Multi-channel Data

Both time-domain and frequency-domain vibration data can be acquired and analyzed in two primary formats (1) steady-state or (2) dynamic. Each of these formats has strengths and weaknesses that must be clearly understood for proper use. Each of these formats can be obtained as single- or multi-channel data. 

Multi-channel data provide the best picture of the relationship between measurement points on a machine-train. Data are acquired simultaneously from all measurement points on the machine-train. With this type of data, the analyst can establish the relationship between machine dynamics and vibration profile of the entire machine. 

Laboratory furnaces. Several types of furnaces are used in the laboratory these are often available as commercial rigs, generally equipped with more or less sophisticated temperature measurement and control devices. As an alternative, a lab-made or commercial furnace and its temperature measuring devices may be connected to a multi-channel data acquisition/actuator/switch unit, to be programmed by a personal computer, in order to plan and carry out thermal treatments, to collect and retrieve measured thermal data, etc. 

Stress measurement 20 channels, multi-channel data acquisition card of high speed, piezoresistive and piezoelectric sensors. 

ABB Argus high speed multi-channel data logger. 

There are two major data-type classifications time-domain and frequency-domain. Each of these can be further divided into steady state and dynamic data formats. In turn, each of these two formats can be further divided into single-channel and multi-channel. 

Fig. 3.3 Velocity control and synchronization of data recording by the multi-channel analyzer (MCA) operated in MCS mode with 512 channels. For the common triangular velocity profile shown here the spectrum is recorded twice, because each velocity increment is reached upon sweeping up and down. The sense of the velocity scales may also be opposite to that shown here, which means the MCA sweep may also start at...

Fig. 3.7 Pulse-height analysis (PHA) Function of the single-channel analyzer (SCA) and data recording by the multi-channel analyzer (MCA). The output (L) of the SCA yields a 5 V squareshaped pulse, a so-called TTL pulse for each y-pulse matching the voltage selection window. The SCA is set to select the Mossbauer pulses for the subsequent measurement...

Accufiber, Inc., Model 100 multi-channel optical fibre thermometer system. Publicity data, Accuft-ber, Inc., Beaverton, Oregon (1989). 

The electrochemical procedure was run with the PalmSens electrochemical analysis system, with the software package. All measurements were carried out using the multi-channel system with a Mux acquisition data that allowed to work with eight electrodes in quick succession. 

A multi-channel sample instrument or an automatic switching valve can be used when multiple locations or samples need to be monitored simultaneously. For example, such systems have been developed and manufactured which can monitor multiple points from a central location, including both continuous and discrete sampling systems. The systems can be connected to either PC s or process computers for further data processing or for activation of process controllers or operation alarms. 

There exist many observational and theoretical studies that are trying to answer these questions. For example, Moron et al. (1998) undertook a detailed analysis of all available data on the spatiotemporal variability of SST worldwide and for individual regions, using Multi-channel Singular Spectrum Analysis (MSSA). The main goal of the analysis was to reveal the laws of variability and inter-basin relationships between... 

A quantitative data analysis of the fluorescence intensity in the 10 detection lanes revealed strong intensity in five lanes, one weak signal in one lane and four lanes without any detectable fluorescence, which is in line with a bi-laminated pattern fed to a multi-channel architecture [162]. 

A test system, controlled by personal computer (PC), was developed to evaluate the performance of the sensors. A schematic of this system is shown in Figure 3. The signals from the sensors were amplified by a multi-channel electrometer and acquired by a 16 bit analog to digital data acquisition board at a resolution of 0.0145 mV/bit. The test fixture provided the electrical and fluid interface to the sensor substrate. It contained channels which directed the sample, reference and calibrator solutions over the sensors. These channels combined down stream of the sensors to form the liquid junction as shown in Figure 1. Contact probes were used to make electrical connection to the substrate. Fluids were drawn through the test fixture by a peristaltic pump driven by a stepper motor and flow of the different fluids was controlled by the pinch valves. 

The method development process will be aided if we are able to use sophisticated instrumentation (see also section 1.7.2). Automated injection and data handling will allow a number of experiments to be performed without the requirement of an analyst being present. Moreover, we have seen in chapter 5 (section 5.6) that the use of sophisticated detection techniques (dual-channel or multi-channel detectors) may be of help in the optimization process. 

The spectrum is scanned repetitively and accumulated until the signaknoise ratio is adequate. Depending on the count-rate, i.e. the strength of the source, this may take a few minutes or several hours. Accumulation is normally in a multi-channel analyser, so that the spectrum is obtained in digitized form and may be transferred directly to a computer which fits a calculated spectrum to the data points modern spectrometers are effectively PCs with built-in data processing. The fitting programme takes estimates of the parameters supplied by the user, from which a trial spectrum is calculated, and an iterative process optimizes the parameters. 

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