Representative metrics

The diversity metric can then be the distance to the nearest object, or the degree of overlap between the two distributions. The second metric has to be calculated on the fly, as it is dependent on the membership of the distribution, which will vary according to which library subset is selected. Diversifying metrics based on molecular properties have been used to cluster corporate databases [34], and so are available to balance out the representative metric. 

In summary, the measures presented in this section represent metrics that assess the goodness of fit in a... 

Table 15.1 compares the risk of fatality with a number of other activities. The term FAFR refers to the number of fatalities per 100,000 hrs (10 hrs) of exposure to the activity in question. For voluntary activities (such as those listed) where exposure varies between activities, it is a more representative metric than fatalities per calendar year (which take no account of relative exposure). The comparative FAFRs were obtained from recent Technis (DJS) studies. 

The matrix gp, represents the components of a covariant second-order tensor called the metric tensor , because it defines distance measurement with respect to coordinates To illustrate the application of this definition in the... 

Representative Method Every controlled-potential or controlled-current coulo-metric method has its own unique considerations. Nevertheless, the following procedure for the determination of dichromate by a coulometric redox titration provides an instructive example. 

The ores of most importance are fluorspar, CaF2 fluorapatite, Ca (P0 2Fj cryoHte [15096-52-3], Na AlF. Fluorspar is the primary commercial source of fluoiine. Twenty-six percent of the world s high quaHty deposits of fluorspar are ia North America. Most of that is ia Mexico. United States production ia 1987—1991 was 314,500 metric tons, most of which occurred ia the Illinois-Kentucky area. Imported fluorspar ia 1990—1991 represented about 82% of U.S. consumption 31% of U.S. fluorspar imports were from Mexico and 29% from China compared to 66% from Mexico ia the 1973—1978 period. The majority of the fluorine ia the earth s cmst is ia phosphate rock ia the form of fluorapatite which has an average fluorine concentration of 3.5%. Recovery of these fluorine values as by-product fluorosiHcic acid from phosphate production has grown steadily, partially because of environmental requirements (see Phosphoric acid and THE phosphates). 

MSW incinerators (qv) are typically designed to reduce the volume of soHd waste and to generate electricity in condensing power stations. Incineration of unprocessed municipal waste alone recovers energy from about 34,500 t/d or 109 million metric tons of MSW aimuaHy in some 74 incinerators throughout the United States. This represents 1.1 EJ (1.05 x 10 Btu) of energy recovered aimuaHy (18). Additionally there are some 20 RDE facihties processing from 200 to 2000 t/d of MSW into a more refined fuel (19). Representative projects are shown in Table 10. 

Much more important is the hydrogenation product of butynediol, 1,4-butanediol [110-63-4]. The intermediate 2-butene-l,4-diol is also commercially available but has found few uses. 1,4-Butanediol, however, is used widely in polyurethanes and is of increasing interest for the preparation of thermoplastic polyesters, especially the terephthalate. Butanediol is also used as the starting material for a further series of chemicals including tetrahydrofuran, y-butyrolactone, 2-pyrrohdinone, A/-methylpyrrohdinone, and A/-vinylpyrrohdinone (see Acetylene-DERIVED chemicals). The 1,4-butanediol market essentially represents the only growing demand for acetylene as a feedstock. This demand is reported (34) as growing from 54,000 metric tons of acetylene in 1989 to a projected level of 88,000 metric tons in 1994. 

Rates of production of lignite have continued to increase since 1960. In 1980 374 x 10 tons of coal equivalent (tee) were produced. One tee is the amount of energy available from combustion of a metric ton of coal having a heat content of 29.3 GJ, ie, 29.3 MJ/kg (12, 600 Btu/lb) (3). In 1989 this figure had risen to 460 x 10 tee. This 23% increase is somewhat less than the 28% increase in hard coal production during this period (see Coal). In 1990 the 1130 X 10 metric tons of lignite produced worldwide represented 24% of the total coal production. 

Refs. 132 and 153. Values are in metric tons. Numbers represent raw data. ... 

The largest oxo producers ia Western Europe are BASE, Hbls, and Hoechst (formerly Ruhrchemie), representing 50—51% of the total regional capacity of 2.527 x 10 metric tons. These companies have the broadest spectmm of products ranging from and adehydes to alcohols and acids. However the primary products are n- and isobutyraldehyde, at combiaed capacities of 1.08 x 10 t. The -butyraldehyde goes principally iato the manufacture of 2-EH. 

Soybeans are the most important oilseed in international trade. The United States, Bra2il, and Argentina are the main suppHers to the export markets. In 1994—1995, United States exports of 22.0 x 10 metric tons represented 32% of the domestic production, 16% of the world crop, and 69% of the international trade in soybeans. The European Union, Japan, Mexico, and Taiwan were the largest importers of soybeans (51). Japan, which produces <5% of its soybean needs, is the largest single soybean customer of the United States. Japan imported 3.4 x 10 t in 1994 (51). The United States also exports processed soybean products, eg, oil and meal. For 1990—1993, an average of 47% of the crop was exported as whole beans and processed products. 

Values in parentheses represent the approximate 1996 production capacity in thousands of metric tons. ... 

Portland cement is the most widely used constmction material in the world (see Cement), especially in Third World nations, because of its availabiHty, ease of use, and versatiHty. Estimated 1989 worldwide production is almost 1.12 biUion metric tons. The United States represented 71.2 million metric tons, ie, fourth, behind China (207 million metric tons), the former USSR (140 million metric tons), and Japan (82 million metric tons). Spain is tenth with 27 million tons. The top 10 world producers of Portland cement account for just under 43% of the total production. 

In 1988, cadmium metal production in the United States increased significantly and imports decreased, but exports increased. Dramatic increases in cadmium prices in 1988 were attributed to the tight supply of cadmium worldwide, heavy speculative trading, and the large quantities of cadmium being purchased by the nickel—cadmium battery industry, particularly in Japan. About 30 countries are cadmium producers, led by Russia, Japan, the United States, Canada, Belgium, Germany, and Mexico, which cumulatively represented 64% of the 1988 reported world cadmium production of 19,773 metric tons. 

The representative price is the company-reported value per metric ton, fob mine or plant. 

In excess of a million metric tons of 0x0 products are produced in the United States annually. They are used in the manufacture of plasticizers, solvents, and detergents. The principal 0x0 alcohol product, 2-ethyl-1-hexanol [104-76-7] is made from propylene [115-07-1] and represents about 75% of the 0x0 market. 

Solution mining produced nearly 23 million metric tons of salt in 1989 representing more than half of the total U.S. salt production (14). Salt brine is made from bedded salt at more than 18 different locations and from 17 salt domes (15). Bedded salt of the salina formation is the most widely and intensively exploited by solution mining. Enormous reserves of salina salt are available. Cost of solution mining salt is usually less than the cost of salt produced by dry mining. The method is particularly good where salt deposits are deep and dry mining would not be feasible. 

The most important chemical reaction of chi orohydrin s is dehydrochloriaation to produce epoxides. In the case of propylene oxide. The Dow Chemical Company is the only manufacturer ia the United States that still uses the chlorohydrin technology. In 1990 the U.S. propylene oxide production capacity was hsted as 1.43 x 10 t/yr, shared almost equally by Dow and Arco Chemical Co., which uses a process based on hydroperoxide iatermediates (69,70). More recentiy, Dow Europe SA, aimounced a decision to expand its propylene oxide capacity by 160,000 metric tons per year at the Stade, Germany site. This represents about a 40% iacrease over the current capacity (71). 

Some 637—1075 biUion metric tons is classified as anthracite and biturninous coals of which 10% is estimated to be suitable for cokemaking. Thus this 60—108 biUion metric tons of coking coal, if recovered in a fully usehil form, represents enough coal to supply coke plants at 1990 consumption rates for about 100—200 years. North America is estimated to possess about 130 biUion metric tons of biturninous coal of which, perhaps, one-tenth would be classified as coking coal, most of which resides in the United States (4). 

Fig. 9. Schematic steam balance where the numbers represent steam flows in metric tons per hour. See Table 3.

Scheme 4 also represents the classical route to isoxazoles, first studied in 1888 by Claisen and his coworkers (1888CB1149). Reaction of a 1,3-diketone with hydroxylamine gives, via the isolable monoxime (108) and the 4-hydroxyisoxazole (109), the isoxazole (110). Unsym-metrical 1,3-diketones result in both possible isomers (110) and (111), but the ratio of the isomeric products can be controlled by the right combination of the 1,3-dicarbonyl component and the reaction conditions used. These important considerations are described in Chapter 4.16, along with the variations possible in the 1,3-dicarbonyl component designed to yield diverse substituents in the resultant isoxazole. 

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