Three-dimensional Character Research Articles

Origin of the improved cycling capability of sol-gel prepared Fe 0.12V 2O 5.16 compared with V 2O 5

A new vanadium iron oxide has been synthesized starting from V 2O 5 xerogel through an exchange reaction. In its Rietveld-determined structure, (FeO 6) apex sharing octahedra link V 2O 5 ribbons and increase the three-dimensional character of the material. This latter point seems to improve the electrochemical behaviour when compared with V 2O 5. Especially, in terms of cycle life, a capacity of 210 Ah/kg is maintained after 40 cycles in the potential window of 3.8-2 V instead of 150 Ah/kg for V 2O 5.

Subsonic drag reduction of the Space Shuttle Orbiter

Various near-wake flow-modifying devices were experimentally evaluated for their effectiveness in increasing base pressure of the Space Shuttle Orbiter at low subsonic speed. The results confirmed the strong three-dimensional character of the Orbiter near wake. A base cavity was found to be the most effective mechanism for increasing base pressure. However, for this mechanism to be effective, the cavity had to be longer than the main engine nozzles. Surface characteristics of the base cavity exposed to freestream had a strong influence on the base pressure. The trapped-vortex mechanism due to a back step was found to be effective in increasing the base pressure only in the region of the orbital-maneuvering-system pods. A combination of base-cavity and trapped-vortex mechanisms increased the base pressure by 25%, and the reduction in total drag was approximately 6%.

Calculation of laminar orthotropic plates in the three-dimensional statement

Increased use of composite materials in engineering has resulted in the need to design laminar structures with a significant gradient of physicomechanical characteristics from layer to layer. The layers may be distinguished by a clearly expressed orthotropy. The operating mode of these structures is three-dimensional. References are devoted to the three-dimensional design of laminar plates in an exact three-dimensional statement. The approaches to solution of these problems, which are presented in these studies, however, may be used for a comparatively narrow class of problems. Two-dimensional models of plates and shells, which reflect the three-dimensional character of the structure`s behavior, have been developed. Their drawback, which significantly complicates implementation, is the existence of derivatives of load in the system of differential equations.

Dimensionality crossovers of the sigma plasmon in coaxial carbon nanotubes.

Dimensionality crossovers of plasmons in carbon nanotubes, modeled as curved layered electron-gas superstructures, are investigated. For small wave vectors, the \ensuremath{\sigma} plasmons exhibit a transition from a one- to a three-dimensional character as the number of graphitic shells increases, in correspondence with recent experiments. For large wave vectors, plasmons of two-dimensional character are predicted.

New ideas on the Kenya rift based on the inversion of the combined dataset of the 1985 and 1989/90 seismic tomography experiments

A tomographic image of the P-velocity structure beneath the central part of the Kenya rift has been obtained from the inversion of the combined data sets of the 1985 and 1989/90 teleseismic experiments. This investigation confirms the three-dimensional character of this rift structure. In the uppermost mantle a steep-sided low-velocity body indicates the presence of partial melt. The maximum anomaly is located where the NW-SE-trending Aswa suture zone of Proterozoic age crosses the N-S-oriented Miocene rift in the area of the Kenya Dome. It is suggested that the development of the rift in this area is controlled by two factors: (1) the old NW-SE-trending Aswa shear zone and (2) a narrow wedge of asthenosphere beneath the rift in the area of the Kenya Dome, which is a clear indication of upper mantle dynamics due to asthenospheric upwelling and which is, at least partially, the driving force of the rift's formation.

Three-dimensional seepage in the cores of rock-and-earth-fill dams

1. Consideration of the three-dimensional character of seepage flow in the region of shore abutments in rock-and-earth-fill dams exerts a major influence on the basic seepage parameters required for the design of the core profile, the gradation of soils in reciprocal filters of transitional layers, etc. 2. The three-dimensional character of the flow exerts the most significant influence on the value of Jdis, especially along the line of contact between the lower face of the core and the shore slope Jdis.S. In that case, the steeper the slope, the greater amount the values of the discharge gradients are lowered. 3. With three-dimensional seepage, increased Jdis values arise in the core primarily along the water line of the lower pool and the line of contact between the lower face and horizontal underflooded sections; it is precisely in this connection that special protection should be specified. 4. In evaluating the seepage resistance of the core soil for contact overflow, it is recommended to use the component of the gradient Jdis normal to the plane of the downstream face Jn.n as the computed discharge pressure gradient. 5. Computational relationships for determination of parameters of three-dimensional seepage, which are required for engineering calculations of the cores of rock-and-earth-fill dams are proposed in the paper. Computational methods based on plane seepage yield significant errors in a number of cases, and should therefore be used with certain caution, even in preliminary stages of design.

A normal sensor hot-wire/film probe method for the analysis of three-dimensional flows

The resolution of the three-dimensional character of flows using hot-wire/film techniques can be achieved using either single or multiple sensors. This paper introduces a rotational technique employing normal straight-sensor probes particularly suitable for three-dimensional laminar or turbulent flows. The technique is based on the linearized constant-temperature anemometer signal in the case of isothermal flows and the corrected linearized signal in flows involving heat transfer. The method has been tested in the isothermal flow field of a round jet discharging to a cross flow in a water channel.

On the two- and three-dimensional character of the absorption spectra of Si/Ge superlattices

The optical properties of some strained symmetrized Si n /Ge n superlattices were studied. In particular the contribution of each direct transition to the absorption spectra and their two- or three-dimensional character is investigated. To achieve this we decomposed each contribution into the density of available superlattice states and the transition probability. It is found that the transition probability is as important is determining the absorption spectra as the density of available states. Furthermore, the signature of direct transitions from the Z point of the superlattice Brillouin zone is predicted to be presented by a structure in the absorption spectra at energies higher than about 0.3 eV above the absorption onset for the case of the Si 5/Ge 5 strained symmetrized superlattice. The possibility arises that transitions from the Z point of the superlattice Brillouin zone can be detected experimentally.

Possibility of Charge Density Wave Instability in the Barium Tungsten Bronze Ba0.15WO3

The electronic band structure of the Ba[sub 0.15]WO[sub 3] phase was calculated by employing the extended Hueckel tight-binding method, and the nature of the partially filled bands was analyzed. Ba[sub 0.15]WO[sub 3] has partially filled bands of one-dimensional (1D) as well as three-dimensional (3D) character. Consequently, Ba[sub 0.15]WO[sub 3] may exhibit a charge density wave (CDW) instability due to the 1D bands but may remain metallic, even after a predicted CDW, because of the 3D band.

Superconductivity in A3C60

Abstract This paper reviews the experimental aspects of superconductivity in alkali-intercalated C 60 . The roles of lattice size, orientational disorder, and three-dimensional character of the C 60 molecule in determining the high superconducting transition temperature are discussed. At present, the majority of experimental results can be accounted for within a traditional, moderate coupling, phonon-mediated pairing formalism. The evidence for strong correlations is briefly discussed.

Raman-scattering study of R2CuO4 (R=Pr, Nd, Sm, and Gd).

For ${\mathrm{Gd}}_{2}$${\mathrm{CuO}}_{4}$, a symmetry-forbidden phonon for the tetragonal T' structure is observed. This shows that oxygen in the ${\mathrm{CuO}}_{2}$ plane is locally distorted along the plane. Such distortion has not been observed for other T'-type superconductors. The normal-mode calculation shows that the correlation between the ${\mathrm{CuO}}_{2}$ plane and R-O layers increases with decreasing ionic radius. The increased three-dimensional character and the appearance of the distortion of O in the ${\mathrm{CuO}}_{2}$ plane along the a axis are useful experimental results that help clarify the mechanism that causes the disappearance of superconductivity for Gd.

Analysis of rolling contact spall life in 440C bearing steel

This paper describes calculations and measurements aimed at resolving and analysing the nucleation and growth components of the near-surface mode of rolling contact failure of 440C steel. Preliminary results of two-body, finite element calculations of repeated rolling contact with a dent in the running surface are described. Measurements of the nucleation and growth components of the life are derived from observations of cracks nucleated at small dents. The three-dimensional character of the spalls is examined. Calculations of the fracture mechanics driving force for surface breaking cracks are reviewed and compared with the measurements. The agreements provide support for the view that surface irregularities and the hydrostatic pressure of fluid in the crack cavity play a role in the nucleation and growth of the spall and that there is a threshold contact pressure for spall growth.

Syntheses, thermal behaviour, and spectroscopic and x-ray studies of quinolinium salts of nickel(II), palladium(II) and platinum(II), 1,2-dithiooxalato- S, S′ complexes. Packing and bonding of the quinolinium bis(1,2-dithiooxalato- S, S′)nickelate(II)

Three quinolinium (HC 9H 7N = Hquin) salts of planar inorganic dithiooxalato complexes: (Hquin) 2[Ni(S 2C 2O 2) 2] ( 1, (Hquin) 2[Pd(S 2C 2O 2) 2] ( 2) and (Hquin) 2[Pt(S 2C 2O 2) 2] ( 3) were synthesized and characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray diffraction techniques. Spectroscopic data support the presence of the aromatic cation and the complex anion. The complexes show a high thermal stability and the thermal studies give evidence that the onset temperatures of their thermal decompositions, the corresponding reaction mechanism and the final solid products are strongly influenced by the atmospheric conditions, as well as the chemical and structural features of the starting compounds. X-ray diffraction analyses show that 2 and 3 are isomorphous with 1, which crystallizes in the monoclinic space group P2 1/ n with Z = 2 so that the anion straddles a crystallographic centre of symmetry. The crystal structure of 1 is built up by layers of quasi-planar [Ni(S 2C 2O 2) 2] 2− complexes (A) and quinolinium cations (C) stacked along the c-axis, following an ⋯ACCACC ⋯ sequence, with alternative interplanar spacings of 3.3–3.8 Å (A ⋯ C) and 3.44 Å (C ⋯ C), which suggest the existence of significant π-π and d z 2 -π interactions between the cations and the complexes' anions. These interactions, together with the electrostatic forces and an extensive network of hydrogen contacts, ensure the lattice cohesion and give the compound a three-dimensional character.

Structural, dynamical, and electronic properties ofCaCuO2

The scalar relativistic version of an accurate first-principles full-potential self-consistent linearized muffin-tin-orbital (LMTO) method has been employed for describing the physical properties of the parent system of the high-${\mathit{T}}_{\mathit{c}}$ oxide superconductors, i.e., ${\mathrm{CaCuO}}_{2}$. The presently employed modified version of the LMTO method is quite fast and extends the usual LMTO-ASA (atomic-sphere approximation) method in the sense that it permits a completely general shape of the potential and the charge density and is also capable of treating distorted lattice structures accurately. The calculated values of the lattice parameters of pure ${\mathrm{CaCuO}}_{2}$ lie within 3% of the experimentally measured values for the Sr-doped system ${\mathrm{Ca}}_{1.86}$${\mathrm{Sr}}_{0.14}$${\mathrm{CuO}}_{2}$. The computed electronic structures and the density of states are quite similar to those of the other oxide superconductors, except for their three-dimensional character because of the presence of strong coupling between the closely spaced ${\mathrm{CuO}}_{2}$ layers. The calculated frequencies for the k=0 frozen phonons for undoped ${\mathrm{CaCuO}}_{2}$ are quite close to the measured data for Sr-doped ${\mathrm{CaCuO}}_{2}$.

Finding noise-related artifacts in scanned-probe microscope images

Scanned probe microscope images often contain structure which does not belong to the actual specimen. Some of this structure arises in time-domain instabilities of the microscope and its environment, some of it arises with imperfect attempts of the feedback loop to hold force or current constant, and some of it reflects tip (as opposed to specimen) structure. We illustrate here: (i) artifacts of the first kind, i.e. those which are independent of tip shape and which exist in the slow-scan limit, (ii) the way in which low-pass filtering can give such artifacts three-dimensional character, and (iii) tests involving Fourier phases and amplitudes in scanned probe images which can signal the presence of such artifacts.The first and best test for artifacts related to time-domain instability is simply to locate precisely the same feature in two micrographs, if possible taken with different scan speeds (e.g. at different magnfications). If the feature remains unchanged in structure and size, then it is unlikely to be a purely time domain artifact.

L→( l-1) AgM 4,5 XAS investigation at the Ag/Si(111)2 × 1 interface

We have studied the evolution of the low-lying unoccupied Ag5p-derived electron states at the Ag/Si(111)2 × 1 interface as a function of the Ag coverage via ( l→( l-1)) AgM 4,5 X-ray absorption spectroscopy. The measured line-shapes are discussed in terms of a transition of the overgrown adlayer from two- to three-dimensional character.

Behavior of the Néel temperature and the staggered susceptibility from two-dimensional to three-dimensional systems

We introduce a three-dimensional character to the transfer of two-dimensional conduction electrons. We investigate how this affects the Néel temperature and the staggered susceptibility within the self-consistent renormalization theory of spin fluctuations for itinerant antiferromagnetism.

Electronic structure of CaCuO2

Abstract The scalar relativistic version of an accurate first principles full potential self-consistent linearized muffintin orbital (LMTO) method has been employed for describing the physical properties of the parent system of the high_Tc oxide superconductors i.e., CaCuO2. The presently employed modified version of the LMTO method is quite fast and goes beyond the usual LMTO_ASA method in the sense that it permits a completely general shape of the potential and the charge density.Also, in contrast to LMTO — ASA, the present method is capable of treating distorted lattice structures accurately. The computed electronic structures and the density of states is quite similar to those of the other oxide superconductors, except of their three-dimensional character because of the presence of strong coupling between the closely spaced CuO2 layers.

Mathematical modeling and the study of the heat exchange process in color kinescopes

We propose a mathematical model for computing the heat exchange in a masked color kinescope taking account of the specific geometry of its shell and the actual three-dimensional character of the heat emission in the mask. We study the temperature field in the mask and determine the size of the integral degree of blackness in the cone coating that guarantees a stable operation of the kinescope. Three figures. Bibliography: 7 titles.

Designing the OSF/MOTIF Graphical User Interface

Design Management Journal (Former Series)Volume 4, Issue 1 p. 19-25 Designing the OSF/MOTIF Graphical User Interface Shiz Kobara, Shiz Kobara Shiz Kobara is a senior user interaction designer in Hewlett-Packard's User Interaction Design department. In 1987 he joined Barry Mathis' department as the visual designer of the OSF/Motif graphical user interface, and conceived of its three-dimensional visual character. Later he wrote a book on design possibilities and best practices with Motif, entitled Visual Design with OSF/Motif.Search for more papers by this author Shiz Kobara, Shiz Kobara Shiz Kobara is a senior user interaction designer in Hewlett-Packard's User Interaction Design department. In 1987 he joined Barry Mathis' department as the visual designer of the OSF/Motif graphical user interface, and conceived of its three-dimensional visual character. Later he wrote a book on design possibilities and best practices with Motif, entitled Visual Design with OSF/Motif.Search for more papers by this author First published: Winter 1993 https://doi.org/10.1111/j.1948-7169.1993.tb00122.x AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume4, Issue1Winter 1993Pages 19-25 RelatedInformation