Measurement chain

Figure 3 presents the dependence of the modulus of the e.m.f induced in the pick-up coil, on the distance between the transducer and the discontinuity, obtained both theoretically using the Rel. (6) and experimentally. The working fi equency is 5 kHz. The transducer has been balanced for a material zone far from the discontinuity. The modulus of the output e.m.f of the utilized control equipment was devided by the overall gain of the measuring chain, to directly obtain the transducer output voltage. 

The time difference (delay) between the measured quantity and the measurement result is called the inertial error. A definition- is the error due to iner tia (mechanical, thermal, etc.) of the parts of a measuring instrument. In ventilation equipment the critical component in the measuring chain, from the dynamic point of view, is often the sensor or the measuring transducer (probe). 

Figure 58.30 Illustration of recommended procedure for measuring chain length...

These tests check the integrity of measurement chains between the sensor and the equipment as well as along the measurement chain. For example, a temperature signal carried over by a current loop is checked against the exact temperature level and the exact conversion levels on the current loop. However, if the temperature sensor contains its own local temperature indicator, this indication will be compared to the temperature available on the control system. 

Unless technically impossible, the accuracy and linearity of each measurement chain shall be checked at least at two different points of the measurement range. Visualization of values transmitted from the sensors to the system controller is made most often directly on the controller itself (screen or printer), using an appropriate submenu of the controller. The accuracy of the values read on the equipment or utilities instmmentation is checked by means of appropriate calibrated reference instmmentation traceable to national official standards. 

One method is to measure chain-transfer coefficients with low-MW analogues of the polymer. Thus Gilchrist (140) measured the rate at which 14C labelled decane was incorporated into polyethylene in the free-radical polymerization, and hence obtained an estimate of the transfer coefficient with methylene groups this was in fair agreement with another estimate obtained from the effect of the addition of fractions of linear polyethylene on the Mn of the branched polyethylene, which could be separated from linear polymer plus grafted branched polymer by column extraction. Low MW polymer may be used as a transfer agent Schulz and co-workers (189) obtained chain-transfer coefficients in styrene polymerization from the effect of added low MW polymer on Mn. 

The Glass Temperature. Determining the glass temperature, Tgt is the most important of the methods that measure chain mobility. The glass temperature, also called the second-order transition temperature, is the temperature at which a polymeric substance turns into a glass on cooling. To put it quite simply, it is the temperature above which the substance is soft and below which it is hard. 

THe network structure of these block polymers can also be altered by actually crosslinking the elastomeric polydiene chains, thus introducing a chemical network. In this approach it was necessary to use a crosslinking method which would not result in any measurable chain scission. Dicumyl peroxide (Dicup) was chosen for crosslinking an SIS polymer since this peroxide is known to accomplish exclusive crosslinking without any observable chain scission (3). The Dicup was dissolved in a THF solution of the polymer, and a cast film was prepared which was then vulcanized in a press at 155 °C for 35 min. A control sample, without Dicup was treated in the same way. 

A sensor is a part of or an element in a measuring chain which converts an environmental parameter (variable) into a signal. Environmental parameters are temperature, pressure and the concentration of gases. 

Fig. 5.5. Complete measurement chain for a LAPS. (1) LAPS sensor, (2) reference electrode, (3) electronic unit, (4) light source and (5) analyte.

Two measurements [31,10] were conducted at a low-inductance vacuum spark plasma and a tokamak plasma respectively. In both cases only the w line was reported. The first study used a double Johann spectrograph and characteristic K lines were used for calibration [31]. The energy of the w was 5.20558(55) keV or a 105 ppm result The second study [10] used a tokamak plasma and claimed an uncertainty of 40 ppm. Close lying Lyman series lines were used for calibration so this was a relative measurement chain assuming one-electron QED. Shorter wavelength calibration lines and helium-like resonances were observed in second order diffraction suggesting the significant systematic shifts discussed above. The third study [11] was a relative measurement to the w line and, as such, can not be compared to absolute measurements. 

The X-ray photons selected by the monochromator are detected and counted by a gas flow proportional counter and a measurement chain designed to amplify the impulses supplied by the counter and shape them for subsequent manipulation. 

The relationship between observed viscosity and intrinsic viscosity depends on the volume occupied by the polymer chains (dependent on the first power of their concentration) and the interactions between polymer chains (in the dilute and semi-dilute regions, dependent on the second power of their concentration). The resulting equation, eqn. (4.17), is known as the Huggins equation, with kii being the (dimensionless) Huggins coefficient, which measures chain-chain interaction ... 

In the case of the reaction between hydrogen and oxygen, the first gaseous reaction to be studied88 where stable and measurable chains occurred, the mechanism has been found to be influenced markedly by pressure. Thus, within certain limits explosive chains are set up from active centers of hydrogen peroxide ... 

Fig. 15 Principle behind the KZAC experiment designed to measure chain exchange kinetics. Two populations of micelles, deuterated yellow ) and proteated (plue) are mixed at r = 0 in a solvent that matches the average color, green (about 50 50 deuterated/proteated solvent molecules). Upon molecular exchange of amphiphiles, the average contrast of the micelles decreases and thus the intensity in the TR-SANS experiment...

In [9] several examples for the simplification of systems are given. Among them are designs withstanding the maximum explosion pressure (Table 2.17 shows that 10 bar is a good choice in case of deflagrations). This saves the necessity of complicated measuring chains and active systems for explosion pressure suppression, which can fail as well. 

Initiating event (typically a Ifequency) Failure of the measuring chain for the control valve or of the control valve itself 1.2... 

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