scholarly journals Performance of Low Output Impedance Composite pH Glass Electrodes

2000 ◽  
Vol 5 (1) ◽  
pp. 64-67 ◽  
Author(s):  
Elisabeta Veress ◽  
Peter Végh
Keyword(s):  
Response Time ◽  
Modified Electrodes ◽  
Calibration Method ◽  
Multiple Point ◽  
Ph Sensors ◽  
Output Impedance ◽  
Noise Sources ◽  
Analog Form ◽  
Glass Electrodes ◽  
Impedance Converter

Low output impedance composite pH sensors were constructed by direct attachment of an impedance converter to laboratory purpose combined pH glass electrodes. The signal was transmitted in analog form by unshielded electric cable. The performance of new and aged composite pH sensors was determined by the multiple-point calibration method. In case of new electrodes, the slope and the response time, as well as the reproducibility, were insignificantly influenced by the converter attached (the mean slope values calculated for the six electrode group studied were 57.80 mV/pH for unmodified electrodes and 57.97 mV/pH for modified electrodes). The electrode response was not affected by the presence of various electromagnetic noise sources or by the input impedance value of the measuring instrument. The slope and the response time of aged sensors were considerably improved using the impedance converter. The response time decreased from about 150–180 sec to about 30 sec and the average slope value increased from 54.94 mV/pH, calculated for unmodified electrodes, to 56.96 mV/pH, for modified electrodes.

Innovation in Noise Mapping in Natural Gas Compressor Stations

2010 ◽  
Author(s):  
K. K. Botros ◽  
A. Hawryluk ◽  
J. Geerligs ◽  
B. Huynh ◽  
R. Phernambucq
Keyword(s):  
Sound Pressure Level ◽  
Gas Turbines ◽  
Sound Pressure ◽  
Dominant Frequency ◽  
Pressure Level ◽  
Multiple Point ◽  
Noise Sources ◽  
Noise Mapping ◽  
Noise Measurements ◽  
Future Work

Noise is generated at gas turbine-based compressor stations from a number of sources, including turbomachinery (gas turbines and compressors), airflow through inlet ducts and scrubbers, exhaust stacks, aerial coolers, and auxiliary systems. Understanding these noise sources is necessary to ensure that the working conditions on site are safe and that the audible noise at neighbouring properties is acceptable. Each noise source has different frequency content, and the overall sound pressure level (OSPL) at any location in the station yard or inside the compressor building is the result of a superposition of these noise sources. This paper presents results of multiple-point spectral noise measurements at three of TransCanada’s compressor stations on the Alberta System. A method is described to determine the overall noise map of the station yard using Delaunay Triangulation and Natural-Neighbour Interpolation techniques. The results are presented in OSPL maps, as well as animated pictures of the sound pressure level (SPL) in frequency domain which will be shown on a video at the conference. The latter will be useful in future work to determine the culprit sources and the respective dominant frequency range that contributes the most to the OSPL.

scholarly journals DRIVER OUTPUT IMPEDANCE CALIBRATION SYSTEM WITH COMPARATOR UNIT OFFSET CANCELLATION

2021 ◽  
Vol 55 (1 (254)) ◽  
pp. 81-89
Author(s):  
Vazgen S. Gevorgyan
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Channel Length ◽  
Fine Tuning ◽  
Reference Frequency ◽  
Output Impedance ◽  
Noise Sources ◽  
Digital To Analog Converter ◽  
Offset Cancellation ◽  
Offset Voltage

In modern integrated circuits, the channel length of the transistors is reduced, and the supply voltages are also reduced. But the threshold voltages of the transistors cannot be reduced so quickly due to the physical properties of the materials used, which decreases the operating range of the transistors and makes noises comparable to them. Therefore, it is necessary to eliminate the influence of noise sources in the circuits, in particular, reflections between the transmission line and the output of the transmitter. A system is proposed for calibrating the output impedance of the transmitter based on an accurate external resistor with comparator unit offset voltage compensation. Existing analog and reference frequency based solutions have key disadvantages such as the inability to compensate the offset voltage after the integrated circuit is fabricated, and the distribution of the calibration voltage across the Input/Output device and constant power consumption during the operation. The proposed circuit includes a high-precision digital-to-analog converter to compensate the comparator offset voltage. It generates calibration codes for the pull-up and pull-down parts of the transmitter output buffer, and provides fine tuning of the output impedance. The circuit was modeled using 16 nm FinFET process elements and simulated with HSPICE simulator.

Transmitter Output Impedance Calibration Method

2018 ◽  
Author(s):  
Vagaen Sh. Melikyan ◽  
Andranik K. Hayrapetyan ◽  
Bagrat E. Baghramyan ◽  
Arman S. Trdatyan ◽  
Artur Kh. Mkhitaryan ◽  
...  
Keyword(s):  
Calibration Method ◽  
Output Impedance
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