13 research outputs found
Characterization of cryogenic direct-drive ICF targets during layering studies and just prior to shot time
The characterization of OMEGA cryogenic targets is based
on shadowgraphs obtained from multiple angular views taken with the target
in the layering sphere. The D ice has been observed to
re-layer during slow rotations, leading to procedural changes that avoid
re-layering thus ensuring high-quality, spherical-harmonic, 3-D ice layer
reconstructions. Shadowgrams taken inside the target chamber within 20 ms of
shot time have verified that the ice layers remain preserved during the
transport
Progress in direct-drive inertial confinement fusion research at the laboratory for laser energetics
Direct-drive inertial confinement fusion (ICF) is
expected to demonstrate high gain on the National Ignition Facility (NIF) in
the next decade and is a leading candidate for inertial fusion energy
production. The demonstration of high areal densities in hydrodynamically
scaled cryogenic DT or D implosions with neutron yields that are a
significant fraction of the âcleanâ 1-D predictions will validate the
ignition-equivalent direct-drive target performance on the OMEGA laser at
the Laboratory for Laser Energetics (LLE). This paper highlights some
of the recent experimental and theoretical progress toward this validation.â©The NIF will initially be configured for x-ray drive and with no beams
placed at the target equator to provide a symmetric irradiation of a
direct-drive capsule. LLE is developing the âpolar-direct-driveâ (PDD)
approach that repoints beams toward the target equator. Initial 2-D
simulations have shown ignition. â©LLE is currently constructing the multibeam, 2.6-kJ/beam, petawatt laser
system OMEGA EP. Integrated fast-ignition experiments, combining the OMEGA
EP and OMEGA laser systems, will begin in FY08
The Use of Base Rate Information as a Function of Experienced Consistency
Three experiments examine the effect of base rate consistency under direct experience. Base rate consistency was manipulated by blocking trials and setting base rate choice reinforcement to be either consistent or inconsistent across trial blocks. Experiment 1 shows that, contrary to the usual finding, participants use base rate information more than individuating information when it is consistent, but less when it is inconsistent. In Experiment 2, this effect was replicated, and transferred in verbal questions posed subsequently. Despite experience with consistent base rates increasing sensitivity to base rates in word problems, verbal responses were far from normative. In Experiment 3, participantsâ use of base rates was once again moderated by its consistency, but this effect was itself moderated by the diagnosticity of base rate information. Participants were highly accurate in estimating experienced base rates. These studies demonstrate that base rate usage is complex and a function of how base rates are presented (experienced versus summary statistics) and response format (choice proportions versus probability estimates). Knowledge of base rates was insufficient for proper usage in verbal word problems. Although choice proportions showed a sophisticated sensitivity to experienced base rate information, participants seemed unable to demonstrate a similar sophistication when given typical word problems indicating that base rate neglect is a function of information representation and not an inherent processing bias. Copyright Springer 2005base rate neglect, decision making, learning, choice, direct experience, diagnosticity,
Progress in direct-drive inertial confinement fusion
Significant progress has been made in direct-drive inertial confinement fusion research at the Laboratory for Laser Energetics since the 2009 IFSA Conference [R.L. McCrory et al., J. Phys.: Conf. Ser. 244, 012004 (2010)]. Areal densities of 300mg/cm2 have been measured in cryogenic target implosions with neutron yields 15% of 1-D predictions. A model of crossed-beam energy transfer has been developed to explain the observed scattered-light spectrum and laserâtarget coupling. Experiments show that its impact can be mitigated by changing the ratio of the laser beam to target diameter. Progress continues in the development of the polar-drive concept that will allow direct-driveâignition experiments to be conducted on the National Ignition Facility using the indirect-drive-beam layout
A Comprehensive Review Of The Tourism Forecasting Literature
Major Reports of Tourism Forecasting Studies Are Classified by Forecasting Method Employed, Reviewed, Compared, and Critiqued. a Partial Meta-Analysis is Used to Attempt to Gauge Relative Accuracy of the Various Approaches Used in Differing Situations. Summary Statements on the Relative Usefulness of the Different Methods in Specific Forecasting Situations Are Provided. Some Conclusions Are Drawn to Aid Future Conduct and Reporting of Tourism Forecasting Reports. -Author
Shock wave physics and detonation physics â a stimulus for the emergence of numerous new branches in science and engineering
In the period of the Cold War (1945â1991), Shock Wave Physics and Detonation Physics
(SWP&DP) â until the beginning of WWII mostly confined to gas dynamics, high-speed
aerodynamics, and military technology (such as aero- and terminal ballistics, armor
construction, chemical explosions, supersonic gun, and other firearms developments) â
quickly developed into a large interdisciplinary field by its own. This rapid expansion
was driven by an enormous financial support and two efficient feedbacks: the
Terminal Ballistic Cycle and the Research &
Development Cycle. Basic knowledge in SWP&DP, initially gained
in the Classic Period (from 1808) and further extended in the
Post-Classic Period (from the 1930s to present), is now increasingly
used also in other branches of Science and Engineering (S&E). However, also
independent S&E branches developed, based upon the fundamentals of SWP&DP,
many of those developments will be addressed (see Tab. 2). Thus, shock wave and detonation
phenomena are now studied within an enormous range of dimensions, covering microscopic,
macroscopic, and cosmic dimensions as well as enormous time spans ranging from
nano-/picosecond shock durations (such as produced by ultra-short laser pulses) to shock
durations that continue for centuries (such as blast waves emitted from ancient supernova
explosions). This paper reviews these developments from a historical perspective