Quick-closing valve is actuated by explosive discharge

Remotely controlled plug-type valve shuts off a high-pressure, high-temperature gas flow in a few milliseconds. The valve is actuated by a commercially available electrically initiated squib of low explosive power. More rapid closure is attainable with squibs containing heavier explosive changes

Asymmetric Power Among Agents and the Generation and Maintenance of Cooperation in International Relations

The question addressed in this analysis is whether endowing agents with various forms of asymmetric power makes cooperation more likely across a variety of structural settings of conflict and cooperation present in international relations. To address this question, an agent-based model incorporating asymmetric power among agents in a set of (2 Â 2) games that represent different forms of conflict and cooperation prevalent in international relations (Chicken, Stag, Assurance, Deadlock, and Prisoner's Dilemma) is developed and analyzed via simulation. Simulation results indicate that the introduction of asymmetric power substantially increases the chances that both cooperative agents survive and cooperative worlds evolve. This is particularly the case when agents are endowed with the ability to selectively interact with other agents. Also, anticipated variations in outcomes across the game structures regarding the likelihood of cooperation are supported. Whether and how cooperation evolves in social settings characterized by the presence of selfish agents engaged in repeated relations without central authority has been of considerable importance to scholars of international politics and of interest to scholars across all the social sciences as well as philosophy, biology, and computer science. 1 International relations scholars have been particularly interested in various features of nation-states, the relations among nation-states, and the structural environment in which nation-states are embedded that make cooperation either possible or more likely. Studying the evolution of cooperation in the context of the Repeated Prisoner's Dilemma (RPD) has proven to be quite fruitful for international relations scholars. Yet, the RPD framework is also restrictive in a variety of ways. 3 For instance, while the RPD captures one important type of relationship among nation-states in the international system, there are a number of other structural settings that (1984), the Repeated Prisoner's Dilemma (RPD) has become the central metaphor for the evolution of cooperation in populations of selfish agents without central authority

Mode conversion studies in TFTR

Mode converted Ion Bernstein Waves (IBW) have important potential applications in tokamak reactors. These applications include on or off axis electron heating and current drive and the channeling of alpha particle power for both current drive and increased reactivity. Efficient mode conversion electron heating with a low field side antenna, with both on and off axis power deposition, has been demonstrated for the first time in TFTR in D{sup 3}He-{sup 4}He plasmas. Up to 80% of the Ion Cyclotron Range of Frequency (ICRF) power is coupled to electrons at the mode conversion surface. Experiments during deuterium and tritium neutral beam injection (NBI) indicate that good mode conversion efficiency can be maintained during NBI if sufficient {sup 3}He is present. No evidence of strong alpha particle heating by the IBW is seen. Recent modeling indicates that if the mode converted IBW is preferentially excited off the horizontal midplane then the resultant high poloidal mode number wave may channel alpha particle power to either electrons or ions. In TFTR both the propagation of the IBW and its effect on the alpha particle population is being investigated. Experiments with 2 MW of ICRF power launched with {+-} 90{degree} antenna phasing for current drive show that electron heating and sawtooth activity depend strongly on the direction of the launched wave. The noninductively driven current could not be experimentally determined in these relatively high plasma current, short pulse discharges. Experiments at higher RF power and lower plasma current are planned to determine on and off axis current drive efficiency

Recent results from the TFTR ICRF DT Program

The first experiments to be performed with ICRF heating of DT plasmas are reported. ICRF heating of minority ions, tritium (second harmonic resonance), as well as direct electron heating are being performed during the DT phase of TFTR. RF power modulation and Fourier transform techniques are used to attempt to elucidate the competition between tritium second harmonic, direct electron, and {sup 3}He fundamental heating in DT plasmas. A significant fraction of the RF power has been found to couple to the tritium ions via second harmonic heating. Relevant RF coupling physics is investigated using {sup 3}He minority heating (43 MHz), H minority heating (64 MHz), and mode conversion (43 MHz, comparable densities of {sup 3}He and {sup 4}He) at a toroidal field of 4.5T

Military spending and economic growth in China: a regime-switching analysis

This article has been made available through the Brunel Open Access Publishing Fund.This article investigates the impact of military spending changes on economic growth in China over the period 1953 to 2010. Using two-state Markov-switching specifications, the results suggest that the relationship between military spending changes and economic growth is state dependent. Specifically, the results show that military spending changes affect the economic growth negatively during a slower growth-higher variance state, while positively within a faster growth-lower variance one. It is also demonstrated that military spending changes contain information about the growth transition probabilities. As a policy tool, the results indicate that increases in military spending can be detrimental to growth during slower growth-higher growth volatility periods. © 2014 © 2014 The Author(s). Published by Taylor & Francis

High-harmonic fast wave heating experiments in CDX-U

One of the primary objectives of the proposed National Spherical Tokamak Experiment (NSTX) is the investigation of very high {beta} regimes. Consequently, finding efficient methods of non-inductive heating and current drive required to heat and sustain such plasmas is of considerable importance. High-frequency fast waves are a promising candidate in this regard. However, in NSTX, the field-line pitch at the outer midplane will range from 0 up to 60 degrees from plasma start-up to current flattop. Thus, antenna strap orientation with respect to the edge magnetic field may have a serious impact on power coupling and absorption. To address this issue, the vacuum vessel of the Current Drive Experiment -- Upgrade (CDX-U) spherical tokamak has been upgraded to accommodate a rotatable two-strap antenna capable of handling several hundred kilowatts in short pulses. Details of the antenna design and results from loading measurements made as a function of power, strap angle, and strap phasing will be presented. Results from microwave scattering experiments will also be discussed

Low activity blankets for experimental power reactors

Results of current studies aimed at the development of low activity blankets for Tokamak experimental power reactors are presented. First wall loadings in the range of 0.5 to 1.0 MW(th)/m$sup 2$ have been assumed. Blanket designs are developed for both circular plasma reactors (R = 6.25m, a = 2.1m) and non-circular plasma reactors (R = 4.0m, a = 1.0m, b = 3.0m). For each of these two reactor choices, two blanket options are described. 1) In the first option, the blanket is thick graphite block structure (approximately 50cm thickness) with SAP coolant tubes carrying helium imbedded deep within the graphite to minimize radiation damage. The neutron and gamma energy deposited in the graphite is radiated along internal slots to the coolant tubes where approximately 80 percent of the fusion energy is carried off by He at 380$sup 0$C. The remaining 20 percent of the fusion energy is removed by a separate He stream at a slightly lower temperature. The maximum graphite surface temperature is relatively low (approximately 1700$sup 0$C at 1 MW(th)/m2). 2) In the second blanket option, the blanket is composed of aluminum modules. The aluminum shell (5000 series alloy) is maintained at a low temperature (approximately 200$sup 0$C) by a water coolant stream. Approximately 40 percent of the fusion energy is removed in this circuit. The remaining 60 percent of the fusion energy is deposited in a thermally insulated hot interior (SiC and B$sub 4$C) where it is transferred to a separate He coolant, with exit temperature of 700$sup 0$C. (auth