Inner Structure (inner + structure)

Distribution by Scientific Domains

Selected Abstracts

Micro-CT scanning analysis for inner structure of porous media

Zhang Yang
Abstract A micro-CT scanner was employed to investigate inner characteristics of porous media, and particular cakes were taken as samples. By obtaining the inner pore structure and inner structure reconstruction, porosity and its variation in the samples, water distribution in pores, and other inner characteristics were determined and explored. When the sample was dried after immersion in water, the solid frame shrank, some pores became larger and the porosity increased, while the sample not immersed in water did not change much after being dried. The experiments indicate that micro-CT scanning is an effective technology to study the inner structure of porous materials with pores larger than tens of microns and also can be used to explore some important transport performance. ©2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(4): 208, 214, 2007; Published online in Wiley InterScience (www.interscience. DOI 10.1002/htj.20155 Copyright © 2004 Wiley Periodicals, Inc. [source]

The human hippocampus at 7 T,In vivo MRI

HIPPOCAMPUS, Issue 1 2009
Jens M. Theysohn
Abstract The human hippocampus plays a central role in various neuropsychiatric disorders, such as temporal lobe epilepsy (TLE), Alzheimer's dementia, mild cognitive impairment, and schizophrenia. Its volume, morphology, inner structure, and function are of scientific and clinical interest. Magnetic resonance (MR) imaging is a widely employed tool in neuroradiological workup regarding changes in brain anatomy, (sub-) volumes, and cerebral function including the hippocampus. Gain in intrinsic MR signal provided by higher field strength scanners and concomitant improvements in spatial resolution seem highly valuable. An examination protocol permitting complete, high-resolution imaging of the human hippocampus at 7 T was implemented. Coronal proton density, T2, T2*, and fluid-attenuated inversion recovery contrasts were acquired as well as an isotropic 3D magnetization-prepared rapid acquisition gradient-echo (500 ,m isotropic voxel dimension, noninterpolated). Observance of energy deposition restrictions within acceptable scan times remained challenging in the acquisition of thin, spin-echo-based sections. At the higher resolution enabled by 7 T, demarcation of the hippocampus and some internal features including gray/white matter differentiation and depiction of the hippocampal mantle becomes much more viable when compared with 1.5 T; thus, in the future, this imaging technology might help in the diagnosis of subtle hippocampal changes. © 2008 Wiley-Liss, Inc. [source]

Integrating fault detection and isolation with model predictive control

Barry Lennox
Abstract This paper illustrates how the application of partial least squares (PLS) can be extended to provide an integrated solution to fault detection and isolation, inferential estimation and model predictive control. It is shown that if PLS is used to identify a dynamic model of a plant then the latent variables of the model can identify the suitability of using this model under current conditions. This functionality enables automated model switching in piecewise linear systems. A further advantage of the proposed technique is that the inner structure of the model can be used to provide fault detection and isolation capabilities. By extending the approach to control systems and integrating a dynamic model, identified using the PLS algorithm, within a model predictive controller, similar benefits, such as automatic model selection can be achieved for the control system. The proposed approach is illustrated through its application to the Tennessee Eastman challenge process. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Davydov's solitons in zigzag carbon nanotubes

Larissa Brizhik
Abstract Nonlinear mechanism of charge transport in low-dimensional nanosystems is considered, based on the account of the electron,phonon interaction that arises from the deformation dependencies of the on-site and the hopping interaction energies at intermediatevalues of the corresponding coupling constants. In particular, carbon-type hexagonal zigzag nanotubes are studied. It is shown that in the adiabatic approximation the electron,phonon coupling results in the self-trapping of carriers and formation of polaron (soliton) states. We show that the ground state of an electron in a nanotube is a low-dimensional polaron whose symmetry depends on the strength of the coupling. Namely, at relatively weak coupling, the polaron possesses quasi-one-dimensional properties and has an azimuthal symmetry. When the coupling constant exceeds some critical value, the azimuthal symmetry breaks down and two-dimensional polaron on the nanotube surface is formed. There are also polarons formed by the electrons in the conducting band (or by holes in the valence band) in semiconducting zigzag carbon nanotubes. Such polarons are described by the system of coupled nonlinear Schroedinger equations which admits single-band polarons, and entangled (hybridized) polarons. These two types of polarons possess different energies and symmetry properties. Single-band solutions are one-dimensional polarons: they are azimuthally symmetric and localized along the nanotube axis. The entangled polarons are also self-trapped along the nanotube axis, but possess an inner structure and are modulated around the nanotube. The entangled polarons break the azimuthal symmetry and their energy is lower than the energy of single-band polarons. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]

Three-dimensional visualization of the inner structure of single crystals by step-scanning white X-ray section topography

Taihei Mukaide
Visualization of the three-dimensional distribution of the crystal defects of large single crystals of calcium fluoride has been demonstrated by white X-ray section topography using sheet-like X-rays (BL28B2 at SPring-8). An image of the three-dimensional distribution of the crystal defects was reconstructed by stacking section topographs, which expressed the images of cross sections of the sample. The section topographs were recorded using a CMOS flat-panel imager or a CCD detector combined with scintillator (Gd2O2S:Tb) and relay lens system. The section topographs were measured by repeating cycles of exposure and sample translation along the direction perpendicular to the top face of the sample. Using high-brilliance and high-energy white X-rays (,60,keV) efficiently, visualization of the three-dimensional structure of subgrains of a sample of up to 60,mm in diameter was achieved. Furthermore, the three-dimensional distribution of the glide plane in the crystal was visualized by reconstructing the linear contrast of the glide plane. [source]

Extended defects in ion assisted MBE grown SiGe/Si-nanostructures

P. I. Gaiduk
Abstract MBE-grown SiGe nano-structures assisted with in situ implantation of 1 keV Ge+ ions are investigated by transmission electron (TEM) and atomic force microscopy (AFM). Self-assembled Ge islands of small size and no extended defects are observed by TEM after low ion fluence pre-implantation at high temperature. Implanted SiGe nano-structures of larger size produce threading dislocations. High dose implantation at low temperature results in formation of semi-spherical SiGe/Si nanostructures of a twin-related type. Epitaxial islands of 30-40 nm in base diameter and 11 nm in height, and a density of about 6x1010 cm,2 are produced in this case. It is evidenced by XTEM that the islands have a complicated inner structure and consist of micro-twin nucleus and semi-spherical nano-layers of a various SiGe composition. The results are discussed in terms of strain relaxation through implantation induced defects. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


RATIO, Issue 4 2009
Peter Kivy
It is agreed on all hands that both fictional narratives and the familiar genres of classical music possess an inner structure that both can be perceived and be appreciated aesthetically. It is my argument here that this inner structure plays a crucially different role in fictional narrative than it does in classical music, confining myself here to ,absolute music' (which is to say, pure instrumental music without text, programme, dramatic setting, or other ,extra-musical' content). The argument, basically, is that whereas the sophisticated listener to the absolute music repertory is keenly, consciously aware of the inner structure, the sophisticated reader of fictional narrative, the principal exemplar being the novel, is not so aware. Therefore, whereas musical structure directly contributes to aesthetic satisfaction, narrative structure contributes only indirectly (which is not to deny that, at times, the reader is consciously aware of narrative structure, and that, at such times, it does contribute directly to aesthetic satisfaction). [source]

Strong signature of the active Sun in 100 years of terrestrial insolation data

W. Weber
Abstract Terrestrial solar irradiance data of the Smithsonian Astrophysical Observatory from 1905 to 1954 and of Mauna Loa Observatory from 1958 to 2008 are analyzed. The analysis shows that, with changing solar activity, the atmosphere modifies the solar irradiance on the percentage level, in all likelihood via cosmic ray intensity variations produced by the active sun. The analysis strongly suggests that cosmic rays cause a large part of the atmospheric aerosols. These aerosols show specific absorption and scattering properties due to an inner structure of hydrated ionic centers, most probably of O2 - and O2+ produced by the cosmic rays. [source]

Five-dimensional relativity and extended elementary particles

G. Lessner
Abstract Five-dimensional relativity, based on the 5-dimensional vacuum equations R,, = 0, is interpreted as a general relativistic field theory describing the inner structure of extended elementary particles. The most general} spherically symmetric, purely electric and asymptotically flat solution of the field equations is calculated. The mass formula of this solution depends on two parameters h > 0 and q > 0, and the mass surface over the (h-q)-plane shows two slits at h= and . These slits can be tentatively identified as hadron branch for h= and lepton branch for . In the slits hadrons and leptons with their masses and extensions can be settled in local minima. [source]

Hair interior defect in AKR/J mice

K. A. Giehl
Summary Background., All AKR/J mice have a subtle defect that involves malformation of the central portion of hair fibres that is best visualized under white and polarized light microscopy. Aims., This study sought to characterize the clinical and ultrastructural features of the hair interior defect (HID) phenotype and to determine the chromosomal localization of the hid mutant gene locus. Methods., White and polarized light microscopy combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the HID phenotype. Complementation testing and gene-linkage studies were performed to map the locus. Results., Using SEM, the hair-fibre structure on the surface was found to be similar to hairs obtained from normal BALB/cByJ+/+and C57BL/6 J+/+mice. There were also no differences in sulphur content. TEM revealed degenerative changes in the medulla similar to that seen by light microscopy. This autosomal recessive mutation is called HID (locus symbol: hid). We mapped the hid locus to the distal end of mouse chromosome 1. No genes reported to cause skin or hair abnormalities are known to be within this interval except for the lamin B receptor (Lbr), which had been excluded previously as the cause of the hid phenotype in AKR/J mice. Conclusion., A potentially novel gene or known gene with a novel phenotype resides within this interval, which may shed light on human diseases with defects in the inner structure of the hair fibre. [source]

Vereinfachtes Verfahren zur Vorhersage des Langzeitverhaltens von Holz-Beton-Verbundkonstruktionen

BAUTECHNIK, Issue 4 2005
Ralf Avak Prof. Dr.-Ing.
Für die Bemessung von nachgiebig verbundenen Biegeträgern aus Holz und Beton wird vom praktisch tätigen Ingenieur in der Regel das ,-Verfahren bevorzugt. Das Verfahren ist Bestandteil nationaler, sowie europäischer Holzbauvorschriften [4], [5]. Für die Berechnung des Langzeitverhaltens ist das ,-Verfahren in seiner derzeitigen Form jedoch nur bedingt geeignet, da es z. B. das Schwinden des Betons nicht berücksichtigt. Im folgenden wird aus diesem Grund ein einfaches analytisches Verfahren vorgestellt, bei dem neben dem Kriechverhalten der Materialien Holz und Beton auch deren Schwind- bzw. Quellverformungen sowie das Langzeitverhalten der Schubverbindungsmittel berücksichtigt werden können. Die Anwendung des Verfahrens ist momentan noch auf Innenbauteile beschränkt. Simplified procedure for the description from the long-term behaviour of timber-concrete composite structures. The ,-procedure is favoured to design timber-concrete composite structures. This procedure is component of current national as well as European timber standards [4], [5]. The ,-procedure isn't suitable to describe the long-term behaviour, because it does not consider the shrinkage of concrete for example. A simplified procedure is introduced in the following. This procedure considers creeping of timber and concrete and , for the first time , swelling and shrinkage of these materials, as well as the long-term behaviour of the shear connectors. Currently it is applicable only to inner structures. [source]