MEMS lifetime test setup
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According to international relations theory, deterrence can be used as a tool to achieve stability between potentially hostile nations. India and Pakistan's long history of periodic crises raises the question of how they can achieve deterrence stability. 'Transparency' describes the flow of information between parties and plays a key role in establishing a deterrence relationship. This paper studies the balance needed between opacity and transparency in nuclear topics for the maintenance of deterrence stability between India and Pakistan. States with nuclear weapons are postulated to implement transparency in four categories: potential, capability, intent, and resolve. The study applies these categories to the nuclear components of the ongoing India-Pakistan Composite Dialogue Working Group for Peace and Security including CBMs. To focus our efforts, we defined four scenarios to characterize representative strategic/military/political conditions. The scenarios are combinations of these two sets of opposite poles: competition - cooperation; extremism - moderation (to be understood primarily in a religious/nationalistic sense). We describe each scenario in terms of select focal areas (nuclear doctrine, nuclear command and control, nuclear stockpile, nuclear delivery/defensive systems, and conventional force posture). The scenarios help frame the realm of possibilities, and have been described in terms of expected conditions for the focal areas. We then use the conditions in each scenario to prescribe a range of information-sharing actions that the two countries could take to increase stability. We also highlight the information that should not be shared. These actions can be political (e.g., declarations), procedural (e.g., advance notice of certain military activities), or technologically based (e.g., seismic monitoring of the nuclear test moratorium).
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Assessing the risk of malevolent attacks against large-scale critical infrastructures requires modifications to existing methodologies. Existing risk assessment methodologies consider physical security and cyber security separately. As such, they do not accurately model attacks that involve defeating both physical protection and cyber protection elements (e.g., hackers turning off alarm systems prior to forced entry). This paper presents a risk assessment methodology that accounts for both physical and cyber security. It also preserves the traditional security paradigm of detect, delay and respond, while accounting for the possibility that a facility may be able to recover from or mitigate the results of a successful attack before serious consequences occur. The methodology provides a means for ranking those assets most at risk from malevolent attacks. Because the methodology is automated the analyst can also play 'what if with mitigation measures to gain a better understanding of how to best expend resources towards securing the facilities. It is simple enough to be applied to large infrastructure facilities without developing highly complicated models. Finally, it is applicable to facilities with extensive security as well as those that are less well-protected.
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Over the next decade a significant amount of exploration and new field developments will take place in salt provinces around the world - in the deepwater Gulf of Mexico, and offshore Angola, Brazil, and North and West Africa. Salt formations provide both opportunities and challenges to the design and construction of the often complex wells to be drilled in these locations. An overview of the many geomechanical considerations necessary to ensure successful well construction when drilling in through-, sub- and near-salt environments is presented. The structural styles of deformed sediments adjacent to salt, combined with stress perturbations caused by the presence of salt, are used to assess the risk of encountering zones that might cause wellbore instability or lost-circulation problems. Well design examples are provided that show how near- and through-salt uncertainties may be included within a geomechanical well design for required mud weights while drilling. Salt is found in many hydrocarbon basins around the world. Significant deposits exist in the Gulf of Mexico (GoM), offshore West Africa and Brazil, in the Southern North Sea, Egypt, and the Middle East (Figure 1[1]). In deep water offshore North America, the GoM and offshore Nova Scotia (NE Canada) are notable areas of current oil and gas exploration and production. Significant exploration activity is also targeting areas offshore Angola and Brazil. The extent of deepwater exploration in the GoM is illustrated in Figure 2 that shows the steady march into deeper water, together with a focusing of efforts in the Sigsbee Escarpment areas of Green Canyon, Walker Ridge and Atwater Valley. The deepest wells in the GoM are reaching true vertical depths of up to 32,000 feet, with maximum-recorded downhole pressures in excess of 26,000 psi and bottomhole temperatures in excess of 400 F. Such wells may penetrate considerable thicknesses of salt - up to 20,000 feet of salt is not unheard of. With substantial discoveries and yet-to-find hydrocarbons being overlaid by salt, the impact of this 'mobile' formation on the entrapment of hydrocarbons has received much attention[2]. From a drilling and well integrity standpoint, however, the abundance of salt presents new and significant challenges of a geomechanical nature. Opportunities exist also, as the thick salt sections oftentimes permit the drilling of these deep wells in the first place. During the past five years, the industry has developed a more thorough understanding of salt-related risks. This paper draws upon many of these recent advances to formulate in detail the necessary geomechanical considerations for the successful design of through- and near-salt wells.
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Proposed for publication in Small.
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Proposed for publication in the Journal of Sound and Vibration.
The dynamic response of a thermal data capture unit is calculated for a given missile flight test environment. Power spectral densities calculated from the analytical model were compared with the experimental results. Maximum peak displacements were used to calculate clearances required during the installation phase of system assembly.
Proposed for publication in the Journal of Thermal Spray Technology.
Cold spray, a new member of the thermal spray process family, can be used to prepare dense, thick metal coatings. It has tremendous potential as a spray-forming process. However, it is well known that significant cold work occurs during the cold spray deposition process. This cold work results in hard coatings but relatively brittle bulk deposits. This work investigates the mechanical properties of cold-sprayed aluminum and the effect of annealing on those properties. Cold spray coatings approximately 1 cm thick were prepared using three different feedstock powders: Valimet H-10: Valimet H-20: and Brodmann Flomaster. ASTM E8 tensile specimens were machined from these coatings and tested using standard tensile testing procedures. Each material was tested in two conditions: as-sprayed; and after a 300 C, 22h air anneal. The as-sprayed material showed high ultimate strength and low ductility, with <1% elongation. The annealed samples showed a reduction in ultimate strength but a dramatic increase in ductility, with up to 10% elongation. The annealed samples exhibited mechanical properties that were similar to those of wrought 1100 H14 aluminum. Microstructural examination and fractography clearly showed a change in fracture mechanism between the as-sprayed and annealed materials. These results indicate good potential for cold spray as a bulkforming process.
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Proposed for publication in the International Social Sciences Journal.
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Proposed for publication in the Journal of Solar Energy Engineering.
With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5-9 m), both modern and early designs, the flutter speeds are in the range of 3.5-6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.
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The feasibility of laser welding of fused silica (aka quartz) has been demonstrated recently by others. An application requiring hermetic sealing of a thin, pressure-bearing quartz diaphragm to a thicker frame led us to explore this technique. We found that laser welding techniques normally used for metallic parts caused scorching and uneven melting. Contrary to standard practices (near focus, high travel speed, high power density), successful welds in fused silica required a broad heat source applied over a large area under a slow rotation to gradually heat the glass through the annealing, softening and finally working temperatures. Furthermore, good mechanical contact between the parts to be joined played an even more important role in this process than in typical metallic joints. A 50 W CO2 laser with 4 f.l. ZnSe2 lens and rotary head was used to weld 0.425 OD, 0.006-0.010 thick, disks to 0.500 OD tubing with 0.125 walls. Several joint geometries and beam orientations were investigated. Temperature profiles were measured and compared to an FEM thermal model. We will discuss the effects of laser power, travel speed, number of passes, joint geometry and part thicknesses on achieving hermeticity and cosmetically-acceptable joints.
This perspective of terrorist enemies as networks by two distinguished associate fellows of the Joint Special Operations University (JSOU) follows as a result of its recent initiative to support USSOCOM strategic planning for the Global War on Terrorism. The paper is a manifestation of JSOU's goals for contributing products that will advance SOF strategic art and generating strategic outreach to the military, civilian, and academic communities to enrich those products. Dr. Robert Spulak and Dr. Jessica Glicken Turnley presented the findings of this paper to assembled strategic planners from USSOCOM, other combatant commands, and interagency players at the Center for Special Operations plan development conference, September 2005, in Tampa, Florida. At that meeting, the authors put forward a number of helpful planning concepts based on their professional studies in science and the humanities and their experiences in government and business. The JSOU Strategic Studies Department is pleased to facilitate the association of USSOCOM strategic planners with civilian expertise and insights that can broaden military thought and encourage planning decisions directly relevant to the changing global environment. Through JSOU's strategic outreach initiative, experts in many professional disciplines have signaled their willingness to support the Nation's counterterrorism efforts. In that spirit, JSOU is proud to commend this paper to SOF readers and appreciates the support of Dr. Spulak and Dr. Turnley.