Abstract: The composition, vapour pressure, and heat capacity
of nine biodiesel fuels from different sources were measured. The
vapour pressure of the biodiesel fuels is modeled assuming an ideal
liquid phase of the fatty acid methyl esters constituting the fuel. New
methodologies to calculate the vapour pressure and ideal gas and
liquid heat capacities of the biodiesel fuel constituents are proposed.
Two alternative optimization scenarios are evaluated: 1) vapour
pressure only; 2) vapour pressure constrained with liquid heat
capacity. Without physical constraints, significant errors in liquid
heat capacity predictions were found whereas the constrained
correlation accurately fit both vapour pressure and liquid heat
capacity.
Abstract: Object Relational Databases (ORDB) are complex in
nature than traditional relational databases because they combine the
characteristics of both object oriented concepts and relational
features of conventional databases. Design of an ORDB demands
efficient and quality schema considering the structural, functional
and componential traits. This internal quality of the schema is
assured by metrics that measure the relevant attributes. This is
extended to substantiate the understandability, usability and
reliability of the schema, thus assuring external quality of the
schema. This work institutes a formalization of ORDB metrics;
metric definition, evaluation methodology and the calibration of the
metric. Three ORDB schemas were used to conduct the evaluation
and the formalization of the metrics. The metrics are calibrated using
content and criteria related validity based on the measurability,
consistency and reliability of the metrics. Nominal and summative
scales are derived based on the evaluated metric values and are
standardized. Future works pertaining to ORDB metrics forms the
concluding note.
Abstract: In switch mode power inverters, small sized inverters
can be obtained by increasing the switching frequency. Switching
frequency increment causes high driver losses. Also, high dt
di
and
dt
dv
produced by the switching action creates high Electromagnetic
Interference (EMI) and Radio Frequency Interference (RFI). In this
paper, a series half bridge series resonant inverter circuit is simulated
and evaluated practically to demonstrate the turn-on and turn-off
conditions during zero or close to zero voltage switching. Also, the
reverse recovery current effects of the body diode of the MOSFETs
were investigated by operating above and below resonant frequency.
Abstract: In order to define a new model of Tunisian foot
sizes and for building the most comfortable shoes, Tunisian
industrialists must be able to offer for their customers products able
to put on and adjust the majority of the target population concerned.
Moreover, the use of models of shoes, mainly from others
country, causes a mismatch between the foot and comfort of the
Tunisian shoes.
But every foot is unique; these models become uncomfortable for
the Tunisian foot. We have a set of measures produced from a
3D scan of the feet of a diverse population (women, men ...) and we
try to analyze this data to define a model of foot specific to the
Tunisian footwear design.
In this paper we propose tow new approaches to modeling a new
foot sizes model. We used, indeed, the neural networks, and specially
the Kohonen network.
Next, we combine neural networks with the concept of half-foot
size to improve the models already found. Finally, it was necessary to
compare the results obtained by applying each approach and we
decide what-s the best approach that give us the most model of foot
improving more comfortable shoes.
Abstract: In this paper parametric analytical studies have been carried out to examine the intrinsic flow physics pertaining to the liftoff time of solid propellant rockets. Idealized inert simulators of solid rockets are selected for numerical studies to examining the preignition chamber dynamics. Detailed diagnostic investigations have been carried out using an unsteady two-dimensional k-omega turbulence model. We conjectured from the numerical results that the altered variations of the igniter jet impingement angle, turbulence level, time and location of the first ignition, flame spread characteristics, the overall chamber dynamics including the boundary layer growth history are having bearing on the time for nozzle flow chocking for establishing the required thrust for the rocket liftoff. We concluded that the altered flow choking time of strap-on motors with the pre-determined identical ignition time at the lift off phase will lead to the malfunctioning of the rocket. We also concluded that, in the light of the space debris, an error in predicting the liftoff time can lead to an unfavorable launch window amounts the satellite injection errors and/or the mission failures.
Abstract: A theory for optimal filtering of infinite sets of random
signals is presented. There are several new distinctive features of the
proposed approach. First, a single optimal filter for processing any
signal from a given infinite signal set is provided. Second, the filter is
presented in the special form of a sum with p terms where each term
is represented as a combination of three operations. Each operation
is a special stage of the filtering aimed at facilitating the associated
numerical work. Third, an iterative scheme is implemented into the
filter structure to provide an improvement in the filter performance at
each step of the scheme. The final step of the scheme concerns signal
compression and decompression. This step is based on the solution of
a new rank-constrained matrix approximation problem. The solution
to the matrix problem is described in this paper. A rigorous error
analysis is given for the new filter.
Abstract: A 2.4GHz (RF) down conversion Gilbert Cell mixer,
implemented in a 0.18-μm CMOS technology with a 1.8V supply, is
presented. Current bleeding (charge injection) technique has been
used to increase the conversion gain and the linearity of the mixer.
The proposed mixer provides 10.75 dB conversion gain ( C G ) with
14.3mw total power consumption. The IIP3 and 1-dB compression
point of the mixer are 8dbm and -4.6dbm respectively, at 300 MHz
IF frequencies. Comparing the current design against the
conventional mixer design, demonstrates better performance in the
conversion gain, linearity, noise figure and port-to-port isolation.
Abstract: One of the key research issues in wireless sensor networks (WSNs) is how to efficiently deploy sensors to cover an area. In this paper, we present a Fishnet Based Dispatch Scheme (FiBDS) with energy aware mobility and interest based sensing angle. We propose two algorithms, one is FiBDS centralized algorithm and another is FiBDS distributed algorithm. The centralized algorithm is designed specifically for the non-time critical applications, commonly known as non real-time applications while the distributed algorithm is designed specifically for the time critical applications, commonly known as real-time applications. The proposed dispatch scheme works in a phase-selection manner. In this in each phase a specific constraint is dealt with according to the specified priority and then moved onto the next phase and at the end of each only the best suited nodes for the phase are chosen. Simulation results are presented to verify their effectiveness.
Abstract: This paper presents the study of induced currents and
temperature distribution in gear heated by induction process using 2D
finite element (FE) model. The model is developed by coupling
Maxwell and heat transfer equations into a multi-physics model. The
obtained results allow comparing the medium frequency (MF) and
high frequency (HF) cases and the effect of machine parameters on
the evolution of induced currents and temperature during heating.
The sensitivity study of the temperature profile is conducted and the
case hardness is predicted using the final temperature profile. These
results are validated using tests and give a good understanding of
phenomena during heating process.
Abstract: One of the main image representations in Mathematical Morphology is the 3D Shape Decomposition Representation, useful for Image Compression and Representation,and Pattern Recognition. The 3D Morphological Shape Decomposition representation can be generalized a number of times,to extend the scope of its algebraic characteristics as much as possible. With these generalizations, the Morphological Shape Decomposition 's role to serve as an efficient image decomposition tool is extended to grayscale images.This work follows the above line, and further develops it. Anew evolutionary branch is added to the 3D Morphological Shape Decomposition's development, by the introduction of a 3D Multi Structuring Element Morphological Shape Decomposition, which permits 3D Morphological Shape Decomposition of 3D binary images (grayscale images) into "multiparameter" families of elements. At the beginning, 3D Morphological Shape Decomposition representations are based only on "1 parameter" families of elements for image decomposition.This paper addresses the gray scale inter frame interpolation by means of mathematical morphology. The new interframe interpolation method is based on generalized morphological 3D Shape Decomposition. This article will present the theoretical background of the morphological interframe interpolation, deduce the new representation and show some application examples.Computer simulations could illustrate results.
Abstract: In general the images used for compression are of
different types like dark image, high intensity image etc. When these
images are compressed using Counter Propagation Neural Network,
it takes longer time to converge. The reason for this is that the given
image may contain a number of distinct gray levels with narrow
difference with their neighborhood pixels. If the gray levels of the
pixels in an image and their neighbors are mapped in such a way that
the difference in the gray levels of the neighbor with the pixel is
minimum, then compression ratio as well as the convergence of the
network can be improved. To achieve this, a Cumulative Distribution
Function is estimated for the image and it is used to map the image
pixels. When the mapped image pixels are used the Counter
Propagation Neural Network yield high compression ratio as well as
it converges quickly.
Abstract: Eco-driving allows the driver to optimize his/her behaviour in order to achieve several types of benefits: reducing pollution emissions, increasing road safety, and fuel saving. One of the main rules for adopting eco-driving is to anticipate the traffic events by avoiding strong acceleration or braking and maintaining a steady speed when possible. Therefore, drivers have to comply with speed limits and time headway. The present study explored the role of three types of motivation and social norms in predicting French drivers- intentions to comply with speed limits and time headway as eco-driving practices as well as examine the variations according to gender and age. 1234 drivers with ages between 18 and 75 years old filled in a questionnaire which was presented as part of an online survey aiming to better understand the drivers- road habits. It included items assessing: a) behavioural intentions to comply with speed limits and time headway according to three types of motivation: reducing pollution emissions, increasing road safety, and fuel saving, b) subjective and descriptive social norms regarding the intention to comply with speed limits and time headway, and c) sociodemographical variables. Drivers expressed their intention to frequently comply with speed limits and time headway in the following 6 months; however, they showed more intention to comply with speed limits as compared to time headway regardless of the type of motivation. The subjective injunctive norms were significantly more important in predicting drivers- intentions to comply with speed limits and time headway as compared to the descriptive norms. In addition, the most frequently reported type of motivation for complying with speed limits and time headway was increasing road safety followed by fuel saving and reducing pollution emissions, hence underlining a low motivation to practice eco-driving. Practical implications of the results are discussed.
Abstract: Students often adopt routine practicing as learning
strategy for mathematics. The reason is they are often bound and
trained to solving conventional-typed questions in Mathematics in
high school. This will be problematic if students further consolidate
this practice in university. Therefore, the Department of Mathematics
emphasized and integrated the Discovery-enriched approach in the
undergraduate curriculum. This paper presents the details of
implementing the Discovery-enriched Curriculum by providing
adequate platform for project-learning, expertise for guidance and
internship opportunities for students majoring in Mathematics. The
Department also provided project-learning opportunities to
mathematics courses targeted for students majoring in other science or
engineering disciplines. The outcome is promising: the research
ability and problem solving skills of students are enhanced.
Abstract: Having a very many number of pipelines all over the
country, Iran is one of the countries consists of various ecosystems
with variable degrees of fragility and robusticity as well as
geographical conditions. This study presents a state-of-the-art method
to estimate environmental risks of pipelines by recommending
rational equations including FES, URAS, SRS, RRS, DRS, LURS
and IRS as well as FRS to calculate the risks. This study was carried
out by a relative semi-quantitative approach based on land uses and
HVAs (High-Value Areas). GIS as a tool was used to create proper
maps regarding the environmental risks, land uses and distances. The
main logic for using the formulas was the distance-based approaches
and ESI as well as intersections. Summarizing the results of the
study, a risk geographical map based on the ESIs and final risk score
(FRS) was created. The study results showed that the most sensitive
and so of high risk area would be an area comprising of mangrove
forests located in the pipeline neighborhood. Also, salty lands were
the most robust land use units in the case of pipeline failure
circumstances. Besides, using a state-of-the-art method, it showed
that mapping the risks of pipelines out with the applied method is of
more reliability and convenience as well as relative
comprehensiveness in comparison to present non-holistic methods for
assessing the environmental risks of pipelines. The focus of the
present study is “assessment" than that of “management". It is
suggested that new policies are to be implemented to reduce the
negative effects of the pipeline that has not yet been constructed
completely
Abstract: The paper presents an on-line recognition machine
(RM) for continuous/isolated, dynamic and static gestures that arise
in Flight Deck Officer (FDO) training. RM is based on generic pattern
recognition framework. Gestures are represented as templates using
summary statistics. The proposed recognition algorithm exploits temporal
and spatial characteristics of gestures via dynamic programming
and Markovian process. The algorithm predicts corresponding index
of incremental input data in the templates in an on-line mode.
Accumulated consistency in the sequence of prediction provides a
similarity measurement (Score) between input data and the templates.
The algorithm provides an intuitive mechanism for automatic detection
of start/end frames of continuous gestures. In the present paper,
we consider isolated gestures. The performance of RM is evaluated
using four datasets - artificial (W TTest), hand motion (Yang) and
FDO (tracker, vision-based ). RM achieves comparable results which
are in agreement with other on-line and off-line algorithms such as
hidden Markov model (HMM) and dynamic time warping (DTW).
The proposed algorithm has the additional advantage of providing
timely feedback for training purposes.
Abstract: The main aim of the presented experiments is to
improve behaviour of sandwich structures under dynamic loading,
such as crash or explosion. Several cellular materials are widely used
as core of the sandwich structures and their properties influence
the response of the entire element under impact load. To optimize
their performance requires the characterisation of the core material
behaviour at high strain rates and identification of the underlying
mechanism. This work presents the study of high strain-rate
characteristics of a specific porous lightweight blast energy absorbing
foam using a Split Hopkinson Pressure Bar (SHPB) technique
adapted to perform tests on low strength materials. Two different
velocities, 15 and 30 m.s-1 were used to determine the strain
sensitivity of the material. Foams were designed using two types of
porous lightweight spherical raw materials with diameters of 30-
100 *m, combined with polymer matrix. Cylindrical specimens with
diameter of 15 mm and length of 7 mm were prepared and loaded
using a Split Hopkinson Pressure Bar apparatus to assess the relation
between the composition of the material and its shock wave
attenuation capacity.
Abstract: Film, as an art form playing a vital role and is a powerful tool in documenting, influencing and shaping the society. Films are the collective creation of a large number of separate individuals, each contributing with creative input, unique talents, and technical expertise to the project. Recently, the Malaysian Independent (or “Indie") filmmakers have made their presence felt by winning awards at various international film festivals. Working in the digital video (DV) format, a number of independent filmmakers really hit their stride with a range of remarkably strong titles and international recognition has been quick in coming and their works are now regularly in exhibition or in competition, winning many top prizes at prestigious festivals around the world. The interaction factors among crewmembers are emphasized as imperative for group success. An in-depth interview is conducted to analyze the social interactions and exchanges between filmmakers through Social Exchanges Theory (SET). Certainly the new millennium that was marked as the digital technology revolution has changed the face of filmmaking in Malaysia. There is a clear need to study the Malaysian independent cinema especially from the perspective of understanding what causes the independent filmmakers to work so well given all of the difficulties and constraints.
Abstract: In recent years, rehabilitation has been the subject of extensive research due to increased spending on building work and repair of built works. In all cases, it is absolutely essential to carry out methods of strengthening or repair of structural elements, and that following an inspection analysis and methodology of a correct diagnosis. The reinforced concrete columns are important elements in building structures. They support the vertical loads and provide bracing against the horizontal loads. This research about the behavior of reinforced concrete rectangular columns, rehabilitated by concrete liner, confinement FRP fabric, steel liner or cage formed by metal corners. It allows comparing the contributions of different processes used perspective section resistance elements rehabilitated compared to that is not reinforced or repaired. The different results obtained revealed a considerable gain in bearing capacity failure of reinforced sections cladding concrete, metal bracket, steel plates and a slight improvement to the section reinforced with fabric FRP. The use of FRP does not affect the weight of the structures, but the use of different techniques cladding increases the weight of elements rehabilitated and therefore the weight of the building which requires resizing foundations.
Abstract: Solar Cells are destined to supply electric energy beginning from primary resources. It can charge a battery up to 12V dc. For residential use an inverter for 12V dc to 220Vac conversion is desired. For this a static DC-AC converter is necessarily inserted between the solar cells and the distribution network. This paper describes a new P.W.M. strategy for a voltage source inverter. This modulation strategy reduces the energy losses and harmonics in the P.W.M. voltage source inverter. This technique allows the P.W.M. voltage source inverter to become a new feasible solution for solar home application.
Abstract: Future astronomical projects on large space x-ray
imaging telescopes require novel substrates and technologies for the
construction of their reflecting mirrors. The mirrors must be
lightweight and precisely shaped to achieve large collecting area with
high angular resolution. The new materials and technologies must be
cost-effective. Currently, the most promising materials are glass or
silicon foils. We focused on precise shaping these foils by thermal
forming process. We studied free and forced slumping in the
temperature region of hot plastic deformation and compared the
shapes obtained by the different slumping processes. We measured
the shapes and the surface quality of the foils. In the experiments, we
varied both heat-treatment temperature and time following our
experiment design. The obtained data and relations we can use for
modeling and optimizing the thermal forming procedure.