26,256 research outputs found
Analytical study of the fracture of liquid- filled tanks impacted by hypervelocity particles
Shock waves in water and stress waves in tank walls of water-filled fuel tanks impacted by hypervelocity particle
The effects of ground hydrology on climate sensitivity to solar constant variations
The effects of two different evaporation parameterizations on the climate sensitivity to solar constant variations are investigated by using a zonally averaged climate model. The model is based on a two-level quasi-geostrophic zonally averaged annual mean model. One of the evaporation parameterizations tested is a nonlinear formulation with the Bowen ratio determined by the predicted vertical temperature and humidity gradients near the earth's surface. The other is the linear formulation with the Bowen ratio essentially determined by the prescribed linear coefficient
Real-time Spectroscopy with Sub-GHz Resolution using Amplified Dispersive Fourier Transformation
Dispersive Fourier transformation is a powerful technique in which spectral
information is mapped into the time domain using chromatic dispersion. It
replaces a spectrometer with an electronic digitizer, and enables real-time
spectroscopy. The fundamental problem in this technique is the trade-off
between the detection sensitivity and spectral resolution, a limitation set by
the digitizer's bandwidth. This predicament is caused by the power loss
associated with optical dispersion. We overcome this limitation using Raman
amplified spectrum-to-time transformation. An extraordinary loss-less -11.76
ns/nm dispersive device is used to demonstrate single-shot gas absorption
spectroscopy with 950 MHz resolution--a record in real-time spectroscopy.Comment: The following article has been accepted by Applied Physics Letter
Wave propagation in stepped and joined shells Annual report, 1 Sep. 1968 - 1 Sep. 1969
Shell impact response and wave propagation in cylindrical and conical shells by experimental and analytical method
Flow field predictions for a slab delta wing at incidence
Theoretical results are presented for the structure of the hypersonic flow field of a blunt slab delta wing at moderately high angle of attack. Special attention is devoted to the interaction between the boundary layer and the inviscid entropy layer. The results are compared with experimental data. The three-dimensional inviscid flow is computed numerically by a marching finite difference method. Attention is concentrated on the windward side of the delta wing, where detailed comparisons are made with the data for shock shape and surface pressure distributions. Surface streamlines are generated, and used in the boundary layer analysis. The three-dimensional laminar boundary layer is computed numerically using a specially-developed technique based on small cross-flow in streamline coordinates. In the rear sections of the wing the boundary layer decreases drastically in the spanwise direction, so that it is still submerged in the entropy layer at the centerline, but surpasses it near the leading edge. Predicted heat transfer distributions are compared with experimental data
Querying Geometric Figures Using a Controlled Language, Ontological Graphs and Dependency Lattices
Dynamic geometry systems (DGS) have become basic tools in many areas of
geometry as, for example, in education. Geometry Automated Theorem Provers
(GATP) are an active area of research and are considered as being basic tools
in future enhanced educational software as well as in a next generation of
mechanized mathematics assistants. Recently emerged Web repositories of
geometric knowledge, like TGTP and Intergeo, are an attempt to make the already
vast data set of geometric knowledge widely available. Considering the large
amount of geometric information already available, we face the need of a query
mechanism for descriptions of geometric constructions.
In this paper we discuss two approaches for describing geometric figures
(declarative and procedural), and present algorithms for querying geometric
figures in declaratively and procedurally described corpora, by using a DGS or
a dedicated controlled natural language for queries.Comment: 14 pages, 5 figures, accepted at CICM 201
A length-dynamic Tonks gas theory of histone isotherms
We find exact solutions to a new one-dimensional (1D) interacting particle
theory and apply the results to the adsorption and wrapping of polymers (such
as DNA) around protein particles (such as histones). Each adsorbed protein is
represented by a Tonks gas particle. The length of each particle is a degree of
freedom that represents the degree of DNA wrapping around each histone.
Thermodynamic quantities are computed as functions of wrapping energy, adsorbed
histone density, and bulk histone concentration (or chemical potential); their
experimental signatures are also discussed. Histone density is found to undergo
a two-stage adsorption process as a function of chemical potential, while the
mean coverage by high affinity proteins exhibits a maximum as a function of the
chemical potential. However, {\it fluctuations} in the coverage are
concurrently maximal. Histone-histone correlation functions are also computed
and exhibit rich two length scale behavior.Comment: 5 pp, 3 fig
Magnetic model for Ba_2Cu_3O_4Cl_2
Ba_2Cu_3O_4Cl_2 consists of two types of copper atoms, Cu(A) and Cu(B). We
study the corresponding Heisenberg model with three antiferromagnetic
couplings, J_AA, J_BB and J_AB. We find interesting frustration effects due to
the coupling J_AB.Comment: 6 pages, LaTeX, 3 eps figures, to appear in JMM
In-situ integrated processing and characterization of thin films of high temperature superconductors, dielectrics and semiconductors by MOCVD
In this strategy of depositing the basic building blocks of superconductors, semiconductors, and dielectric having common elements, researchers deposited superconducting films of Y-Ba-Cu-O, semiconductor films of Cu2O, and dielectric films of BaF2 and Y2O3 by metal oxide chemical vapor deposition (MOCVD). By switching source materials entering the chamber, and by using direct writting capability, complex device structures like three-terminal hybrid semiconductors/superconductors transistors can be fabricated. The Y-Ba-Cu-O superconducting thin films on BaF2/YSZ substrates show a T(sub c) of 80 K and are textured with most of the grains having their c-axis or a-axis perpendicular to the substrate. Electrical characteristics as well as structural characteristics of superconductors and related materials obtained by x-ray defraction, electron microscopy, and energy dispersive x-ray analysis are discussed
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