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The article presents information on a research investigating how do adults explain occurrences with which they are not familiar. During the research, the subjects were cordial and cooperative, with very minor exceptions. During the first demonstration, the explanations of predictions included such terms as "air resistance," "more mass per area," "density of what surface there is," and the like. Out of thirty-five, thirty-one subjects predicted correctly. In the second demonstration, there was a sheet of paper on boxes. Predictions in this case varied considerably. In the third demonstration, spool and card experiment was done which is another example of the Bernoulli effect. Twelve predicted the card would fall or drop, 11 predicted that it would be blown away. In fourth demonstration, the prediction given by 11 was correct.

A general geometrical model, based on the assumption of a constant unit-cell configuration for a particular knitted construction and derived by (he present author in a previous publication is applied to plain, interlock, and various rib-knitted constructions to enable simple relations to be derived for the effective diameter and specific volume of the yam as it exists within the fabric the fabric thickness, and the bulk density of the structure. The relations between these parameters and the fabric tightness factor are evaluated quantitatively for fabrics knitted from wool yarns The knitted-fabric parameters evaluated in this paper are difficult to measure experimentally The geometrical approach used gives an assessment that is independent of the problems encountered during experimental measurements of such parameters as fabric thickness and yarn diameter. [ABSTRACT FROM AUTHOR]

In any false-twist-crimping process, a heat treatment followed by a cooling treatment is given to the threadline in the twist zone in order to 'set' the inserted twist. The majority of commercial machines use metal contact heaters to heat the threadline, and cooling is achieved by exposure to ambient air. The data in this paper provide a basis for a simple method of calculating the temperature-time history of the threadline in the twist zone from the known yam and process parameters. Nylon 6.6 yarns were used for the major part of the work, but data are also presented for Terylene, Ulstron, Lycra, and glass-fibre yarns. The measurements cover wide ranges of the process parameters, i.e., linear density, twist, tension, surface temperature, and yarn velocity. [ABSTRACT FROM AUTHOR]

The air-flow technique for the measurement of wool-fibre fineness has advantages over other methods because of its speed and convenience of testing. However, if the wool being tested is in the form of washed corings from greasy bales or corings from scoured bales rather than tops, the sample may contain impurities such as vegetable matter or sand and dust, and, although it is possible for such impurities to be removed, the treatment requires time and the continuous attention and judgement of a trained operator. The effect of the presence of impurities on the indicated mean diameter of wool fibres is therefore a matter of some importance, and an account is given in this paper of an investigation undertaken to study this effect. The theoretical basis of the influence of impurities on the indicated diameter is given, and it is shown that the experimental results are, in general, in agreement with the predicted values. Provided that the amount of vegetable matter present does not exceed 5% and coarse, sandy dirt is present to an amount not exceeding 1%, it is likely that the error in the indicated diameter resulting from the combined effects will fall in the range from 0 to +4.2%, i.e., the error would not exceed ±2.1% at the 95% probability level, which might be an acceptable figure for many purposes if an adjusted calibration were made. [ABSTRACT FROM AUTHOR]

Maintenance of thermal comfort at high activity levels under both hot and cold weather conditions depends on diffusion of Water vapor through textile systems. A maximum of approximately one liter per hour of moisture is available to the average man for evaporative cooling, which is equivalent to a maximum heat loss of 333 kcal/m² hr. However, the amount of heat dissipated in this manner may be limited by clothing, which impedes convective evaporation. Water vapor transfer is thus an important property to be evaluated in military clothing. This paper discusses several methods for measuring the moisture vapor transmission of textile fabrics and proposes mathematical models to predict moisture vapor transmission in terms of simple, readily available fabric geometric properties. One model was based upon a commonly accepted perforated plate theory which considers the fabric as a perforated structure in which moisture vapor diffuses partly through the interyarn spaces and partly through the "non-perforated" areas of the fabric. The other model considered the fabric as a relatively uniform mixture of fiber and air, a valid assumption for most functional, tightly woven military fabrics. In this model, resistance to diffusion was considered as the sum of the air space and "fiber space" resistance over the entire fabric area. This latter model, With a slight adjustment of the film transmission factor, predicted the resistance of a number of cotton and nylon fabrics as measured experimentally. Thus moisture vapor transport capability, and therefore comfort of a fabric at a specified ambient temperature and humidity, can be predicted if the fabric areal density and thickness are known. [ABSTRACT FROM AUTHOR]

Fiber battings are becoming increasingly important for their uses as insulation. This paper reports the results of an investigation of the influence of thickness, applied pressure, bulk density and fiber type on insulation parameters such as Clo and Warmth Factor. The specific Clo value of 3.4 Clo per inch for battings falls between specific Clo values for fabrics and fabric-foam laminates. Warmth Factor, for a given batting weight, increased with thickness; and for a given thickness level, decreased with weight. Neither fiber type, within the limited range investigated, nor batting density had a significant influence on the intrinsic insulation of the battings. [ABSTRACT FROM AUTHOR]

The principle and basic design of a fast machine for the determination of wool and vegetable-matter components in scoured wool are described. The machine is a development of that used in Harker's method for the separation of wool and vegetable matter by reducing the material to a finely divided state and utilizing the different densities of wool and vegetable matter to separate them by flotation. However, in contrast to Harker's method, thermal convection and density gradients are not used; the machine embodies a special centrifuge, in which the separating liquid is controlled at a density of 1.335 ±0.002 g/ml. The problem arising from the presence of low-density vegetable-matter components is discussed, and the means of treating these components to enable separation to proceed are described. The quality of separation is of a high order, and separations can be made in a few minutes. [ABSTRACT FROM AUTHOR]

Variation of the phosphoric acid/water ratio used in the preparation of a dental silicate cement has profound effects on the properties of the cement. Setting time, compressive strength, and resistance to attack by water and acids are among the factors dependent on this ratio, and there is evidence that cementing hydrates of definite composition have been formed in some instances. [ABSTRACT FROM AUTHOR]

The article presents a study examining the density distribution of the dental hard tissues. Previous studies on the density and refractive index of dental hard tissues are discussed. Previous research performed on several types of tissue is mentioned, including research on the density of dental enamel, dentin, and cementum.

Knowledge, information, and bibliographic organization have mathematic properties of 1-1 correspondence, infinity, countability, density, and continuity. A relation between elements of bibliographic organization exists just as a relationship exists between elements in mathematics. Knowledge and information are explained in mathematical terms. The properties of bibliographic organization and mathematics are combined to indicate that bibliographic organization is a form of mathematics. [ABSTRACT FROM AUTHOR]

This paper treats the unfolding problem of estimating the density distribution of particles dispersed in a three-dimensional specimen. A general framework is set in term of a probabilistic model for the distribution of a discrete number of particle sizes with prescribed shapes which are sampled and observed by processes capable of being modeled. The general formulation allows density estimates and standard deviation estimates for each particle size in the distribution to be made with data from observational processes that may distort or truncate the sampled information. The method is related to the earlier works on unfolding or estimating the density distribution of spherical particles sectioned by planar probes. The method is also used to develop a mc re accurate estimate for the density distribution of spherical voids where the observational process is the indirect microscopy of a replicated surface. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "The Thickness and Bulk Density of Plain-Knitted Fabrics," by R. Postle, in a 1971 issue.

A response by R. Postle to a letter to the editor about the article "The Thickness and Bulk Density of Plain-Knitted Fabrics" in a 1971 issue is presented.