scholarly journals LINDA – the Astrid-2 Langmuir probe instrument

2001 ◽  
Vol 19 (6) ◽  
pp. 601-610 ◽  
Author(s):  
B. Holback ◽  
Å. Jacksén ◽  
L. Åhlén ◽  
S.-E. Jansson ◽  
A. I. Eriksson ◽  
...  
Keyword(s):  
Langmuir Probe ◽  
Sampling Rate ◽  
Plasma Temperature ◽  
Plasma Waves ◽  
Ground Contact ◽  
Spatial Structures ◽  
Ionosphere Plasma ◽  
High Sampling Rate ◽  
Temporal Structures ◽  
Instruments And Techniques

Abstract. The Swedish micro-satellite Astrid-2, designed for studies in magnetosperic physics, was launched into orbit on 10 December 1998 from the Russian cosmodrome Plesetsk. It was injected into a circular orbit at 1000 km and at 83 degrees inclination. The satellite carried, among other instruments, a double Langmuir Probe instrument called LINDA (Langmuir INterferometer and Density instrument for Astrid-2). The scientific goals of this instrument, as well as the technical design and possible modes of operation, are described. LINDA consists of two lightweight deployable boom systems, each carrying a small spherical probe. With these probes, separated by 2.9 meters, and in combination with a high sampling rate, it was possible to discriminate temporal structures (waves) from spatial structures. An on-board memory made it possible to collect data also at times when there was no ground contact. Plasma density and electron temperature data from all magnetic latitudes and for all seasons have been collected.Key words. Ionosphere (plasma temperature and density; plasma waves and instabilities; instruments and techniques)

scholarly journals Observation of isotropic electron temperature in the turbulent E region

2001 ◽  
Vol 19 (1) ◽  
pp. 11-15 ◽  
Author(s):  
S. Saito ◽  
S. C. Buchert ◽  
S. Nozawa ◽  
R. Fujii
Keyword(s):  
Electron Temperature ◽  
Plasma Temperature ◽  
Plasma Waves ◽  
Radar Data ◽  
Electron Heating ◽  
Ionosphere Plasma ◽  
E Region ◽  
Eiscat Radar ◽  
The Magnetic Field ◽  
Region Plasma

Abstract. Using EISCAT radar data, we find that electrons are strongly heated in the magnetic field-line direction during high electric field events. The remote site data show that the electron temperature increases in almost the same way in the field-perpendicular direction; electron heating by E region plasma turbulence is isotropic. We discuss the implications of our observation for the "plasmon"-electron as well as the wave Joule heating models of the anomalous electron heating in the E region.Key words. Ionosphere (auroral ionosphere; plasma temperature and density; plasma waves and instabilities)

Intelligent Displacement Measuring System for Rock Stratum

2011 ◽  
Vol 103 ◽  
pp. 583-586
Author(s):  
Feng Ling Li ◽  
Jian Hua Rong ◽  
Yu Ping Zhang
Keyword(s):  
Civil Engineer ◽  
Real Time ◽  
Sampling Rate ◽  
Measuring System ◽  
Displacement Sensor ◽  
Rock Stratum ◽  
Baud Rate ◽  
Real Time Clock ◽  
High Sampling Rate ◽  
Displacement System

Measuring rock stratum displacement in dam grouting process is very important. A new displacement system is designed, comprising a programmable microcontroller Atmega16, a new grating capacitive displacement sensor(GCDS), DS1302 real time clock chip and announciator etc. The system has high sampling rate of 9600 baud rate and can trap the displacement equal to 0.001 millimeter in one second. Equipped with mechanical conveyance system, the system can be applied to the civil engineer. The experiment results show the instrument can measure accurately the displacement value and alarm geologic disaster in time, which can conduct continuous and accurate monitoring and provide operation decisions for dam engineers.

scholarly journals An Automatic Method for Detection and Update of Additive Changes in Road Network with GPS Trajectory Data

2019 ◽  
Vol 8 (9) ◽  
pp. 411 ◽  
Author(s):  
Tang ◽  
Deng ◽  
Huang ◽  
Liu ◽  
Chen
Keyword(s):  
Road Network ◽  
Sampling Rate ◽  
Quality Data ◽  
Automatic Method ◽  
Trajectory Data ◽  
The Road ◽  
High Sampling Rate ◽  
Map Generation ◽  
Gps Trajectory Data ◽  
Gps Trajectory

Ubiquitous trajectory data provides new opportunities for production and update of the road network. A number of methods have been proposed for road network construction and update based on trajectory data. However, existing methods were mainly focused on reconstruction of the existing road network, and the update of newly added roads was not given much attention. Besides, most of existing methods were designed for high sampling rate trajectory data, while the commonly available GPS trajectory data are usually low-quality data with noise, low sampling rates, and uneven spatial distributions. In this paper, we present an automatic method for detection and update of newly added roads based on the common low-quality trajectory data. First, additive changes (i.e., newly added roads) are detected using a point-to-segment matching algorithm. Then, the geometric structures of new roads are constructed based on a newly developed decomposition-combination map generation algorithm. Finally, the detected new roads are refined and combined with the original road network. Seven trajectory data were used to test the proposed method. Experiments show that the proposed method can successfully detect the additive changes and generate a road network which updates efficiently.

All-optical parallelization for high sampling rate photonic ADC in fully digital radar systems

2010 ◽  
Author(s):  
Paolo Ghelfi ◽  
Lingmei Ma ◽  
Xiaoxia Wu ◽  
Minyu Yao ◽  
Alan E. Willner ◽  
...  
Keyword(s):  
Sampling Rate ◽  
Radar Systems ◽  
High Sampling ◽  
High Sampling Rate ◽  
All Optical

scholarly journals High sampling rate thermistor string observations at the slope of Great Meteor Seamount

Ocean Science ◽  
2005 ◽  
Vol 1 (1) ◽  
pp. 17-28 ◽  
Author(s):  
H. van Haren ◽  
R. Groenewegen ◽  
M. Laan ◽  
B. Koster
Keyword(s):  
High Frequency ◽  
North Atlantic Ocean ◽  
Sampling Rate ◽  
Very High Frequency ◽  
High Sampling ◽  
High Sampling Rate ◽  
In Situ Calibration ◽  
Great Meteor Seamount ◽  
Very High

Abstract. A high sampling rate (1 Hz) thermistor string has been built to accommodate the scientific need to accurately monitor high-frequency and vigorous internal wave and overturning processes in the ocean. The thermistors and their custom designed electronics can register temperature at an estimated precision of about 0.001° C with a response time faster than 0.25 s down to depths of 6000 m. With a quick in situ calibration using SBE 911 CTD an absolute accuracy of 0.005° C is obtained. The present string holds 128 sensors at 0.5 m intervals, which are all read-out within 0.5 s. When sampling at 1 Hz, the batteries and the memory capacity of the recorder allow for deployments of up to 2 weeks. In this paper, the instrument is described in some detail. Its performance is illustrated with examples from the first moored observations, which show Kelvin-Helmholtz overturning and very high-frequency (Doppler-shifted) internal waves besides occasionally large turbulent bores moving up the sloping side of Great Meteor Seamount, Canary Basin, North-Atlantic Ocean.

Torsional Vibration Detection Using High Sampling Rate and High Resolution Keyphasor Information

2013 ◽  
Author(s):  
Huageng Luo ◽  
Roengchai Chumai ◽  
Nicolas Peton ◽  
Brian Howard ◽  
Arun Menon
Keyword(s):  
Torsional Vibration ◽  
Sampling Rate ◽  
Synchronous Motor ◽  
Rotating Machinery ◽  
Normal Operation ◽  
Machinery Condition Monitoring ◽  
Vibration Detection ◽  
High Sampling ◽  
High Sampling Rate ◽  
Phase Demodulation

Torsional vibration excitation in rotating machinery can cause system reliability issues or even catastrophic failures. Torsional vibration detection and monitoring becomes an important step in rotating machinery condition monitoring, especially for those machines driven by a variable frequency drive (VFD), a pulse width modulation motor (PWM), or a synchronous motor (SM), etc. Traditionally, the torsional vibration is detected by a phase demodulation process applied to the signals generated by tooth wheels or optical encoders. This demodulation based method has a few unfavorable issues: the installation of the tooth wheels needs to interrupt the machinery normal operation; the installation of the optical barcode is relatively easier, however, it suffers from short term survivability in harsh industrial environments. The geometric irregularities in the tooth wheel and the end discontinuity in the optical encoder will sometimes introduce overwhelming contaminations from shaft order response and its harmonics. In addition, the Hilbert Transform based phase demodulation technique has inevitable errors caused by the edge effect in FFT and IFFT analyses. Fortunately, in many industrial rotating machinery applications, the torsional vibration resonant frequency is usually low and the Keyphasor® and/or encoder for speed monitoring is readily available. Thus, it is feasible to use existing hardware for torsional vibration detection. In this paper, we present a signal processing approach which used the Keyphasor/encoder data digitized by a high sampling rate and high digitization resolution analog-to-digital (A/D) convertor to evaluate the torsional vibration directly. A wavelet decomposition (WD) based method was used to separate the torsional vibration from the shaft speed, so that the time history of the torsional vibrations can be extracted without significant distortions. The developed approach was then validated through a synchronous motor fan drive and an industrial power generation system. Detailed results are presented and discussed in this paper.

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