Abstract: This paper proposes an active soft-switching circuit for
bridge converters aiming to improve the power conversion efficiency.
The proposed circuit achieves loss-less switching for both main and
auxiliary switches without increasing the main switch current/voltage
rating. A winding coupled to the primary of power transformer
ensures ZCS for the auxiliary switches during their turn-off. A 350 W,
100 kHz phase shifted full bridge (PSFB) converter is built to validate
the analysis and design. Theoretical loss calculations for proposed
circuit is presented. The proposed circuit is compared with passive
soft switched PSFB in terms of efficiency and loss in duty cycle.
Abstract: In this paper, a new method of image edge-detection
and characterization is presented. “Parametric Filtering method" uses
a judicious defined filter, which preserves the signal correlation
structure as input in the autocorrelation of the output. This leads,
showing the evolution of the image correlation structure as well as
various distortion measures which quantify the deviation between
two zones of the signal (the two Hamming signals) for the protection
of an image edge.
Abstract: This research study the application of the immobilized
TiO2 layer and Cu-TiO2 layer on graphite substrate as a negative
electrode or anode for Li-ion battery. The titania layer was produced
through chemical bath deposition method, meanwhile Cu particles
were deposited electrochemically. A material can be used as an
electrode as it has capability to intercalates Li ions into its crystal
structure. The Li intercalation into TiO2/Graphite and Cu-
TiO2/Graphite were analyzed from the changes of its XRD pattern
after it was used as electrode during discharging process. The XRD
patterns were refined by Le Bail method in order to determine the
crystal structure of the prepared materials. A specific capacity and the
cycle ability measurement were carried out to study the performance
of the prepared materials as negative electrode of the Li-ion battery.
The specific capacity was measured during discharging process from
fully charged until the cut off voltage. A 300 was used as a load.
The result shows that the specific capacity of Li-ion battery with
TiO2/Graphite as negative electrode is 230.87 ± 1.70mAh.g-1 which is
higher than the specific capacity of Li-ion battery with pure graphite
as negative electrode, i.e 140.75 ±0.46mAh.g-1. Meanwhile
deposition of Cu onto TiO2 layer does not increase the specific
capacity, and the value even lower than the battery with
TiO2/Graphite as electrode. The cycle ability of the prepared battery
is only two cycles, due to the Li ribbon which was used as cathode
became fragile and easily broken.
Abstract: In this paper, a theoretical formula is presented to
predict the instantaneous folding force of the first fold creation in a
square column under axial loading. Calculations are based on analysis
of “Basic Folding Mechanism" introduced by Wierzbicki and
Abramowicz. For this purpose, the sum of dissipated energy rate under
bending around horizontal and inclined hinge lines and dissipated
energy rate under extensional deformations are equated to the work rate
of the external force on the structure. Final formula obtained in this
research, reasonably predicts the instantaneous folding force of the first
fold creation versus folding distance and folding angle and also predicts
the instantaneous folding force instead of the average value. Finally,
according to the calculated theoretical relation, instantaneous folding
force of the first fold creation in a square column was sketched
versus folding distance and was compared to the experimental results
which showed a good correlation.
Abstract: Multimedia distributed systems deal with heterogeneous
data, such as texts, images, graphics, video and audio. The specification
of temporal relations among different data types and distributed
sources is an open research area. This paper proposes a fully
distributed synchronization model to be used in multimedia systems.
One original aspect of the model is that it avoids the use of a common
reference (e.g. wall clock and shared memory). To achieve this, all
possible multimedia temporal relations are specified according to
their causal dependencies.
Abstract: We introduce and study the class of weak almost Dunford-Pettis operators. As an application, we characterize Banach lattices with the weak Dunford-Pettis property. Also, we establish some sufficient conditions for which each weak almost Dunford-Pettis operator is weak Dunford-Pettis. Finally, we derive some interesting results.
Abstract: The complexity of lignocellulosic biomass requires
a pretreatment step to improve the yield of fermentable sugars. The
efficient pretreatment of corn cobs using microwave and potassium
hydroxide and enzymatic hydrolysis was investigated. The
objective of this work was to characterize the optimal condition of
pretreatment of corn cobs using microwave and potassium
hydroxide enhance enzymatic hydrolysis. Corn cobs were
submerged in different potassium hydroxide concentration at varies
temperature and resident time. The pretreated corn cobs were
hydrolyzed to produce the reducing sugar for analysis. The
morphology and microstructure of samples were investigated by
Thermal gravimetric analysis (TGA, scanning electron microscope
(SEM), X-ray diffraction (XRD). The results showed that lignin
and hemicellulose were removed by microwave/potassium
hydroxide pretreatment. The crystallinity of the pretreated corn
cobs was higher than the untreated. This method was compared
with autoclave and conventional heating method. The results
indicated that microwave-alkali treatment was an efficient way to
improve the enzymatic hydrolysis rate by increasing its
accessibility hydrolysis enzymes.
Abstract: Heat transfer from two cam shape cylinder in tandem
arrangement had been studied numerically.
The distance between the centers of cylinders (L) is allowed to
vary to change the longitudinal pitch ratio (L/Deq). The equivalent
diameter of the cylinder (Deq) is 27.6 mm and longitudinal pitch ratio
varies in range 2
Abstract: The IDR(s) method based on an extended IDR theorem was proposed by Sonneveld and van Gijzen. The original IDR(s) method has excellent property compared with the conventional iterative methods in terms of efficiency and small amount of memory. IDR(s) method, however, has unexpected property that relative residual 2-norm stagnates at the level of less than 10-12. In this paper, an effective strategy for stagnation detection, stagnation avoidance using adaptively information of parameter s and improvement of convergence rate itself of IDR(s) method are proposed in order to gain high accuracy of the approximated solution of IDR(s) method. Through numerical experiments, effectiveness of adaptive tuning IDR(s) method is verified and demonstrated.
Abstract: The research investigates the effects of super plasticizer and molarity of sodium hydroxide alkaline solution on the workability, microstructure and compressive strength of self compacting geopolymer concrete (SCGC). SCGC is an improved way of concreting execution that does not require compaction and is made by complete elimination of ordinary Portland cement content. The parameters studied were superplasticizer (SP) dosage and molarity of NaOH solution. SCGC were synthesized from low calcium fly ash, activated by combinations of sodium hydroxide and sodium silicate solutions, and by incorporation of superplasticizer for self compactability. The workability properties such as filling ability, passing ability and resistance to segregation were assessed using slump flow, T-50, V-funnel, L-Box and J-ring test methods. It was found that the essential workability requirements for self compactability according to EFNARC were satisfied. Results showed that the workability and compressive strength improved with the increase in superplasticizer dosage. An increase in strength and a decrease in workability of these concrete samples were observed with the increase in molarity of NaOH solution from 8M to 14M. Improvement of interfacial transition zone (ITZ) and micro structure with the increase of SP and increase of concentration from 8M to 12M were also identified.
Abstract: Mercury is a natural occurring element and present in
various concentrations in the environment. Due to its toxic effects, it
is desirable to research mercury sensitive materials to adsorb
mercury. This paper describes the preparation of Au nanoparticles for
mercury adsorption by using a microwave (MW)-polyol method in
the presence of three different Sodium Chloride (NaCl)
concentrations (10, 20 and 30 mM). Mixtures of spherical, triangular,
octahedral, decahedral particles and 1-D product were obtained using
this rapid method. Sizes and shapes was found strongly depend on the
concentrations of NaCl. Without NaCl concentration, spherical,
triangular plates, octahedral, decahedral nanoparticles and 1D
product were produced. At the lower NaCl concentration (10 mM),
spherical, octahedral and decahedral nanoparticles were present,
while spherical and decahedral nanoparticles were preferentially form
by using 20 mM of NaCl concentration. Spherical, triangular plates,
octahedral and decahedral nanoparticles were obtained at the highest
NaCl concentration (30 mM). The amount of mercury adsorbed using
20 ppm mercury solution is the highest (67.5 %) for NaCl
concentration of 30 mM. The high yield of polygonal particles will
increase the mercury adsorption. In addition, the adsorption of
mercury is also due to the sizes of the particles. The sizes of particles
become smaller with increasing NaCl concentrations (size ranges, 5-
16 nm) than those synthesized without addition of NaCl (size ranges
11-32 nm). It is concluded that NaCl concentrations affects the
formation of sizes and shapes of Au nanoparticles thus affects the
mercury adsorption.
Abstract: In recent years a number of applications with multirobot
systems (MRS) is growing in various areas. But their design
is in practice often difficult and algorithms are proposed for the
theoretical background and do not consider errors and noise in real
conditions, so they are not usable in real environment. These errors
are visible also in task of target localization enough, when robots
try to find and estimate the position of the target by the sensors.
Localization of target is possible also with one robot but as it was
examined target finding and localization with group of mobile robots
can estimate the target position more accurately and faster. The
accuracy of target position estimation is made by cooperation of
MRS and particle filtering. Advantage of usage the MRS with particle
filtering was tested on task of fixed target localization by group of
mobile robots.
Abstract: In this paper, an inventory model with finite and
constant replenishment rate, price dependant demand rate, time
value of money and inflation, finite time horizon, lead time and
exponential deterioration rate and with the objective of maximizing
the present worth of the total system profit is developed. Using a
dynamic programming based solution algorithm, the optimal
sequence of the cycles can be found and also different optimal
selling prices, optimal order quantities and optimal maximum
inventories can be obtained for the cycles with unequal lengths,
which have never been done before for this model. Also, a
numerical example is used to show accuracy of the solution
procedure.
Abstract: Cryptography, Image watermarking and E-banking are
filled with apparent oxymora and paradoxes. Random sequences are
used as keys to encrypt information to be used as watermark during
embedding the watermark and also to extract the watermark during
detection. Also, the keys are very much utilized for 24x7x365
banking operations. Therefore a deterministic random sequence is
very much useful for online applications. In order to obtain the same
random sequence, we need to supply the same seed to the generator.
Many researchers have used Deterministic Random Number
Generators (DRNGs) for cryptographic applications and Pseudo
Noise Random sequences (PNs) for watermarking. Even though,
there are some weaknesses in PN due to attacks, the research
community used it mostly in digital watermarking. On the other hand,
DRNGs have not been widely used in online watermarking due to its
computational complexity and non-robustness. Therefore, we have
invented a new design of generating DRNG using Pi-series to make it
useful for online Cryptographic, Digital watermarking and Banking
applications.
Abstract: Passive systems were born with the purpose of the
greatest exploitation of solar energy in cold climates and high
altitudes. They spread themselves until the 80-s all over the world
without any attention to the specific climate and the summer
behavior; this caused the deactivation of the systems due to a series
of problems connected to the summer overheating, the complex
management and the rising of the dust.
Until today the European regulation limits only the winter
consumptions without any attention to the summer behavior but, the
recent European EN 15251 underlines the relevance of the indoor
comfort, and the necessity of the analytic studies validation by
monitoring case studies.
In the porpose paper we demonstrate that the solar wall is an
efficient system both from thermal comfort and energy saving point
of view and it is the most suitable for our temperate climates because
it can be used as a passive cooling sistem too. In particular the paper
present an experimental and numerical analisys carried out on a case
study with nine different solar passive systems in Ancona, Italy.
We carried out a detailed study of the lodging provided by the
solar wall by the monitoring and the evaluation of the indoor
conditions.
Analyzing the monitored data, on the base of recognized models
of comfort (ISO, ASHRAE, Givoni-s BBCC), is emerged that the
solar wall has an optimal behavior in the middle seasons. In winter
phase this passive system gives more advantages in terms of energy
consumptions than the other systems, because it gives greater heat
gain and therefore smaller consumptions. In summer, when outside
air temperature return in the mean seasonal value, the indoor comfort
is optimal thanks to an efficient transversal ventilation activated from
the same wall.
Abstract: Many companies have switched their processes to project-oriented in the last years. This brings new possibilities and effectiveness not only in the field of external processes connected with the product delivery but also the internal processes as well. However centralized project organization which is based on the role of project manager in the team has proved insufficient in some cases. Agile methods of project organization are trying to solve this problem by bringing new view on the project organization, roles, processes and competences. Scrum is one of these methods which builds on the principles of knowledge management to drive the project to effectiveness from all view angles. Using this method to organize internal and delivery projects helps the organization to create and share knowledge throughout the company. It also supports forming unique competences of individuals and project teams and drives innovations in the company.
Abstract: School homework has been synonymous with students- life in Chinese national type primary schools in Malaysia. Although many reports in the press claimed that students were burdened with too much of it, homework continues to be a common practice in national type schools that is believed to contribute to academic achievement. This study is conducted to identify the relationship between the burden of school homework and academic achievement among pupils in Chinese National Type Primary School in the state of Perak, Malaysia. A total of 284 students (142 from urban and 142 from rural) respectively were chosen as participants in this study. Variables of gender and location (urban/rural areas) has shown significant difference in student academic achievement. Female Chinese student from rural areas showed a higher mean score than males from urban area. Therefore, the Chinese language teachers should give appropriate and relevant homework to primary school students to achieve good academic performance.
Abstract: As the data-driven economy is growing faster than
ever and the demand for energy is being spurred, we are facing
unprecedented challenges of improving energy efficiency in data
centers. Effectively maximizing energy efficiency or minimising the
cooling energy demand is becoming pervasive for data centers. This
paper investigates overall energy consumption and the energy
efficiency of cooling system for a data center in Finland as a case
study. The power, cooling and energy consumption characteristics
and operation condition of facilities are examined and analysed.
Potential energy and cooling saving opportunities are identified and
further suggestions for improving the performance of cooling system
are put forward. Results are presented as a comprehensive evaluation
of both the energy performance and good practices of energy
efficient cooling operations for the data center. Utilization of an
energy recovery concept for cooling system is proposed. The
conclusion we can draw is that even though the analysed data center
demonstrated relatively high energy efficiency, based on its power
usage effectiveness value, there is still a significant potential for
energy saving from its cooling systems.
Abstract: The Norwegian Military Academy (Army) has
initiated a project with the main ambition to explore possible avenues
to enhancing operational effectiveness through an increased use of
simulation-based training and exercises. Within a cost/benefit
framework, we discuss opportunities and limitations of vertical and
horizontal integration of the existing tactical training system. Vertical
integration implies expanding the existing training system to span the
full range of training from tactical level (platoon, company) to
command and staff level (battalion, brigade). Horizontal integration
means including other domains than army tactics and staff
procedures in the training, such as military ethics, foreign languages,
leadership and decision making. We discuss each of the integration
options with respect to purpose and content of training, "best
practice" for organising and conducting simulation-based training,
and suggest how to evaluate training procedures and measure
learning outcomes. We conclude by giving guidelines towards further
explorative work and possible implementation.
Abstract: New nondestructive technique, namely an inverse technique based on vibration tests, to characterize nonlinear mechanical properties of adhesive layers in sandwich composites is developed. An adhesive layer is described as a viscoelastic isotropic material with storage and loss moduli which are both frequency dependent values in wide frequency range. An optimization based on the planning of experiments and response surface technique to minimize the error functional is applied to decrease considerably the computational expenses. The developed identification technique has been tested on aluminum panels and successfully applied to characterize viscoelastic material properties of 3M damping polymer ISD-112 used as a core material in sandwich panels.