Overall stopping power

Note that the sensitivity of a PET scanner increases as the square of the detector efficiency, which depends on the scintillation decay time and stopping power of the detector. This is why LSO, LYSO and GSO detectors are preferred to Nal(Tl) or BGO detectors (see Table 2.1). In 2D acquisitions, system sensitivity is compromised because of the use of septa between detector rings, whereas these septa are retracted or absent in 3D acquisition, and hence the sensitivity is increased by a factor of 4-8. However, in 3D mode, random and scatter coincidences increase significantly, the scatter fraction being 30—40% compared to 15-20% in 2D mode. The overall sensitivities of PET scanners for a small-volume source of activity are about 0.2-0.5% for 2D acquisition and about 2-10% for 3D acquisition, compared to 0.01-0.03% for SPECT studies (Cherry et al, 2003). The greater sensitivity of the PET scanner results from the absence of collimators in data acquisition. 

The spin-exchange contribution to the overall mass stopping power becomes important for energies below 25 eV. 

The electrons, Hberated at the anode, travel by electrical cable through the external load, such as an electric motor, to the cathode. If the external circuit is open the reaction is stopped, no fuel is consumed, and no power is generated. The electrolytic reaction, then, is controlled by the load connected to the cell. The overall fuel cell reaction is... 

For TAD, the overall computational work to advance the system by a given time scales at best as Nz y, where y — Tiow/Thigh. The power of — y comes from the reduction in thigh,stop from Equation (13) as how.short decreases with N, one power of N comes from the cost of each high-T force call, and the other power of N comes from the fact that accepting a transition advances the system by a time inversely... 

The prototype fast breeder reactor "Monju was constructed in 1990. The output operation had been carried out and preparations for the full-power operation were being made (O Fig. 58.13). However, it caused sodium leaks from the secondary system on December 8, 1995 and the operation has heen suspended. As of 2009, the overall plant and its functions, including long-stopped as well as improved facilities, have been checked, and preparations to restart operation are under way. 

The overall GM electrification strategy ranges from lower levels of vehicle electrification like stop-start systems over mild and full hybrid systems to plug-in vehicles [3,4]. This class includes EREVs based on Voltec systems, as well as mass production BEVs like the Chevrolet Spark, and EV prototypes such as the GM EN-V two-wheeler or the Opel Meriva MeRegioMobil (enabling bidirectional power flow [3]). Finally, FCEVs utilize the... 

Failsafe Operation—Utilize sensors, controls and logic in such a manner that their failure or loss of power would produce the least undesirable consequences. In case of power failure, circuits must be manually re-energized to restart. The overall start and stop function must be hardwired, which eliminates the dependence on an electronic device or controller. 

The first reason was that this Government-funded project had cut comers to save money - power stations depend on everything working, so any normal power station would have two Condensate Extraction Pumps to pump water out of the turbine condenser, two Heater Drains Pumps to pump water through the feed heaters, and two Main Boiler Feed Pumps to drive water into the boilers. Each of the pumps could do the job by itself, but a redundant spare would normally be provided to ensure overall plant reliability. However, at PFR we only had one of each. This will have saved a lot of money during constmction, but it had been a false economy, since one failure meant the whole power station stopped making electricity. 

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