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Point Position (point + position)

Distribution by Scientific Domains

Chemistry	33%

Selected Abstracts

Design of WiFi/WiMAX dual-band E-shaped patch antennas through cavity model approach

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2010
Heng-Tung Hsu
Abstract The design of dual-band, single patch microstrip antenna covering 2.4 and 3.5 GHz for WiFi and WiMAX applications based on E-shaped patch is presented. Although cavity model analysis is included in the design procedure, the slotted configuration is treated as the perturbed cavity to characterize the resonant frequencies of corresponding modes. Additionally, the feed point position is determined through the field distribution resulted from the modal analysis. A new equivalent circuit model based on the coupled resonators theory is proposed for analysis purposes. The relationship between cavity model analysis and antenna resonances is further evidenced by the surface current distributions on the conductors. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 471,474, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24954 [source]

Small microstrip patch antennas with short-pin using a dual-band operation

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2008
Cheol Yoon
Abstract This article presents the design and fabrication of a short-pin dual-band E-shaped microstrip patch antenna for application in a 2.630,2.655 GHz band satellite-DMB with a 5.725,5.825 GHz band wireless LAN. The prototype consist of a short-pin and E-shaped patch. To obtain sufficient bandwidth in VSWR < 2, an air layer is inserted between the ground plane and the substrate. A small short-pin patch that has a dual-band characteristic is used. Important design parameters are the slot's existence, length, the air-gap's height, the feed point's position, and the short-pin's existence and point position. From these optimized parameters, an E-shaped antenna is fabricated and measured. The measured results of the fabricated antenna are obtained individually at 200 and 700 MHz bandwidths in VSWR < 2 referenced to the center frequency, and the individual gain at 8.79 and 10.26 dBi. The experimental 3 dB beam width is shown to be broad across the pass band in the E-plane, and in the H-plane is individually 73°, 65°, 74°, and 42°, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 367,371, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23099 [source]

Form, symmetry and packing of biomacromolecules.

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2010

The differentiation of the human rhinovirus into serotypes, all having very similar structures and the same architecture, is shown to be related to the packing of the viruses in the crystal and to its space-group symmetry. The molecular crystallographic properties (here described in terms of a molecular lattice ,M instead of the form lattice ,F considered in previous publications) appear to be compatible with the crystal structure and with the packing lattice ,P, introduced in Part I [Janner (2010). Acta Cryst. A66, 301,311]. On the basis of the enclosing forms of the capsid, a sphere packing is considered, where the spheres touch at kissing points. Residues of each of the four coat proteins (VP1, VP2, VP3, VP4), having a minimal distance from the kissing points, define a set of kissing point related (KPR) residues. In this set only four different residues occur, one for each coat protein, ordered into symmetric clusters {already classified in a previous publication [Janner (2006). Acta Cryst. A62, 270,286]} and indexed by neighbouring lattice points of ,P (or equivalently of ,M). The indexed KPR residues allow a fingerprint characterization of the five rhinovirus serotypes whose structures are known (HRV16, HRV14, HRV3, HRV2 and HRV1A). In the fingerprint they occur as internal (if inside the given capsid), as external (if belonging to the neighbouring viruses) or as a contact residue (if at a kissing point position). The same fingerprint, periodically extended, permits a coarse-grained reconstruction of the essential properties of the crystal packing, invariant with respect to the space group of the serotype. [source]

Face modeling and editing with statistical local feature control models

INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 6 2007
Yu Zhang
Abstract This article presents a novel method based on statistical facial feature control models for generating realistic controllable face models. The local feature control models are constructed based on the exemplar 3D face scans. We use a three-step model fitting approach for the 3D registration problem. Once we have a common surface representation for examples, we form feature shape spaces by applying a principal component analysis (PCA) to the data sets of facial feature shapes. We compute a set of anthropometric measurements to parameterize the exemplar shapes of each facial feature in a measurement space. Using PCA coefficients as a compact shape representation, we approach the shape synthesis problem by forming scattered data interpolation functions that are devoted to the generation of desired shape by taking the anthropometric parameters as input. The correspondence among all exemplar face textures is obtained by parameterizing a 3D generic mesh over a 2D image domain. The new feature texture with desired attributes is synthesized by interpolating the exemplar textures. With the exception of an initial tuning of feature point positions and assignment of texture attribute values, our method is fully automated. In the resulting system, users are assisted in automatically generating or editing a face model by controlling the high-level parameters. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 341,358, 2007 [source]

Calculation of the instrumental function in X-ray powder diffraction

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2006
A. D. Zuev
A new method for calculating the total instrumental function of a conventional Bragg,Brentano diffractometer has been developed. The method is based on an exact analytical solution, derived from diffraction optics, for the contribution of each incident ray to the intensity registered by a detector of limited size. Because an incident ray is determined by two points (one is related to the source of the X-rays and the other to the sample) the effects of the coupling of specific instrumental functions, for example, equatorial and axial divergence instrumental functions, are treated together automatically. The intensity at any arbitrary point of the total instrumental profile is calculated by integrating the intensities over two simple rectangular regions: possible point positions on the source and possible point positions on the sample. The effects of Soller slits, a monochromator and sample absorption can also be taken into account. The main difference between the proposed method and the convolutive approach (in which the line profile is synthesized by convolving the specific instrumental functions) lies in the fact that the former provides an exact solution for the total instrumental function (exact solutions for specific instrumental functions can be obtained as special cases), whereas the latter is based on the approximations for the specific instrumental functions, and their coupling effects after the convolution are unknown. Unlike the ray-tracing method, in the proposed method the diffracted rays contributing to the registered intensity are considered as combined (part of the diffracted cone) and, correspondingly, the contribution to the instrumental line profile is obtained analytically for this part of the diffracted cone and not for a diffracted unit ray as in ray-tracing simulations. [source]