real Life ◽  
Ambulatory Assessment ◽  
Computer Assisted ◽  
Affective Valence ◽  
Time Data ◽  
Physiological Processes ◽  
Context Specific ◽  
Questionnaire Studies

Convergent experimental data, autobiographical studies, and investigations on daily life have all demonstrated that gathering information retrospectively is a highly dubious methodology. Retrospection is subject to multiple systematic distortions (i.e., affective valence effect, mood congruent memory effect, duration neglect; peak end rule) as it is based on (often biased) storage and recollection of memories of the original experience or the behavior that are of interest. The method of choice to circumvent these biases is the use of electronic diaries to collect self-reported symptoms, behaviors, or physiological processes in real time. Different terms have been used for this kind of methodology: ambulatory assessment, ecological momentary assessment, experience sampling method, and real-time data capture. Even though the terms differ, they have in common the use of computer-assisted methodology to assess self-reported symptoms, behaviors, or physiological processes, while the participant undergoes normal daily activities. In this review we discuss the main features and advantages of ambulatory assessment regarding clinical psychology and psychiatry: (a) the use of realtime assessment to circumvent biased recollection, (b) assessment in real life to enhance generalizability, (c) repeated assessment to investigate within person processes, (d) multimodal assessment, including psychological, physiological and behavioral data, (e) the opportunity to assess and investigate context-specific relationships, and (f) the possibility of giving feedback in real time. Using prototypic examples from the literature of clinical psychology and psychiatry, we demonstrate that ambulatory assessment can answer specific research questions better than laboratory or questionnaire studies.

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