Observation window

There are two different methods to experimentally define void fraction. The first is based on analyzing the images of gas-liquid interfaces recorded in the observation window of the channel (Triplett et al. 1999b Serizawa et al. 2002 Kawahara et al. 2002). For example, in experiments by Kawahara et al. (2002) at low liquid flow rates, most of the recorded images showed either liquid flowing alone or a gas core... 

More recent chromatogram chambers - e.g. the AMD system (Fig. 11) - only possess a small observation window and this can, if necessary, be covered with a black cloth. Development in the DC-Mat (Fig. 12) or the ADC (Fig. 13) automatic development chambers is carried out entirely in the dark. 

We look once more at the phase diagram of C02 in Figure 5.5. The simplest way of obtaining the data needed to construct such a figure would be to take a sample of C02 and determine those temperatures and pressures at which the liquid, solid and gaseous phases coexist at equilibrium. (An appropriate apparatus involves a robust container having an observation window to allow us to observe the meniscus.) We then plot these values of p (as y ) against T (as V). 

Glazing applications, shatter-resistant glazing, architectural and protective glazing, windows and skylights, sight glasses (e.g. observation windows), transparent thermo-formed products... 

Figure E-1. Chimney-type strand burner with observation windows.

In spite of the fact that real systems are finite, it is not always clear which is the appropriate L value. In practice L is taken as the observation size L, provided that Ls is smaller than the actual system size. Thus, the value of a can be determined experimentally from Eq. (5.7b). Note that within this choice g depends on the size Ls of the observation window. In the case of measurements performed with an AFM Ls is taken as the image size. 

The carbon arc apparatus is shown schematically in Figure 10.2.2. The reaction chamber, which is usually made of stainless steel, is connected to vacuum pumps and a gas supply line through valves. The front of the chamber has an observation window to enable monitoring the arc discharge (19). Electrodes, mounted on the end flanges, are supported horizontally. Alternatively, the electrodes can be fixed vertically (20). The electrodes and chamber walls can be cooled by water-cooling devices if necessary. 

In the wall of the gallery facing the observation post there are observation windows at intervals of 1 and 2 m along its whole length, through which the course of firing is watched. 

In the above fig, number 3 indicates agitator, 11 - the inlet pipe for gas, 5 the shelves for coal dust, 9 the mortar for shooting coal dust into expln chamber and 10 - observation windows... 

Bio-Logic Instrument and Laboratories (Meylan, France) manufactures an SFM-3 stopped-flow instrument (Fig. 4.17) that consists of three independent drive syringes driven by stepping motors, two mixers and a delay line, three observation windows, replaceable cuvettes, no stop-syringes, and efficient temperature regulation. At maximum flow rate, the minimum dead times range from 1.0 to 4.9 ms for fluorescence detection and 1.3 ms for transmittance. Currently, the Bio-Logic MOS-IOOO optical system employs fluorescence or absorbance detection, which is not suitable... 

The permeability of borosilicate glass to He is about 3 x 10 6mbar L s 1 mm m-2 bar-1 at 20 °C. Its permeability is due to its quartz content, quartz having a high permeability to He. A system is fitted with 5 x DN100CF observation windows made of borosilicate glass (thickness = 6 mm). 

At low pressures, < 1 mTorr, and when the photomultiplier was in the backwards position, the logarithmic decay plots were not linear over the whole timebase. The probable explanation is that the linear section at short times involved practically no errors due to diffusion however, at long times, some of the molecules may have been deactivated by hitting the chamber walls or observation window. The analysis was therefore carried out only for the first 120 jus of the decay curve. 

As in standard kinetics experiments, an amount of substance formed or consumed in a finite time interval, At, is what is actually measured. If the sampling interval At (i.e. observation window) is between times ti and t2 (i.e. between molecular ion lifetimes and t2), the number (per time) of fragment ions formed in this interval is... 

In a real instrument, some parameter (e.g. magnetic induction) is swept so as to obtain a spectrum and the observed signal (ion currents) is related to the actual numbers (per time), N, of ions through an apparatus function. This is the convolution relationship [807]. For this discussion, the relevant points concerning instrumental influences can be brought out by simply introducing a collection efficiency (or transmission factor) G. The collection efficiency, G, is that proportion of the actual number (per time) of ions, formed within the observation window At of the experiment, which reaches the detector. 

Equations (8)—(10) apply to all the various types of mass spectrometric experiments and these expressions define the nature of the information the experiments seek to provide. In Sect. 3, the various experimental techniques are reviewed and each in turn is related to these basic expressions [eqn. (8) etc.]. In reviewing results in subsequent sections (Sects. 4—8), it is assumed, unless there is evidence to the contrary, that experiments have been conducted with adequate attention to all the many instrumental effects. That is to say, it is assumed that reported ion intensities, abundances, peak heights, voltages or ion currents do accurately portray the numbers (per time), 7, of ions (or ion currents) arriving at the detector and that these numbers, 7m in the case of fragment ions m, are a true measure of the numbers, Nm, of ions formed within the observation window of the experiment. 

The product ions appearing in an FI mass spectrum are formed within picoseconds, following formation of the molecular ion. This is provided the decomposition is unimolecular. Referring to eqn. (9), the limits t and t2 to the observation window are zero and of the order of 1 or 10 ps, respectively. The limit t2 depends upon the relative masses m/M of the reactant M+ and fragment ions m+ and therefore is different for different peaks in the mass spectrum. As m/M increases towards unity, so t2 increases, (i.e. At increases as the mass of the neutral eliminated decreases). 

The ion currents, 7ml, (numbers of ions per time) measured represent fragment ions formed within an observation window, whose limits depend upon the resolution in the measurement of translational energy [28]. It is arranged for these limits to be sufficiently close to each other so that the measured ion current, Iml, divided by the observation window (At = t2—t1) is proportional to the rate of decomposition dlVml/dt at that time (see Sect. 2.5). 

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