Modes of Measurement

Several modes of measurement are used in the tomographic system. The most rapid one is applied as an estimation mode, the estimation error being a factor of 1.5 to 2 higher than that one of the conventional mode. With the estimation mode defective section can be detected rapidly and then they can be quantitatively investigated in detail using other modes... 

Electrochemical sensors play a crucial role in environmental and industrial monitoring, as well as in medical and clinical analysis. The common feature of all electroanalytical sensors is that they rely on the detection of an electrical property (i.e., potential, resistance, current) so that they are normally classified according to the mode of measurement (i.e., potentiometric, conductometric, amperometric). A number of surveys have been published on this immense field. The reader may find the major part of the older and recent bibliography in the comprehensive reviews of Bakker et al. [109-111]. Pejcic and De Marco have presented an interesting survey... 

Reference Acceptor passivated and cone, in cm-3 Mode of hydrogenation and temperature Mode of measurement of passivation Distinctness of plateau... 

Figure 11.5 Typical curve for a continuous titration calorimetry study of an exothermic reaction, using the calorimeter of Figure 11.1 in the heat flow isothermal mode of measurement./ is the frequency of the constant energy pulses supplied to the heater C in Figure 11.1 b. Adapted from [196,197],...

These chapters divide the discussion of electrochemical sensors by the mode of measurement. This chapter is an introduction to the general parameters and characteristics of electrochemical sensors. Chapter 6 focuses on potentiometric sensors, which measure voltage. Chapter 7 describes amperometric sensors, which measure current. Chapter 8 examines conductometric sensors, which measure conductivity. 

The introduction of backscattering ROA brought two additional principal modes of measurement which bear some similarities to the two right-angle measurements just described. One of these is backscattering DCPi ROA [35]. The CID and CIS expressions for this form of ROA are [26,35,103] ... 

The three-electrode arrangement can be used equally well if the potential between the working and reference electrodes is controlled and the current flowing through the working and counter electrodes is measured. Details of this mode of measurement are discussed later. 

With these definitions in mind, let us now consider the measurement of heats of adsorption. In fig. 1.7 two usual modes of measuring this heat are sketched. Figure 1.7a represents the closed mode, fig. 1.7b the open one. 

For the in situ evaluation of thin-layer plates, several modes of measuring are possible. Measurements in the reflectance mode and in the fluorescence mode are the most commonly used ones. Scanning in the transmission mode and simultaneous reflectance and transmission mode are also in use. 

During the 1970s the ECD became firmly established as the most sensitive gas chromatographic detector for some compounds. The kinetic model was described in terms of a numerical solution of the differential equations. This was assisted by the development of the constant current mode of measuring the response and the development of Ni-63 sources for the detector. The purification of the carrier gas and the further development of capillary columns improved the operation of the ECD. In addition, chemical reactions were used to make derivatives with a greater sensitivity in the ECD. Other ion molecule reactions were used to improve the sensitivity of... 

For the measurement of the viscosity of liquids such as molten glasses, rotational method is frequently used. In the viscosity range 10 - 10 Pa s the classical rotational devices can be applied. However, the same devices could also be applied for viscosities up to 10 Pa-s working in the so-called a-periodical mode of measurement. 

As already pointed out the apparent molecular weights of dissolved substances—and consequently the thermodynamic degree of ionisation or activity coefficient a in the case of an electrolyte—as determined by freezing point data are necessarily those which would be obtained from direct measurements of osmotic pressure or from emf measurements, since these different modes of measurement are related thermodynamically It will be recalled that the activity coefficient a for an ion is less than the y value over a wide range of concentration... 

It is important to recognize that environmental scientists make measurements for a variety of reasons, each of which imposes its own requirements and constraints on the instrumentation and measurement systems to be used. General environmental measurement modes include exploratory mapping and surveying, process investigations, baseline establishment and trend monitoring, and emission-deposition and other flux measurements. Table 1 lists some of the goals that drive each mode of measurement and some of the measurement system capabilities that they require. 

The value of computing derivative spectra to correct for non-linear baseline signals is frequently exploited in reflectance spectrometry. Rapid measurement of the chemical composition of materials and products by diffuse reflectance spectroscopy in the near-infrared (NIR) region (800-2600 nm) is routine in many industries. Because most bulk materials are not transparent the mode of measurement is generally reflectance. For powder samples the intensity of... 

The use of piezoelectric crystals for measuring dissolved CO2 was investigated (22). Crystals were coated with didodecylamine (DDDA) or dioctadecylamine (DODA) and placed in a chamber separated from the sample solution by a Teflon membrane, a Polyvinyl chloride membrane, or a Fluoropore filter with polyethylene web backing. The DDDA was 33 times more sensitive to H2O vapor than to CO2. The membranes were not sufficient for a selective measurement of CO2, and a differential mode of measurement was used to circumvent H2O vapor interference. 

The potential of the peak Ep is indicative of which species is involved. If the reduction (or oxidation) mechanism is diffusion-controlled the concentration of the species controls the Faradaic current. Since differential pulse polarography effectively displays the derivative of this current, theoretically it is the area under the peak which is proportional to the concentration. However, provided the shape of the peak does not change, the height of the peak is also proportional to concentration. The choice between the two modes of measurement will be discussed later. 

Each Riemann metric is known to produce a Euclidean metric in each tangent space. With respect to the mode of measurement (3), the surface... 

Thermomechanical measurements can be carried out on a wide range of solid samples. The most usual mode of measurement is either in compression (for self-supporting samples) or tension (for thin films and fibres). Some materials exhibit anisotropic behaviour (particularly films or crystals) in that changes in dimensions will differ depending upon which axis the measurements are performed. 

Different modes of strength testing have evolved based on different levels of technologic sophistication. The practical impHcation of contextual dependencies on the provided mechanical environment of the strength measures must be considered during selection of the appropriate mode of measurement. In this regard, equipment that can measure strength in different modes is more efficient in terms of both initial... 

Table L Low-Enei gy Excitation Modes of Measured Polymers.

The next calibration concerns the area of the DSC trace or the amplitude at any one temperature. The peak area below the baseline in Fig. 4.62 can be compared with the melting peaks of standard materials such as the benzoic acid, urea, indium, or anthracene, listed at the bottom of the figure. The amplitudes measured from the baseline established in the heat-capacity mode of measurement are usually compared with the heat capacity of standard aluminum oxide in the form of sapphire. The heat capacity of sapphire is free of transitions over a wide temperature range and has been... 

Next, a mathematical description of T is given for a quasi-isothermal run. This type of run does not only simplify the mathematics, it also is a valuable mode of measuring Cp as described in Sect. 4.4.5. In addition, standard TMDSC with y O is linked to the same analysis by a pseudo-isothermal data treatment as described in Sect. 4.4.3. 

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