Whole Range Of Sizes Research Articles

The Comprehensive Design of Pumps, Water Turbines and Compressors

Centrifugal pumps and compressors perform the same function of fluid transference; a boiler feed pump also operating as a turbo-compressor, when deprived of water, illustrates the design problems involved in each sphere of duty. Water turbines are reversed pumps. Pump design theory has in the past been unnecessarily complicated; in contrast, a simple system taking into account the combination of impeller and casing gives satisfactory results over the whole range of size, specific speed and characteristics. Flow passage geometry, with exact knowledge of the accelerations in three dimensions, is attained by the concept of the impeller with its flow surfaces generated as a gear wheel, improving efficiency and cavitation performance. Critical speeds and mechanical failure modes illustrate the relationship of pumps to turbo-compressors. Experience of 20000 pumps and 700 water turbines from 5 gallons to 5 million gal/min (of which a statistically significant number were tested on site by the user's staff and instruments on a ‘no tolerance penalty/bonus’ contract) resulted in efficiency bonus payments ranging up to 10 per cent of the contract price. Worldwide, for comparable numbers, higher efficiencies have not yet been published. Imperial units are occasionally used to help mental arithmetic and to illustrate historical data.

Conductivity of microemulsions: refinement of charge fluctuation model

The aim of this Comment is to propose a refined theoretical treatment by distinguishing the Born radius of droplets from the Stockes radius. It will be demonstrated that such an approach improves the concordance between the theory and experiments over the whole range of sizes of microemulsion droplets

Effects of the inability of suspension‐feeding protozoa to collect all cell sizes of a bacterial population

The effects of the inability of suspension-feeding protozoa to collect bacteria over the whole range of sizes in the bacterial size distribution were examined by constructing mathematical models based on this assumption. Systems of suspension-feeding protozoa grown on both growing and nongrowing bacteria were examined in both batch and continuous culture. The models were able to predict three experimental observations common in such systems. Some additional features of the systems which should be useful in interpreting results of experiments with suspension feeding protozoa and in designing new experiments were predicted, also.

The catalytic activity of Rh supported particles for pentane hydrogenolysis

The hydrogenolysis of pentane by Rh particles was studied. Supported catalysts of different crystal structures and a whole range of sizes were prepared in a number of substrates. TON data is reported as a function of particle dispersion. The results are explained In terms of the surface roughness observed on the particles.

Determination of Average Grain Sphericity in Granular Porous Media

ABSTRACT Natural granular porous media are composed of particles of varying grain shapes and grain volumes. The average grain sphericity of a finite number of grains with varying grain sphericity and grain volume is of much practical value and utility. Average grain sphericity is shown to be a function of fractional porosity and specific surface of the natural porous media as well as of specific spherical surface per unit solid volume if the natural irregular grains are replaced by fictitious spheres of equal volume as those of natural grains. These three variables can be easily measured by thin section or by thin section cum loose grain methods but the thin section method is preferred because of its greater accuracy in the whole range of size of interest, its ease and quickness, and its appli ability to consolidated as well as unconsolidated granular media.

The hierarchy model of the size distribution of centres

textabstractWe know that human beings live in centres, that is, cities, towns and villages of different size. Both large and small centres have a number of advantages and disadvantages, different for different people and this is why we have a whole range of sizes. Statistically, we even find that the size distribution is fairly regular. No scientific explanation worthy of that name has been advanced so far. Neither do we know whether or not the existing distribution is optimal.

THE HIERARCITY MODEL OF THE SIZE DISTRIBUTION OF CENTRES

We know that human beings live in centres, that is, cities, towns and villages of different size. Both large and small centres have a number of advantages and disadvantages, different for different people and this is why we have a whole range of sizes. Statistically, we even find that the size distribution is fairly regular. No scientific explanation worthy of that name has been advanced so far. Neither do we know whether or not the existing distribution is optimal.

ON THE RELATIONSHIP BETWEEN CENTRAL FUNCTION AND SIZE OF PLACE

Central place analysis has been predicated to a considerable extent upon the general existence of a continuous geometric scale of size of central place, in accordance with the rank-size rule on the one hand, yet divided into discrete size classes on the other. Furthermore, cities within such size groups are believed to be functionally differentiated. Based upon a number of empirical tests in the State of Georgia, both in complete detail for a six-county area centering on the City of Athens and in less detail using secondary state-wide data, evidence is here presented showing that sizes of place do not conform closely to the rank-size rule, although they do reflect closely their own logarithmic regression curve; that there is little evidence of discrete size groupings; and that intensity of service by type of activity varies significantly with size of place. Furthermore, it is shown that the formula N = aPb, indicating the rate of change of number of establishments with change in size of place, does not provide an acceptable estimator throughout the whole range of size of place.

雷雨の雨滴観測

As a part of an artificial rain experiment, an observaticn of raindrop in thunderstcrm was made in August, 1952 in Kawagoe district. Observers made simultaneous observaticns being distributed in about twenty places.It was found that the falling pattern of rain and amount of rain had much d_??_fferences in these respective places, which were only 2-3km apart each other, and also that the raindrop which predcminates over the amount of rain was neither large one nor p_??_r_??_icle of small size, but moderate droplet of 1 to 4mm in diameter.There are many methods for raindrop observation which have been devised so far concerning rain research, among which no one that is available with exactness for the whole range of sizes is found. For instance, a good method for observing fog particle is not suitable for large raindrop and so on, and such a phenomena as of raindrop which size varies in large extent from fog particle to 6mm diameter droplet can not be observed satisfactorily by only one method. Then a several methods ought to be used in parallel, and an idea to use in combination the following three methods which are selected from the existing ones by comparing them each other from practical point of view may be sufficient for the observation of large ranged size drops.For drizzle: MgO method.For moderate raindrop: Special filter paper method and absorbing method.For large raindrop: Standard mesh screen method.It is desirable to make fine network of observation for highly changeful phenomena such as thunderstorm, because an observation at only one spot can hardly catch the general structure of the phenomena. Or, in the case a thunderstorm is progressing to some direction, it would be sufficient to distribute the observers on a line which is perpendicular to the path.Though the analysis made in this paper was not sufficient always as the observationaldata used for the analysis were rather poor, the followings are summar zed as the result of the analysis: 1) A general view of raindrop observations at twenty places is shown in Table I.2) The variaticns of numbers of raindrop by time and place are shown in Fig. 9.3) The amount of rain specified for drops of each size, being calibrated from raindrop, are shown in Figs. 10 and 11.4) A several patterns are seen in size distribution from the observational results.5) The raindrop which predominates over the amount of rain is droplet of 1-4mm in diameter.6) The heavy rain which controls the amount of rain falls neither in the beginning of the thunderstorm nor in the end, but in the middle and for two or three times.7) The rain area starts in a small one, and then expands and diminishes rapidly.8) The maximum rainfall area was an oval of 160km2, which major and minor axes were 22 and 12km respectively.

Aircraft Engines and the Future

THE Wilbur Wright Lecture this year is certainly one of the most thought‐provoking that has been delivered. Read in conjunction with the James Forrest Lecture, printed in our last issue, it gives a very complete picture of where we stand in aircraft and engines to‐day. This general survey comes very appropriately in time to appear in this number, which is devoted almost entirely to engines, and gives an opportunity that does not often occur of reading precept and practice simultaneously. Mr. Ricardo represents perhaps the most expert opinion obtainable in England on the general aspects of internal‐combustion engine design, and it is interesting to turn from his views to the other articles dealing with practice as exemplified in an American, a German, a British, and a French‐designed engine respectively: the wide field of which incidentally emphasises the attitude adopted in this paper from the beginning of endeavouring to maintain an international outlook. From another point of view they have a no less wide appeal, covering as they do almost the whole range of sizes in modern engines, from the 50 h.p. light aeroplane unit, through the 220 h.p. so‐called “Diesel” and the latest 300 h.p. interceptor fighter engine, to the largest 500‐h.p. air‐cooled radial.