Abstract: Following the current economic challenges and competition, all systems, whatever their field, must be efficient and operational during their activity. In this context, it is imperative to anticipate, identify, eliminate and estimate the failures of systems, which may lead to an interruption of their function. This need requires the management of possible risks, through an assessment of the failures criticality following a dependability approach. On the other hand, at the time of new information technologies and considering the networks field evolution, the data transmission has evolved towards a multipoint communication, which can simultaneously transmit information from a sender to multiple receivers. This article proposes the failures criticality assessment of a multipoint communication network, integrates a database of network failures and their quantifications. The proposed approach is validated on a case study and the final result allows having the criticality matrix associated with failures on the considered network, giving the identification of acceptable risks.
Abstract: The next generation mobile communication systems i.e. fourth generation (4G) was developed to accommodate the quality of service and required data rate. This project focuses on multiple access technique proposed in 4G communication systems. It is attempted to demonstrate the IDMA (Interleave Division Multiple Access) technology. The basic principle of IDMA is that interleaver is different for each user whereas CDMA employs different signatures. IDMA inherits many advantages of CDMA such as robust against fading, easy cell planning; dynamic channel sharing and IDMA increase the spectral efficiency and reduce the receiver complexity. In this, performance of IDMA is analyzed using QC-LDPC coding scheme further it is compared with LDPC coding and at last BER is calculated and plotted in MATLAB.
Abstract: A torsional piezoelectric ultrasonic transducer design
is proposed to measure shear moduli in soft tissue with direct
access availability, using shear wave elastography technique. The
measurement of shear moduli of tissues is a challenging problem,
mainly derived from a) the difficulty of isolating a pure shear wave,
given the interference of multiple waves of different types (P, S,
even guided) emitted by the transducers and reflected in geometric
boundaries, and b) the highly attenuating nature of soft tissular
materials. An immediate application, overcoming these drawbacks,
is the measurement of changes in cervix stiffness to estimate the
gestational age at delivery. The design has been optimized using
a finite element model (FEM) and a semi-analytical estimator of
the probability of detection (POD) to determine a suitable geometry,
materials and generated waves. The technique is based on the time
of flight measurement between emitter and receiver, to infer shear
wave velocity. Current research is centered in prototype testing and
validation. The geometric optimization of the transducer was able
to annihilate the compressional wave emission, generating a quite
pure shear torsional wave. Currently, mechanical and electromagnetic
coupling between emitter and receiver signals are being the research
focus. Conclusions: the design overcomes the main described
problems. The almost pure shear torsional wave along with the short
time of flight avoids the possibility of multiple wave interference.
This short propagation distance reduce the effect of attenuation, and
allow the emission of very low energies assuring a good biological
security for human use.
Abstract: In this paper, we consider a non-identically independently distributed (non-i.i.d.) Hoyt fading single-input multiple-out put (SIMO) channel, where the transmitter sends some confidential information to the legitimate receiver in presence of an eavesdropper. We formulated the probability of non-zero secrecy mutual information; secure outage probability and average secrecy mutual information (SMI) for the SIMO wireless communication system. The calculation has been carried out using small limit argument approximation (SLAA) on zeroth-order modified Bessel function of first kind. In our proposed model, an eavesdropper observes transmissions of information through another Hoyt fading channel. First, we derived the analytical expression for non-zero secrecy mutual information. Then, we find the secure outage probability to investigate the outage behavior of the proposed model. Finally, we find the average secrecy mutual information. We consider that the channel state information (CSI) is known to legitimate receiver.
Abstract: Improving added value and productivity of services entails improving both value-in-exchange and value-in-use. Value-in-use is realized by value co-creation, where providers and receivers create value together. In higher education services, value-in-use comes from learners achieving learning outcomes (e.g., knowledge and skills) that are consistent with their learning goals. To enhance the learning outcomes of a learner, it is necessary to enhance and utilize the abilities of the teacher along with the abilities of the learner. To do this, however, the learner and the teacher need to build a consensus about their respective roles. Teachers need to provide effective learning content; learners need to choose the appropriate learning strategies by using the learning content through consensus building. This makes consensus building an important factor in value co-creation. However, methods to build a consensus about their respective roles may not be clearly established, making such consensus difficult. In this paper, we propose some strategies for consensus building between a teacher and a learner in value co-creation. We focus on a teacher and learner co-design and propose an analysis method to clarify a collaborative design process to realize value co-creation. We then analyze some counseling data obtained from a university class. This counseling aimed to build a consensus for value-in-use, learning outcomes, and learning strategies between the teacher and the learner.
Abstract: Wireless networks are built upon the open shared
medium which makes easy for attackers to conduct malicious
activities. Jamming is one of the most serious security threats to
information economy and it must be dealt efficiently. Jammer
prevents legitimate data to reach the receiver side and also it
seriously degrades the network performance. The objective of this
paper is to provide a general overview of jamming in wireless
network. It covers relevant works, different jamming techniques,
various types of jammers and typical prevention techniques.
Challenges associated with comparing several anti-jamming
techniques are also highlighted.
Abstract: Fading noise degrades the performance of cellular
communication, most notably in femto- and pico-cells in 3G and 4G
systems. When the wireless channel consists of a small number of
scattering paths, the statistics of fading noise is not analytically
tractable and poses a serious challenge to developing closed
canonical forms that can be analysed and used in the design of
efficient and optimal receivers. In this context, noise is multiplicative
and is referred to as stochastically local fading. In many analytical
investigation of multiplicative noise, the exponential or Gamma
statistics are invoked. More recent advances by the author of this
paper utilized a Poisson modulated-weighted generalized Laguerre
polynomials with controlling parameters and uncorrelated noise
assumptions. In this paper, we investigate the statistics of multidiversity
stochastically local area fading channel when the channel
consists of randomly distributed Rayleigh and Rician scattering
centers with a coherent Nakagami-distributed line of sight component
and an underlying doubly stochastic Poisson process driven by a
lognormal intensity. These combined statistics form a unifying triply
stochastic filtered marked Poisson point process model.
Abstract: A solar receiver is designed for operation under
extremely uneven heat flux distribution, cyclic weather, and cloud
transient cycle conditions, which can include large thermal stress and
even receiver failure. In this study, the effect of different oil velocity
on convection coefficient factor and impact of wind velocity on local
Nusselt number by Finite Volume Method will be analyzed. This
study is organized to give an overview of the numerical modeling
using a MATLAB software, as an accurate, time efficient and
economical way of analyzing the heat transfer trends over stationary
receiver tube for different Reynolds number. The results reveal when
oil velocity is below 0.33m/s, the value of convection coefficient is
negligible at low temperature. The numerical graphs indicate that
when oil velocity increases up to 1.2 m/s, heat convection coefficient
increases significantly. In fact, a reduction in oil velocity causes a
reduction in heat conduction through the glass envelope. In addition,
the different local Nusselt number is reduced when the wind blows
toward the concave side of the collector and it has a significant effect
on heat losses reduction through the glass envelope.
Abstract: This paper describes a subarray based low
computational design method of multiuser massive multiple
input multiple output (MIMO) system. In our previous works, use of
large array is assumed only in transmitter, but this study considers
the case both of transmitter and receiver sides are equipped with
large array antennas. For this aim, receive arrays are also divided
into several subarrays, and the former proposed method is modified
for the synthesis of a large array from subarrays in both ends.
Through computer simulations, it is verified that the performance
of the proposed method is degraded compared with the original
approach, but it can achieve the improvement in the aspect of
complexity, namely, significant reduction of the computational load
to the practical level.
Abstract: Cole-Cole parameters of 40 post-menopausal women
are compared with their DEXA bone mineral density measurements.
Impedance characteristics of four extremities are compared; left and
right extremities are statistically same, but lower extremities are
statistically different than upper ones due to their different fat
content. The correlation of Cole-Cole impedance parameters to bone
mineral density (BMD) is observed to be higher for dominant arm.
With the post-menopausal population, ANOVA tests of the dominant
arm characteristic frequency, as a predictor for DEXA classified
osteopenic and osteoporic population around lumbar spine, is
statistically very significant. When used for total lumbar spine
osteoporosis diagnosis, the area under the Receiver Operating Curve
of the characteristic frequency is 0.830, suggesting that the Cole-Cole
plot characteristic frequency could be a useful diagnostic parameter
when integrated into standard screening methods for osteoporosis.
Moreover, the characteristic frequency can be directly measured by
monitoring frequency driven angular behavior of the dominant arm
without performing any complex calculation.
Abstract: In this paper, we consider a cognitive relay network
(CRN) in which the primary receiver (PR) is protected by peak
transmit power ¯PST and/or peak interference power Q constraints.
In addition, the interference effect from the primary transmitter (PT)
is considered to show its impact on the performance of the CRN. We
investigate the outage probability (OP) and outage capacity (OC) of
the CRN by deriving closed-form expressions over Rayleigh fading
channel. Results show that both the OP and OC improve by increasing
the cooperative relay nodes as well as when the PT is far away from
the SR.
Abstract: Multiple User Interference (MUI) considers the
primary problem in Optical Code-Division Multiple Access
(OCDMA), which resulting from the overlapping among the users. In
this article we aim to mitigate this problem by studying an
interference cancellation scheme called successive interference
cancellation (SIC) scheme. This scheme will be tested on two
different detection schemes, spectral amplitude coding (SAC) and
direct detection systems (DS), using partial modified prime (PMP) as
the signature codes. It was found that SIC scheme based on both SAC
and DS methods had a potential to suppress the intensity noise, that is
to say it can mitigate MUI noise. Furthermore, SIC/DS scheme
showed much lower bit error rate (BER) performance relative to
SIC/SAC scheme for different magnitude of effective power. Hence,
many more users can be supported by SIC/DS receiver system.
Abstract: In this paper, we present a four-step ortho-rectification
procedure for real-time geo-referencing of video data from a low-cost
UAV equipped with a multi-sensor system. The basic procedures for
the real-time ortho-rectification are: (1) decompilation of the video
stream into individual frames; (2) establishing the interior camera
orientation parameters; (3) determining the relative orientation
parameters for each video frame with respect to each other; (4)
finding the absolute orientation parameters, using a self-calibration
bundle and adjustment with the aid of a mathematical model. Each
ortho-rectified video frame is then mosaicked together to produce a
mosaic image of the test area, which is then merged with a well
referenced existing digital map for the purpose of geo-referencing
and aerial surveillance. A test field located in Abuja, Nigeria was
used to evaluate our method. Video and telemetry data were collected
for about fifteen minutes, and they were processed using the four-step
ortho-rectification procedure. The results demonstrated that the
geometric measurement of the control field from ortho-images is
more accurate when compared with those from original perspective
images when used to pin point the exact location of targets on the
video imagery acquired by the UAV. The 2-D planimetric accuracy
when compared with the 6 control points measured by a GPS receiver
is between 3 to 5 metres.
Abstract: In recent years, multi-antenna techniques are being considered as a potential solution to increase the flow of future wireless communication systems. The objective of this article is to study the emission and reception system MIMO (Multiple Input Multiple Output), and present the different reception decoding techniques. First we will present the least complex technical, linear receivers such as the zero forcing equalizer (ZF) and minimum mean squared error (MMSE). Then a nonlinear technique called ordered successive cancellation of interferences (OSIC) and the optimal detector based on the maximum likelihood criterion (ML), finally, we simulate the associated decoding algorithms for MIMO system such as ZF, MMSE, OSIC and ML, thus a comparison of performance of these algorithms in MIMO context.
Abstract: UAV’s are small remote operated or automated aerial
surveillance systems without a human pilot aboard. UAV’s generally
finds its use in military and special operation application, a recent
growing trend in UAV’s finds its application in several civil and nonmilitary
works such as inspection of power or pipelines. The
objective of this paper is the augmentation of a UAV in order to
replace the existing expensive sonar (Sound Navigation And
Ranging) based equipment amongst small scale fisherman, for whom
access to sonar equipment are restricted due to limited economic
resources. The surveillance equipment’s present in the UAV will
relay data and GPS (Global Positioning System) location onto a
receiver on the fishing boat using RF signals, using which the
location of the schools of fishes can be found. In addition to this, an
emergency beacon system is present for rescue operations and drone
recovery.
Abstract: A compound parabolic concentrator (CPC) is a wellknown
non-imaging concentrator that will concentrate the solar
radiation onto receiver (PV cell). One of disadvantage of CPC is has
tall and narrow height compared to its diameter entry aperture area.
Therefore, for economic reason, a truncation had been done by
removed from the top of the full height CPC. This also will lead to
the decreases of concentration ratio but it will be negligible. In this
paper, the flux distribution of untruncated and truncated 2-D hollow
compound parabolic trough concentrator (hCPTC) design is
presented. The untruncated design has initial height H=193.4mm
with concentration ratio C_(2-D)=4. This paper presents the optical
simulation of compound parabolic trough concentrator using raytracing
software TracePro. Results showed that, after the truncation,
the height of CPC reduced 45% from initial height with the
geometrical concentration ratio only decrease 10%. Thus, the cost of
reflector and material dielectric usage can be saved especially at
manufacturing site.
Abstract: A new steganographic method via the use of numeric
data on public websites with a self-authentication capability is
proposed. The proposed technique transforms a secret message into
partial shares by Shamir’s (k, n)-threshold secret sharing scheme with
n = k + 1. The generated k+1 partial shares then are embedded into the
numeric items to be disguised as part of the website’s numeric content,
yielding the stego numeric content. Afterward, a receiver links to the
website and extracts every k shares among the k+1 ones from the stego
numeric content to compute k+1 copies of the secret, and the
phenomenon of value consistency of the computed k+1 copies is taken
as an evidence to determine whether the extracted message is authentic
or not, attaining the goal of self-authentication of the extracted secret
message. Experimental results and discussions are provided to show
the feasibility and effectiveness of the proposed method.
Abstract: One of the crucial parameters of digital cryptographic
systems is the selection of the keys used and their distribution. The
randomness of the keys has a strong impact on the system’s security
strength being difficult to be predicted, guessed, reproduced, or
discovered by a cryptanalyst. Therefore, adequate key randomness
generation is still sought for the benefit of stronger cryptosystems.
This paper suggests an algorithm designed to generate and test
pseudo random number sequences intended for cryptographic
applications. This algorithm is based on mathematically manipulating
a publically agreed upon information between sender and receiver
over a public channel. This information is used as a seed for
performing some mathematical functions in order to generate a
sequence of pseudorandom numbers that will be used for
encryption/decryption purposes. This manipulation involves
permutations and substitutions that fulfill Shannon’s principle of
“confusion and diffusion”. ASCII code characters were utilized in the
generation process instead of using bit strings initially, which adds
more flexibility in testing different seed values. Finally, the obtained
results would indicate sound difficulty of guessing keys by attackers.
Abstract: Employer branding is considered as a useful tool for
addressing the global-local problem facing complex organisations
that have operations scattered across the globe and face challenges of
dealing with the local environment alongside. Despite being an
established field of study within the Western developed world, there
is little empirical evidence concerning the relevance of employer
branding to global companies that operate in the under-developed
economies. This paper fills this gap by gaining rich insight into the
implementation of employer branding programs in a foreign
multinational operating in Pakistan dealing with the global-local
problem. The study is qualitative in nature and employs semistructured
and focus group interviews with senior/middle managers
and local frontline employees to deeply examine the phenomenon in
case organisation. Findings suggest that authenticity is required in
employer brands to enable them to respond to the local needs thereby
leading to the resolution of the global-local problem. However, the
role of signaling theory is key to the development of authentic
employer brands as it stresses on the need to establish an efficient and
effective signaling environment where in signals travel in both
directions (from signal designers to receivers and backwards) and
facilitate firms with the global-local problem. The paper also
identifies future avenues of research for the employer branding field.
Abstract: The idea of the asynchronous transmission in
wavelength division multiplexing (WDM) ring MANs is studied in
this paper. Especially, we present an efficient access technique to
coordinate the collisions-free transmission of the variable sizes of IP
traffic in WDM ring core networks. Each node is equipped with a
tunable transmitter and a tunable receiver. In this way, all the
wavelengths are exploited for both transmission and reception. In
order to evaluate the performance measures of average throughput,
queuing delay and packet dropping probability at the buffers, a
simulation model that assumes symmetric access rights among the
nodes is developed based on Poisson statistics. Extensive numerical
results show that the proposed protocol achieves apart from high
bandwidth exploitation for a wide range of offered load, fairness of
queuing delay and dropping events among the different packets size
categories.