61,680 research outputs found
Application of P & SH-waves for rock anisotropy studies: Genting Highlands case study
No full textSeismic refraction surveys utilizing P & SH-waves were carried out over an abandoned quarry
at Genting Highlands in order to study the anisotropy of the bedrock of that site. Shear (S) and
compression (P) acoustic velocities of the subsurface refractor have shown significant variations in their
spatial distribution. These variations in velocity values were compiled and then qualitatively correlated
with surface fracture surveys conducted during the course of acquiring the field data.
Seismic P & SH-wave velocity values obtained from in situ measurements have been used for
calculating the anisotropy percentage and slowness factor. The petrophysical parameters computed are
then contoured to identify the orientation of fracture zones along the refractor surface
SH-Struct: An Affirmative Advanced Method for Mining Frequent Patterns
No full textData Mining requires versatile computational techniques for analyzing patterns among large and diversified databases. One of the most influential and typically emerging research area is to develop impinging structures for valid frequent patterns. In this paper, we have formulated a novel data structure known as SH-Struct (Soft-Hyperlinked Structure) which mines the complete frequent itemset using SH-Mine algorithm. This algorithm enables frequent pattern mining with different supports. Fundamentally, SH-Struct is a tree structure which maintains H-Struct (Hyperlinked Structure) at each level of the tree called SH-Tree to improvise storage compression and reserves frequent patterns very fast using SH-Mine algorithm. To validate the effectiveness of our structure here we present the performance study of SH-mine and FP (Frequent Pattern)- growth algorithm highlighting space and time payoffs for two categories of databases: sparse and dense. The experimental results show the prominent behavior of proposed method and incite us to further deploy it in more dense and dynamic databases such as temporal databases for generating more prognostic outcomes. </p
Adapting DVB-SH system parameters to mobile environments
No full textA performance analysis of the digital video broadcasting
- satellite to handheld (DVB-SH) system in presence of ground mobile terminals (GMTs) is presented. The paper focuses on the Doppler spread issue. Indeed, the mobility of
GMTs induces a Doppler spread in the orthogonal frequency
division multiplexing (OFDM) signal that destroys the orthogonality of subcarriers. The loss of orthogonality produces inter-carrier interference (ICI) and hence a degradation of the system performance in terms of symbol error probability. The paper presents the conditions in which this degradation can be compensated for by an increase in the signal to noise ratio (SNR) at the receiver side. The result depends on both the modulation scheme and the speed of GMTs. Inversely, having a maximum allowable margin on the received SNR allows us to determine an upper bound on the mobile station velocity
Generic approach for hierarchical modulation performance analysis: application to DVB-SH
No full textBroadcasting systems have to deal with channel diversity in order to offer the best rate to the users. Hierarchical
modulation is a practical solution to provide several rates in function of the channel quality. Unfortunately the performance evaluation of such modulations requires time consuming simulations. We propose in this paper a novel approach based on the channel capacity to avoid these simulations. The method allows to study the performance in terms of spectrum efficiency of hierarchical and also classical modulations combined with error correcting codes. Our method will be applied to the DVB-SH standard which considers hierarchical modulation as an optional feature
VCSEL array module using (111) facet mirrors of a v-gooved silicon optical bench and angled fibers
No full textWe propose an advanced scheme of optical subassembly (OSA) using a silicon optical bench (SiOB) for the vertical-cavity surface-emitting laser (VCSEL) array. The VCSEL beams were deflected on the (111) end facets of the V-grooves in a SiOB and were coupled into the angled fibers. The inclined, angle and position of the fibers were designed to maximize the coupling efficiency. The fabricated OSA showed a coupling efficiency of 30%-50% and a large misalignment tolerance of about 90 mum along the longitudinal direction of the V-grooves. Data transmission of 2.5 Gb/s x 12 channels was demonstrated with clear eye diagrams
COMPATIBILITY AND CRYSTALLIZATION IN POLYNETHYLENE OXIDE)-POLY(METHYL METHACRYLATE) SEMIINTERPENETRATING POLYMER NETWORK
No full textDifferential scanning calorimetry together with dynamic mechanical analysis were employed to investigate the crystallinity and the miscibility in poly(ethylene oxide)/crosslinked poly (methyl methacrylate) semi-IPN (interpenetrating polymer networks). The crystallinity of poly(ethylene oxide) in the semi-IPN is found to depend on the crosslink density of PMMA as well as the overall content of PEO. Of special interest is that an increase in the crosslink density tends to increase the crystallinity contrary to our expectation, indicating crystallization and phase separation may proceed simultaneously during IPN formation. The investigation of glass transition behaviors with dynamic mechanical analysis suggests phase separation (i.e., there exist two amorphous phases: one PEO-rich phase, the other a PMMA-rich phase). (C) 1993 John Wiley Sons, Inc
Differentiation of SH-SY5Y neuroblastoma cells using retinoic acid and BDNF: A model for neuronal and synaptic differentiation in neurodegeneration
No full textThere has been much interest in the use of cell culture models of neurones, to avoid the animal welfare and cost issues of using primary and human-induced pluripotent stem cell (hiPSC)-derived neurones respectively. The human neuroblastoma cell line, SH-SY5Y, is extensively used in laboratories as they can be readily expanded, are of low cost and can be differentiated into neurone-like cells. However, much debate remains as to their phenotype once differentiated, and their ability to recapitulate the physiology of bona fide neurones. Here, we characterise a differentiation protocol using retinoic acid and BDNF, which results in extensive neurite outgrowth/branching within 10 days, and expression of key neuronal and synaptic markers. We propose that these differentiated SH-SY5Y cells may be a useful substitute for primary or hiPSC-derived neurones for cell biology studies, in order to reduce costs and animal usage. We further propose that this characterised differentiation timecourse could be used as an in vitro model for neuronal differentiation, for proof-of principle studies on neurogenesis, e.g. relating to neurodegenerative diseases. Finally, we demonstrate profound changes in Tau phosphorylation during differentiation of these cells, suggesting that they should not be used for neurodegeneration studies in their undifferentiated state
Detailed structure of the hexagonally packed mesostructured carbon material CMK-3
No full textDetailed investigation of the ordered mesoporous CMK-3 carbon using XRD structural modeling based on the continuous electron density representation and the Rietveld technique allowed deriving comprehensive and consistent information on the material anatomy. The electron density distribution map agrees with carbon 'bridges', which seem to be attributed to the material interconnecting carbon nanorods in the CMK-3 mesostructure. These carbon 'bridges' are supposed to be derived from former complementary mesopores of the SBA-15 template used. (C) 2002 Elsevier Science Ltd. All rights reserved.We are grateful to the INTAS Fellowship grant for Young Scientists YSF 2001/ 2-3, INTAS grant (proposal 2283) and joint grant KRSF-RFBR 02-03-97704. R. Ryoo gratefully acknowledges that this work was supported in
part by the Ministry of Science and Technology through Creative Research Initiative Program, and by School of Molecular Science through Brain Korea 21 Project
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