Signal Conditioning Equipment Research Articles

Upgrade of EAST data acquisition system

After the 2021 spring campaign, EAST (Experimental Advanced Superconducting Tokamak) facility carried out maintenance. EAST data acquisition system, which is responsible for the unified diagnostic data acquisition and long-term data storage, also has been upgraded. This article will present an overview of the upgrade data acquisition system. The EAST data acquisition system consists of a DAQ console, DAQ units, and data storage database. The DAQ console is used to manage the data acquisition configuration information and control the data acquisition workflow. The old DAQ console has been developed for many years, however, it has become inadequate with increasing of data acquisition units. After upgrade, it is replaced by a data acquisition workflow control program and a configuration management module. The configuration management module provides a website based on Spring Boot framework for administrator and diagnostic users to manage the DAQ units, data storage servers, and signal conditioning equipment, while the data acquisition workflow control program runs as a Linux service. Up to 65 DAQ units with about 4000 channels are distributed in different physical positions for different diagnostic systems. The raw diagnostic data acquired by DAQ units is quasi-real-time transferred to the data storage database. The data acquisition driver plugin has been updated for various kinds of data acquisition cards. The data server cluster keeps these data with MDSPlus for long-term storage. The upgraded data acquisition system has been used in the EAST campaign.

REJECTION OF HARMONIC AND TRANSIENT DISTURBANCES OF A SMART STRUCTURE WITH PIEZOELECTRIC ACTUATORS

Light flexible structures are easily prone to vibrate due to external forces or due to forces generated in the inner structure. This situation is common in machinery or mechanical structures with rotational devices. The unwanted vibration of such structures can be compensated with the addition of piezoelectric actuators for active vibration control (AVC). The rejection of harmonic disturbances is frequently done with controllers based on the internal model principle. The goal of this research is to reduce the effect of harmonic disturbances with known (measured) time-varying frequencies acting on a system as well as to increase the damping of the system for the transient response (first mode of vibration). The experimental setup is made up of a slender aluminium flexible beam, a pair of piezoelectric actuators, an accelerometer and two DC motors, as well as the data acquisition and signal conditioning equipment. The harmonic disturbance is generated by DC motors. The control design utilizes an augmented description of the plant. The plant including the disturbance is modelled as a polytopic linear parameter-varying (pLPV) system. An observer-based gain-scheduling controller is calculated based on quadratic stability and the stability is guaranteed for the specified range of variation of the scheduling parameters, also restriction in the performance is introduced in the sense of the H 2 -norm. Experimental results show very good disturbance cancellation.

Using the noise analysis technique to detect response time problems in the sensing lines of nuclear plant pressure transmitters

Blockages, voids, and leaks contribute to nearly 70 percent of the age-related problems in the sensing lines that connect pressure, level, and flow transmitters in nuclear plants to the processes they measure, reducing their speed of response. Only the noise analysis technique provides an effective means for testing response times when a nuclear plant is operating. It also makes possible the simultaneous testing of response time of multiple pressure transmitters and is applicable for both force-balance and motion-balance transmitter types. The technique involves three steps -- data acquisition, data qualification, and data analysis. Commercial signal-conditioning equipment is used to extract the noise from the transmitter output by removing the DC component of the signal and amplifying the AC component. The AC signal is then digitized; qualified for stationarity, linearity, and other abnormalities; and then analyzed in the frequency domain and/or time domain. Tests performed by the author has validated the accuracy of the noise analysis technique and yielded the following conclusions: Long sensing lines and blockages increase the response time of a pressure sensing system. Increases in response times caused by sensing-line length and blockages depend on the compliance of the transmitter. The response time of transmitters with larger compliances is more sensitive to sensing-line length and blockages than that of transmitters with small compliances. When noise analysis identifies a sensing-line blockage, the line must be purged (flushed) and noise tests repeated to ensure the problem is resolved.

Determination of optimum response requrements for underwater fiber-optic and electroacoustic transducers

To aid in the design of new sensors the methodology of determining the optimum sensitivity, linearity, and dynamic range requirements of underwater acoustic sensors is described. The relationships between the commonly specified ‘‘rated’’ sensitivity and its ‘‘absolute’’ detectability are explored in terms of the required minimum and maximum detectable signal levels and background noise in the operating environment and signal conditioning equipment. Performance limitations of fiber-optic and electroacoustic sensor designs and cost tradeoffs between the sensor and signal conditioning equipment are compared.

An instrumented cylinder for the measurement of instantaneous local heat flux in high temperature fluidized beds

An instrumented cylinder which contains an abrasion resistant, fast responding (settling time of approximately 2 ms) heat flux transducer, along with associated analog signal conditioning equipment, is developed for the measurement of instantaneous local heat transfer rates to an immersed horizontal cylinder in a high temperature fluidized bed. Analog signal conditioning is used to provide a d.c. voltage which is linearly related to the instantaneous local heat flux. This voltage is suitable for direct oscillographic recording or digital data acquisition. Instantaneous local heat transfer coefficient data obtained in a 30 × 60 cm cross section high temperature fluidized bed of 0.9 mm mean diameter particles at 562°C are presented. Spatially-averaged heat transfer coefficient data, obtained using the instrumented cylinder in fluidized beds with temperatures up to 743°C, are in very good agreement with published correlations.

The use of an IBM personal computer (PC) for performing room acoustics measurements

The general acceptance of the PC microcomputer and the subsequent availability of additional hardware and software have offered researchers and practitioners some formidable tools for acoustical investigations. Using an IBM portable PC, ILS signal-processing software, and additional signal gathering and signal conditioning equipment, an inexpensive and portable room acoustics and data collection system was developed for the purpose of investigating the acoustics of theaters, concert halls, and other assembly spaces. This system will be described, and the results of data will be presented and discussed.

A transducer for the measurement of instantaneous local heat flux to surfaces immersed in high-temperature fluidized beds

An abrasion resistant, fast responding (settling time approximately 5 ms) heat flux transducer with associated analog signal conditioning equipment has been developed for the measurement of instantaneous local heat transfer rates to surfaces immersed in fluidized beds at combustion-level temperatures. Analog signal conditioning is used to provide a d.c. voltage which is linearly related to the instantaneous local heat flux. This voltage is suitable for direct oscillographic recording or digital data acquisition. Instantaneous local bed-to-wall heat flux data obtained in a small (102 × 102 mm) electrically heated fluidized bed at 282°C are presented.

Some factors affecting long‐term stability of strain measurements using metal foil gauges

The stability of long‐term strain measurements is very much dependent on the correct selection of techniques, materials and equipment for the conditions under which the measurements are to be taken.Temperature effects are also a major factor. Temperature‐induced changes in resistance of the Wheat‐stone bridge completion and balancing components can result in an output signal indistinguishable from that produced by change of gauge resistance due to surface strain. The signal conditioning and readout equipment can also be affected by temperature and become an additional source of instability.The term ‘instability’, in strain gauging, generally refers to ‘zero drift’ and random deviations of readings when the loading conditions are stationary. In particular it refers to those situations where a measurement system has been balanced and measurements have been taken with a particular load condition which cannot be repeated to re‐check the original zero.In this paper the major sources of instability are identified and recommendations are made as to how best to obtain long‐term stability of strain measurements using metal foil gauges.Information on principal error sources in strain measurement systems using metal foil gauges is included for completeness and because an appreciation of these sources is also vitally important.

Computers for the Rubber and Plastics Industry: Mini, Midi, and Micro

Small computers, known popularly as mini-computers, have become available comercially in great profusion during the past few years. The distinguishing characteristics of these machines are low cost, small physical size, work-shop or factory environment capability, computational speed and logic identical to larger and more expensive machines, and their seemingly instant popularity for myriads of new uses. It should also be noted that integrated circuit technology is only the trigger of this boom of small low-cost computers. Low cost stems also from high-volume production for the original equipment manufacturers market, removal of much of the external connector and signal conditioning equipment, borrowing of programming systems and packages from older and more expensive designs of computers, and separate pricing for systems engineering and applications programs. Projects which are to make use of mini-computers must take full cognizance of these as well as the prior list of characteristics.