Transmitter Units

A factor which previously limited installation of automatic corrosion monitoring systems was the cost of cabling between sensors and control room instrumentation-this was particularly relevant to the electrical resistance (ER) systems. Developments to overcome this have included transmitter units at the probe location providing the standard 4-20 mA output (allowing use of standard cable) for onward transmission to data systems or the use of radio linkage which has been successfully used for other process-plant instrumentation. 

A complete range of instrumentation is available from portable units to automatic systems utilising many probes. Transmitter units are available which can be located at the probe and transmit ER data into the 4-20 mA standard instrument signal. Radio linkage from transmitter to control room or nearby offshore platform is available commercially. A satellite link has been used to monitor offshore platform ER probes at the onshore base in a Norwegian oilfield. 

Figure 5. Practical telephone transmitter unit now manufactured, using polymer...

In many instruments the meter read-out is calibrated in absorbance units using a logarithmic scale while other instruments retain the convenience of a linear scale but convert the signal from the detector to a logarithmic one by electronic or mechanical means. It is essential when using a photometric instrument to know if it is calibrated in absorbance or transmittance units. 

It has proven feasible to take the electrical output from photocells or phototubes and either with or without amplification record the magnitude and duration of the output. The recording may be made either in the form of a line tracing on a moving chart or may be converted to numerical values and printed by a read-out device. Further refinements can be supplied in which the instrument converts optical densities (or transmittance units) to concentration values. More intricate recording colorimeters or spectrophotometers are also available for continuous scanning and recording of complete spectra from ultraviolet to infrared. No further discussion of these will be attempted since they do not serve a normal function in routine clinical chemistry laboratories. 

Figure 2. ARC AS deck unit showing filter transport mechanism (A), aspirating motor (B), motor controllers (C), radiation-counting photomultiplier tid)es (D), pulse amplifier transmitter units (E), high- and low-voltage power supplies (F), calibration counter (G), filter supply roll (H), and takeup roll (I).

The measured signal to noise (s/n) from an optical system can be calculated as the full transmitted signal divided by the RMS noise (in transmittance units). Thus, for a 100% line with RMS noise as 0.001 %T, the s/n = 100/0.01 = 10,000 1. This applies when RMS noise is calculated as... 

The omnipresence of deoxyribonucleic acid (DNA) within cells piqued curiosity. Miescher discovered the DNA molecule in 1869, which was 3 years after Mendel published his experiments on heredity in plants. Mendle s work incorporated the notion that a gene is a conserved and transmittable unit of trait information. However, science had to wait until 1943 for the hnk to be made between the manifestation of traits and the presence of DNA within a cell. Oswald Theodore Avery (1877-1955) and his coworkers showed that by simply adding the DNA from a virulent form of the bacterium Pneumococcus to a suspension of nonvirulent Pneumococcus, the nonvirulent bacterium acquired the traits of the virulent form. With this link estabhshed, the nature of the DNA molecule became a subject of intense interest. In 1951, Pauling and Corey proposed that the DNA molecule forms an a-hehx structure, and experimental evidence was reported by Watson and Crick in 1953. 

In the Avery system, the pacer transmitter unit is powered by 9-V batteries. The Mark IV transmitter has a battery indicatar light, which flashes on inspiration. The battery indicator will stop flashing as the power is reduced to a critical level, approximately 24 to 36 hours in advance of loss of transmitter output. In the latest transmitter model, there is an additional circuit that maintains transmitter output as voltage decreases, so that there is no effect on ventilation however, in older models, as battery output decreases, so does the stimulus output and consequently the ventilation. Therefore, battery maintenance must occur on a regular schedule. 

The rest of this paper is designed as follows In Section 2, MCF is introduced Section 3 reviews some parametric models. The proposed non-par-ametric model is discussed in Section 4. Aircraft Radar Transmitter Unit (Case Study) is studied by parametric and non-parametric methods in Section 5. Finally, conclusions and discussions are given in Section 6. 

CASE STUDY AIRCRAFT S RADAR TRANSMITTER UNIT... 

We studied a (repairable) radar transmitter unit. This transmitter was the part of the main surveillance radar (PS-37) of the AJ 37 strike aircraft. The data were right-hand censored by two processes failure and discard. The study considers 83 repairable units. Figure 1 displays the transmitter repair data of 50 units, separately. Each line in the figure shows the failure history of a component and each bullet point shows the aircraft unit s age in hours when a transmitter was repaired. For example, Transmitter S/N 40 was repaired at 840.72, 884.18, and 932.74 hours, and was observed for 2186.47 hours. The latest age is called the unit s censoring age. ... 

Individual or multi-probe transmitter units are available that are mounted local to the probe and used to receive, process, and transmit the probe signals to a remote interrogation unit. The interrogation unit may be either a dedicated chart recorder, a digital display unit or a process computer. 

Computers dedicated to corrosion monitoring may be used to receive data from corrosion probes, either via transmitter units or multiplexers. The computer facilities enable selection of recording... 

Transmittance, % Transmittance or Percent Transmittance Units used to measure the amount of infrared radiation transmitted by a sample. It is often used as the y-axis unit in infrared spectra. 

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