74,139 research outputs found
Intersystem soft handover for converged DVB-H and UMTS networks
Get PDFDigital video broadcasting for handhelds (DVB-H) is the standard for broadcasting Internet Protocol (IP) data services to mobile portable devices. To provide interactive services for DVB-H, the Universal Mobile Telecommunications System (UMTS) can be used as a terrestrial interaction channel for the unidirectional DVB-H network. The converged DVB-H and UMTS network can be used to address the congestion problems due to the limited multimedia channel accesses of the UMTS network. In the converged network, intersystem soft handover between DVB-H and UMTS is needed for an optimum radio resource allocation, which reduces network operation cost while providing the required quality of service. This paper deals with the intersystem soft handover between DVB-H and UMTS in such a converged network. The converged network structure is presented. A novel soft handover scheme is proposed and evaluated. After considering the network operation cost, the performance tradeoff between the network quality of service and the network operation cost for the intersystem soft handover in the converged network is modeled using a stochastic tree and analyzed using a numerical simulation. The results show that the proposed algorithm is feasible and has the potential to be used for implementation in the real environment
Breaking New Ground in East Asia Library History
No full textReview of Peter X. Zhou. Collecting Asia: East Asian Libraries in North America (2010).Published in H-Net Reviews in the Humanities and Social Sciences and available at: http://www.h-net.org/reviews/showrev.php?id=32231March 201
Electroresistance effect in La1−xCaxMnO3 (0<x<1) ceramics
No full textElectroresistance (ER) effects were investigated for a full series of manganite ceramics La1-xCaxMnO3 (0 < x < 1) synthesized by solid state reaction The results indicate that while the ER effects are large only in the presence of electrically active high E-field boundaries the equilibrium or metastable electronic-magnetic states in the adjoining domains are also significant as a large ER occurs only at x = 0 51 and x = 0 17 those compositions are both near a two-phase coexistence region i e close to a compositional regime where equilibrium insulating/metallic phase domains and interfaces would occur spontaneously (C) 2010 Elsevier Ltd All rights reserve
Measurement of w-InN/h-BN Heterojunction Band Offsets by X-Ray Photoemission Spectroscopy
No full textX-ray photoelectron spectroscopy has been used to measure the valence band offset (VBO) of the w-InN/h-BN heterojunction. We find that it is a type-II heterojunction with the VBO being -0.30 +/- A 0.09 eV and the corresponding conduction band offset (CBO) being 4.99 +/- A 0.09 eV. The accurate determination of VBO and CBO is important for designing the w-InN/h-BN-based electronic devices
Interplay between geological materials and the environment at the Dazu Rock Carvings, China
No full textThe study of the historical built environment is of great significance to the heritage conservation and the reconstruction of the level of anthropogenic pollution in the past. On the Dazu Rock Carvings, China, a black to reddish-brown, relatively dense mineral film with a thickness of approximately 150 μm was observed on the surface of the sandstone. The chemical composition of the mineral film studied by Scanning Electron Microscopy- Energy Dispersive Spectroscopy (SEM-EDS), Electron Probe Micro- Analyz (EPMA), X-ray Absorption Spectroscopy (XAS), Total Organic Carbon (TOC), and Ion Chromatography (IC), revealed that its development was comprehensively controlled by environmental conditions, especially by environmental pollution. The mineral film consisted primarily of clay minerals and iron oxide. It also contained a large amount of detrital quartz and feldspar, with a clear boundary with the underlying mineral matrix. The bacterial community was also investigated by next generation sequencing and its potential metabolisms through PICRUSt2. The mineral film on the surface of sandstone and its microbial community may provide a certain degree of protection for the internal structure. As a passive sampler, the variation of the concentration of pollution elements in the mineral film is helpful to understand the past environmental pollution of the city. Besides the relevance for stone heritage conservation, this study provides insights into the interplay between geological materials and the environment
The generation and validation of a CUF-based FEA model with laser-based experiments
Get PDFArchitectural structures today are increasingly complex and structural health monitoring plays an important role in guaranteeing their safety. How to improve the reliability of deformation analysis is, thus, one of the key problems. This article combines laser-based measurement technology and the Carrera unified formulation (CUF) method to investigate the deformation of engineering structures. Within this article, we simulate architectural structures using the CUF geometric model, which is consistent with the results of the laser tracker experiment. We aimed at constructing an intelligent and efficient CUF model which can be applied extensively in the monitoring of various constructs, such as tunnels and bridges. The innovation of this article is that high-accuracy laser tracker technology is integrated with an effective CUF model to investigate the load-displacement relationship considering lateral displacement
Benchmarks for higher-order modes evaluation in the free vibration response of open thin-walled beams due to the cross-sectional deformations
Get PDFHighly flexible thin-walled beams with complex open cross-sections are sensitive to torsional and warping effects. The analysis of higher-order vibration modes in these structures needs more accurate and precise methods in order to achieve reliable results and detect the cross-sectional deformations in the structures’ free vibration response. This paper analyzes higher vibration modes in a series of thin-walled beams, which were proposed by Chen as benchmark problems. These are all open-section thin-walled beams with complex geometries. Global vibration modes, such as bending and torsion, related to the rigid cross-sectional deformations can be detected via classical and shear refined theories. However, cross-sectional deformations appear at higher frequencies, and these modes are mixed with the global ones. To highlight this fact, this paper compares classical beam theories with refined ones based on the Carrera Unified Formulation (CUF) and the shell results using the commercial finite element (FE) software and the data available from the literature. The CUF FEs based on the power of cross-sectional deformation coordinates (x, z) and those based on the Lagrangian polynomials are implemented and compared using Modal Assurance Criterion. A number of interesting conclusions are drawn about the effectiveness of classical and CUF-based results. The need for models capable of detecting cross-sectional deformations is outlined. In fact, many modes are lost by classical beam theories; on the other hand, they show rigid cross-section modes that do not really exist. This fact is also confirmed by the shell models, which are more expensive in terms of computational costs regarding the efficient CUF ones proposed here
Solving Fokker-Planck equations on cantor sets using local fractional decomposition method
No full textThe local fractional decomposition method is applied to approximate the solutions for Fokker-Planck equations on Cantor sets with local fractional derivative. The obtained results give the present method that is very effective and simple for solving the differential equations on Cantor set
A survey of handover algorithms in DVB-H
No full textDigital Video Broadcasting for Handhelds (DVB-H) is a standard for
broadcasting IP Datacast (IPDC) services to mobile handheld terminals.
Based on the DVB-T standard, DVB-H adds new features such as time
slicing, MPE-FEC, in-depth interleavers, mandatory cell id identifier,
optional 4K-modulation mode and the use of 5 MHz bandwidth in addition
to the usually used 6, 7, or 8 MHz raster. IPDC over DVB-H is proposed
for ETSI to complement the DVB-H standard by combining IPDC and
DVB-H in an end-to-end system. Handover in such unidirectional broadcasting
networks is a novel issue. In the last few years since the birth of
DVB-H technology, great attention has been given to the performance
analysis of DVB-H mobile terminals. Handover is one of the main research
topics for DVB-H in mobile scenarios. Better reception quality and greater
power efficiency are considered to be the main targets of handover
research for DVB-H. New algorithms for different handover stages in
DVB-H have been the subject of recent research and are currently being
studied. Further novel algorithms need to be designed to improve the
mobile reception quality. This article provides a comprehensive survey of
the handover algorithms in DVB-H. A systematic evaluation and categorization
approach is proposed based on the problems the algorithms solve
and the handover stages being focused on. Criteria are proposed and analyzed
to facilitate designing better handover algorithms for DVB-H that
have been identified from the research conducted by the author
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