Pumping mode

FIG. 18-22 Typical draft tube circulator, sbown bere for down-pumping mode for tbe impeller in tbe draft tube. 

Mobile phases employed for the separations are housed in a cartridge and delivered to the LC columns through a set of binary HPLC pumps (Shimadzu Corporation), as shown in Figure 6.2. The pumps provide a flow rate accuracy of 2% or 2 fiL (whichever is greater) in constant flow pumping mode, with a flow rate precision of 0.3%. A degasser (two channels internal volume of 195 /.d. /channel) is also housed in the pump module employed to minimize the occurrence of air bubbles. 

All systems presented in this section show lasing only in the optical pumping mode. There is much interest in electrically pumped devices, but for molecular glasses the difficulties in achieving high excitation densities and low absorption due to charge carriers and electrodes have yet to be overcome. This problem and the related semiconducting polymer lasers that are based on the same principles will not be covered here, but are treated in recent reviews [214-216]. 

Notice that the heat exchanger is an evaporator in the air-conditioning mode, and a condenser in the heat-pump mode. Therefore, the refrigerant is on the hot side in the heat-pump mode and on the cold side in the air-conditioning mode when the system is built using CyclePad. 

Many AB5 hydrides have AH 8 kcal so that at 0-100°C (of interest for chemical heat pump action), the hydrogen dissociation pressures change roughly by one order of magnitude. This implies that a metal hydride pair could function in the heat pump mode even if their enthalpies were exactly the same, provided... 

A number of runs were carried out with the pump stopped but liquid flowing through the wide-open recycle valve w h an upstream pressure of 500 to 600 kPa [73 to 87 psi). This resulted in little change in performance over the pumping mode. This, combined with the Ap observation, suggests that most of the droplet breakup is taking place in the separator-level control valves. 

The main energy consumers in the pumping mode are the cooling unit, with the highest demand for electrical energy, the circulation pump, the CO2 pre-heater, and the evaporator. 

The electrical power consumption of the refrigerator depends only on the separation condition. The pumping mode is optimal for high extraction pressures (more than 150 bar), low extraction temperatures (40 to 80°C), and separation pressure between 45 and 60 bar. 

Figure 8.1-7. Comparison between compressor- and pump-mode operation for fish oil extraction with different solvent/feed ratios.

For (x - A)=0, as in the absence of non-linear terms (x=A=0), the pumped modes k acquire a Planck-type distribution, p=0, modified only by the term Sk, and consistent with the set of rate equations, Eq. (13),... 

Picosecond pulses can be produced in a number of different types of laser systems. As an example, a brief description is first given of a synchronously pumped c.w. dye laser such as can be readily assembled from commercially available units. Generation of repetitive subnanosecond pulses in a c.w. laser by mode-locked synchronous pumping was first described by Harris et al. [12]. The essential features of such a system are shown in Fig. 3. In this system, an acousto-optically mode-locked ion laser is used to pump the dye laser. In order to achieve synchronous pumping, the length of the dye cavity must be adjusted so that the dye laser intermode spacing is an integral multiple of the pump mode-locker frequency. 

The catalysts were tested in a fixed bed reactor (diameter 0.76-cm, length 26 cm) at the temperature of 25°C and pressure of 20 bars. In each run, 10 ml (ca.l 1 g) of catalyst was used. The reaction mixture isobutane /1-butene (10/1 ratio) was fed by HPLC pump (mode 1). 

The time-resolved Raman spectra were measured with a picosecond time-resolved Raman spectrometer which employs a standard pump-probe technique. The details of the spectrometer have been publish elsewhere. The followings are concise description of the apparatus The output from a synchronously pumped mode-locked dye laser is amplified with the output from a cw Nd YAG regenerative amplifier. The second harmonic (294 nm, 2 kHz, 1-2 mW) of the amplified light (588 nm, 3.2 ps, 2 kHz, 15 mW) was used as a... 

The principle of this apparatus has been precisely described in an entry (see entry Dual Countercurrent Chromatography) devoted to this topic in this volume. Two main parameters for using a two-phase solvent system with this apparatus are the choice of the heavier or the lighter mobile phase and the pumping mode [i.e., from the tail to the head or the head to the tail of the column (as a rotating coil defines a tail and a head, carrying, for instance, a small solid from the tail to the head)]. 

Ito has, consequently, decided to carry out a systematic study with 15 solvents [1]. His first conclusion was that only one condition was optimal among the two pumping modes for a given phase (i.e., lighter or heavier phase). The second conclusion was that the pumping modes to be used are reversed if the liquid phase is chosen as lighter instead of heavier, or vice versa. 

The general principle of this type of apparatus is described in the corresponding entry (see entry Cross-Axis Coil Planet Centrifuge for the Separation of Proteins) of this volume. Contrary to the two previous CCC devices, four main parameters have to be considered here. Two of them are common to the other types of CCC units (i.e., choice of a lighter or a heavier phase and pumping mode from tail to head or from head to tail). Two additional parameters intervene the pumping direction, from the inside to the outside of the core or reverse, and the rotation direction, clockwise or counterclockwise. 

We perform concrete calculations in the complex P-representation [Drummond 1980 McNeil 1983] in the frame of both probability distribution functions and stochastic equations for the complex c-number variables. We follow the standard procedures of quantum optics to eliminate the reservoir operators and to obtain a master equation for the density operator of the modes. The master equation is then transformed into a Fokker-Planck equation for the P-quasiprobability distribution function. In particular, for an ordinary NOPO and in the case of high cavity losses for the pump mode (73 7), if in the operational regime the pump depletion effects are involved, this approach yields... 

Recall, that we consider the regime of adiabatic elimination of the pump mode. In this approach the stochastic amplitudes 0 3 and p3 are given by... 

Here e = k E/73, A = k2/73. So Eqs. (10a), (10b) and the corresponding equations for a2, p2 involve the depletion effect of the pump mode, which leads to the appearance of the above-threshold operational regime. 

The propeller rotates clockwise in a down-pumping mode. The vessel (glass beaker) has a diameter of 7.2 cm and the fluid height is 6.5 cm corresponding to a stirred volume of 264 cm. The same fluid as the one considered in the coaxial mixer experiments was used. The rotating speed and the volume concentration of the particles were varied in order to investigate the... 

Catalytic reactors, where the incorporation of an appropriate catalyst can increase the conversion and lead to an increase in selectivity. These reactors can operate according to either a pumping mode or a "fuel-cell mode . 

Figure 12.2 Schematic representations ofthe cathode processes on an oxide electrolyte pumping mode.

Tire pumping mode, by applying an external potential. As shown in Figure 12.5, the oxygen feed can be increased (according to Faraday s law or with the NEMCA... 

The results have been recently obtained by Olsen et al. [38], and they show that even for almost vanishingly small e, which is inversely proportional to the initial mean value of the number of the pump mode photons, usually very large, the quantum fluctuations have huge macroscopic effect on the system dynamics. It is evident that the quantum noise, which is always present, is responsible for the oscillations between the two regimes of second-harmonic generation and downconversion. The period of oscillation is becoming infinite as e vanishes. 

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