Abstract: Modern low earth orbit (LEO) satellites that require multi-mission flexibility are highly likely to be repositioned between different operational orbits. While executing this process the satellite may experience high levels of vibration and environmental hazards, exposing the deployed solar panel to dangerous stress levels, fatigue and space debris, hence it is desirable to retract the solar array before satellite repositioning to avoid damage or failure.
A novel concept of deployable/retractable hybrid solar array systemcomposed of both rigid and flexible solar panels arranged within a petal formation, aimed to provide a greater power to volume ratio while dramatically reducing mass and cost is proposed.
Abstract: Sandwich structure composites produced by epoxy
core and aluminium skin were developed as potential building
materials. Interface bonding between core and skin was controlled by
varying kenaf content. Five different weight percentage of kenaf
loading ranging from 10 wt% to 50 wt% were employed in the core
manufacturing in order to study the mechanical properties of the
sandwich composite. Properties of skin aluminium with epoxy were
found to be affected by drying time of the adhesive. Mechanical
behavior of manufactured sandwich composites in relation with
properties of constituent materials was studied. It was found that 30
wt% of kenaf loading contributed to increase the flexural strength and
flexural modulus up to 102 MPa and 32 GPa, respectively. Analysis
were done on the flatwise and edgewise compression test. For
flatwise test, it was found that 30 wt% of fiber loading could
withstand maximum force until 250 kN, with compressive strength
results at 96.94 MPa. However, at edgewise compression test, the
sandwich composite with same fiber loading only can withstand 31
kN of the maximum load with 62 MPa of compressive strength
results.
Abstract: The 6th version of Universal modeling method for
centrifugal compressor stage calculation is described. Identification
of the new mathematical model was made. As a result of
identification the uniform set of empirical coefficients is received.
The efficiency definition error is 0,86 % at a design point. The
efficiency definition error at five flow rate points (except a point of
the maximum flow rate) is 1,22 %. Several variants of the stage with
3D impellers designed by 6th version program and quasi threedimensional
calculation programs were compared by their gas
dynamic performances CFD (NUMECA FINE TURBO).
Performance comparison demonstrated general principles of design
validity and leads to some design recommendations.
Abstract: Fiber Bragg optic sensor is embedded in composite
material to detect and monitor the damage that occurs in composite
structures. In this paper, we deal with the mode-Ι delamination to
determine the material strength to crack propagation, using the
coupling mode theory and T-matrix method to simulate the FBGs
spectrum for both uniform and non-uniform strain distribution. The
double cantilever beam test is modeled in FEM to determine the
longitudinal strain. Two models are implemented, the first is the
global half model, and the second is the sub-model to represent the
FBGs with higher refined mesh. This method can simulate damage in
composite structures and converting strain to a wavelength shifting in
the FBG spectrum.
Abstract: This study was carried out to evaluate the nutritional
composition of the African River Prawn (Macrobrachium
vollenhovenii) in relation to Chokor (traditional) and Altona
(improved traditional) drying techniques used in the preservation and
processing of prawns by carrying out proximate composition
analysis. The value obtained for the proximate analysis of Chokor
and Altona smoke dried prawns were; Moisture (14.90% and
15.15%), Dry matter (85.10% and 84.85%), Protein (55.80% and
58.87%), Crude fat (1.95% and 1.98%), Crude fibre (21.40% and
13.11%), Carbohydrate (0.54% and 0.54%) and Ash (19.76% and
15.86%) respectively. The proximate mineral composition of Chokor
and Altona smoke dried prawns were; Calcium (5.66% and 4.20%)
and Phosphorus (9. 22% and 6.34%) respectively. Result shows there
was no loss of nutritional value with respect to Chokor and Altona
drying techniques used in the processing of prawns.
Abstract: Ocimum americanum L (Lamiaceae) is an annual herb
that is native to tropical Africa. The in vitro and in vivo antioxidant
activity of its aqueous extract was carefully investigated by assessing
the DPPH radical scavenging activity, ABTS radical scavenging
activity and hydrogen peroxide radical scavenging activity. The
reducing power, total phenol, total flavonoids and flavonols content
of the extract were also evaluated. The data obtained revealed that the
extract is rich in polyphenolic compounds and scavenged the radicals
in a concentration dependent manner. This was done in comparison
with the standard antioxidants such as BHT and Vitamin C. Also, the
induction of oxidative damage with paracetamol (2000 mg/kg)
resulted in the elevation of lipid peroxides and significant (P < 0.05)
decrease in activities of superoxide dismutase, glutathione
peroxidase, glutathione reductase and catalase in the liver and kidney
of rats. However, the pretreatment of rats with aqueous extract of O.
americanum leaves (200 and 400 mg/kg) and silymarin (100 mg/kg)
caused a significant (P < 0.05) reduction in the values of lipid
peroxides and restored the levels of antioxidant parameters in these
organs. These findings suggest that the leaves of O. americanum have
potent antioxidant properties which may be responsible for its
acclaimed folkloric uses.
Abstract: This study concerned the dynamic behavior of the
wind turbine rotor. Before all we have studied the loads applied to the
rotor, which allows the knowledge their effect on the fatigue, also
studied the rotor with longitudinal crack in order to determine stress,
strain and displacement. Firstly we compared the first six modes
shapes between cracking and uncracking of HAWT rotor. Secondly
we show show evolution of first six natural frequencies with
longitudinal crack propagation. Finally we conclude that the residual
change in the natural frequencies can be used as in shaft crack
diagnosis predictive maintenance.
Abstract: Speech enhancement is a long standing problem with
numerous applications like teleconferencing, VoIP, hearing aids and
speech recognition. The motivation behind this research work is to
obtain a clean speech signal of higher quality by applying the optimal
noise cancellation technique. Real-time adaptive filtering algorithms
seem to be the best candidate among all categories of the speech
enhancement methods. In this paper, we propose a speech
enhancement method based on Recursive Least Squares (RLS)
adaptive filter of speech signals. Experiments were performed on
noisy data which was prepared by adding AWGN, Babble and Pink
noise to clean speech samples at -5dB, 0dB, 5dB and 10dB SNR
levels. We then compare the noise cancellation performance of
proposed RLS algorithm with existing NLMS algorithm in terms of
Mean Squared Error (MSE), Signal to Noise ratio (SNR) and SNR
Loss. Based on the performance evaluation, the proposed RLS
algorithm was found to be a better optimal noise cancellation
technique for speech signals.
Abstract: The aim of this study is to develop an anterior lumbar
interbody fusion (ALIF) PEEK cage suitable for Korean people. In this
study, CT images were obtained from Korean male (173cm, 71kg) and
3D Korean lumbar models were reconstructed based on the CT images
to investigate anatomical characteristics. Major design parameters of
anterior lumbar interbody fusion (ALIF) PEEK Cage were selected
using the morphological measurement information of the Korean
Lumbar models. Through finite element analysis and mechanical tests,
the developed ALIFPEEK Cage prototype was compared with the
Fidji Cage (Zimmer. Inc, USA) and it was found that the ALIF
prototype showed similar and/or superior mechanical performance
compared to the FidJi Cage. Also, clinical validation for the ALIF
PEEK Cage prototype was carried out to check predictable troubles in
surgical operations. Finally, it is considered that the convenience and
stability of the prototype was clinically verified.
Abstract: The Standard Penetration Test (SPT) is the most
common in situ test for soil investigations. On the other hand, the
Cone Penetration Test (CPT) is considered one of the best
investigation tools. Due to the fast and accurate results that can be
obtained it complaints the SPT in many applications like field
explorations, design parameters, and quality control assessments.
Many soil index and engineering properties have been correlated to
both of SPT and CPT. Various foundation design methods were
developed based on the outcome of these tests. Therefore it is vital to
correlate these tests to each other so that either one of the tests can be
used in the absence of the other, especially for preliminary evaluation
and design purposes.
The primary purpose of this study was to investigate the
relationships between the SPT and CPT for different type of sandy
soils in Florida. Data for this research were collected from number of
projects sponsored by the Florida Department of Transportation
(FDOT), six sites served as the subject of SPT-CPT correlations. The
correlations were established between the cone resistance (qc), sleeve
friction (fs) and the uncorrected SPT blow counts (N) for various
soils.
A positive linear relationship was found between qc, fs and N for
various sandy soils. In general, qc versus N showed higher
correlation coefficients than fs versus N. qc/N ratios were developed
for different soil types and compared to literature values, the results
of this research revealed higher ratios than literature values.
Abstract: Numeracy, like Literacy is considered to be a core
value of modern societies. Most higher education institutions in
South Africa include being numerate as an important graduate
attribute. It is argued that a suitability numerate society contributes to
social justice, empowerment, financial and environmental
sustainability and a lack of numeracy practices can contribute to
disempowerment.
Numeracy is commonly misconstrued as a basic and simple
practice, similar in nature to basic arithmetic. This study highlights
the complexities of higher education numeracy practices by analyzing
a programme in a higher education institution in South Africa using
the New Literacies Studies perspective.
Abstract: The industrial process adds to engineering wood
products features absent in solid wood, with homogeneous structure
and reduced defects, improved physical and mechanical properties,
bio-deterioration, resistance and better dimensional stability,
improving quality and increasing the reliability of structures wood.
These features combined with using fast-growing trees, make them
environmentally ecological products, ensuring a strong consumer
market. The wood I-joists are manufactured by the industrial profiles
bonding flange and web, an important aspect of the production of
wooden I-beams is the adhesive joint that bonds the web to the
flange. Adhesives can effectively transfer and distribute stresses,
thereby increasing the strength and stiffness of the composite. The
objective of this study is to evaluate different resins in a shear strain
specimens with the aim of analyzing the most efficient resin and
possibility of using national products, reducing the manufacturing
cost. First was conducted a literature review, where established the
geometry and materials generally used, then established and analyzed
8 national resins and produced six specimens for each.
Abstract: The western Tombolo of the Giens peninsula in
southern France, known as Almanarre beach, is subject to coastal
erosion. We are trying to use computer simulation in order to propose
solutions to stop this erosion. Our aim was first to determine the main
factors for this erosion and successfully apply a coupled hydrosedimentological
numerical model based on observations and
measurements that have been performed on the site for decades.
We have gathered all available information and data about waves,
winds, currents, tides, bathymetry, coastal line, and sediments
concerning the site. These have been divided into two sets: one
devoted to calibrating a numerical model using Mike 21 software, the
other to serve as a reference in order to numerically compare the
present situation to what it could be if we implemented different
types of underwater constructions.
This paper presents the first part of the study: selecting and
melting different sources into a coherent data basis, identifying the
main erosion factors, and calibrating the coupled software model
against the selected reference period.
Our results bring calibration of the numerical model with good
fitting coefficients. They also show that the winter South-Western
storm events conjugated to depressive weather conditions constitute a
major factor of erosion, mainly due to wave impact in the northern
part of the Almanarre beach. Together, current and wind impact is
shown negligible.
Abstract: The tombolo of Giens is located in the town of Hyères
(France). We recall the history of coastal erosion, and prominent
factors affecting the evolution of the western tombolo. We then
discuss the possibility of stabilizing the western tombolo. Our
argumentation relies on a coupled model integrating swells, currents,
water levels and sediment transport. We present the conclusions of
the simulations of various scenarios, including pre-existing
propositions from coastal engineering offices. We conclude that
beach replenishment seems to be necessary but not sufficient for the
stabilization of the beach. Breakwaters reveal effective particularly in
the most exposed northern area. Some solutions fulfill conditions so
as to be elected as satisfactory. We give a comparative analysis of the
efficiency of 14 alternatives for the protection of the tombolo.
Abstract: The use of technology in the classroom is an issue that
is constantly evolving. Digital age students learn differently than their
teachers did, so now the teacher should be constantly evolving their
methods and teaching techniques to be more in touch with the
student. In this paper a case study presents how were used some of
these technologies by accompanying a classroom course, this in order
to provide students with a different and innovative experience as their
teacher usually presented the activities to develop. As students
worked in the various activities, they increased their digital skills by
employing unknown tools that helped them in their professional
training. The twenty-first century teacher should consider the use of
Information and Communication Technologies in the classroom
thinking in skills that students of the digital age should possess. It
also takes a brief look at the history of distance education and it is
also highlighted the importance of integrating technology as part of
the student's training.
Abstract: Physical properties of uranium dinitride (UN2) were
investigated in detail using first principle calculations based on
density functional theory (DFT). To study the strong correlation
effects due to 5f uranium valence electrons, the on-site coulomb
interaction correction U via the Hubbard-like term (DFT+U) was
employed. The UN2 structural, mechanical and thermodynamic
properties were calculated within DFT and Various U of DFT+U
approach.
The Perdew–Burke–Ernzerhof (PBE.5.2) version of the
generalized gradient approximation (GGA) is used to describe the
exchange-correlation with the projector-augmented wave (PAW)
pseudo potentials.
A comparative study shows that results are improved by using the
Hubbard formalism for a certain U value correction like the structural
parameter. For some physical properties the variation versus
Hubbard-U is strong like Young modulus but for others it is weakly
noticeable such as bulk modulus.
We noticed also that from U=7.5 eV, elastic results don’t agree
with the cubic cell because of the C44 values which turn out to be
negative.
Abstract: In this research the effects of adding silica and
alumina nanoparticles on flow ability and compressive strength of
cementitious composites based on Portland cement were investigated.
In the first stage, the rheological behavior of different samples
containing nanosilica, nanoalumina and polypropylene, polyvinyl
alcohol and polyethylene fibers were evaluated. With increasing of
nanoparticles in fresh samples, the slump flow diameter reduced.
Fibers reduced the flow ability of the samples and viscosity
increased. With increasing of the micro silica particles to cement
ratio from 2/1 to 2/2, the slump flow diameter increased. By adding
silica and alumina nanoparticles up to 3% and 2% respectively, the
compressive strength increased and after decreased. Samples
containing silica nanoparticles and fibers had the highest compressive
strength.
Abstract: A novel hybrid model of the lumbar spine, allowing
fast static and dynamic simulations of the disc pressure
and the spine mobility, is introduced in this work. Our
contribution is to combine rigid bodies, deformable finite
elements, articular constraints, and springs into a unique model
of the spine. Each vertebra is represented by a rigid body
controlling a surface mesh to model contacts on the facet
joints and the spinous process. The discs are modeled using
a heterogeneous tetrahedral finite element model. The facet
joints are represented as elastic joints with six degrees of
freedom, while the ligaments are modeled using non-linear
one-dimensional elastic elements. The challenge we tackle
is to make these different models efficiently interact while
respecting the principles of Anatomy and Mechanics.
The mobility, the intradiscal pressure, the facet joint force and
the instantaneous center of rotation of the lumbar spine are
validated against the experimental and theoretical results of
the literature on flexion, extension, lateral bending as well as
axial rotation.
Our hybrid model greatly simplifies the modeling task and
dramatically accelerates the simulation of pressure within the
discs, as well as the evaluation of the range of motion and the
instantaneous centers of rotation, without penalizing precision.
These results suggest that for some types of biomechanical
simulations, simplified models allow far easier modeling and
faster simulations compared to usual full-FEM approaches
without any loss of accuracy.
Abstract: The present paper summarizes the analysis of the
request for consultation of information and data on industrial
emissions made publicly available on the web site of the Ministry of
Environment, Land and Sea on integrated pollution prevention and
control from large industrial installations, the so called “AIA Portal”.
As a matter of fact, a huge amount of information on national
industrial plants is already available on internet, although it is usually
proposed as textual documentation or images.
Thus, it is not possible to access all the relevant information
through interoperability systems and also to retrieval relevant
information for decision making purposes as well as rising of
awareness on environmental issue.
Moreover, since in Italy the number of institutional and private
subjects involved in the management of the public information on
industrial emissions is substantial, the access to the information is
provided on internet web sites according to different criteria; thus, at
present it is not structurally homogeneous and comparable.
To overcome the mentioned difficulties in the case of the
Coordinating Committee for the implementation of the Agreement
for the industrial area in Taranto and Statte, operating before the
IPPC permit granting procedures of the relevant installation located
in the area, a big effort was devoted to elaborate and to validate data
and information on characterization of soil, ground water aquifer and
coastal sea at disposal of different subjects to derive a global
perspective for decision making purposes. Thus, the present paper
also focuses on main outcomes matured during such experience.
Abstract: In this paper we describe one critical research
program within a complex, ongoing multi-year project (2010 to 2014
inclusive) with the overall goal to improve the learning outcomes for
first year undergraduate commerce/business students within an
Information Systems (IS) subject with very large enrolment. The
single research program described in this paper is the analysis of
student attitudes and decision making in relation to the availability of
formative assessment feedback via Web-based real time conferencing
and document exchange software (Adobe Connect). The formative
assessment feedback between teaching staff and students is in respect
of an authentic problem-based, team-completed assignment. The
analysis of student attitudes and decision making is investigated via
both qualitative (firstly) and quantitative (secondly) application of the
Theory of Planned Behavior (TPB) with a two statistically-significant
and separate trial samples of the enrolled students. The initial
qualitative TPB investigation revealed that perceived self-efficacy,
improved time-management, and lecturer-student relationship
building were the major factors in shaping an overall favorable
student attitude to online feedback, whilst some students expressed
valid concerns with perceived control limitations identified within the
online feedback protocols. The subsequent quantitative TPB
investigation then confirmed that attitude towards usage, subjective
norms surrounding usage, and perceived behavioral control of usage
were all significant in shaping student intention to use the online
feedback protocol, with these three variables explaining 63 percent of
the variance in the behavioral intention to use the online feedback
protocol. The identification in this research of perceived behavioral
control as a significant determinant in student usage of a specific
technology component within a virtual learning environment (VLE)
suggests that VLEs could now be viewed not as a single, atomic
entity, but as a spectrum of technology offerings ranging from the
mature and simple (e.g., email, Web downloads) to the cutting-edge
and challenging (e.g., Web conferencing and real-time document
exchange). That is, that all VLEs should not be considered the same.
The results of this research suggest that tertiary students have the
technological sophistication to assess a VLE in this more selective
manner.