Abstract: Consumer electronics are pervasive. It is impossible to
imagine a household or office without DVD players, digital cameras,
printers, mobile phones, shavers, electrical toothbrushes, etc. All
these devices operate at different voltage levels ranging from 1.8 to
20 VDC, in the absence of universal standards. The voltages
available are however usually 120/230 VAC at 50/60 Hz. This
situation makes an individual electrical energy conversion system
necessary for each device. Such converters usually involve several
conversion stages and often operate with excessive losses and poor
reliability. The aim of the project presented in this paper is to design
and implement a multi-channel DC/DC converter system,
customizing the output voltage and current ratings according to the
requirements of the load. Distributed, multi-agent techniques will be
applied for the control of the DC/DC converters.
Abstract: The transient thermoelastic response of thick hollow cylinder made of functionally graded material under thermal loading is studied. The generalized coupled thermoelasticity based on the Green-Lindsay model is used. The thermal and mechanical properties of the functionally graded material are assumed to be varied in the radial direction according to a power law variation as a function of the volume fractions of the constituents. The thermal and elastic governing equations are solved by using Galerkin finite element method. All the finite element calculations were done by using commercial finite element program FlexPDE. The transient temperature, radial displacement, and thermal stresses distribution through the radial direction of the cylinder are plotted.
Abstract: This paper deals with the tuning of parameters for Automatic Generation Control (AGC). A two area interconnected hydrothermal system with PI controller is considered. Genetic Algorithm (GA) and Particle Swarm optimization (PSO) algorithms have been applied to optimize the controller parameters. Two objective functions namely Integral Square Error (ISE) and Integral of Time-multiplied Absolute value of the Error (ITAE) are considered for optimization. The effectiveness of an objective function is considered based on the variation in tie line power and change in frequency in both the areas. MATLAB/SIMULINK was used as a simulation tool. Simulation results reveal that ITAE is a better objective function than ISE. Performances of optimization algorithms are also compared and it was found that genetic algorithm gives better results than particle swarm optimization algorithm for the problems of AGC.
Abstract: Herein, we report the different types of surface morphology due to the interaction between the pure protein Insulin (INS) and catanionic surfactant mixture of Sodium Dodecyl Sulfate (SDS) and Cetyl Trimethyl Ammonium Bromide (CTAB) at air/water interface obtained by the Langmuir-Blodgett (LB) technique. We characterized the aggregations by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) in LB films. We found that the INS adsorption increased in presence of catanionic surfactant at air/water interface. The presence of small amount of surfactant induces two-stage growth kinetics due to the pure protein absorption and protein-catanionic surface micelle interaction. The protein remains in native state in presence of small amount of surfactant mixture. Smaller amount of surfactant mixture with INS is producing surface micelle type structure. This may be considered for drug delivery system. On the other hand, INS becomes unfolded and fibrillated in presence of higher amount of surfactant mixture. In both the cases, the protein was successfully immobilized on a glass substrate by the LB technique. These results may find applications in the fundamental science of the physical chemistry of surfactant systems, as well as in the preparation of drug-delivery system.
Abstract: This paper concerns about the experimental and
numerical investigations of energy absorption and axial tearing
behaviour of aluminium 6060 circular thin walled tubes under static
axial compression. The tubes are received in T66 heat treatment
condition with fixed outer diameter of 42mm, thickness of 1.5mm
and length of 120mm. The primary variables are the conical die
angles (15°, 20° and 25°). Numerical simulations are carried on
ANSYS/LS-DYNA software tool, for investigating the effect of
friction between the tube and the die.
Abstract: The success of an e-learning system is highly
dependent on the quality of its educational content and how effective,
complete, and simple the design tool can be for teachers. Educational
modeling languages (EMLs) are proposed as design languages
intended to teachers for modeling diverse teaching-learning
experiences, independently of the pedagogical approach and in
different contexts. However, most existing EMLs are criticized for
being too abstract and too complex to be understood and manipulated
by teachers. In this paper, we present a visual EML that simplifies the
process of designing learning scenarios for teachers with no
programming background. Based on the conceptual framework of the
activity theory, our resulting visual EML focuses on using Domainspecific
modeling techniques to provide a pedagogical level of
abstraction in the design process.
Abstract: In this work, ionic liquids (ILs) for CO2 capturing in typical absorption/stripper process are considered. The use of ionic liquids is considered to be cost-effective because it requires less energy for solvent recovery compared to other conventional processes. A mathematical model is developed for the process based on Peng-Robinson (PR) equation of state (EoS) which is validated with experimental data for various solutions involving CO2. The model is utilized to study the sorbent and energy demand for three types of ILs at specific CO2 capturing rates. The energy demand is manifested by the vapor-liquid equilibrium temperature necessary to remove the captured CO2 from the used solvent in the regeneration step. It is found that higher recovery temperature is required for solvents with higher solubility coefficient. For all ILs, the temperature requirement is less than that required by the typical monoethanolamine (MEA) solvent. The effect of the CO2 loading in the sorbent stream on the process performance is also examined.
Abstract: In this work we adopt a combination of Laplace
transform and the decomposition method to find numerical solutions
of a system of multi-pantograph equations. The procedure leads to a
rapid convergence of the series to the exact solution after computing a
few terms. The effectiveness of the method is demonstrated in some
examples by obtaining the exact solution and in others by computing
the absolute error which decreases as the number of terms of the series
increases.
Abstract: The principle concern of this paper is to determine the
impact of solar absorption coefficient of external wall on building
energy consumption. Simulations were carried out on a typical
residential building by using the simulation Toolkit DeST-h. Results
show that reducing solar absorption coefficient leads to a great
reduction in building energy consumption and thus light-colored
materials are suitable.
Abstract: In this research the level of mercury is analyzed in
muscle tissue of Otolithes ruber retailed in Hamedan, Iran were
determined by flame atomic absorption spectrometry after wet
digestion. Analysis of mercury was carried out by
spectrophotometrically. The average concentration of Hg in muscle
tissue of Otolithes ruber was 0.030±0.026 -g/g so lower than to
compare with the Maximum Allowable Concentration determined by
FAO/WHO Codex Alimentarius Commission.
Abstract: The design of Automatic Generation Control (AGC) system plays a vital role in automation of power system. This paper proposes Hybrid Neuro Fuzzy (HNF) approach for AGC of two-area interconnected reheat thermal power system with the consideration of Generation Rate Constraint (GRC). The advantage of proposed controller is that it can handle the system non-linearities and at the same time the proposed approach is faster than conventional controllers. The performance of HNF controller has been compared with that of both conventional Proportional Integral (PI) controller as well as Fuzzy Logic Controller (FLC) both in the absence and presence of Generation Rate Constraint (GRC). System performance is examined considering disturbance in each area of interconnected power system.
Abstract: It is impossible to think about democracy without elections. The litmus test of any electoral process in any country is the possibility of a one time minority to become a majority at another time and a peaceful transition of power. In many countries in Sub-Saharan Africa though the multi-party elections appeared to be competitive they failed the acid test of democracy: peaceful regime change in a free and fair election. Failure to solve electoral disputes might lead to bloody electoral conflicts as witnessed in many emerging democracies in Africa. The aim of this paper is to investigate electoral conflicts in Africa since the end of the Cold War by using the 2005 post-election violence in Ethiopia as a case study. In Ethiopia, the coming to power of the EPRDF in 1991 marked the fall of the Derg dictatorial military government and the beginning of a multi-party democracy. The country held multi-party parliamentary elections in 1995, 2000, and 2005 where the ruling EPRDF party “won" the elections through violence, involving intimidation, manipulation, detentions of political opponents, torture, and political assassinations. The 2005 electoral violence was the worst electoral violence in the country-s political history that led to the death of 193 protestors and the imprisonment of more than 40, 000 people. It is found out that the major causes of the 2005 Ethiopian election were the defeat of the ruling party in the election and its attempt to reverse the poll results by force; the Opposition-s lack of decisive leadership; the absence of independent courts and independent electoral management body; and the ruling party-s direct control over the army and police.
Abstract: This work considered the thermodynamic feasibility
of scrubbing volatile organic compounds into biodiesel in view of
designing a gas treatment process with this absorbent. A detailed
vapour – liquid equilibrium investigation was performed using the
original UNIFAC group contribution method. The four biodiesels
studied in this work are methyl oleate, methyl palmitate, methyl
linolenate and ethyl stearate. The original UNIFAC procedure was
used to estimate the infinite dilution activity coefficients of 13
selected volatile organic compounds in the biodiesels. The
calculations were done at the VOC mole fraction of 9.213x10-8. Ethyl
stearate gave the most favourable phase equilibrium. A close
agreement was found between the infinite dilution activity coefficient
of toluene found in this work and those reported in literature.
Thermodynamic models can efficiently be used to calculate vast
amount of phase equilibrium behaviour using limited number of
experimental data.
Abstract: This paper considers the effect of heat generation
proportional l to (T - T∞ )p , where T is the local temperature and T∞
is the ambient temperature, in unsteady free convection flow near the
stagnation point region of a three-dimensional body. The fluid is
considered in an ambient fluid under the assumption of a step change
in the surface temperature of the body. The non-linear coupled partial
differential equations governing the free convection flow are solved
numerically using an implicit finite-difference method for different
values of the governing parameters entering these equations. The
results for the flow and heat characteristics when p ≤ 2 show that
the transition from the initial unsteady-state flow to the final steadystate
flow takes place smoothly. The behavior of the flow is seen
strongly depend on the exponent p.
Abstract: We investigated oxidative DNA damage caused by
radio frequency radiation using 8-oxo-7, 8-dihydro-2'-
deoxyguanosine (8-oxodG) generated in mice tissues after exposure
to 900 MHz mobile phone radio frequency in three independent
experiments. The RF was generated by a Global System for Mobile
Communication (GSM) signal generator. The radio frequency field
was adjusted to 25 V/m. The whole body specific absorption rate
(SAR) was 1.0 W/kg. Animals were exposed to this field for 30 min
daily for 30 days. 24 h post-exposure, blood serum, brain and spleen
were removed and DNA was isolated. Enzyme-linked
immunosorbent assay (ELISA) was used to measure 8-oxodG
concentration. All animals survived the whole experimental period.
The body weight of animals did not change significantly at the end of
the experiment. No statistically significant differences observed in
the levels of oxidative stress. Our results are not in favor of the
hypothesis that 900 MHz RF induces oxidative damage.
Abstract: The aim of this study was to compare the solubility of selected volatile organic compounds in water and silicon oil using the simple static headspace method. The experimental design allowed equilibrium achievement within 30 – 60 minutes. Infinite dilution activity coefficients and Henry-s law constants for various organics representing esters, ketones, alkanes, aromatics, cycloalkanes and amines were measured at 303K. The measurements were reproducible with a relative standard deviation and coefficient of variation of 1.3x10-3 and 1.3 respectively. The static determined activity coefficients using shaker flasks were reasonably comparable to those obtained using the gas liquid - chromatographic technique and those predicted using the group contribution methods mainly the UNIFAC. Silicon oil chemically known as polydimethysiloxane was found to be better absorbent for VOCs than water which quickly becomes saturated. For example the infinite dilution mole fraction based activity coefficients of hexane is 0.503 and 277 000 in silicon oil and water respectively. Thus silicon oil gives a superior factor of 550 696. Henry-s law constants and activity coefficients at infinite dilution play a significant role in the design of scrubbers for abatement of volatile organic compounds from contaminated air streams. This paper presents the phase equilibrium of volatile organic compounds in very dilute aqueous and polymeric solutions indicating the movement and fate of chemical in air and solvent. The successful comparison of the results obtained here and those obtained using other methods by the same authors and in literature, means that the results obtained here are reliable.
Abstract: The highly nonlinear characteristics of drying
processes have prompted researchers to seek new nonlinear control
solutions. However, the relation between the implementation
complexity, on-line processing complexity, reliability control
structure and controller-s performance is not well established. The
present paper proposes high performance nonlinear fuzzy controllers
for a real-time operation of a drying machine, being developed under
a consistent match between those issues. A PCI-6025E data
acquisition device from National Instruments® was used, and the
control system was fully designed with MATLAB® / SIMULINK
language. Drying parameters, namely relative humidity and
temperature, were controlled through MIMOs Hybrid Bang-bang+PI
(BPI) and Four-dimensional Fuzzy Logic (FLC) real-time-based
controllers to perform drying tests on biological materials. The
performance of the drying strategies was compared through several
criteria, which are reported without controllers- retuning. Controllers-
performance analysis has showed much better performance of FLC
than BPI controller. The absolute errors were lower than 8,85 % for
Fuzzy Logic Controller, about three times lower than the
experimental results with BPI control.
Abstract: The research object was wheat bread. Experiments
were carried out at the Faculty of Food Technology of the Latvia
University of Agriculture. An active packaging in combination with
modified atmosphere (MAP, CO2 60% and N2 40%) was examined
and compared with traditional packaging in air ambiance. Polymer
Multibarrier 60, PP and OPP bags were used. Influence of iron based
oxygen absorber in sachets of 100 cc obtained from Mitsubishi Gas
Chemical Europe Ageless® was tested on the quality during the shelf
of wheat bread. Samples of 40±4 g were packaged in polymer
pouches (110 mm x 120 mm), hermetically sealed by MULTIVAC
C300 vacuum chamber machine, and stored in room temperature
+21.0±0.5 °C. The physiochemical properties – weight losses,
moisture content, hardness, pH, colour, changes of atmosphere
content (CO2 and O2) in headspace of packs, and microbial
conditions were analysed before packaging and in the 7th, 14th, 21st
and 28th days of storage.
Abstract: Termination Mechanism is an indispensible part of the
emergency management mechanism. Despite of its importance in both
theory and practice, it is almost a brand new field for researching. The
concept of termination mechanism is proposed firstly in this paper,
and the design and implementation which are helpful to guarantee the
effect and integrity of emergency management are discussed secondly.
Starting with introduction of the problems caused by absent
termination and incorrect termination, the essence of termination
mechanism is analyzed, a model based on Optimal Stopping Theory is
constructed and the termination index is given. The model could be
applied to find the best termination time point.. Termination decision
should not only be concerned in termination stage, but also in the
whole emergency management process, which makes it a dynamic
decision making process. Besides, the main subjects and the procedure
of termination are illustrated after the termination time point is given.
Some future works are discussed lastly.
Abstract: Sickness absence represents a major economic and
social issue. Analysis of sick leave data is a recurrent challenge to analysts because of the complexity of the data structure which is
often time dependent, highly skewed and clumped at zero. Ignoring these features to make statistical inference is likely to be inefficient
and misguided. Traditional approaches do not address these problems. In this study, we discuss model methodologies in terms of statistical techniques for addressing the difficulties with sick leave data. We also introduce and demonstrate a new method by performing a longitudinal assessment of long-term absenteeism using
a large registration dataset as a working example available from the Helsinki Health Study for municipal employees from Finland during the period of 1990-1999. We present a comparative study on model
selection and a critical analysis of the temporal trends, the occurrence
and degree of long-term sickness absences among municipal employees. The strengths of this working example include the large
sample size over a long follow-up period providing strong evidence in supporting of the new model. Our main goal is to propose a way to
select an appropriate model and to introduce a new methodology for analysing sickness absence data as well as to demonstrate model
applicability to complicated longitudinal data.