1,543 Matching Results

Search Results

Advanced search parameters have been applied.

Bio-Treatment of Energetic Materials Using White-Rot Fungus

Description: The nitramine explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), is used by militaries around the world in high yield munitions and often in combination with hexahydro- 1,3,5-trirdtro- 1,3,5- triazine (RDX). Improper handling and disposal of manufacturing wastewater may lead to environmental contamination. In the past wastewater was collected in disposal lagoons where it evaporated, and deposited large amounts of explosives on the lagoon floor. Although lagoon disposal is no longer practiced, thousands of acres have been already contaminated. RDX and, to a lesser extent, HMX have leached through the soil subsurface and contaminated groundwater ( 1,2). Likewjse, burning of substandard material or demilitarization of out-of-date muriitions has also led to environmental contamination. The current stockpile of energetic materials at DOE sites requires resource recovery or disposition (RRD). A related challenge exists in the clean-up of the DOE sites where soil and ground water are contaminated with explosives. Current technologies such as incineration, molten salt process, supercritical water oxidation are expensive and have technical hurdles. Open burning and open detonation(OB/OD) is not encouraged by regulatory agencies for disposal of explosives. Hence, there is need for a safe . technology to degrade these contaminants. The fi.mgal process does not employ open burning or open detonation to destroy energetic materials. The fimgal process can be used by itself, or it can augment or support other technologies for the treatment of energetic materials. The proposed enzyme technology will not release any air pollutants and will meet the regulations of Clean Air Act amendments, the Resource Conservation and Recovery Act, and the Federal. Facilities Compliance Act. The goal for this project was to test the ability of white-rot fungus to degrade HMX. In our study, we investigated the biodegradation of HMX using white-rot fungus in liquid and solid cultures. The degradation of HMX was studied at 1, 10, 100 ...
Date: November 12, 1998
Creator: Shah, MM
Partner: UNT Libraries Government Documents Department

On improving the penetration of commercial shaped charge perforators

Description: Computational analysis demonstrated that the penetration of a shaped charge jet could be substantially enhanced by imploding the liner in a high pressure light gas atmosphere. The gas pressure helps confine the jet on the axis of penetration in the latter stages of formation. A light gas, such as helium or hydrogen, is required in order to keep the gas density low enough so as not to inhibit liner collapse. The computational analysis has now been experimentally confirmed.
Date: April 1, 1999
Creator: Glenn, L A
Partner: UNT Libraries Government Documents Department

CRT compatibility evaluation of LX-16 and Halthane 73-18

Description: A preliminary compatibility study was carried out between the plastic-bonded PETN-based high explosive LX-16 and the adhesive Halthane 73-18. The work, based on the Chemical Reactivity Test (CRT), used non-standard times and temperatures to find conditions corresponding to accelerated decomposition. This study is a prequel to a more comprehensive isothermal and thermal cycling study that will include both material evaluation and test fire.
Date: August 24, 1999
Creator: Foltz, M F; Reyes, P & Foster, P A
Partner: UNT Libraries Government Documents Department

Thermal decomposition of HMX: Low temperature reaction kinetics and their use for assessing response in abnormal thermal environments and implications for long-term aging

Description: The thermal decomposition of HMX between 175 and 200{degree}C has been studied using the simultaneous thermogravimetric modulated beam mass spectrometer (STMBMS) apparatus with a focus on the initial stages of the decomposition. The identity of thermal decomposition products is the same as that measured in previous higher temperature experiments. The initial stages of the decomposition are characterized by an induction period followed by two acceleratory periods. The Arrhenius parameters for the induction and two acceleratory periods are (Log(A) = 18.2 {plus_minus} 0.8, Ea = 48.2 {plus_minus} 1.8 kcal/mole), (Log(A) = 17.15 {plus_minus} 1.5 and Ea = 48.9 {plus_minus} 3.2 kcal/mole), (Log A) = 19.1 {plus_minus} 3.0 and Ea = 52.1 {plus_minus} 6.3 kcal/mole), respectively. This data can be used to calculate the time and temperature required to decompose a desired fraction of a sample that is being prepared to test the effect of thermal degradation on its sensitivity or burn rates. It can also be used to estimate the extent of decomposition that may be expected under normal storage conditions for munitions containing HMX. This data, along with previous mechanistic studies conducted at higher temperatures, suggest that the process that controls the early stages of decomposition of HMX in the solid phase is scission of the N-NO{sub 2} bond, reaction of the N0{sub 2} within a ``lattice cage`` to form the mononitroso analogue of HMX and decomposition of the mononitroso HMX within the HMX lattice to form gaseous products that are retained in bubbles or diffuse into the surrounding lattice.
Date: December 1, 1995
Creator: Behrens, R. & Bulusu, S.
Partner: UNT Libraries Government Documents Department

CRT compatibility evaluation of LX-16 and Halthane 73-18

Description: A preliminary compatibility study was carried out between the plastic-bonded PETN- based high explosive LX-16 and the adhesive Halthane 73-l 8. The work, based on the Chemical Reactivity Test (CRT), used non-standard times and temperatures to find conditions corresponding to accelerated decomposition. This study is a prequel to a more comprehensive isothermal and thermal cycling study that will include both material evaluation and test tire.
Date: March 26, 1999
Creator: Foltz, M F & Foster, P A
Partner: UNT Libraries Government Documents Department

Numerical simulation of damage and fracture in concrete from shaped charge jets

Description: This paper addresses numerical simulation of damage and fracture in concrete from the impact and penetration of shaped charge jets. We have modeled the jet penetration process with CALE, a two dimensional arbitrary Lagrange Eulerian hydrocode. We have looked at several constitutive models ranging from simple pressure dependent yield to more complex deviatoric models that include the effects of dilatency. Evaluation of the concrete material models is based on comparison to experimental results of an aluminum lined shaped charge fired against a high strength concrete target at several standoff distances.
Date: September 13, 2000
Creator: Murphy, M J; Baum, D W; Clark, D B; McGuire, E M & Simonson, S C
Partner: UNT Libraries Government Documents Department

Modeling Initiation in Exploding Bridgewire Detonators

Description: One- and two-dimensional models of initiation in detonators are being developed for the purpose of evaluating the performance of aged and modified detonator designs. The models focus on accurate description of the initiator, whether it be an EBW (exploding bridgewire) that directly initiates a high explosive powder or an EBF (exploding bridgefoil) that sends an inert flyer into a dense HE pellet. The explosion of the initiator is simulated using detailed MHD equations of state as opposed to specific action-based phenomenological descriptions. The HE is modeled using the best available JWL equations of state. Results to date have been promising, however, work is still in progress.
Date: May 18, 2005
Creator: Hrousis, C A
Partner: UNT Libraries Government Documents Department

A logic model for cook-off phenomenology in high explosives

Description: Logic models are valuable tools in the development of predictive models for complex physical processes. The use of deductive logic in the form of a possibility tree makes it straightforward to develop a comprehensive set of unique, alternative paths that describe the system. We demonstrate the power of this approach for the complex process of cook-off of high explosives (HE). The possibility tree describes the causal paths from heating HE to the alternative end states. One of these end states is a violent reaction. Conversion of the tree to the equivalent digraph yields a valuable visualization tool for examining the relationships between sub-processes and provides a sound framework for the development of analytical models.
Date: January 1, 2003
Creator: Eisenhawer, S. W. (Stephen W.); Bott, T. F. (Terrence F.); Luck, L. B.; Kingson, J. & Key, B. P. (Brian P.)
Partner: UNT Libraries Government Documents Department

ASME code ductile failure criteria for impulsively loaded pressure vessels

Description: Ductile failure criteria suitable for application to impulsively loaded high pressure vessels that are designed to the rules of the ASME Code Section VI11 Division 3 are described and justified. The criteria are based upon prevention of load instability and the associated global failure mechanisms, and on protection against progressive distortion for multiple-use vessels. The criteria are demonstrated by the design and analysis of vessels that contain high explosive charges.
Date: January 1, 2003
Creator: Nickell, Robert E.; Duffey, T. A. (Thomas A.) & Rodriguez, E. A. (Edward A.)
Partner: UNT Libraries Government Documents Department

Ultrasonic Characterization of Potting Voids (An interim report)

Description: This interim report summarizes the efforts to date to develop an ultrasonic technique for detecting and sizing potting voids between a high explosive material and a metallic baclung. This report presents the results for two tasks. The first task was to establish that ultrasonic energy penetrates LX-17. Then once the acoustic properties of LX-17 were measured, a demonstration experiment substantiated that voids could be detected and imaged.
Date: April 23, 2001
Creator: Quarry, M & Thomas, G
Partner: UNT Libraries Government Documents Department

Statistical Considerations in Designing Tests of Mine Detection Systems: II - Measures Related to the False Alarm Rate

Description: The rate at which a mine detection system falsely identifies man-made or natural clutter objects as mines is referred to as the system's false alarm rate (FAR). Generally expressed as a rate per unit area or time, the FAR is one of the primary metrics used to gauge system performance. In this report, an overview is given of statistical methods appropriate for the analysis of data relating to FAR. Techniques are presented for determining a suitable size for the clutter collection area, for summarizing the performance of a single sensor, and for comparing different sensors. For readers requiring more thorough coverage of the topics discussed, references to the statistical literature are provided. A companion report addresses statistical issues related to the estimation of mine detection probabilities.
Date: August 1, 1998
Creator: Simonson, K.M.
Partner: UNT Libraries Government Documents Department

Vicarious amination of nitroarenes with trimethylhydrazinium iodine

Description: This paper investigated the use of 1,1,1-trimethylhydrazinium iodide as a vicarious nucleophilic substitution reagent for introducing amino groups into nitroaromatic substrates. The substrates included nitroarenes, polynitrobenzenes, picramide, TNB,TNT, and dinitropyrazole; other nitroazoles are being studied.
Date: November 10, 1995
Creator: Pagoria, P.F.; Schmidt, R.D. & Mitchell, A.R.
Partner: UNT Libraries Government Documents Department

Changes to the LANL gas-driven two-stage gun: Magnetic gauge instrumentation, etc.

Description: Our gas-driven two-stage gun was designed and built to do initiation studies on insensitive high explosives as well as other equation of state experiments on inert materials. Our preferred method of measuring initiation phenomena involves the use of magnetic particle velocity gauges. In order to accommodate this type of gauging in our two-stage gun, projectile velocity was sacrificed in favor of a larger experimental target area (obtained by using a 50 mm diameter launch tube). We have used magnetic gauging on our 72-mm bore diameter single-stage gun for over 15 years and it has proven a very effective technique to monitor reactive shock wave evolution. This technique has now been adapted to our gas-driven two-stage gun. We describe the method used, as well as some of the difficulties that arose while installing this technique. Several magnetic gauge experiments have been completed on plastic materials. Waveforms obtained in one experiment are given, along with the Hugoniot information that was obtained. This new technique is now working quite well, as is evidenced by the data. To our knowledge, this is the first time magnetic gauging has been used on a two-stage gun. We have also made changes to the burst diaphragm package in the transition section to ensure that the petals do not break off during the opening process and to increase the burst pressure. This will also be discussed briefly.
Date: December 31, 1996
Creator: Sheffield, S.A.; Gustavsen, R.L.; Martinez, A.R. & Alcon, R.R.
Partner: UNT Libraries Government Documents Department

Shock wave structure in heterogeneous reactive media

Description: Continuum mixture theory and mesoscale modeling are applied to describe the behavior of shock-loaded heterogeneous media. One-dimensional simulations of gas-gun experiments demonstrate that the wave features are well described by mixture theory, including reflected wave behavior and conditions where significant reaction is initiated. Detailed wave fields are resolved in numerical simulations of impact on a lattice of discrete explosive {open_quotes}crystals{close_quotes}. It is shown that rapid distortion first occurs at material contact points; the nature of the dispersive fields includes large amplitude fluctuations of stress over several particle pathlengths. Localization of energy causes {open_quotes}hot-spots{close_quotes} due to shock focusing and plastic work as material flows into interstitial regions.
Date: June 1, 1997
Creator: Baer, M.R.
Partner: UNT Libraries Government Documents Department

Low amplitude impact testing and analysis of pristine and aged solid high explosives

Description: The critical impact velocities of 60.1 mm diameter blunt steel projectiles required for ignition of exothermic chemical reaction were determined for heavily confined charges of new and aged (15-30 years) solid HMX-based high explosives. The explosives in order of decreasing impact sensitivity were: PBX 9404; LX-lo; LX-14; PBX 9501; and LX-04. Embedded pressure gauges measured the interior pressure histories. Stockpile aged LX-04 and PBX 9501 from dismantled units were tested and compared to freshly pressed charges. The understanding of explosive aging on impact ignition and other hazards must improve as systems are being deployed longer than their initial estimated lifetimes. The charges that did not react on the first impact were subjected to multiple impacts. While the violence of reaction increased with impact velocity, it remained much lower than that produced by an intentional detonation. Ignition and Growth reactive flow models were developed to predict HMX-based explosive impact sensitivity in other geometries and scenarios.
Date: August 17, 1998
Creator: Chidester, S K; Garza, R & Tarver, C M
Partner: UNT Libraries Government Documents Department

Evaluation Techniques and Properties of an Exact Solution to a Subsonic Free Surface Jet Flow

Description: Computational techniques for the evaluation of steady plane subsonic flows represented by Chaplygin series in the hodograph plane are presented. These techniques are utilized to examine the properties of the free surface wall jet solution. This solution is a prototype for the shaped charge jet, a problem which is particularly difficult to compute properly using general purpose finite element or finite difference continuum mechanics codes. The shaped charge jet is a classic validation problem for models involving high explosives and material strength. Therefore, the problem studied in this report represents a useful verification problem associated with shaped charge jet modeling.
Date: April 1, 2002
Partner: UNT Libraries Government Documents Department

First-principles study of high explosive decomposition energetics

Description: The mechanism of the gas phase unimolecular decomposition of hexahydro-1,3,5,- trinitro- 1,3,5,-triazine (RDX) has been investigated using first principles gradient corrected density functional theory. Our results show that the dominant reaction channel is the N-NO* bond rupture, which has a barrier of 34.2 kcal/mol at the B- PW9 l/cc-pVDZ level and is 18.3 kcal/mol lower than that of the concerted ring fission to three methylenenitramine molecules. In addition, we have carried out a systematic study of homolytic bond dissociation energies of 14 other high explosives at the B-PW91/D95V level. We find that the correlation between the weakest bond strength and high explosive sensitivity is strong
Date: August 21, 1998
Creator: Wu, C J
Partner: UNT Libraries Government Documents Department

Statistical Considerations in Designing Tests of Mine Detection Systems: 1 - Measures Related to the Probability of Detection

Description: One of the primary metrics used to gauge the performance of mine detection systems is PD, the probability of detecting an actual mine that is encountered by the sensor. In this report statistical issues and techniques that are relevant to the estimation of PD are discussed. Appropriate methods are presented for summarizing the performance of a single detection system, for comparing different systems, and for determining the sample size (number of target mines) required for a desired degree of precision. References are provided to pertinent sources within the extensive literature on statistical estimation and experimental design. A companion report addresses the estimation of detection system false alarm rates.
Date: August 1, 1998
Creator: Simonson, K.M.
Partner: UNT Libraries Government Documents Department

Yuma proving grounds automatic UXO detection using biomorphic robots

Description: The current variety and dispersion of Unexploded Ordnance (UXO) is a daunting technological problem for current sensory and extraction techniques. The bottom line is that the only way to insure a live UXO has been found and removed is to step on it. As this is an upsetting proposition for biological organisms like animals, farmers, or Yuma field personnel, this paper details a non-biological approach to developing inexpensive, automatic machines that will find, tag, and may eventually remove UXO from a variety of terrains by several proposed methods. The Yuma proving grounds (Arizona) has been pelted with bombs, mines, missiles, and shells since the 1940s. The idea of automatic machines that can clean up after such testing is an old one but as yet unrealized because of the daunting cost, power and complexity requirements of capable robot mechanisms. A researcher at Los Alamos National Laboratory has invented and developed a new variety of living robots that are solar powered, legged, autonomous, adaptive to massive damage, and very inexpensive. This technology, called Nervous Networks (Nv), allows for the creation of capable walking mechanisms (known as Biomorphic robots, or Biomechs for short) that rather than work from task principles use instead a survival-based design philosophy. This allows Nv based machines to continue doing work even after multiple limbs and sensors have been removed or damaged, and to dynamically negotiate complex terrains as an emergent property of their operation (fighting to proceed, as it were). They are not programmed, and indeed, the twelve transistor Nv controller keeps their electronic cost well below that of most pocket radios. It is suspected that advanced forms of these machines in huge numbers may be an interesting, capable solution to the problem of general and specific UXO identification, tagging, and removal.
Date: July 1, 1996
Creator: Tilden, M.W.
Partner: UNT Libraries Government Documents Department