4,171 research outputs found
Expandable space frames
Expandable space frames having essentially infinite periodicity limited only by practical considerations, are described. Each expandable space frame comprises a plurality of hinge joint assemblies having arms that extend outwardly in predetermined symmetrically related directions from a central or vertex point. The outer ends of the arms form one part of a hinge point. The outer expandable space frame also comprises a plurality of struts. The outer ends of the struts from the other part of the hinged joint. The struts interconnect the plurality of hinge point in sychronism, the spaceframes can be expanded or collapsed. Three-dimensional as well as two-dimensional spaceframes of this general nature are described
A generalization of Hawking's black hole topology theorem to higher dimensions
Hawking's theorem on the topology of black holes asserts that cross sections
of the event horizon in 4-dimensional asymptotically flat stationary black hole
spacetimes obeying the dominant energy condition are topologically 2-spheres.
This conclusion extends to outer apparent horizons in spacetimes that are not
necessarily stationary. In this paper we obtain a natural generalization of
Hawking's results to higher dimensions by showing that cross sections of the
event horizon (in the stationary case) and outer apparent horizons (in the
general case) are of positive Yamabe type, i.e., admit metrics of positive
scalar curvature. This implies many well-known restrictions on the topology,
and is consistent with recent examples of five dimensional stationary black
hole spacetimes with horizon topology . The proof is inspired
by previous work of Schoen and Yau on the existence of solutions to the Jang
equation (but does not make direct use of that equation).Comment: 8 pages, latex2e, references updated, minor corrections, to appear in
Communications in Mathematical Physic
Existence, Regularity, and Properties of Generalized Apparent Horizons
We prove a conjecture of Tom Ilmanen's and Hubert Bray's regarding the
existence of the outermost generalized apparent horizon in an initial data set
and that it is outer area minimizing.Comment: 16 pages, thoroughly revised, no major changes, to appear in Comm.
Math. Phy
Defect topologies in chiral liquid crystals confined to mesoscopic channels
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 142, 194704 (2015) and may be found at https://doi.org/10.1063/1.4920979.We present Monte Carlo simulations in the grand canonical and canonical ensembles of a chiral liquid crystal confined to mesochannels of variable sizes and geometries. The mesochannels are taken to be quasi-infinite in one dimension but finite in the two other directions. Under thermodynamic conditions chosen and for a selected value of the chirality coupling constant, the bulk liquid crystal exhibits structural characteristics of a blue phase II. This is established through the tetrahedral symmetry of disclination lines and the characteristic simple-cubic arrangement of double-twist helices formed by the liquid-crystal molecules along all three axes of a Cartesian coordinate system. If the blue phase II is then exposed to confinement, the interplay between its helical structure, various anchoring conditions at the walls of the mesochannels, and the shape of the mesochannels gives rise to a broad variety of novel, qualitative disclination-line structures that are reported here for the first time.DFG, 65143814, GRK 1524: Self-Assembled Soft-Matter Nanostructures at Interface
Utilization requirements. A southern California Gas Company project SAGE report: Utilization requirements
Utilization requirements are given and comparisons made of two phase III SAGE (solar assisted gas energy) installations in California: (1) a retrofit installation in an existing apartment building in El Toro, and (2) an installation in a new apartment building in Upland. Such testing in the field revealed the requirements to be met if SAGE-type installations are to become commercially practical on a widespread basis in electric and gas energy usage
Use of the STAR PROCESS for Children with Sensory Processing Challenges
Background: This study examined the effectiveness of the STAR PROCESS, an intensive, short-term intervention that combines principles of sensory integration, relationship-based therapy, and parental-therapist collaboration for children with sensory processing challenges.
Method: A nonconcurrent multiple baseline, repeated measures design was used. Four boys, aged 5 years 0 months to 7 years 9 months, participated in this study. The mean length of intervention was 22 sessions delivered 3 to 5 times per week. A behavioral coding system was used to measure change in four areas: play level, positive affect, joint attention, and novel use of equipment. The theory of change reflects the use of multisensory experiences in combination with parent participation to impact outcomes.
Results: Improvement was noted in play level in all of the participants. Multisensory experiences and parent participation were associated with these changes in two participants.
Discussion: The study results suggest a feasible methodology to study occupational therapy interventions. The behavioral coding system was sensitive to change. Play abilities changed in all four children. Preliminary support was provided for the theory of change combining multisensory experiences with parent participation.
Conclusion: A targeted treatment approach that emphasizes parents as play partners in a multisensory environment shows promise in remediating these deficits
Multilayer approximation for a confined fluid in a slit pore
A simple Lennard-Jones fluid confined in a slit nanopore with hard walls is
studied on the basis of a multilayer structured model. Each layer is
homogeneous and parallel to the walls of the pore. The Helmholtz energy of this
system is constructed following van der Waals-like approximations, with the
advantage that the model geometry permits to obtain analytical expressions for
the integrals involved. Being the multilayer system in thermodynamic
equilibrium, a system of non-linear equations is obtained for the densities and
widths of the layers. A numerical solution of the equations gives the density
profile and the longitudinal pressures. The results are compared with Monte
Carlo simulations and with experimental data for Nitrogen, showing very good
agreement.Comment: 6 pages, 5 figures
Expandable space frames
Frame consists of struts connected by hinge joint assemblies. Because struts are hinged, entire frame can be collapsed during transportation and expanded at construction site. Frame has two types of hinge joint assemblies; one for three-dimensional space frame expansion and another for two-dimensional expansion
VASCOMP 2. The V/STOL aircraft sizing and performance computer program. Volume 6: User's manual, revision 3
This report describes the use of the V/STOL Aircraft Sizing and Performance Computer Program (VASCOMP II). The program is useful in performing aircraft parametric studies in a quick and cost efficient manner. Problem formulation and data development were performed by the Boeing Vertol Company and reflects the present preliminary design technology. The computer program, written in FORTRAN IV, has a broad range of input parameters, to enable investigation of a wide variety of aircraft. User oriented features of the program include minimized input requirements, diagnostic capabilities, and various options for program flexibility
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