Weighing methods

Rogers used two methods to determine the burning rate. They will be referred to here as (1) weighing method (2) mass-balance method. Rogers used the latter method to verify the former method. 

Rogers presented a comprehensive theory of the weighing method including an uncertainty analysis. 

As the cut and weigh method above, the planimeter method is a perimeter method that makes use of a surveyor s or draftsman s instrument called a planimeter. Using this technique the baseline is drawn as usual. The perimeter of the peak is then traced using the eyepiece containing cross-hairs of the planimeter. 

The cut and weigh method is quite time consuming. However with adequate control of variable paper density it has real value for irregularly shaped peaks. 

The British equivalent to ISO 2781 is BS 903 Part Al2 which is identical to the international method. Rather surprisingly, ASTM does not appear to have a specific method for density at the present time. There is, however, a section on density in the standard on chemical analysis of rubber products, D2973, which briefly gives methods by pycnometer, hydrostatic weighing and a compressed volume densimeter. The weighing method does not mention the use of a sinker for densities less than 1. There is also a method for density of rubber chemicals, D1817)4, which uses the pycnometer method and, interestingly, specifies a vacuum pump to remove air before the measurement.. 

Kloubek, J., Friml, K., and Krejci, F. 1976. Determination of dynamic surface tension with various stalagmometers by drop weighing method. Collect. Czech. Chem. Commun. 41 1845-1852. 

The volume diameter of a particle may be useful in applications where equivalent volume is of primary interest, such as in the estimation of solids holdup in a fluidized bed or in the calculation of buoyancy forces of the particles. The volume of a particle can be determined by using the weighing method. Sauter s diameter is widely used in the field of reacting gas-solid flows such as in studies of pulverized coal combustion, where the specific surface area is of most interest. 

Figure 4.1 Illustration of the cut-and-weigh method for peak area integration.

Hydrostatic Weighing Method The volume of a solid sample is determined by comparing the mass of the sample in air with the mass of sample immersed in a liquid with a known density. The volume of sample may be calculated using the difference between the two measured mass values divided by the density of the liquid. This method can be used to determine the bulk or apparent volume. It is extremely important that the suspending liquid does not interact with the powder under investigation. 

Note Westphal Balance Method is described under Hydrostatic Weighing Method in Vol 3 of Encycl, p D68... 

For distributions of irr ular-shaped particles, the size distribution measured is dependent on the method of measurement. For this reason, the sizing method employed should duplicate the property of interest (e.g., for pigments, the projected area diameter is of interest for catalyst substrates, the surface to volume diameter is of interest, etc.). There are many different methods of measuring size distribution. Table 2.2 gives the most common methods utilized and the typefs) of size dimen-sion(s) measured. These methods of size measurement have to be coupled with either some counting or weighing method to determine the... 

For the microwave regeneration, firstly, put the adsorption column packed with the polymeric adsorbent on which the saturated amount adsorbed of VOCs was qo in microwave oven, and subsequently, use synchronously microwave to beat the column and N2 to sweep the VOCs desorbed from the adsorbent out. Regeneration efficiency of the adsorbent was measured every thirty seconds by weighing method until regeneration operation ended. 

In addition to these weighing methods of determining gas gravity, a method based on the effusion of gases through a small orifice can he employed. This method is based on Graham s Law which may be stated The rate of effusion of a gas throu an orifice is inversely proportional to the square root of the gas density. Consequently, the... 

IR Analysis. IR absorption spectra were determined on neat samples of shale oils to furnish data for estimates of various olefinic types of compounds. Samples were run on a high-resolution, double-beam grating spectrophotometer at 0.1-mm path length between KBr plates. Quantitative measurements were made using the cut and weigh method with baselines drawn from point to point of minimum absorption. 

DIN 52 451 1983 Testing of building B sealants determination of the change in volume after thermal stress dipping and weighing method. 

Quantification of each spectral region was carried out by cut and weigh methods (35) and are shown in Table VI for Como Creek. The aliphatic region I increased from 24.5% in stream humic substances to 43 and 40% in foam fulvic and humic acids, respectively. In contrast, the aromatic peak decreased from 34% in stream humic substances to 21 and 27% in foam fulvic and humic acids, respectively, while the... 

Indirectly, volume may be determined by two weighing methods. One method consists in saturating the specimen by immersion in a suitable liquid, kerosene or water, and weighing it in this state. The same test piece is then weighed while suspended in the liquid. From these weights the exterior volume of the specimen, in cubic centimeters, is computed from the relation v — (w — s)/5, where v = exterior... 

The area-to-mass relations for the homopolymer and methyl tosylate were obtained from the areas under the GPC traces (ARI) of solutions having known concentrations of Isolated homopolymer and MeOTs. Areas were measured by the paper-weighing method. 

The weighing methods belong to the oldest and most frequently used techniques in the past. They are based on the extraction of oil products from a sample of water with a solvent and the subsequent determination of the weight of extracted substances after distillation [13-1-5, 66]. The volumetric methods are based on distillation of the volatile oil substances from water and measuring their volume after condensation [67, 68]. 

The weighing method takes a long time, but is more accurate than the reference method. In the reference method, the total dry extract is calculated from the relative density d, measured by areom-etry. Relative density is determined by measuring the density (/y) of a wine at 20°C and that of a dilute alcohol mixture with the same alcohol content (/a). The equation for relative density is as follows dt = 1.0018(/y — /a) - - 1.000. 

Therefore, when it is advisable the feature selection, weighing methods determine the importance of the scaled features for a certain classification problem Consider a pattern vector X = (X j,X 2/--- ip) Assuming that the data matrix X can be p>artitioned into a number Q of classes, let xj a pattern vector belonging to class C. The averaged patterns m and represent the general mean vector and the C-class mean, according to ... 

The average daily iron intake, as derived from dietary surveys at the three school cafeterias using a 3-day food weighing method, was approximately 17 mg, with no difference between the schools. Although this iron intake is adequate when compared with the RDA, the bioavailability is likely low given that most of the daily... 

In this step data is collected for all the relevant processes in the process tree. In cases where there are no standardised production modules for processes, empirical data has to be identified. This empirical data must be based on a statistically-relevant time period and the averaging and weighing methods must be thoroughly reported. 

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