Repeatability, instrument

Cracks and kernel integrity are not the only criteria used for describing rice quality, because color, glass transition temperature, and so on are even easier to measure with instruments. Sensory characteristics, such as smell, taste, texture, are less easy to evaluate. In this chapter, only the main criteria, accessible by means of repeatable instrumental measurements, are detailed, namely the mechanical properties. The effect of drying on both paddy and parboiled paddy rice is discussed. 

Cleaning and Recalibration—Qean any coked or sooted parts per manufacturer s instructions. After any cleaning or adjustment, assemble and leak check the apparatus. Repeat instrument calibration prior to reanalysis of the test specimen. 

With the right software controlling the instrument, it is possible for the above process to be repeated n times,... 

Most of the experimental information concerning copolymer microstructure has been obtained by physical methods based on modern instrumental methods. Techniques such as ultraviolet (UV), visible, and infrared (IR) spectroscopy, NMR spectroscopy, and mass spectroscopy have all been used to good advantage in this type of research. Advances in instrumentation and computer interfacing combine to make these physical methods particularly suitable to answer the question we pose With what frequency do particular sequences of repeat units occur in a copolymer. 

Accuracy and Repeatability Definitions of terminology pertaining to process measurements can be obtained from standard S5I.I from the International Society of Measurment and Control (ISA) and standard RC20-II from the Scientific Apparatus Manufac turers Association (SAMA), both of which are updated periodically. An appreciation of accuracy and repeatability is especially important. Some apphcations depend on the accuracy of the instrument, but other apphcations depend on repeatability. Excellent accuracy imphes excellent repeatabihty however, an instrument can have poor accuracy but excellent repeatability. In some apphcations, this is acceptable, as discussed below. 

Repeat everything at every thousand RPM, switching the instrument to the higher range when needed. 

After the completion of the balanced acceleration and deceleration runs, the unbalance weight must be placed at the predetermined location and the acceleration and deceleration test repeated using the same recording instrumentation. The results should be compared to the appropriate computer predictions and the API acceptance criteria applied. Acceptance criteria were added in the API 617 sixth edition. 

If the hypothesis or model does not seem to be a good predictor of what is happening in the building, you probably need to collect more information about the occupants, HVAC system, pollutant pathways, or contaminant sources. Under some circumstances, detailed or sophisticated measurements of pollutant concentrations or ventilation quantities may be required. Outside assistance may be needed if repeated efforts fail to produce a successful hypothesis or if the information required calls for instruments and procedures that are not available in-house. Analysis of the information collected during the LAQ investigation could produce any of the following results ... 

The planning of measurements is the first consideration to obtain information by the measurement approach. Why is it essential to make plans before any action is taken. Could one not just take the instruments and carry out the monitoring. In very simple situations this approach might provide a satisfactory result, but it could result in failure as well. In complicated situations failure, in terms of missing information, would be likely. Hence in order to obtain a sufficient quantity of high-quality information and to avoid the need to repeat any measurement or monitoring, and thus to save time and effort, the planning of measurements is essential. 

The question is often asked. How often should calibration be carried out Is it sufficient to do it once, or should it be repeated The answer to this question depends on the instrument type. A very simple instrument that is robust and stable may require calibrating only once during its lifetime. Some fundamental meters do not need calibration at all. A Pitot-static tube or a liquid U-tube manometer are examples of such simple instruments. On the other hand, complicated instruments with many components or sensitive components may need calibration at short intervals. Also fouling and wearing are reasons not only for maintenance but also calibration. Thus the proper calibration interval depends on the instrument itself and its use. The manufacturers recommendations as well as past experience are often the only guidelines. 

Usually there is no opportunity to repeat the measurements to determine the experimental variance or standard deviation. This is the most common situation encountered in field measurements. Each measurement is carried out only once due to restricted resources, and because field-measured quantities are often unstable, repetition to determine the spread is not justified. In such cases prior knowledge gained in a laboratory with the same or a similar meter and measurement approach could be used. The second alternative is to rely on the specifications given by the instrument manufacturer, although instrumenr manufacturers do not normally specify the risk level related to the confidence limits they are giving. 

The bias error is a quantity that gives the total systematic error of a measuring instrument under defined conditions. As mentioned earlier, the bias should be minimized by calibration. The repeatability error consists of the confidence limits of a single measurement under certain conditions. The mac-curacy or error of indication is the total error of the instrument, including the... 

The second, mechanical and electrical manometers, require more frequent calibration. Changes in the elastic properties of the pressure transducer, wearing in mechanical parts, and electronic circuitry drift influence the properties of the instruments, giving rise to repeated calibration. 

Knowing what checks have been made using the instrument since it was last checked, so that you can repeat them should the instrument be subsequently found out of calibration - this is only necessary for instruments whose accuracy drifts over time, i.e. electronic equipment. (It is not normally necessary for mechanical devices. You will need a traceability system for this purpose.)... 

Accuracy of data The microprocessor should be capable of automatically acquiring accurate, repeatable data from equipment included in the program. The elimination of user input on filter settings, bandwidths and other measurement parameters would greatly improve the accuracy of acquired data. The specific requirements that determine data accuracy will vary depending on the type of data. For example, a vibration instrument should be able to average... 

The general idea of peptide sequencing by Edman degradation is to cleave one amino acid at a time from an end of the peptide chain. That terminal amino acid is then separated and identified, and the cleavage reactions are repeated on the chain-shortened peptide until the entire peptide sequence is known. Automated protein sequencers are available that allow as many as 50 repetitive sequencing cycles to be carried out before a buildup of unwanted by products interferes with the results. So efficient are these instruments that sequence information can be obtained from as little as 1 to 5 picomoles of sample—less than 0.1 /xg. 

The weep point or strain-to-first-crack in a wall for filament-wound pipe constructed using isophthalic plastic is currently found to be not less than 0.009 in./in. This has been repeatedly demonstrated by careful coupon testing and burst testing of pipes with strain gauge instrumentation attached. 

Inspection tolerance can be divided into two major components the accuracy variability of the instruction and the repeatability of the measuring method. The calibration and accuracy of the instrument are documented and certified by its manufacturer, and it is periodically checked. Understanding the overall inspection process is extremely useful in selecting the proper method for measuring a specific dimension. When all the inspection methods available provide an acceptable level of accuracy, the most economical method should be used. 

These spectra not only confirm the primary structure of the repeat unit of the polymer but also strongly suggest that no side reactions are detectable within the limitations of the instrument. In the 13C NMR spectrum (vide infra) all resonances can be unequivocally assigned, demonstrating the clean nature of the... 

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