Abstract: A complete spectral representation for the
electromagnetic field of planar multilayered waveguides
inhomogeneously filled with omega media is presented. The problem
of guided electromagnetic propagation is reduced to an eigenvalue
equation related to a 2 ´ 2 matrix differential operator. Using the
concept of adjoint waveguide, general bi-orthogonality relations for
the hybrid modes (either from the discrete or from the continuous
spectrum) are derived. For the special case of homogeneous layers
the linear operator formalism is reduced to a simple 2 ´ 2 coupling
matrix eigenvalue problem. Finally, as an example of application, the
surface and the radiation modes of a grounded omega slab waveguide
are analyzed.
Abstract: This paper proposed a stiffness analysis method for a
3-PRS mechanism for welding thick aluminum plate using FSW
technology. In the molding process, elastic deformation of lead-screws
and links are taken into account. This method is based on the virtual
work principle. Through a survey of the commonly used stiffness
performance indices, the minimum and maximum eigenvalues of the
stiffness matrix are used to evaluate the stiffness of the 3-PRS
mechanism. Furthermore, A FEA model has been constructed to verify
the method. Finally, we redefined the workspace using the stiffness
analysis method.
Abstract: In order to research Internet quantificationally and
better model the performance of network, this paper proposes a novel
AS level network performance model (MNPM), it takes autonomous
system (AS) as basic modeling unit, measures E2E performance
between any two outdegrees of an AS and organizes measurement
results into matrix form which called performance matrix (PM).
Inter-AS performance calculation is defined according to performance
information stored in PM. Simulation has been implemented to verify
the correctness of MNPM and a practical application of MNPM
(network congestion detection) is given.
Abstract: Quantitative measurements of tumor in general and tumor volume in particular, become more realistic with the use of Magnetic Resonance imaging, especially when the tumor morphological changes become irregular and difficult to assess by clinical examination. However, tumor volume estimation strongly depends on the image segmentation, which is fuzzy by nature. In this paper a fuzzy approach is presented for tumor volume segmentation based on the fuzzy connectedness algorithm. The fuzzy affinity matrix resulting from segmentation is then used to estimate a fuzzy volume based on a certainty parameter, an Alpha Cut, defined by the user. The proposed method was shown to highly affect treatment decisions. A statistical analysis was performed in this study to validate the results based on a manual method for volume estimation and the importance of using the Alpha Cut is further explained.
Abstract: DS-CDMA system is well known wireless
technology. This system suffers from MAI (Multiple Access
Interference) caused by Direct Sequence users. Multi-User Detection
schemes were introduced to detect the users- data in presence of
MAI. This paper focuses on linear multi-user detection schemes used
for data demodulation. Simulation results depict the performance of
three detectors viz-conventional detector, Decorrelating detector and
Subspace MMSE (Minimum Mean Square Error) detector. It is seen
that the performance of these detectors depends on the number of
paths and the length of Gold code used.
Abstract: Application of nanoparticles as additives in membrane
synthesis for improving the resistance of membranes against fouling
has triggered recent interest in new membrane types. However, most
nanoparticle-enhanced membranes suffer from the tradeoff between
permeability and selectivity. In this study, nano-WS2 was explored as
the additive in membrane synthesis by non-solvent induced phase
separation. Blended PES-WS2 flat-sheet membranes with the
incorporation of ultra-low concentrations of nanoparticles (from 0.025
to 0.25%, WS2/PES ratio) were manufactured and investigated in
terms of permeability, fouling resistance and solute rejection.
Remarkably, a significant enhancement in the permeability was
observed as a result of the incorporation of ultra-low fractions of
nano-WS2 to the membrane structure. Optimal permeability values
were obtained for modified membranes with 0.10%
nanoparticle/polymer concentration ratios. Furthermore, fouling
resistance and solute rejection were significantly improved by the
incorporation of nanoparticles into the membrane matrix. Specifically,
fouling resistance of modified membrane can increase by around 50%.
Abstract: Repetitive systems stand for a kind of systems that
perform a simple task on a fixed pattern repetitively, which are
widely spread in industrial fields. Hence, many researchers have been
interested in those systems, especially in the field of iterative learning
control (ILC). In this paper, we propose a finite-horizon tracking
control scheme for linear time-varying repetitive systems with uncertain
initial conditions. The scheme is derived both analytically
and numerically for state-feedback systems and only numerically for
output-feedback systems. Then, it is extended to stable systems with
input constraints. All numerical schemes are developed in the forms
of linear matrix inequalities (LMIs). A distinguished feature of the
proposed scheme from the existing iterative learning control is that
the scheme guarantees the tracking performance exactly even under
uncertain initial conditions. The simulation results demonstrate the
good performance of the proposed scheme.
Abstract: Two short sediment cores collected from mangrove
areas of Manori and Thane creeks along Mumbai coast were analysed
for sediment composition and metals (Fe, Mn, Cu, Pb, Co, Ni, Zn, Cr
and V). The statistical analysis of Pearson correlation matrix proved
that there is a significant relationship between metal concentration
and finer grain size in Manori creek while poor correlation was
observed in Thane creek. Based on the enrichment factor, the present
metal to background metal ratios clearly reflected maximum
enrichment of Cu and Pb in Manori creek and Mn in Thane creek.
Geoaccumulation index calculated indicate that the study area is
unpolluted with respect to Fe, Mn, Co, Ni, Zn and Cr in both the
cores while moderately polluted with Cu and Pb in Manori creek.
Based on contamination degree, both the core sediments were found
to be considerably contaminated with metals.
Abstract: In this paper, we study a class of serially concatenated block codes (SCBC) based on matrix interleavers, to be employed in fixed wireless communication systems. The performances of SCBC¬coded systems are investigated under various interleaver dimensions. Numerical results reveal that the matrix interleaver could be a competitive candidate over conventional block interleaver for frame lengths of 200 bits; hence, the SCBC coding based on matrix interleaver is a promising technique to be employed for speech transmission applications in many international standards such as pan-European Global System for Mobile communications (GSM), Digital Cellular Systems (DCS) 1800, and Joint Detection Code Division Multiple Access (JD-CDMA) mobile radio systems, where the speech frame contains around 200 bits.
Abstract: The least mean square (LMS) algorithmis one of the
most well-known algorithms for mobile communication systems
due to its implementation simplicity. However, the main limitation
is its relatively slow convergence rate. In this paper, a booster
using the concept of Markov chains is proposed to speed up the
convergence rate of LMS algorithms. The nature of Markov
chains makes it possible to exploit the past information in the
updating process. Moreover, since the transition matrix has a
smaller variance than that of the weight itself by the central limit
theorem, the weight transition matrix converges faster than the
weight itself. Accordingly, the proposed Markov-chain based
booster thus has the ability to track variations in signal
characteristics, and meanwhile, it can accelerate the rate of
convergence for LMS algorithms. Simulation results show that the
LMS algorithm can effectively increase the convergence rate and
meantime further approach the Wiener solution, if the
Markov-chain based booster is applied. The mean square error is
also remarkably reduced, while the convergence rate is improved.
Abstract: This paper aims at presenting the biotechnology used
to obtain collagen-based gels from shark (Squalus acanthias) and brill
skin, marine fish growing in the Black Sea. Due to the structure of its
micro-fibres, collagen can be considered a nanomaterial; in order to
use collagen-based matrixes as biomaterial, rheological studies must
be performed first, to state whether they are stable or not. For the
triple-helix structure to remain stable within these gels at room or
human body temperature, they must be stabilized by reticulation.
Abstract: In the last few years, three multivariate spectral
analysis techniques namely, Principal Component Analysis (PCA),
Independent Component Analysis (ICA) and Non-negative Matrix
Factorization (NMF) have emerged as effective tools for oscillation
detection and isolation. While the first method is used in determining
the number of oscillatory sources, the latter two methods
are used to identify source signatures by formulating the detection
problem as a source identification problem in the spectral domain.
In this paper, we present a critical drawback of the underlying linear
(mixing) model which strongly limits the ability of the associated
source separation methods to determine the number of sources
and/or identify the physical source signatures. It is shown that the
assumed mixing model is only valid if each unit of the process gives
equal weighting (all-pass filter) to all oscillatory components in its
inputs. This is in contrast to the fact that each unit, in general, acts
as a filter with non-uniform frequency response. Thus, the model
can only facilitate correct identification of a source with a single
frequency component, which is again unrealistic. To overcome
this deficiency, an iterative post-processing algorithm that correctly
identifies the physical source(s) is developed. An additional issue
with the existing methods is that they lack a procedure to pre-screen
non-oscillatory/noisy measurements which obscure the identification
of oscillatory sources. In this regard, a pre-screening procedure
is prescribed based on the notion of sparseness index to eliminate
the noisy and non-oscillatory measurements from the data set used
for analysis.