Measurement simultaneous

Many instrument manufacturers produce simultaneous TG-DTA apparatus. The advantage of such apparatus is not only that the sample and experimental conditions are identical but also that standard reference materials for DTA and DSC can be used for temperature calibration (see Section 2.2.1.7). [Pg.17]

The gaseous products evolved during TG measurements are analyzed by coupling an appropriate instrument to the TG apparatus. Mass spectrometers (TG-MS), Fourier transform infrared spectrometers (TG-FTIR) and gas chromatographs (TG-GC) will be described in Section 2.4. [Pg.17]

In this work, a microwave interferometric method and apparatus for vibration measurements is described. The principle of operation is based on measurement of the phase of reflected electromagnetic wave changing due to vibration. The most important features of the method are as follows simultaneous measurement of tlie magnitude and frequency of the rotating object high measurement accuracy weak influence of the roll diameter, shape and distance to the object under test. Besides, tlie reflecting surface can be either metallic or non-metallic. Some technical characteristics are given. [Pg.654]

Almost all microwave methods are non-contact [1] and allow simultaneous measurement of the magnitude and the frequency of vibrations. The distance between the inspected surface and microwave sensor can vary from several millimeters to a few meters. However, the accuracy of the measurement of vibration magnitude also depends on a distance between the microwave sensor and the object as well as the shape of the inspected surface. [Pg.654]

One feature of this inequality warrants special attention. In the previous paragraph it was shown that the precise measurement of A made possible when v is an eigenfiinction of A necessarily results in some uncertainty in a simultaneous measurement of B when the operators /land fido not conmuite. However, the mathematical statement of the uncertainty principle tells us that measurement of B is in fact completely uncertain one can say nothing at all about B apart from the fact that any and all values of B are equally probable A specific example is provided by associating A and B with the position and momentum of a particle moving along the v-axis. It is rather easy to demonstrate that [p, x]=- ih, so that If... [Pg.16]

Ren B, Li W H, Mao B W, Gao J S and Tian Z Q 1996 Optical fiber Raman spectroscopy combined with scattering tunneling microscopy for simultaneous measurements ICORS 96 XVth Int. Conf on Raman Spectroscopy ed S A Asher and P B Stein (New York Wley) pp 1220-1... [Pg.1231]

Simultaneous measurements of stratospherio HO NO and < 1-.. oomparison with a photoohemioal model J. [Pg.1259]

For some experiments, it may be helpfiil to obtain a reference signal to correct for fluctuations and long-tenu drift in the pump laser. This correction is best accomplished by perfonumg simultaneous measurements of the... [Pg.1281]

Figure Bl.19.23. Principle of simultaneous measurement of nomial and lateral (torsional) forces. The intensity difference of the upper and lower segments of the photodiode is proportional to the z-bending of the cantilever. The intensity difference between the right and left segments is proportional to the torsion, t, of the force sensor. (Taken from [110], figure 2.)...

Meyer G and Amer N M 1990 Simultaneous measurement of lateral and normal forces with an optical-beam-deflection atomic force microscope Appl. Phys. Lett. 57 2089... [Pg.1725]

The accurate and absolute measurement of the distance, D, between the surfaces is central to the SFA teclmique. In a typical experiment, the SFA controls the base position, z, of the spring and simultaneously measures D, while the spring constant, k, is a known quantity. Ideally, the simple relationship A F(D) = IcA (D-z ) applies. Since surface forces are of limited range, one can set F(D = go) = 0 to obtain an absolute scale for the force. Furthennore, SF(D = cc)/8D 0 so that one can readily obtain a calibration of the distance control at large distances relying on an accurate measurement of D. Therefore, D and F are obtained at high accuracy to yield F(D), the so-called force versus distance cur >e. [Pg.1732]

To measure friction and shear response, one has to laterally drive one surface and simultaneously measure the response of a lateral spring mount. A variety of versions have been devised. Lateral drives are often based on piezoelectric or bimorph deflection [13, 71] or DC motor drives, whereas the response can be measured via strain gauges, bimorphs, capacitive or optical detection. [Pg.1738]

The description of chemical reactions as trajectories in phase space requires that the concentrations of all chemical species be measured as a function of time, something that is rarely done in reaction kinetics studies. In addition, the underlying set of reaction intennediates is often unknown and the number of these may be very large. Usually, experimental data on the time variation of the concentration of a single chemical species or a small number of species are collected. (Some experiments focus on the simultaneous measurement of the concentrations of many chemical species and correlations in such data can be used to deduce the chemical mechanism [7].)... [Pg.3057]

It is thus often said that measurements for operators that do not commute interfere with one another. The simultaneous measurement of the position and momentum along the... [Pg.50]

The swelling of the adsorbent can be directly demonstrated as in the experiments of Fig. 4.27 where the solid was a compact made from coal powder and the adsorbate was n-butane. (Closely similar results were obtained with ethyl chloride.) Simultaneous measurements of linear expansion, amount adsorbed and electrical conductivity were made, and as is seen the three resultant isotherms are very similar the hysteresis in adsorption in Fig. 4.27(a), is associated with a corresponding hysteresis in swelling in (h) and in electrical conductivity in (c). The decrease in conductivity in (c) clearly points to an irreversible opening-up of interparticulate junctions this would produce narrow gaps which would function as constrictions in micropores and would thus lead to adsorption hysteresis (cf. Section 4.S). [Pg.236]

The phase Doppler method utilizes the wavelength of light as the basis of measurement. Hence, performance is not vulnerable to fluctuations in light intensity. The technique has been successfully appHed to dense sprays, highly turbulent flows, and combustion systems. It is capable of making simultaneous measurements of droplet size, velocity, number density, and volume flux. [Pg.334]

Sihcon charge coupled devices (CCDs), commonly used in soHd-state video cameras and in research appHcations, are being appHed to low light level spectroscopy appHcations. The main advantage of area array CCDs over linear photodiode detectors is the two-dimensional format, which provides simultaneous measurements of spatial and spectral data. [Pg.398]

Vahdation of the measurements may require the simultaneous measurement of pressure and temperature. Typical sample locations do not have thermowells and pressure indicators. Consequently, modifications will be reqmred to facilitate validation. [Pg.2559]

Multi- or simultaneous measurement of nano-level properties and nanolevel functions of materials ... [Pg.23]

A further critical point are the intensities correlated to spectra of the pure elements. Calculated and experimentally determined values can diverge considerably, and the best data sets for 7 measured on pure reference samples still show a scatter of up to 10%. The use of an internal standard or a simultaneously measured external standard seems to be the most successful way to reducing the inaccuracy below 10%. (Eor a more detailed discussion of background subtraction and quantification see, e.g., Seah [2.9].)... [Pg.18]

Depth-sensing nanoindentation is one of the primary tools for nanomechanical mechanical properties measurements. Major advantages to this technique over AFM include (1) simultaneous measurement of force and displacement (2) perpendicular tip-sample approach and (3) well-modeled mechanics for dynamic measurements. Also, the ability to quantitatively infer contact area during force-displacement measurements provides a very useful approach to explore adhesion mechanics and models. Disadvantages relative to AFM include lower force resolution, as well as far lower spatial resolution, both from the larger tip radii employed and a lack of sample positioning and imaging capabilities provided by piezoelectric scanners. [Pg.212]

RosaZeiser, A., Weilandt, E., Hild, S. and Marti, O., The simultaneous measurement of elastic, electrostatic and adhesive properties by scanning force microscopy pulsed-force mode operation. Measur. Sci. Techno ., 8(11), 1333-1338 (1997). [Pg.217]

To examine the response of PVDF to a higher pressure, ramp-type loading, an experimental arrangement with a ceramic Pyroceram similar to that of the fused quartz loading was employed. In this case, the loading wave transmitted through the Pyroceram is only approximately known and a simultaneous measurement must be carried out of the wave transmitted through the pyroceram and the response of the PVDF. [Pg.108]

Persily, A., and Norford, L. (1987). Simultaneous Measurements of Infiltration and Intake in an Office Building. ASHRAE Transactions 93(2) 42-56. [Pg.59]

Instruments providing simultaneous measurement of a number of parameters on multi-element probes have been developed, including potential noise , galvanic coupling, potential monitoring, and a.c. impedance . [Pg.37]

The effects of adsorbed inhibitors on the individual electrode reactions of corrosion may be determined from the effects on the anodic and cathodic polarisation curves of the corroding metaP . A displacement of the polarisation curve without a change in the Tafel slope in the presence of the inhibitor indicates that the adsorbed inhibitor acts by blocking active sites so that reaction cannot occur, rather than by affecting the mechanism of the reaction. An increase in the Tafel slope of the polarisation curve due to the inhibitor indicates that the inhibitor acts by affecting the mechanism of the reaction. However, the determination of the Tafel slope will often require the metal to be polarised under conditions of current density and potential which are far removed from those of normal corrosion. This may result in differences in the adsorption and mechanistic effects of inhibitors at polarised metals compared to naturally corroding metals . Thus the interpretation of the effects of inhibitors at the corrosion potential from applied current-potential polarisation curves, as usually measured, may not be conclusive. This difficulty can be overcome in part by the use of rapid polarisation methods . A better procedure is the determination of true polarisation curves near the corrosion potential by simultaneous measurements of applied current, corrosion rate (equivalent to the true anodic current) and potential. However, this method is rather laborious and has been little used. [Pg.810]

If we combine mechanics in this way with unobservable receipts, deterministic systems show some cpialitative features that resemble quantum, mixed-state systems. I hus one can always measure the real momentum in event 1 by the location of event 2. But one cannot yet observe the receipt momentum of event 1, because it is not until event 2 that it first combines with any real momeiituni - which cannot be observed until some subsequent event 3 - by which time it is already mixed with another estimate And so on. One can never simultaneously measure both estimate and receipts, though all adds up eventually. And all this involves no probabilities at all, just temporary inaccessibility of information [iuinsky82]... [Pg.664]

The greatest uncertainty in instruments such as the Intoxilizer lies in the conversion from BrAc to BAC values. The factor of 2100 referred to previously can vary considerably depending on the circumstances under which the sample is taken. Simultaneous measurements of BrAc and BAC values suggest that the factor can be anywhere between 1800 and 2400. This means that a calculated BAC value of 0.100% could be as low as 0.086% or as high as 0.114%. [Pg.43]

Another way of obtaining information on the time-averaged mobility of charge carriers on their way across a sample of arbitrary thickness is, to simultaneously measure the current and the stationary charge earners density via transient absorption and to infer the mobility from j-rnpF. Such experiments have been performed on blends of conjugated oligomers derived from /m-siilbene amine and a... [Pg.527]

As pointed out above, accumulatory pressure and weight loss measurements usually refer to the total reaction. When there are several volatile products, it is necessary to identify all components and investigate progressive changes in gas composition. Quantitative determinations of the amounts of each product (EGA) should, ideally, be combined with measurements of the total extent of reaction, although Gam [143] has recommended caution in the interpretation of results from simultaneous measurements. [Pg.21]

The electrochemical quartz crystal microbalance (EQCM) is a powerful tool for elucidating interfacial reactions based on the simultaneous measurement of electrochemical parameters and mass changes at electrode surfaces. The microbalance is based on a quartz crystal wafer, which is sandwiched between two electrodes, used to induce an electric field (Figure 2-20). The field produces a mechanical oscillation... [Pg.52]

Such approximation is valid when the thickness of the polymeric layer is small compared to die thickness of die crystal, and the measured frequency change is small with respect to the resonant frequency of the unloaded crystal. Mass changes up to 0.05% of die crystal mass commonly meet this approximation. In die absence of molecular specificity, EQCM cannot be used for molecular-level characterization of surfaces. Electrochemical quartz crystal microbalance devices also hold promise for the task of affinity-based chemical sensing, as they allow simultaneous measurements of both tile mass and die current. The principles and capabilities of EQCM have been reviewed (67,68). The combination of EQCM widi scanning electrochemical microscopy has also been reported recently for studying die dissolution and etching of various thin films (69). The recent development of a multichannel quartz crystal microbalance (70), based on arrays of resonators, should further enhance die scope and power of EQCM. [Pg.54]

When these are close together, most of the simultaneously measured velocities will relate to fluid in the same eddy and the correlation coefficient will be high. When the points are further apart the correlation coefficient will fall because in an appreciable number of the pairs of measurements the two velocities will relate to different eddies. Thus, the distance apart of the measuring stations at which the correlation coefficient becomes very poor is a measure of scale of turbulence. Frequently, different scales of turbulence can be present simultaneously. Thus, when a fluid in a tube flows past an obstacle or suspended particle, eddies may form in the wake of the particles and their size will be of the same order as the size of the particle in addition, there will be larger eddies limited in size only by the diameter of the pipe. [Pg.702]

The experimental investigations of boiling instability in parallel micro-channels have been carried out by simultaneous measurements of temporal variations of pressure drop, fluid and heater temperatures. The channel-to-channel interactions may affect pressure drop between the inlet and the outlet manifold as well as associated temperature of the fluid in the outlet manifold and heater temperature. Figure 6.37 illustrates this phenomenon for pressure drop in the heat sink that contains 13 micro-channels of d = 220 pm at mass flux G = 93.3kg/m s and heat flux q = 200kW/m. The temporal behavior of the pressure drop in the whole boiling system is shown in Fig. 6.37a. The considerable oscillations were caused by the flow pattern alternation, that is, by the liquid/two-phase alternating flow in the micro-channels. The pressure drop FFT is presented in Fig. 6.37b. Under... [Pg.313]

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