The Air Base has long been a potential target of attack for enemy planners. An effective way to attack the United States Air Force (USAF) is to avoid its usual dominance in the air and use an asymmetrical approach, attacking air bases with ground forces inserted into the Joint Rear Area. The history of airbase ground attacks from 1942 to 1994, documented in the book Snakes in the Eagles' Nest, shows that the dominant strategy employed by air base attackers has been the standoff attack. Roughly, 75 percent of all airbase attacks have been through the use of rockets or mortar fire from outside the airbase's perimeter defenses. In Vietnam, where the defenses against penetrating ground attacks were emphasized, this percentage rose to 96 percent. Historically, robust main operating bases, with passive defensive measures such as hardened facilities and redundant systems, have been able to withstand standoff attacks. The relative inaccuracy of the attacker's standoff systems and their limited ability to sustain fire on the air base minimized damage. Times have changed and the USAF finds itself operating in an expeditionary mode across the globe. Expeditionary Air Forces cannot depend on the luxury of operating off airfields with the robust infrastructure of main operating bases. In addition, the emergence of man portable, guided munitions for mortars and guided anti-tank missiles has increased the accuracy of potential standoff weapons. Finally, the sophistication of Improvised Explosive Devices in Iraq and of modern radio-controlled model aircraft suggests the potential for attackers to build their own guided standoff weapons. The potential for a "one shot, one kill" standoff weapon is here today, negating the effectiveness of passive hardening measures. Disrupting these attacks will take new strategies. Understanding current Joint and USAF doctrine is the first step. Areas for further study include disrupting the enemy forces before they launch a standoff attack, intercepting the standoff round in flight and mitigating the damage on impact are discussed.

Understanding the impacts of explosive contamination on vegetation is key to understanding explosives behavior in the environment. I quantified shrub growth responses to 1,3,5-trinitroperhydro-1,35-triazine (RDX) soil contamination across three life stages and I hypothesized that RDX would have the greatest impact on seed germination. Morella cerifera seeds were germinated on soils amended with RDX up to 1500 mg RDX kg-1 dry soil. Juvenile and adult individuals were exposed for 6 weeks to soil amended with RDX up to 750 and 1500 mg RDX kg-1 dry soil, respectively. Morphological responses were quantified for juveniles while physiological measurements were quantified for adults. RDX induced a significant response in all age groups and, in accordance with the hypothesis, germination was the most impacted of the three stages. Impacts varied by concentration in addition to life stage, showing that many variables influence plant response to RDX.

The prevalence of injuries from improvised explosive devices (IEDs) in recent U.S. military conflicts has highlighted the lack of knowledge of the acute and long-term consequences of blast exposure. Real-world blast exposure is complex and multi-phasic. It is unclear whether the shock wave component of blast exposure (primary blast) can cause traumatic brain injury (TBI); however, other blast components, such as tertiary blast (inertial loading mechanics), have known potential to injure the brain. Clinical and in vivo studies suggest that complex blast loading of the whole body and head can result in acute and delayed behavioral deficits and neurodegeneration, yet tertiary blast exposure or injury to the body can initiate a systemic response that complicates understanding of this pathology. To set safe thresholds for primary blast exposure and design headgear that can guard against primary blast, tolerance criteria for primary blast specific to brain must be defined. We developed and validated a model of primary blast injury for use with in vitro organotypic hippocampal slice cultures (OHSCs) and determined that primary blast without concomitant tertiary blast loading or systemic response can injure isolated brain samples. This work was the first to define a cell death tolerance criterion for OHSCs to primary blast and report that the threshold for deficits in neuron function was below the threshold for cell death. Mild TBI (mTBI) or concussion, by definition, results in an altered mental state that can include loss of consciousness (LOC) for less than 30 minutes, dizziness, confusion, and retrograde amnesia. These symptoms typically subside within a week after injury; however, for some patients who experience multiple concussions over a relatively short period, these symptoms can persist for a year or longer; persistence of mTBI symptoms is called post-concussion syndrome (PCS). Studies suggest an initial mechanical trauma to the brain can initiate a period of time during which the brain is more vulnerable to additional injury. Little is known about this phenomenon; therefore the current standard of care for patients suffering from concussion is rest and removal from activities with a risk of additional brain trauma. During combat deployment, over 89% of service members reported an incidence of altered mental state and over 86% reported LOC following 2 or more exposures to blast. We evaluated the response of OHSCs to repetitive primary blast (shock wave loading) and repetitive tertiary blast (stretch injury) separately, characterizing the period of vulnerability that follows an initial insult to define safe rest-periods after blast-exposure and better understand pathologies of more complex injuries, i.e. combined primary and tertiary blast. Long-term potentiation (LTP) was significantly reduced by 2 primary blast exposures delivered 24 hours apart. An initial shock wave exposure increased tissue vulnerability to subsequent exposure, which lasted as long as 72 hours but not longer than 144 hours. Repetitive primary blast exposure also increased microglial activation. Similarly, a single mild stretch injury initiated a period of heightened vulnerability to subsequent mild stretch that lasted at least 72 hours but not longer than 144 hours long. Repetitive stretch injury significantly increased cell death, nitrite concentration, and astrogliosis and significantly reduced LTP. We also tested delayed administration of memantine as a treatment for repetitive stretch injury. Memantine is approved by the Food & Drug Administration for the treatment of Alzheimer’s disease, and preclinical studies suggest memantine may be neuroprotective following TBI. Cell death was reduced and LTP was rescued by delayed memantine treatment. Along with further preclinical and clinical investigation of repetitive primary and tertiary blast exposure, these studies may aid in setting safe rest periods and identifying new therapies for service members exposed to blast. This research has shown that primary and tertiary blast exposure can injure OHSCs causing cell death, altering neuron function, and increase vulnerability to a subsequent exposure. These studies expand our understanding of the neuropathology of primary and tertiary blast loading and evaluate methods to improve outcome after repetitive injuries with complementary strategies including rest periods and drug-treatment.

Triacetone triperoxide has been synthesised for a range of experimental studies towards the reactivity, stability and gas phase metal complexation of the explosive. Reaction with transition metals was performed and a series of molten TATP experiments conducted at 120 °C. The effect of a molten state on the degradation, conformation and reactivity of TATP has been studied with the formation of diacetone diperoxide, acetone and acetic acid degradation products observed. The complexation of TATP with a range of metals has been studied by electrospray ionisation-mass spectrometry, yielding [M+Cat]+ ions for all of the alkali metals. The first observations of a [TATP+Ag]+ adduct have been made. The formation of [2TATP+Li+LiX]+ (X = Br, Cl) and [2TATP+Ag]+ sandwich complexes was also observed. Collision cross sections (CCS) for the lithium-containing complexes of TATP were measured by travelling wave ion mobility-mass spectrometry, comparing well to computationally determined structures.

Cinder Cone is the most recent cinder cone eruption in the continental United States at ~350 years old. This study examines the physical characteristics of the explosive deposit of the volcano in order to infer eruption timing, style, and mechanisms. Building on previous work and using spatial extent, field relationships, and grain size, componentry, and textural data of ten samples from one column, this study demonstrates that Cinder Cone erupted in at least two distinct phases with at least two distinct eruption styles. This speaks to the changing magma supply and transport processes occurring beneath the volcano. Curiosities about the eruption include the extensive degree of contamination that contributed abundant quartz xenocrysts to all the deposits. Future work includes determining the extent and mechanism/s of contamination and tephra component creation. These data are important for informing hazard assessments of areas with abundant cinder cone volcanoes.

No description available.

No description available.

<p>Impact waves are used in many different industries and are classified according to whether they cause plastic or elastic deformations. In the plastic deformation mode, these waves can be used to produce special electrical joints. In the elastic deformation mode, they can be used to detect leakage or to measure the thickness of pipes. Both modes have applications in offshore technology. In this thesis the application of impact waves in the plastic deformation mode and explosive welding are discussed. In the explosive welding (EXW) process a high velocity oblique impact produced by a carefully controlled explosion occurs between two or more metals. The high velocity impact causes the metals to behave like fluids temporarily and weld together. This process occurs in a short time with a high rate of energy.</p><p>EXW is a well known method for joining different metals together. It is a multidisciplinary research area and covers a wide range of science and technology areas including wave theory, fluid dynamics, materials science, manufacturing and modeling. Many of the important results in EXW research are obtained from experimentation.</p><p>This thesis is mainly based on experimental work. However, it begins with a review of the fundamental theory and mechanisms of explosive welding and the different steps of a successful welding operation. Many different EXW tests are done on horizontal and vertical surfaces with unequal surface areas, and on curved surfaces and pipes. The remainder of the thesis evaluates the results of these experiments, measures the main parameters, and shows the results of simulations to verify the experimental results. The thesis ends with a number of suggestions for improving and optimizing the EXW process. One of these improvements is a model for joining metallic plates with unequal surface areas. An Al-Cu joint based on this model is used in the ALMAHDI aluminum factory, a large company in southern Iran that produces more than 200,000 tons of aluminum per year. Improved methods are also suggested for joining curved surfaces. These methods may have extensive applications in pipelines in oil and gas industries, especially in underwater pipes.</p> / <p>Impact vågor används i många olika branscher och klassificeras enligt de deformationer de orsakat: elastiska och plastiska deformationer. I plastisk deformation mode, dessa vågor skulle kunna användas för att framställa särskild elektrisk lederna. I deformationen läge, de skulle kunna användas för att upptäcka läckage eller mäta tjockleken på rören. Båda har tillämpningar inom offshore-teknik. I denna avhandling tillämpningen av effekterna vågor i plastisk deformation mode och explosiva svetsning diskuteras. I den explosiva svetsning (EXW) process hög hastighet sned effekt som produceras av en noggrant kontrollerad explosion uppstår mellan två eller flera metaller. Den höga hastigheten effekt gör att metaller gå ihop samtidigt som beter sig som vätskor. Denna process sker i en kort tid med hög energi.</p><p>EXW är en känd metod för att gå med olika metaller tillsammans. Det är ett tvärvetenskapligt forskningsområde och omfattar ett brett spektrum av naturvetenskap och teknik, inklusive våg teori, vätskor dynamik, materialvetenskap, tillverkning och modellering. Många av de viktiga resultat i EXW forskning har erhållits från experiment.</p><p>Denna uppsats bygger främst på experimentella verk. Det kommer dock att börja med en genomgång av grundläggande teori och mekanism av explosiva svetsning och de olika stegen i en lyckad welding operation. Då många olika EXW tester göras på horisontella och vertikala ytor med icke lika ytor och på krökta ytor och ledningar. Utvärdering av resultaten, som mäter de viktigaste parametrarna, som utför vissa simuleringar för att verifiera experimentella resultat och några förslag för att förbättra och optimera EXW process utgör de andra delarna av uppsatsen. En av dessa förbättringar är en modell för att gå med metalliska plattor med icke-lika ytor. En Al-Cu gemensamt bygger på denna modell används i ALMAHDI aluminium fabrik, ett stort företag i södra Iran att produktionen är mer än 200000 ton per år. Dessutom en del andra förbättrade metoder föreslås för att gå med krökta ytor. Dessa metoder kan få omfattande tillämpningar inom olje-och gasindustrin som rörledningar, särskilt under rören.</p>

Thesis (M.Ed.)--North-West University, Potchefstroom Campus, 2008.

Impact waves are used in many different industries and are classified according to whether they cause plastic or elastic deformations. In the plastic deformation mode, these waves can be used to produce special electrical joints. In the elastic deformation mode, they can be used to detect leakage or to measure the thickness of pipes. Both modes have applications in offshore technology. In this thesis the application of impact waves in the plastic deformation mode and explosive welding are discussed. In the explosive welding (EXW) process a high velocity oblique impact produced by a carefully controlled explosion occurs between two or more metals. The high velocity impact causes the metals to behave like fluids temporarily and weld together. This process occurs in a short time with a high rate of energy. EXW is a well known method for joining different metals together. It is a multidisciplinary research area and covers a wide range of science and technology areas including wave theory, fluid dynamics, materials science, manufacturing and modeling. Many of the important results in EXW research are obtained from experimentation. This thesis is mainly based on experimental work. However, it begins with a review of the fundamental theory and mechanisms of explosive welding and the different steps of a successful welding operation. Many different EXW tests are done on horizontal and vertical surfaces with unequal surface areas, and on curved surfaces and pipes. The remainder of the thesis evaluates the results of these experiments, measures the main parameters, and shows the results of simulations to verify the experimental results. The thesis ends with a number of suggestions for improving and optimizing the EXW process. One of these improvements is a model for joining metallic plates with unequal surface areas. An Al-Cu joint based on this model is used in the ALMAHDI aluminum factory, a large company in southern Iran that produces more than 200,000 tons of aluminum per year. Improved methods are also suggested for joining curved surfaces. These methods may have extensive applications in pipelines in oil and gas industries, especially in underwater pipes. / Impact vågor används i många olika branscher och klassificeras enligt de deformationer de orsakat: elastiska och plastiska deformationer. I plastisk deformation mode, dessa vågor skulle kunna användas för att framställa särskild elektrisk lederna. I deformationen läge, de skulle kunna användas för att upptäcka läckage eller mäta tjockleken på rören. Båda har tillämpningar inom offshore-teknik. I denna avhandling tillämpningen av effekterna vågor i plastisk deformation mode och explosiva svetsning diskuteras. I den explosiva svetsning (EXW) process hög hastighet sned effekt som produceras av en noggrant kontrollerad explosion uppstår mellan två eller flera metaller. Den höga hastigheten effekt gör att metaller gå ihop samtidigt som beter sig som vätskor. Denna process sker i en kort tid med hög energi. EXW är en känd metod för att gå med olika metaller tillsammans. Det är ett tvärvetenskapligt forskningsområde och omfattar ett brett spektrum av naturvetenskap och teknik, inklusive våg teori, vätskor dynamik, materialvetenskap, tillverkning och modellering. Många av de viktiga resultat i EXW forskning har erhållits från experiment. Denna uppsats bygger främst på experimentella verk. Det kommer dock att börja med en genomgång av grundläggande teori och mekanism av explosiva svetsning och de olika stegen i en lyckad welding operation. Då många olika EXW tester göras på horisontella och vertikala ytor med icke lika ytor och på krökta ytor och ledningar. Utvärdering av resultaten, som mäter de viktigaste parametrarna, som utför vissa simuleringar för att verifiera experimentella resultat och några förslag för att förbättra och optimera EXW process utgör de andra delarna av uppsatsen. En av dessa förbättringar är en modell för att gå med metalliska plattor med icke-lika ytor. En Al-Cu gemensamt bygger på denna modell används i ALMAHDI aluminium fabrik, ett stort företag i södra Iran att produktionen är mer än 200000 ton per år. Dessutom en del andra förbättrade metoder föreslås för att gå med krökta ytor. Dessa metoder kan få omfattande tillämpningar inom olje-och gasindustrin som rörledningar, särskilt under rören.