Discrete particle counter

Only through discrete particle counting can air cleanliness be verified, and the cleanliness class of the sampled environment established. " Periodic in-process monitoring of workstations, buffer rooms, anterooms, production areas, and any other area about which a definitive air cleanliness statement is made or reasonably assumed, should be carried out in accordance with SOPs or industry standards. A discrete particle counter (DPC) with an adequate sampling rate, calibration features, and dynamic range should be used for sample acquisition, based on the specified air cleanliness level. ... 

The size distribution of the particulate matter in the 0.01-5 ym size range is analyzed on line using an electrical mobility analyzer and an optical particle counter. Samples of particles having aerodynamic diameters between 0.05 and 4 ym are classified according to size using the Caltech low pressure cascade impactor. A number of analytical procedures have been used to determine the composition distribution in these particles. A discrete mode of particles is observed between 0.03 and 0.1 ym. The major components of these particles are volatile elements and soot. The composition of the fine particles varies substantially with combustor operating conditions. 

In this example, one periodic element (a cross-over) of the laboratory scale version of Katapak -S was selected for the detailed CFD simulation with CFX-5. This solver uses the finite volume discretization method in combination with hybrid unstructured grids. Around 1,100 spherical particles of 1 mm diameter were included in the computational domain. As the liquid flows through the catalyst-filled channels at operating conditions below the load point (cf. Moritz and Hasse, 1999), permeability of the channel walls made of the wire mesh is not taken into account by this particular model. The catalyst-filled channels are considered fully wetted by the liquid creeping down, whereas the empty channels are completely occupied by the counter-current gas. It means that the bypass flow... 

For each absorbed x-ray photon or neutron, the proportional or scintillation counter produces a discrete electric pulse. The flux J of the beam of x-rays or neutrons is measured as the number of counts of such pulses observed per second. If measurements are made repeatedly with a beam of constant flux, the number of counts observed during a fixed time period is not exactly the same, but is rather subject to statistical fluctuations. The arrival time of any one particle (x-ray photon or neutron) is totally uncorrelated with the arrival time of the next particle. The flux J of the particles,... 

Measurements of production cross sections are performed with a wide range of both radiochemical and direct counter techniques. Historically, radiochemical techniques were particularly useful for measuring heavy residues, for which discrete Z and A identification are difficult to determine with nuclear particle detectors in reactions with normal kinematics. However, with the availability of very heavy-ion beams and the widespread use of reverse kinematics, the measurement of mass (dcr dA), charge (dcr dZ), and isotope (dheavy residues, these values are frequently summarized graphically in terms of an excitation function, or cross section as a function of projectile energy, as in O Fig. 3.11. Extensive listings of production cross sections are maintained in several databases (IAEA 2010 NEA 2010 NNDC 2010 RNDC 2003). 

A few comments are necessary about the angular momentum. First, classical mechanics treats possible angular momentum values as continuous, whereas quantum mechanics limits angular momentum to discrete, quantized values. Second, the quantized angular momentum does not depend on mass or moment of inertia. This is completely counter to the ideas of classical mechanics, where the mass of a particle is intimately tied to its momentum. This is another example in which quantum mechanics departs from the ideas of classical mechanics. 

Quantum theory emerged from a series of observations made during the late nineteenth century, from which two important conclusions were drawn. The first conclusion, which countered what had been supposed for two centuries, is that energy can be transferred between systems only in discrete amounts. The second conclusion is that light and particles have properties in common electromagnetic radiation (light), which had long been considered to be a wave, in fact behaves like a stream of particles, and electrons, which since their discovery in 1897 had been supposed to be particles, but in fact behave like waves. In this section we review the evidence that led to these conclusions, and establish the properties that a vahd system of mechanics must accommodate. 

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