Tilt, Warp, and Simultaneous Precessions in Disks

Warps are suspected in disks around massive compact objects. However, the proposed warping source -- non-axisymmetric radiation pressure -- does not apply to white dwarfs. In this letter we report the first Smoothed Particle Hydrodynamic simulations of accretion disks in SU UMa-type systems that naturally tilt, warp, and simultaneously precess in the prograde and retrograde directions using white dwarf V344 Lyrae in the Kepler field as our model. After ~79 days in V344 Lyrae, the disk angular momentum L_d becomes misaligned to the orbital angular momentum L_o. As the gas stream remains normal to L_o, hydrodynamics (e.g., the lift force) is a likely source to disk tilt. In addition to tilt, the outer disk annuli cyclically change shape from circular to highly eccentric due to tidal torques by the secondary star. The effect of simultaneous prograde and retrograde precession is a warp of the colder, denser midplane as seen along the disk rim. The simulated rate of apsidal advance to nodal regression per orbit nearly matches the observed ratio in V344 Lyrae.Comment: 3 figures, Lette

Mississippi Test Facility research projects

Research capabilities of Louisiana State University are reported for sustaining a program which complements the Mississippi Test Facility. Projects reported during this period are discussed and include the development of a spectral analyzer, and investigations of plant physiology. Papers published during this period are also listed

Facility research capabilities at Louisiana State University

Efforts of LSU are reported to develop research capabilities for supporting the NASA Mississippi Test Facility. Research activities reported include remote sensing technology and salt water encroachment

Interpretation of remote sensing data in the Bayou LaFourche delta of south Louisiana

There are no author-identified significant results in this report

The Harlem Children's Zone, Promise Neighborhoods, and the Broader, Bolder Approach to Education

Examines the role of community services in raising academic achievement in the Harlem Children's Zone. Questions the effectiveness of replicating the neighborhood approach, rather than the schools-only approach, in the Promise Neighborhoods Initiative

Pseudacris clarkii

Number of Pages: 3Integrative BiologyGeological Science

The design and construction of a Hohlraum spectral analyzer

Design and construction of Hohlraum spectral analyzer to aid in research of air pollutant

Formal verification of AI software

The application of formal verification techniques to Artificial Intelligence (AI) software, particularly expert systems, is investigated. Constraint satisfaction and model inversion are identified as two formal specification paradigms for different classes of expert systems. A formal definition of consistency is developed, and the notion of approximate semantics is introduced. Examples are given of how these ideas can be applied in both declarative and imperative forms

A study of the thermal conductance of bolted joints Final report

Design-oriented approach for predicting thermal resistance of bolted lap joint including bibliograph