Measurement instruments

ASTM D2244, Methodfor Calculation of Color Differencesfrom Instrumentally Measured Color Coordinates, Vol. 6.01, ASTM, Philadelphia, Pa., 1989. 

Preliminary Test Operation of the unit shoiild be set at the test protocol conditions. A preliminaiy set of samples should be taken to identify problems with instruments, measurements, and sample locations. This preliminaiy set of measurements should also be an yzed in the same manner that the full-test results will be analyzed to ensure that the measurements wiU lead to the desired results. Modifications to the test protocol can be made prior to exerting the effort and resources necessary for the complete test. 

The diagnostics applied to shock experiments can be characterized as either prompt or delayed. Prompt instrumentation measures shock velocity, particle velocity, stress history, or temperature during the initial few shock transits of the specimen, and leads to the basic equation of state information on the specimen material. Delayed instrumentation includes optical photography and flash X-rays of shock-compression events, as well as post-mortem examinations of shock-produced craters and soft-recovered debris material. 

Discuss the use of data telemetered to the office of the air pollution control agency from automatic instruments measuring ambient air quality and automatic instruments measuring pollutant emissions to the atmosphere as air pollution control regulatory means. 

A calibration facility must produce the desired velocity range for the meter to be calibrated. The air temperature should be kept constant over the test to ensure constant density. For thermal anemometers, velocity calibration only is not sufficient. They should also be checked for temperature compensation. In the case of omnidirectional probes, sensitivity to flow direction should be tested. In the case of low-speed (thermal) anemometers, their self-convection error should be measured, and, for instruments measuring flow fluctuation (turbulence), dynamic characteristics testing should be carried out as well. ... 

The square law relationship also implies that the instrument measures RMS values. It can be used on either A.C. (up to the lower audio range if special compensating circuits are employed) or D.C. The instrument reading can be... 

The instrument measures the hue rms values and units are available to cover the frequency range from D.C. to 100 MHz. The major drawback is the susceptibility to damage by overloads (even those of short duration) unless appropriate protection is provided. The accuracy can also be affected by ambient temperature changes. 

On October 3, 1940, at a meeting in Washington called by Division B of the National Defense Research Committee, mention was made of the need for an instrument which could measure and indicate the partial pressure of oxygen in a gas. During the next few days we devised and constructed a simple and effective instrument for this purpose. This instrument measures the volume... 

In this study we intend to investigate if a correlation between sensory evaluation and instrumental measurements of the low-methoxyl pectin jellies could be established. 

Evaluation of these optical properties may be done by simple observation this approach is useful clinically (Knibbs, Plant Pearson, 1986), since acceptability of the colour match to the surrounding tooth material can be readily seen without the need for instrumental measurement. On the other hand, for quantitative evaluation of optical properties, some kind of instrumental measurement is necessary, and the property usually evaluated is opacity. 

So far, the nature of the variables was the same for all data sets, viz. sensory attributes. This is not strictly required. One may also analyze sets of data referring to different types of data (processing conditions, composition, instrumental measurements, sensory variables). However, regression-type methods are better suited for linking such diverse data sets, as explained in the next section. 

Beilken et al. [ 12] have applied a number of instrumental measuring methods to assess the mechanical strength of 12 different meat patties. In all, 20 different physical/chemical properties were measured. The products were tasted twice by 12 panellists divided over 4 sessions in which 6 products were evaluated for 9 textural attributes (rubberiness, chewiness, juiciness, etc.). Beilken etal. [12] subjected the two sets of data, viz. the instrumental data and the sensory data, to separate principal component analyses. The relation between the two data sets, mechanical measurements versus sensory attributes, was studied by their intercorrelations. Although useful information can be derived from such bivariate indicators, a truly multivariate regression analysis may give a simpler overall picture of the relation. 

Instrument measurement response can often be important in the overall system response. The thermal response of a simple thermometer bulb, immersed in fluid, as shown in Fig. 2.6, is the result of a simple heat balance in which... 

Over the years, many instruments have been developed for and used in the scientific laboratory. Today, the computer is used as a major tool in the scientific laboratory for the capture, manipulation, transfer, and storage of data. Consequently, the concern for data quality has shifted from the instruments that are used in the generation of the data to these electronic systems, often neglecting the fact that the data are only as accurate as the instrument measurements. For instance, many electronic systems can be used in chromatography analysis, from the electronic log book where the test substance inventory is kept, throughout data capture in the instrument, to the digitized electronic signal that is the raw data on the computer network. For crop residue samples, the... 

In principle, all elements can be determined by AAS, since the atoms of any element can be excited and are therefore capable of absorption. The limitations lie practically only in the field of instrumentation. Measurements below 200 mn in the vacuum UV range are difficult, owing to the incipient absorption of atmospheric oxygen. With modified instruments and a shielded flame or a graphite furnace, it is possible to determine such elements as iodine at 183.0 nm, sulfur at 180.7 nm, and phosphorous at 177.5 nm, 178.3 nm and 178.8 nm. 

In the broadest sense, thermal analysis (TA) measures physical changes in a material as a function of temperature. TA instruments measure variables in a sample such as heat flow, weight, dimensions, etc. A typical fingerprint of a compound might be the endothermic peak on a thermogram indicating a sample s crystalline melt. 

The worst operating condition in a common design practice consists of overly conservative assumptions on the hot-channel input. These assumptions must be realistically evaluated in a subchannel analysis by the help of in-core instrumentation measurements. In the early subchannel analysis codes, the core inlet flow conditions and the axial power distribution were preselected off-line, and the most conservative values were used as inputs to the code calculations. In more recent, improved codes, the operating margin is calculated on-line, and the hot-channel power distributions are calculated by using ex-core neutron detector signals for core control. Thus the state parameters (e.g., core power, core inlet temper-... 

As a result of analytical measurements, signals are obtained and, in the case of instrumental measurements, signals functions, y = f(z). The record of the signal intensity as a function of the signal position, Fig. 3.8, represents a two-dimensional signal function which can be back-transformed into two-dimensional analytical information, x = /(Q). 

Sensitivity is a significant characteristic in all scientific disciplines which have to do with measurements. Sensitivity is defined from the viewpoint of instrumental measuring as the change in the response of a measuring instrument divided by the corresponding change in the stimulus (ISO... 

Instrumental measurement of whiteness has been the subject of much research. The parameters needed for unambiguous characterisation in the assessment of whiteness and tint of fluorescent substrates have been reviewed [21]. The importance of seeking good correlation between different instruments is stressed [20]. Various trials have demonstrated that it is possible to adjust modern instruments used to measure the optical characteristics of FBA-treated samples of paper so that the results agree with a standard deviation of the order of one CIE whiteness unit [22]. 

Methods for the instrumental measurement of whiteness are well established but visual comparison remains important, even in well-equipped laboratories. Some degree of quantification is achieved by the method of paired comparisons, in which a panel of observers is presented with pairs of FBA-treated samples and asked to decide, without undue delay, which is the brighter. The total of positive scores can be used as a measure of whiteness and the results presented graphically as shown in Figure 11.7. Although time-... 

The most idealized configuration is depicted in Fig. 12.3. Even in this simplified situation, it is required that RG Ctot > > Tacq (Tacq = shortest acquisition time of the instrument measuring 7 ). 

The traditional way in which smoke obscuration has been measured is by determining the maximum smoke density (or the specific maximum smoke density) by means of a smoke density chamber developed by the National Bureau of Standards (NBS smoke chamber, ASTM E662). This instrument measures the obscuration inside a static 500 L chamber, after a sample has been exposed, vertically, to a 2.5 W/cm2 radiant source. 

Using basic pH leads to higher plateau rate constants, indicating that the ratedetermining step is reaction 18. Reaction 17 must be at least as fast as the rate of 02 addition in the highest 02 concentration used, kn 8 x 105 s 1, which is the limit of the instrument measurement. The G of benzene in pulse radiolysis was found to be equal to that of the nitroform anion (1.6 x 10-7 molJ-1) as can be expected from reactions 17-19. Since the yield of the cyclohexadienylperoxyl radical is 2.9 x 10-7 mol. 1 1 it means that only a fraction (ca 60%) of the cyclohexadienylperoxyl radicals eliminates HO2. The H02 elimination occurs by H-transfer of the allylic hydrogen to the oxygen... 

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