Associated particle method

The nanosecond pulsed beam with time gating at the detector and the associated particle method (APM) render the three-dimensional (3D) elemental analysis of solids possible (Overley 1987 Rynes et al. 1999). The APM is based mainly on the D-D and D-T reactions by the detection of He and He particles, respectively, emitted at 180° to the neutron direction. The 4-5 cm/ns travel time of the neutrons allows the imaging of the interrogated volume along the direction of the ns pulsed neutrons with a spatial resolution of 5 cm. Some 2D-3D fast neutron imaging principles and techniques are summarized by Gozani (1994), Mikerov et al. (1998, 2001), and Chen and Lanza (2001), while typical thermal neutron radiography systems are demonstrated by Balasko et al. 1998, 2001) and Shaikh et al. (1998, 2001). 

Andersen et a/.," with a saccharine-particle method, found a weak positive association between tracheobronchial clearance and nasal clearance. A strong positive correlation would have indicated that information about the tracheobronchial clearance rate can be derived by studying clearance rates in the nose, which is more accessible. The saccharine method was shown to be a useful clinical tool for evaluating the status of the nasal mucociliary function in human subjects exposed to ambient pollutants or to controlled concentrations of specific pollutant gases or aerosols. 

In this article, we begin by reviewing the variety of problems associated with laboratory and flight investigations of hypersonic rarefied flows. Then a complete review of computational methodologies is provided. This includes both continuum and particle methods. The focus is on particle methods and details are provided on general concepts. Then, several of the most commonly employed chemistry models are described in detail. There are two components to any chemistry model the rate of chemical reaction, and the mechanics of chemical reaction. These are discussed separately. Models for gas-surface interaction and hybrid methods that use both continuum and particle descriptions of the gas flow are also briefly reviewed. Results are reviewed for hypersonic conditions in air applicable to the Space Shuttle and to ballistic missiles where both dissociation and exchange reactions are important. The behavior of rarefled flow chemistry models is first considered in a test cell environment. Then, the models are applied to... 

In the absence of any significant body of experimental data for rarefied, hypersonic flows, vehicle design has depended greatly on computational modeling. In this section, we briefly review continuum approaches for computing rarefied gas flows. We then pass on to a more complete description of the methods and models associated with a particle formulation. Hybrid methods that combine continuum and particle methods are reviewed briefly. 

Fundamentals of SP fluctuatbns. In the calculation methods section, I described the recent and ongoing flurry of activity in the area of fundamental calculations of the SP supermoment reversal fluctuations themselves and their dependencies on applied field, underlying magneto-crystalline anisotropy, etc. Such work is vital in that it links the main microscopic fluctuations that determine sample response and its time evolution to their fundamental causes and the associated particle features and material properties. All areas of science and technology that involve magnetic nanoparticles can only benefit from these fundamental advances. 

Combination of the sealed tube accelerator and the associated alpha-particle method (ARM)... 

Box 2 Length and timescales, and associated computational methods in electronic, particle-based, mesoscale, and continuum simulations of polymers... 

As early as 1973 Chorin (1973, 1989, 1994) introduced the two-dimensional random vortex method, a particle method for the solution of the Navier-Stokes equations. These particles can be thought of as carriers of vorticity. Weak solutions to the conservation equations are obtained as superpositions of point vertices, the evolution of which is described by deterministic ODEs. A random walk technique is used to approximate diffusion, and vorticity creation at boundaries to represent the no-slip boundary condition. The extension to three dimensions followed in 1982 (Beale and Majda 1982). An important improvement in stability and smoothness was achieved by Anderson and Greengard (1985) by removing the singularities associated with point vertices. Anderson and Greengard (1988) and Marchioro and Pulvirenti (1984) have written comprehensive reviews of the method. 

Size reduction (qv) or comminution is the first and very important step in the processing of most minerals (2,6,10,20—24). It also involves large expenditures for heavy equipment, energy, operation, and maintenance. Size reduction is necessary because the value minerals are intimately associated with gangue and need to be Hberated, and/or because most minerals processing/separation methods require the ore mass to be of certain size and/or shape. Size reduction is also required in the case of quarry products to produce material of controlled particle size (see Size measurement of particles). In some instances, hberation of valuables or impurities from the ore matrix is achieved without any apparent size reduction. Scmbbers and attritors used in the industrial minerals plants, eg, phosphate, mtile, glass sands, or clay, ate examples. 

The most comprehensive set of test methods for calcium carbonate has been assembled by the Pulverized Limestone Division of the National Stone Association. Methods for particle size, brightness, +325 mesh (44 -lm), and percentage of calcium carbonate have been pubflshed standards are available and have been well characterized (5). The Technical Association of the Pulp and Paper Industry (TAPPl) has pubflshed methods for calcium carbonate used in the paper industry (6). 

Testing. The Technical Association of the Pulp and Paper Industry (TAPPl) gives test methods that are widely used by kaolin suppHers to the paper iadustry. These iaclude tests for viscosity, viscosity stabiUty, brightness, pH, particle size distribution, moisture content, and screen residue (12). 

Because enzymes can be intraceUularly associated with cell membranes, whole microbial cells, viable or nonviable, can be used to exploit the activity of one or more types of enzyme and cofactor regeneration, eg, alcohol production from sugar with yeast cells. Viable cells may be further stabilized by entrapment in aqueous gel beads or attached to the surface of spherical particles. Otherwise cells are usually homogenized and cross-linked with glutaraldehyde [111-30-8] to form an insoluble yet penetrable matrix. This is the method upon which the principal industrial appHcations of immobilized enzymes is based. 

One should compare capabilities to the electron beam X-ray emission methods of Chapter 3. The major difference is the higher lateral resolution with electron beams and the associated mapping capabilides. Another difference is the shorter probing depth possible with electrons, except when compared to the specialized TXRF method. Comparing electron-beam EDS to X-ray/particle EDS or electron-beam WDS to X-ray/particle WDS, the electron beams have poorer detection limits because of the greater X-ray bacl ound associated with electron... 

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