Pump synchronously

The RPS provides the control for the RPS breakers in the EM pump/synchronous machine power circuit. As part of a normal scram sequence, the RPS will release these breakers to initiate an EM pump coast down of the primary flow. 

The experimental apparatus is depicted in figure 2. A mode-locked, argonr-ion laser is used to pump synchronously two matched dye lasers. The dye laser autocorrelation pulse typically has durations of 2 to 3 ps FWHM, a repetition rate of 80 MHz and an average power in each output beam of 30—40 mW. The dye laser outputs are tuned to the frequencies and Ug such that W -Wg equals the frequency of the LO phonons, tLhen these two beams are... 

Today the author would prefer an arrangement with a titanium sapphire laser pumping synchronously an OPO (see Sect. 2.1.1). 

The Cardiac Cycle. The heart (Eig. lb) performs its function as a pump as a result of a rhythmical spread of a wave of excitation (depolarization) that excites the atrial and ventricular muscle masses to contract sequentially. Maximum pump efficiency occurs when the atrial or ventricular muscle masses contract synchronously (see Eig. 1). The wave of excitation begins with the generation of electrical impulses within the SA node and spreads through the atria. The SA node is referred to as the pacemaker of the heart and exhibits automaticity, ie, it depolarizes and repolarizes spontaneously. The wave then excites sequentially the AV node the bundle of His, ie, the penetrating portion of the AV node the bundle branches, ie, the branching portions of the AV node the terminal Purkinje fibers and finally the ventricular myocardium. After the wave of excitation depolarizes these various stmetures of the heart, repolarization occurs so that each of the stmetures is ready for the next wave of excitation. Until repolarization occurs the stmetures are said to be refractory to excitation. During repolarization of the atria and ventricles, the muscles relax, allowing the chambers of the heart to fill with blood that is to be expelled with the next wave of excitation and resultant contraction. This process repeats itself 60—100 times or beats per minute... 

Power is generated by the pressurized gas expanding through an 11,000 rpm single-stage, radial-inflow turbine expander, which drives a synchronous generator. Exhaust gas from the expander is liquified by air-cooled condensers and is pumped back to the heat exchangers to repeat the cycle. 

Normal electric motor speeds run from the standard induction speeds for direct connection of 3600, 1800 and 1200 rpm to the lower speed standards of the synchronous motors, and then to the somewhat arbitrary speeds established by V-belt or gear drives. For some cases, the pump speed is set by the type of drivers available, such as a gasoline engine. 

In many respects the time-resolved pump-probe technique is similar to the CW counterpart. The use of pulsed laser light permits direct probing of both the magnitude of the PA and its dynamics. The experimental arrangement is practically the same as for the CW version, i.e., both pump and probe beams are focused and overlapped onto same spot on a sample. In addition, the pump and probe pulses are synchronized so that the lime interval t between them is constant and confined to a certain time range (in our case up to 3 ns). 

Several laser systems have been used in our time-resolved PM measurements. For the ultrafast measurements, a colliding pulse mode-locked (CPM) dye laser was employed [11]. Its characteristic pulsewidth is about 70 fs, however, its wavelength is fixed at 625 nin (or 2.0 cV). For ps measurements at various wavelengths two synchronously pumped dye lasers were used (12], Although their time resolution was not belter than 5 ps, they allowed us to probe in the probe photon energy range from 1.25 cV to 2.2 cV. In addition, a color center laser... 

Fig. 9.9 Experimental set-up 1 test module, 2 heater, 3 electrical contact, 4 micro-channel, 5 Pyrex, 6 peristaltic pump, 7 and 8 pressure and temperature measurements, 9 cooler, 10 reservoir, 77 IR camera, 72 microscope, 13 high-speed video camera, 14 PC, 75 synchronizer, 16 video recorder. Reprinted from Peles et al. (2001) with permission...

The commercially available laser source is a mode-locked argon-ion laser synchronously pumping a cavity-dumped dye laser. This laser system produces tunable light pulses, each pulse with a time duration of about 10 picoseconds, and with pulse repetition rates up to 80 million laser pulses/second. The laser pulses are used to excite the sample under study and the resulting sample fluorescence is spectrally dispersed through a monochromator and detected by a fast photomultiplier tube (or in some cases a streak camera (h.)) ... 

Summing up, a robust and easy to handle SMB-design uses 4 zones, a recycling pump fixed in respect to the columns and two pumps for the control of the outlet flow rates. Extremely high precision of all technical components of the SMB is needed. All pumps and valves have to be exactly synchronized. The flow rates should not vary by more thanl % from the preset value. All connections between the different parts of the system must be carefully optimized in order to minimize the dead volume. All columns should be stable and nearly identical in performance. If the SMB-technology is to be used in Biotechnology, GMP issues (cleaning, process and software validation) also have to be considered. In addition and as with any continuous process in that particular area, the definition of a batch could be a problem. 

Fig. 6.12. Data obtained by the single-photon wavelength 340 nm observation wavelength timing technique using a mode-locked ion- 390 nm. Reference scattering solution argon laser that synchronously pumps a cavity- (Ludox). Number of channels 900 channel dumped dye laser. Sample solution of POPOP width 4.68 ps. Result t = 1.05 + 0.01 ns in cyclohexane (undegassed). Excitation x = 1.055.

More recently Ghiggino and co-workers(32) have applied laser scanning confocal fluorescence lifetime microscopy to the study of polyvinyl alcohol films containing rhodamine B (650 nm emission) and cresyl violet (632 nm emission). Synchronously pumped dye laser excitation and APD detection were used with optical fiber coupling. A schematic diagram of their apparatus is shown in Figure 12.5. 

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