The reference points

In the early days of nuclear energy, in particular in a country without previous experience, for example in military applications, it was very difficult for a safety reviewer to obtain data and information on which a review could be based. The available criteria were scarce, the data on already built plants were in some case difficult to obtain and the research was at an initial stage. 

data and information are much more abundant. These include  

However, there is no Decision Machine available, either in the form of technical guides or handbooks, and experts are frequently compelled to take subjective technical decisions and to accept the related responsibility. In fact, the practical cases are always so specific that they cannot be covered by an all-embracing handbook. Moreover, even if such a tool existed, in case of judicial trial, the compliance with the handbook could frequently be considered only an extenuation of the possible guUt of the technical expert. Historical examples exist of technical specialists who have been sentenced in a case of a pressure vessel explosion, although in due course they had verified its compliance with the technical standards in force. In case of accident, in fact, the technical expert must demonstrate the application of all the means suggested by the status of the technical knowledge . Only completely new phenomena escape this criterion. 

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Corrections of the reference points of a curve may be made, if required by editing the DAC table or graphically editing the DAC points. 

Knowing these parameters the reference point PReX Rjf, aR f) in the general DGS-diagram is determined, examples in fig. 4 ... 

The difference in gain AV (between the recording curve and the reference point) which is necessary to adjust the specified registration curve with its maximum at 80% screen height ... 

An interesting historical application of the Boltzmann equation involves examination of the number density of very small spherical globules of latex suspended in water. The particles are dishibuted in the potential gradient of the gravitational field. If an arbitrary point in the suspension is selected, the number of particles N at height h pm (1 pm= 10 m) above the reference point can be counted with a magnifying lens. In one series of measurements, the number of particles per unit volume of the suspension as a function of h was as shown in Table 3-3. 

Procedure. Compute the slope of the function by a linear least squares procedure and obtain a value of Boltzmann s constant. How many particles do you expect to find 125 pm above the reference point Take the uncertainty you have calculated for the slope, as the uncertainty in k. Is the modem value of = 1.381 x 10 within these enor limits ... 

We ai e free to pick a tefei ence poitit of energy once, but otily otice, for each system, l,et us choose the reference point t.. We have obtained the energy eigenvalues of the x bond in ethylene as one [f greater than y. 011)11 bunding) and one p lower than y ( bunding) (Fig, 6-3),... 

Bond energies relative to energy levels other than x = 0 are invariant. The reference point x = 0 is an almost universal convention in simple Huckel theory, however, and we shall continue to use it. 

A modified definition of resonance energy has been introduced by Dewar (66T(S8)75, 69JA6321) in which the reference point is the corresponding open-chain polyene. In principle this overcomes the difficulties inherent in comparing observed stability with that of an idealized molecule with pure single and double bonds, as thermochemical data for the reference acyclic polyenes are capable of direct experimental determination. In practice, as the required data were not available, recourse was made to theoretical calculations using a semiempirical SCF-MO method. The pertinent Dewar Resonance Energies are listed in Table 30. 

T, = Temperature of the flowing gas at any section x-ft from the reference point, °F... 

When dealing with the motions of rigid bodies or systems of rigid bodies, it is sometimes quite difficult to directly write out the equations of motion of the point in question as was done in Examples 2-6 and 2-7. It is sometimes more practical to analyze such a problem by relative motion. That is, first find the motion with respect to a nonaccelerating reference frame of some point on the body, typically the center of mass or axis of rotation, and vectorally add to this the motion of the point in question with respect to the reference point. 

The reference point of the weight was initial steady-state weight at 400 °C in air. In a few cases, the sample was kept for 3-72 h at the same temperature to see whether the weight changed further or not. It was found that the weight essentially reached in equilibrium at each temperature with 3 H. The number by the points (3, 11, 72) indicate the extra hours waited for this purpose. 

The type of thermometer used to interpolate between the reference points depends on the temperature interval. 

The total number of spatial coordinates for a molecule with Q nuclei and N electrons is 3(Q + N), because each particle requires three cartesian coordinates to specify its location. However, if the motion of each particle is referred to the center of mass of the molecule rather than to the external spaced-fixed coordinate axes, then the three translational coordinates that specify the location of the center of mass relative to the external axes may be separated out and eliminated from consideration. For a diatomic molecule (Q = 2) we are left with only three relative nuclear coordinates and with 3N relative electronic coordinates. For mathematical convenience, we select the center of mass of the nuclei as the reference point rather than the center of mass of the nuclei and electrons together. The difference is negligibly small. We designate the two nuclei as A and B, and introduce a new set of nuclear coordinates defined by... 

The lowest level of the conduction band for metals Vc and the highest level of the valence band for semiconductors is very often used as a reference point for the energies of the Fermi levels in this book, however, the energy of a free electron at rest in a vacuum will be used as the reference point for the scale of the Fermi levels (cf. Fig. 3.2.). 

For example, when = 200 mW is attenuated to / ml = 20 mW, then the attenuator indicates an output power P = -10 dB (see also Table 2.2). And when / ml = 2 mW, then P = -20 dB. Every additional attenuation by a factor of 10 gives another -10 dB in P. This type of device is usable to 50-60 dB attenuation, which also corresponds to the lower power limit at which the spectrometer is still operable. Note that, in addition to the relative dB scale, microwave engineers also use an absolute dBm scale. The m in dBm is shorthand for milliwatt and defines the reference point of this scale ... 

The reference point is an external signal applied to the summing point of the control system to cause the plant to produce a specified action. This signal represents the desired value of a controlled variable and is also called the "setpoint."... 

For electrons in a metal the work function is defined as the minimum work required to take an electron from inside the metal to a place just outside (c.f. the preceding definition of the outer potential). In taking the electron across the metal surface, work is done against the surface dipole potential x So the work function contains a surface term, and it may hence be different for different surfaces of a single crystal. The work function is the negative of the Fermi level, provided the reference point for the latter is chosen just outside the metal surface. If the reference point for the Fermi level is taken to be the vacuum level instead, then Ep = —, since an extra work —eoV> is required to take the electron from the vacuum level to the surface of the metal. The relations of the electrochemical potential to the work function and the Fermi level are important because one may want to relate electrochemical and solid-state properties. 

Many of the procedures have been validated in the Liverpool laboratories (by GP). Other protocols were kindly submitted by colleagues from the USA, Japan, the UK and mainland Europe. The names of the contributors are given at the start of the corresponding protocol. These descriptions of the recipes also contain references to the literature. In these cases the references point the reader to the more practical aspects of the topic and are meant to complement rather than repeat the references given in the first, overview chapter. 

The description of chemical reactivity implies, among other aspects, the study of the way in which a molecule responds to the attack of different types of reagents. In order to establish this response, one usually adopts the electronic structure of the molecule in its isolated state as the reference point and considers the effects of an attacking reagent on this state. This procedure leads to the description of what we may call the inherent chemical reactivity of a molecule. 

The values of the two derivatives, /°(r) and A/(r), at the reference point N0, may be approximated through this smooth quadratic interpolation between the points pWn (r), pNo(r), and Pnm(r), when combined with the two conditions,... 

The angular velocity vector tok and the linear velocity vk of the reference point of the rigid body k (Fig. 2.1b) are calculated recursively from the corresponding quantities of the preceding rigid body p(lc) ... 

Denoting the vector from the reference point to the center of mass of the rigid body k by Yi<, its mass by and its inertia tensor by h (Fig. 2.1b), the kinetic energy can be computed in a linear loop over all rigid bodies... 

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