Peak Linear Acceleration

Figure 4. Effect of pubes of irradiation on the ESR signal intensity for radicals in beef at —40°C. Beef samples contained NaCl and tripolyphosphate and had been heat treated to approximately 73°C. Signal intensity corresponds to the peak-to-peak height of the two most intense Lines in the spectrum (38). Each spectrum was scanned within 10 seconds after each 5 fisec pube from a 10 MeV linear accelerator. After every 15 pubes, several minutes elapsed before the pulsing was reinitiated. The dose per pube was approximately 1 kGy.

While the Hybrid III manikin can reproduce some human responses, the head and neck system does not introduce appropriate head rotation lag (see neck angle versus head angle in Fig, 10.11c) or torque at the occipital condyles joint (see moment of force OC joint versus time (Fig. 10.11c)]. Note, however, that the linear acceleration of the center of gravity of the head is well reproduced by the manikin, except for the peak acceleration at 100 ms [see response of head acceleration versus time (Fig. 10.11/)]. In contrast, the three-dimensional head and neck model for MADYMO can be seen to reproduce most human responses when active muscle behavior is included (the continuous lines in Fig. 10.12). In this computer model, the neck muscles are represented by simple cords between anatomical attachment points on the head and the base of the neck. 

The Peak Linear Head (Brain) Acceleration (PLA) is the maximum value of the translational acceleration measured at the centre of gravity of the test headform during impact. Usually it is stated as a number multiplied by the gravitational acceleration constant g . This method ignores the duration of the impact. 

The beams coming from cyclic and linear accelerators consist of short pulses of particles, that is, their beam has a time structure as shown in Fig. 50.25. The repetition frequency of the bunches ( microstructure ) is determinedbytheRFsystem, while the macrostructure can be varied by switching on and off the acceleration process. Taking into account the duty factor, which is the fraction of time when there is current, the peak current is much higher than the measured average current of the beam. 

Figure 22.9 plots the peak surface acceleration to peak base acceleration ratios as computed for each vertical array for both the flights. All values are larger than unity indicating an amplification of the acceleration from the base to the surface. The amplification ratio decreases with an increase of the input motion amplitude, due to the non-linear soil behavior. The response of the reference array (ESB box) is always larger than the soil. The amplification along the tunnel array is... 

Because of different period elongations in the two numerical methods, their comparison at each time instant is not especially meaningful. Table PI5.5 shows that the linear acceleration method gives a more accurate value for the peak response. 

At present FELs with output powers of several kilowatts in the infrared and several watts in the visible have been realized. The Stanford FEL reaches, for example, 130 kW at 3.4 pm, whereas from a cooperation between TRW and Stanford University, peak powers of 1.2 MW at A = 500 mm were reported. During recent years a large FEL called FLASH has been build at DESY, where part of the linear accelerator TESLA is used for the FEL. At electron energies between 0.37 and 1.25 GeV the spectral range covers the soft X-ray region between 4.2 and 45 nm. The parameters of this FEL are compiled in Table 5.6. 

Recorded in real earthquakes multiplied by a linear scaling factor to achieve compatibility with the peak ground acceleration or other scalar measure of seismic intensity (e.g., spectral acceleration at the fundamental period of the structure)... 

The above hazard levels can be associated to major seismic demand parameters, such as the peak ground acceleration (PGA). For instance, in the study by Papazachos et al. (1993), Greece was divided into four zones, and based on this work. Table 3 depicts the PGA levels for two return periods, Tr, utilizing the following log-linear formula ... 

Campbell KW (1981) Near-source attenuation of peak horizontal acceleration. Bull Seismol Soc Am 71 2039-2070 Campbell KW, Bozorgnia Y (2008) NGA ground motion model for the geometric mean horizontal component of PGA, PGV, PGD and 5 % damped linear elastic response spectra for periods ranging fiom 0.01 to 10 s. Earthq Spectra 24 139-171... 

The spectmm from an undulator is very different, and numerous peaks result from interference effects within the undulator. When the electron acceleration is confined to the orbit plane and the emission angle very low, the radiation is strongly elliptically polarised and, in the orbit plane itself, it is to within a few per cent linearly polarised. Use of a sequence of permanent magnets with magnetisation arranged in a spiral sequence enables circularly polarised radiation to be extracted from such a helical undulator and this radiation is particularly important for magnetic studies. 

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