Search

In evolutionary algorithms and metaheuristics, defining when applying a specific operator is important. Besides, in complex optimization problems, multiple populations can be used to explore the search space simultaneously. However, one of the main problems is extracting information from the populations and using it to evolve the solutions. This article presents the inequality-based multi-population differential evo-lution (IMDE). This algorithm uses the K-means to generate subpopulations (settlements). Two variables are extracted from the settlements, the diversity and the Gini index, which measure the solutions' distribution and the solutions' inequality regarding fitness. The Gini index and the diversity are used in the IMDE to dynamically modify the scalation factor and the crossover rate. Experiments over a set of benchmark functions with different degrees of complexity validate the performance of the IMDE. Besides comparisons, statistical and ranking average validate the search capabilities of the IMDE.

This report describes methods for predicting blast overpressure outside suppressive structures. Prediction curves are in scaled form. Data are compred to free-field data for large high-explosive detonations on the ground., See also ADA025 502 and ADA024591.

The Damaged Weapons Facility (DWF), planned for construction at the Pantex Plant, will consist of several rooms and interconnecting corridors. It is being designed to essentially completely contain explosive effects in the event of an accidental explosion during weapon disassembly. Because of the complex geometry of the facility, the rational prediction of initial and later reflected shock wave loading, and the longer-term gas pressure loading, is very difficult. Accordingly, a one-eighth scale, overstrength, steel 'loads' model of the facility has been built and tested. Tests include detonations within the model of various weights and types of spherical and cylindrical explosives, at several charge locations within the high bay area of the facility. This paper summarizes shock and gas pressure measurements taken within the model, and compares test results to current methods for estimating these transient pressures and to data from other investigators., This article is from 'Minutes of the Explosives Safety Seminar (20th) Held at OMNI International Hotel, Norfolk, Virginia on 24-26 August 1982. Volume I,' ADA124400.

Gas pressures from explosions within enclosures, as opposed to shock loads, can be the dominant loads causing structural failure. This paper reviews test results and prediction methods for gas pressures for many types of internal explosions including high explosives plus combustibles, gas mixtures and dust suspensions., This article is from 'The Interaction of Non-Nuclear Munitions with Structures: Symposium Proceedings Held at U.S. Air Force Academy, Colorado on May 10-13, 1983. Part 1,' AD-A132 115, p177-181.

The phenomenon of quasi-static pressure enhancement produced when combustible materials are placed near HE sources has been recently discovered. The effects of placing solid and liquid combustible materials near detonating explosives on internal blast loading was measured during tests conducted in a one-eighth scale model of a containment structure. In many cases, dramatic increases in gas pressures resulted. Principal conclusions of this study are: Combustible materials near explosives can markedly increase gas pressures in enclosed structures; There is a lack of data on HE-combustible combinations; Quasi-static loading calculations should include estimates of contributions from the burning of combustible materials whenever such materials are expected to be in intimate contact with HE sources; and Effects of combustibles should be investigated further to determine methods for prediction. Variations in charge to combustible mass, charge type, structure volume, degree of venting and degree of contact between HE and combustible should be studied., This article is from 'Minutes of the Explosives Safety Seminar (21st) Held at Houston, Texas on 28-30 August 1984. Volume 1,' AD-A152 062, p395-415.

This report documents work performed for the Edgewood Arsenal Suppressive Structures program. Included were the development of approximate energy solutions for the response of structures to blast loading, the analysis of strain data from the Category I 1/4-scale model tests, and calculations of pressure-time histories for the burning of M10 propellants in the Category V shield.

Prepared in cooperation with Lawrence Livermore National Lab., Livermore, CA.

This report is the first in a series describing the development of methods for estimating dynamic loading and plastic response of suppressive structures. It covers application to containment of the blast from an accidental explosion in a melt loading operation, and includes preliminary developments of methods to predict blast loads and plastic structural response.

The report discusses the preliminary design and analyses of a suppressive structure for a melt loading operation having a capacity of 2500 lb of high explosive. The basic structural concept consists of a complete box- shaped steel frame supporting vented panels. The structure is designed to withstand blast loads and fragment impacts., See also ADA029386.

This report presents the results of a design study for a structure to suppress blast and fragment effects from detonation of a large quantity of Comp B explosive in a melt kettle. A number of design concepts were evaluated, and a specific configuration recommended. Relatively detailed design drawings were prepared., See also report dated Nov 1975, ADA022333.

This report describes methods for estimating shock pressures and vented gas pressures within suppressive structures and for estimated attenuated blast wave properties outside. Data are fitted to scaling laws, and prediction equations given with limits of validity. A computer code for predicting venting pressures is described., See also ADA024378.

This report describes an experimental program conducted in support of the US Army Modernization Program. Normal and oblique reflected blast parameters, including peak pressure and impulse, were measured to characterize the explosive output of multiperforated M26E1 propellant. Three sizes of spherical propelllant charges were fired over a reflecting surface on which an array of pressure transducers was used to obtain pressure-time histories at scaled distances. A series of Pentolite tests was also conducted at similar scaled distances to establish a baseline for comparing the reflected blast parameters measured in the propellant experiments. The blast pressure and impulse data obtained showed that at the scaled distances tested the maximum explosive output of M26E1 propellant is comparable to Pentolite.

An experimental program was performed to investigate the effect of high-velocity fragments alone and coupled with a blast pressure to determine whether accurate simulation testing of aircraft fuel tanks in a near-miss exploding warheadenvironment must include the blast threat. A series of tests was conducted to synchronize the fragments and blast pressure loading. Experiments were then conducted using a simulated fuel tank which included replaceable front and rear walls. The fuel tank, empty and full of water, was tested with five steel rectangular prism fragments alone, and the combination of the same fragments with a blast pressure wave of similar magnitude and duration as would be generated by an exploding warhead. Four types of aluminum front panels were tested using two types of aluminum and two thicknesses of each. The rear panel used on the full tank tests was the same for all these tests. The report presents the complete experimental program, a description of the test facilities, the simulation techniques and the instrumentation used in the program. Structural damage of the test panels are depicted by photographs of each panel. The results indicate that the addition of blast pressure can definitely enhance the fragment damage to the panels, particularly with an empty fuel tank. (Author)

This report describes an experimental program conducted in support of the Army Plant Modernization Program. Air blast parameters including peak pressure and specific impulse were measured for multiple charges, detonated simultaneously, in three different geometrical configurations: grouped, horizontal and vertical arrays. A series of single charge tests was also conducted to establish a baseline from which the effects of multiple charges could be determined. A model analysis was developed and used to design and interpret the model experiments. In the experiments, pentolite spheres modeling potential explosive sources were detonated near a reflecting surface. Blast measurements were made directly below the charges and at various slant distances using piezoelectric transducers. The impulse was obtained by numerically integrating the pressure traces. Plots of peak pressure, impulse, duration and arrival time are presented and the differences between single and multiple charges are highlighted., Also available as GIDEP-E134-1238.

Anti-aircraft missile warheads pose a severe threat to aircraft even when the missile misses the aircraft. The threat from missile warheads can be divided into two primary areas for proximity detonation, fragments and blast. This report describes the development, calibration, and testing of a blast simulator capable of varying the blast parameters (i.e., pressure, impulse, and time duration), simulating those obtained at various standoff distances from a prototype warhead detonation. (Author)

Laboratory experiments were conducted to obtain incident overpressure data from frangible spheres pressurized with a flash evaporating fluid in liquid and vapor form. Glass spheres under higher than ambient internal pressure of Freon-12 were purposely burst to obtain time histories of overpressure. Non-dimensional peak pressures, arrival and duration times, and impulses are presented, and whenever possible plotted and compared with compiled data for Pentolite high explosive. The data are generally quite repeatable and show differences from blast data produced by condensed high explosives.