Sheltering effect

Figure 7. Sheltering effect of particles in the spray zone of a fluidized bed coater.

Raupach and Thom [522] explained this fact by shading some EPR elements by another ones ( shelter effect ). However, the mechanism of this effect has not been clarified is it a result of the vorticity behind obstacles, or of the extreme turbulence level, or of the basic difference between the natural forest canopy and laboratory models A possible consequence of aeroelasticity of canopy elements was also listed, [522], All these mean that the purposeful experiments should still be carried out as well as the mathematical models should be developed that account for a particular behavior of EPR elements (like the freedom of droplets to be drifted by the flow). 

The foregoing description of the production of forces and of the subsequent power requirements is centred on a single flat blade impeller. If more blades were added, it may at first sight seem that the power would increase in proportion, but this is not so, because the blades are subjected to a diminishing local normal velocity. The wake influence of upstream blades is similar to a sheltering effect and the power increases in proportion to the numbers of blades raised to a power in the range 0.5-0.8. 

M. Jensen, Shelter Effect Investigations. Danish Technical Press, Copenhagen, 1954. 

Are the seals or shelters effective in excluding moisture and debris from the dock ... 

I have described Lifshin as a specialist in characterisation . This is almost a contradiction in terms, because the techniques that are sheltered under the characterisation umbrella are so numerous, varied and sophisticated that nobody can be truly expert in them all, even if his entire working time is devoted to the pursuit of characterisation. The problem is more serious for other materials scientists whose primary interest lies elsewhere. As Lifshin has expressed it in the preface to an encyclopedia of materials characterisation (Cahn and Lifshin 1993), scientists and engineers have enough difficulty in keeping up with advances in their own fields without having to be materials characterisation experts. However, it is essential to have enough basic understanding of currently used analytical methods to be able to interact effectively with such experts (my italics). ... 

Because the positive pole is relatively sheltered from close approach, these solvents cannot effectively solvate anions, which, therefore, display an enhanced nucleophilicity... 

Following an accident, tlie effects on individuals able to escape or remain in a shelter (or equivalent) differ from tliose for people in Uie open. Factors to consider in relation to building types and human beliavior include ... 

The nature of the hazard considering both intensity and duration. Shelters vary in tlic degree of protection provided. For tliermal tmd toxic hazards, shelters can liave a beneficial effect. However, for explosions, tlie hazard maybe greater because of the possibility of the building collapsing. 

Other models may be used to consider tlie effects of escape or evacuation, sheltering, protective equipment, or otlier factors (e.g., water contamination) tliat may be considered in a risk study. 

Schirm, m. screen shelter, shade umbrella parachute visor (of a cap) Bot.) umbel, -bild, n. screen image, schirmen, v.t. screen shelter protect. Schirm-gitter, n. Radio) screen grid, -gitter-rohre, /. screen id tube, -pflanze, /. umbelliferous plant, -wirkung, /. screening or shielding effect. 

Effect of mass The rate of rusting of steel in the atmosphere is affected to some extent by the mass of the part concerned, because this determines the speed at which the surface temperature adjusts itself to fluctuations in the ambient temperature, the amount of condensation during humid periods, and the time during which dew or rain remains in contact with the steel. For example, in a test over 12 months at the National Chemical Laboratory under sheltered conditions outdoors, thick steel plates rusted more than thin ones as is shown below. 

Statements of this kind can give only a general idea of the improvements to be gained by the use of low-alloy steels in the atmosphere, because so much depends upon the conditions of exposure. In particular, the beneficial effects observed in the open air do not generally extend to conditions where the steel is enclosed and sheltered from the rain. Thus, the rates of rusting of bare steels, exposed for five years in Dove Holes Tunnel, England, were as follows ... 

Table 3.22B Effect of periodic washing (every six months) and shelter from rain on 316S33...

A typical test installation uses a frame to support racks on which the specimens are mounted by means of porcelain or plastics insulators. The insulators may be spaced to take specimens varying in size from 10-1 x 13-4cm to 10-1 X 32cm and even larger specimens may be used for certain tests. Special types of exposure have been devised to take into account important effects of partial shelter and accumulation of pools of water, as in the case of the specimen and method of support used by Pilling and Wesley to compare steels for roofing. 

Chapter 4 described methods for limiting the time of exposure to weapons of mass destruction that utilize no explosives (e.g., aerosol delivery) or use of conventional explosives (e.g., dirty bomb). The basic procedure is to leave the contaminated area as quickly as possible, enter a nearby building to shelter against airborne contamination, remove soiled articles of clothing, and wash all exposed body parts (including the mouth and hair) as soon as possible. In Chapter 4, the time factor is applied primarily to limit the chances of potential future health effects. In this section, the time factor is applied after a nuclear explosion to prevent serious bodily harm and death. 

Figure 5.2 illustrates the effectiveness of an underground shelter to limit radiation dose. In the open, an individual will receive an unshielded radiation dose (D). If the individual is in a deep hole with only a thin overhead cover (e.g., plywood), the dose level drops by about a factor of ten (D/10). While this is better than being in an open area, fatal doses might still be received. If the cover is made of about one foot of concrete, the dose level drops by a factor of about 100 (D/100). Two feet or more of concrete will reduce dose levels by a factor of about 5000 (D/5000).2... 

Although not as effective as a thick layer of concrete, multiple layers of other materials (e.g., a roof and several floors) may also be effective shields. For example, fallout will land on the roof of a multiple-story building. The roof and floors will keep the fallout away from individuals seeking shelter in inner rooms or a basement. Additionally, the multiple layers of wood, steel, and concrete help reduce dose levels in the shelter. 

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