Cooks Distance

Because MiniTab and other software packages also can provide values for leverage (/ ,) and Cook s distance, let us look at them relative to the previous analysis with the two data points ( 4 and 23) in the analysis. 

Recall that the hi value measures the distance for the x value. The formula is  

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Cook s Distance Plot (Model Diagnostic) A statistic known as Cook s distance can be used to detect calibration data outliers by identilying which samples are most influential on the model. Now that the selected variables have been finalized, it is good practice to examine the calibration data for influential samples. These samples should be investigated and removed if it is determined that they have an unusual effect on the model. 

FIGURE 5.69. Cook s distance versus sample number for component A. 

Cook s distance plot (Cook s distance vs. sample number)... 

Cook s Distance Plot (Model Diagnostic) In Figure 5.80, the Cook s distance is plotted versus sample number for tlie three-variable caustic model. All values are much less than 1 (the maximum is 0.14), which is an indication that no samples are potentially over ) influential on the model parameters. 

Accdg to Cook, Langweiler assumed for the plain-wave deton behind the wave front a simplified constant p(x) (density-distance) and W(x) (particle velocity-distance) contour followed by a sharp (presumably discontinuous) rarefaction. He gave as the velocity of the rarefaction front the value (D+W)/2, where (D) is detonation velocity. Then he deduced that in an explosive of infinite lateral extent, the compres-sional region or detonation head of the wave should grow in thickness in accordance with the equation ... 

The geometrical model of Cook (Ref 8, pp 125-28) is based on the detonation head having flat density-distance p(x) and particle velocity-distance contours behind the... 

Detonation, Ideal and Nonideal. Accdg to Cook (Ref 2, p 44), an ideal detonation corresponds to the theoretical maximum or hydrodynamic value D. This maximum velocity D is subject to direct experimental determination it is the steady value attained at a sufficiently long distance from the initiator in a tube or charge of diameter sufficiently large that further in-... 

M.A. Cook et al, JApplPhys 30, 1579-84(1959) (Instrumented Card-Gap or SPHF-Plate Test) 23) Baum, Stanyukovich Shekhter (1959). 754-71 (Deton by influence thru air) 771-78 (Deton by influence thru condensed media) 778-81 (Safe distances for propagation of deton betw some expl chges used in Rus coal mines) 23a) Liquid Propellants Info Agency, Applied Physics Lab, Johns Hopkins Univ, "Liquid Propellants Test Methods, Test No 1, Card-Gap Test for Shock Sensitivity of Liquid Monopropellants (March i960)... 

Dunkle (Ref 3) made the following r emark "I hate to disagree with Cook, but I would call a detonation propagating at less than sonic velocity a deflagration. Evidently the wave sets up sound waves ahead which go at successively faster rates, thus telescoping into a shock wave which initiates detonation some distance ahead of the low-velocity wave ... 

Cook et al (Ref 6) considered that the jump condition of NDZ theory is not a satisfactory solution, but that pressure in the reaction zone is limited to values no greater than the pressure P at the C-J plane, except possibly for an extremely short distance of perhaps several mean free paths at the extreme front where thermal equilibrium may not exist (Ref 7, p 174)... 

A modification of the above underwater method studied by Cook (p 37) is the measurement of the spall-dome velocity at the surface , caused by explosion at a fixed distance beneath the surface. The method (which is not described in Cook s book) is best applied by use of calibration curves employing as suitable standard a selected explosive. It has been claimed that the method is reproducible within 5 to 10% and gives data generally in fair accord with expectations from theoretical calculations, provided the depth and extent of the pond are sufficient to avoid shock reflections. In many cases, however, there was a necessity of taking into consideration the rate of evaporation of water at the gas bubble-water interface (Ref 17, p 37)... 

Measurement of detonation pressure) 363-69 (Peak pressure-distance relationships curves) 41) Cook (1958), 32-35 (Measurement of deton pressure) 265-68 (Maximum available work and peak blast pressure) 4la) I. Ginsburgh, JAppl-Phys 29, 1381-82(1958) (Abnormal pressures in a shock tube) 41b) D. Price, ChemRevs 59, 801-25(1959) (Substituted in her discussions the term "detonation pressure for "brisance and "detonation energy for "power ) 42) Baum, Stanyu-kovich Shekhter (1959), 139-43 (Bichel bomb for detn of pressure) 43) Bandurin Rukin (1959), 69-74 (Pressure of gases formed on expln in a closed vessel)... 

Detonation, Shock Transmission from Explosive to Metal Plate. Accdg to Cook (Ref 3, p 1H)> R.W. Goranson is credited with suggesting that it is possible to determine the p(x), W(x) and p(x) distribution in the detonation wave by studying the characteristics of the shock wave transmitted from the explosive into a thin metal plate in shock loading of the plate by a detonation wave. In this theory, when a plane detonation wave strikes a metal plate at normal incidence, a shock wave is transmitted into the plate and another is reflected back into the incident wave such. as to give a pressure-distance profile like that illustrated in Fig 5.17 [reproduced by Cook from the paper of Walsh Christian (Ref 1)]. 

Methods of measuring underwater shock waves by crusher gauges, diaphragm gauges piezoelectric gauges are thoroughly described by Cole (Ref 3) in Chapter 7. Cook (Ref 7) describes the use of a 16- to 64-frame/sec camera to measure the free surface vel produced by a shock wave at the surface, and the determination of the underwater pressure-distance curve for TNT... 

American Table of Distances for Storage of Explosives, as revised and approved by the Institute of Makers of Explosives,.September 30, 1955, is given by Sax(1957), 154-7 and Cook(1958), 354-6... 

This teat is conducted by placing the assembly vertically, at a known stand-off distance, above several layers of 0.5 inch thick armor-plate steel and detonating the charge. After detonation,the depth of hole, its average diameter at the top, and its volume are determined. Refs 1)TM 9—1910(1955),78—85 2)PATR 1740, Rev 1(1958) 3)Cook( 1958),226-64... 

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