Abstract: In this paper, we present a quantum statistical
mechanical formulation from our recently analytical expressions for
partial-wave transition matrix of a three-particle system. We report
the quantum reactive cross sections for three-body scattering
processes 1+(2,3)→1+(2,3) as well as recombination
1+(2,3)→1+(3,1) between one atom and a weakly-bound dimer. The
analytical expressions of three-particle transition matrices and their
corresponding cross-sections were obtained from the threedimensional
Faddeev equations subjected to the rank-two non-local
separable potentials of the generalized Yamaguchi form. The
equilibrium quantum statistical mechanical properties such partition
function and equation of state as well as non-equilibrium quantum
statistical properties such as transport cross-sections and their
corresponding transport collision integrals were formulated
analytically. This leads to obtain the transport properties, such as
viscosity and diffusion coefficient of a moderate dense gas.
Abstract: This paper investigates the effectiveness of two
natural zeolites in reducing expansion of concrete due to alkali-silica
reaction. These natural zeolites have different reactive silica content.
Three aggregates; two natural sands and one crushed stone aggregate
were used while preparing mortar bars in accordance with accelerated
mortar bar test method, ASTM C1260. Performances of natural
zeolites are compared by examining the expansions due to alkali
silica reaction. Natural zeolites added to the mixtures at 10% and
20% replacement levels by weight of cement. Natural zeolite with
high reactive silica content had better performance on reducing
expansions due to ASR. In this research, using high reactive zeolite at
20% replacement levels was effective in mitigating expansions.
Abstract: Photovoltaic (PV) power generation systems, mainly
small scale, are rapidly being deployed in Jordan. The impact of these
systems on the grid has not been studied or analyzed. These systems
can cause many technical problems such as reverse power flows and
voltage rises in distribution feeders, and real and reactive power
transients that affect the operation of the transmission system. To
fully understand and address these problems, extensive research,
simulation, and case studies are required. To this end, this paper
studies the cloud shadow effect on the power generation of a ground
mounted PV system installed at the test field of the Renewable
Energy Center at the Applied Science University.
Abstract: The use of Flexible AC Transmission System
(FACTS) devices in a power system can potentially overcome
limitations of the present mechanically controlled transmission
system. Also, the advance of technology makes possible to include
new energy storage devices in the electrical power system. The
integration of Superconducting Magnetic Energy Storage (SMES)
into Static Synchronous Compensator (STATCOM) can lead to
increase their flexibility in improvement of power system dynamic
behaviour by exchanging both active and reactive powers with power
grids. This paper describes structure and behaviour of SMES,
specifications and performance principles of the STATCOM/SMES
compensator. Moreover, the benefits and effectiveness of integrated
SMES with STATCOM in power systems is presented. Also, the
performance of the STATCOM/SMES compensator is evaluated
using an IEEE 3-bus system through the dynamic simulation by
PSCAD/EMTDC software.
Abstract: The recent interest in alternative and renewable
energy systems results in increased installed capacity ratio of such
systems in total energy production of the world. Specifically, Wind
Energy Conversion Systems (WECS) draw significant attention
among possible alternative energy options, recently. On the contrary
of the positive points of penetrating WECS in all over the world in
terms of environment protection, energy independence of the
countries, etc., there are significant problems to be solved for the grid
connection of large scale WECS. The reactive power regulation,
voltage variation suppression, etc. can be presented as major issues to
be considered in this regard. Thus, this paper evaluates the
application of a Static VAr Compensator (SVC) unit for the reactive
power regulation and operation continuity of WECS during a fault
condition. The system is modeled employing the IEEE 13 node test
system. Thus, it is possible to evaluate the system performance with
an overall grid simulation model close to real grid systems. The
overall simulation model is developed in
MATLAB/Simulink/SimPowerSystems® environments and the
obtained results effectively match the target of the provided study.
Abstract: This paper presents a power control for a Doubly Fed
Induction Generator (DFIG) using in Wind Energy Conversion
System (WECS) connected to the grid. The proposed control strategy
employs two nonlinear controllers, Backstipping (BSC) and slidingmode
controller (SMC) scheme to directly calculate the required
rotor control voltage so as to eliminate the instantaneous errors of
active and reactive powers. In this paper the advantages of BSC and
SMC are presented, the performance and robustness of this two
controller’s strategy are compared between them. First, we present a
model of wind turbine and DFIG machine, then a synthesis of the
controllers and their application in the DFIG power control.
Simulation results on a 1.5MW grid-connected DFIG system are
provided by MATLAB/Simulink.
Abstract: Sodium formate is the chemical substance used for
food additive. Catalase is the important antioxidative enzyme in
protecting the cell from oxidative damage by reactive oxygen species
(ROS). The resultant level of oxidative stress in sodium formatetreated
lymphocytes was investigated. The sodium formate
concentrations of 0.05, 0.1, 0.2, 0.4 and 0.6 mg/mL were treated in
human lymphocytes for 12 hours. After 12 treated hours, catalase
activity change was measured in sodium formate-treated
lymphocytes. The results showed that the sodium formate
concentrations of 0.4 and 0.6 mg/mL significantly decreased catalase
activities in lymphocytes (P < 0.05). The change of catalase activity
in sodium formate-treated lymphocytes may be the oxidative damage
marker for detect sodium formate exposure in human.
Abstract: This paper is focused on the reference current
calculation in the compensation mode of the active DC traction
substations. The so-called p-q theory of the instantaneous reactive
power is used as theoretical foundation. The compensation goal of
total compensation is taken into consideration for the operation under
both sinusoidal and nonsinusoidal voltage conditions, through the
two objectives of unity power factor and perfect harmonic
cancelation. Four blocks of reference current generation implement
the conceived algorithms and they are included in a specific Simulink
library, which is useful in a DSP dSPACE-based platform working
under Matlab/Simulink. The simulation results validate the
correctness of the implementation and fulfillment of the
compensation tasks.
Abstract: Si ion implantation was widely used to synthesize
specimens of SiO2 containing supersaturated Si and subsequent high
temperature annealing induces the formation of embedded
luminescent Si nanocrystals. In this work, the potentialities of excimer
UV-light (172 nm, 7.2 eV) irradiation and rapid thermal annealing
(RTA) to enhance the photoluminescence and to achieve low
temperature formation of Si nanocrystals have been investigated. The
Si ions were introduced at acceleration energy of 180 keV to fluence of
7.5 x 1016 ions/cm2. The implanted samples were subsequently
irradiated with an excimer-UV lamp. After the process, the samples
were rapidly thermal annealed before furnace annealing (FA).
Photoluminescence spectra were measured at various stages at the
process. We found that the luminescence intensity is strongly
enhanced with excimer-UV irradiation and RTA. Moreover, effective
visible photoluminescence is found to be observed even after FA at
900 oC, only for specimens treated with excimer-UV lamp and RTA.
We also prepared specimens of Si nanocrystals embedded in a SiO2 by
reactive pulsed laser deposition (PLD) in an oxygen atmosphere. We
will make clear the similarities and differences with the way of
preparation.
Abstract: This work consists of a numerical simulation of
convective heat transfer in a vertical plane channel filled with a heat
generating porous medium, in the absence of local thermal
equilibrium. The walls are maintained to a constant temperature and
the inlet velocity is uniform. The dynamic range is described by the
Darcy-Brinkman model and the thermal field by two energy
equations model. A dimensionless formulation is developed for
performing a parametric study based on certain dimensionless groups
such as, the Biot interstitial number, the thermal conductivity ratio
and the volumetric heat generation, q '''. The governing equations are
solved using the finite volume method, gave rise to a multitude of
results concerning in particular the thermal field in the porous
channel and the existence or not of the local thermal equilibrium.
Abstract: This paper presents an application of Artificial Neural
Network (ANN) algorithm for improving power system voltage
stability. The training data is obtained by solving several normal and
abnormal conditions using the Linear Programming technique. The
selected objective function gives minimum deviation of the reactive
power control variables, which leads to the maximization of
minimum Eigen value of load flow Jacobian. The considered reactive
power control variables are switchable VAR compensators, OLTC
transformers and excitation of generators. The method has been
implemented on a modified IEEE 30-bus test system. The results
obtain from the test clearly show that the trained neural network is
capable of improving the voltage stability in power system with a
high level of precision and speed.
Abstract: This paper proposes a novel heuristic algorithm that aims to determine the best size and location of distributed generators in unbalanced distribution networks. The proposed heuristic algorithm can deal with the planning cases where power loss is to be optimized without violating the system practical constraints. The distributed generation units in the proposed algorithm is modeled as voltage controlled node with the flexibility to be converted to constant power factor node in case of reactive power limit violation. The proposed algorithm is implemented in MATLAB and tested on the IEEE 37 -node feeder. The results obtained show the effectiveness of the proposed algorithm.
Abstract: More than 3000 plants of notable phyto-therapeutic
value grow in South Africa; these include Cissampelos capensis,
commonly known in Afrikaans as dawidjie or dawidjiewortel. C.
capensis is the most significant and popular medicinal plant used by
the Khoisan as well as other rural groups in the Western region of
South Africa. Its rhizomes are traditionally used to treat male fertility
problems. Yet, no studies have investigated the effects of this plant or
its extracts on human spermatozoa. Therefore, this study aimed at
investigating the effects of C. capensis rhizome extract (CRE)
fractions on ejaculated human spermatozoa in vitro. Spermatozoa
from a total of 77 semen samples were washed with human tubular
fluid medium supplemented with bovine serum albumin (HTF-BSA)
and incubated for 2 hours with 20 μg/ml progesterone (P4) followed
by incubation with different concentrations (0, 0.05, 0.5, 5, 50, 200
μg/ml) of fractionated CRE (F1=0% MeOH, F2=30% MeOH,
F3=60% MeOH and F4=100% MeOH) for 1.5 hours at 37°C. A
sample without addition of CRE fractions served as control. Samples
were analyzed for sperm motility, reactive oxygen species (ROS),
DNA-fragmentation, acrosome reaction and capacitation. Results
showed that F1 resulted in significantly higher values for ROS,
capacitation and hyper-activation compared to F2, F3, and F4 with
P4-stimulated samples generally having higher values. No significant
effect was found for the other parameters. In conclusion, alkaloids
present in F1 of CRE appear to have triggered sperm intrinsic ROS
production leading to sperm capacitation and acrosome reaction
induced by P4.
Abstract: Among various active filters, shunt active filter is a
viable solution for reactive power and harmonics compensation. In
this paper, the SRF plan is used to generate current reference for
compensation and conventional PI controllers were used as the
controller to compensate the reactive power. The design of the closed
loop controllers is reserved simple by modeling them as first order
systems. Computationally uncomplicated and efficient SVM system
is used in the present work for better utilization of dc bus voltage.
The rating of shunt active filter has been finalized based on the
reactive power demand of the selected reactive load. The proposed
control and SVM technique are validated by simulating in MATLAB
software.
Abstract: In a practical power system, the power plants are not
located at the same distance from the center of loads and their fuel
costs are different. Also, under normal operating conditions, the
generation capacity is more than the total load demand and losses.
Thus, there are many options for scheduling generation. In an
interconnected power system, the objective is to find the real and
reactive power scheduling of each power plant in such a way as to
minimize the operating cost. This means that the generator’s real and
reactive powers are allowed to vary within certain limits so as to meet
a particular load demand with minimum fuel cost. This is called
optimal power flow problem. In this paper, Economic Load Dispatch
(ELD) of real power generation is considered. Economic Load
Dispatch (ELD) is the scheduling of generators to minimize total
operating cost of generator units subjected to equality constraint of
power balance within the minimum and maximum operating limits of
the generating units. In this paper, genetic algorithms are considered.
ELD solutions are found by solving the conventional load flow
equations while at the same time minimizing the fuel costs.
Abstract: The rationale behind this study is considering
combating and preventing the phenomenon of trafficking in human
beings from a multidisciplinary perspective that involves many layers
of the society.
Trafficking in human beings is an abhorrent phenomenon highly
affecting negatively the victims and their families in both human and
material aspect, sometimes causing irreversible damages. The longer
term effects of this phenomenon, in countries with a weak economic
development and extremely young and dynamic population, such as
Kosovo, without proper measures to prevented and control can cause
tremendous damages in the society. Given the fact that a complete
eradication of this phenomenon is almost impossible, efforts should
be concentrated at least on the prevention and controlling aspects.
Treating trafficking in human beings based on traditional police
tactics, methods and proceedings cannot bring satisfactory results.
There is no doubt that a multi-disciplinary approach is an
irreplaceable requirement, in other words, a combination of authentic
and functional proactive and reactive methods, techniques and tactics.
Obviously, police must exercise its role in preventing and combating
trafficking in human beings, a role sanctioned by the law, however,
police role and contribution cannot by any means considered
complete if all segments of the society are not included in these
efforts. Naturally, civil society should have an important share in
these collaborative and interactive efforts especially in preventive
activities such as: awareness on trafficking risks and damages,
proactive engagement in drafting appropriate legislation and
strategies, law enforcement monitoring and direct or indirect
involvement in protective and supporting activities which benefit the
victims of trafficking etc.
Abstract: Due to the continuous increment of the load demand,
identification of weaker buses, improvement of voltage profile and
power losses in the context of the voltage stability problems has
become one of the major concerns for the larger, complex,
interconnected power systems. The objective of this paper is to
review the impact of Flexible AC Transmission System (FACTS)
controller in Wind generators connected electrical network for
maintaining voltage stability. Wind energy could be the growing
renewable energy due to several advantages. The influence of wind
generators on power quality is a significant issue; non uniform power
production causes variations in system voltage and frequency.
Therefore, wind farm requires high reactive power compensation; the
advances in high power semiconducting devices have led to the
development of FACTS. The FACTS devices such as for example
SVC inject reactive power into the system which helps in maintaining
a better voltage profile. The performance is evaluated on an IEEE 14
bus system, two wind generators are connected at low voltage buses
to meet the increased load demand and SVC devices are integrated at
the buses with wind generators to keep voltage stability. Power
flows, nodal voltage magnitudes and angles of the power network are
obtained by iterative solutions using MIPOWER.
Abstract: One of the key aspects of power quality improvement
in power system is the mitigation of voltage sags/swells and flicker.
Custom power devices have been known as the best tools for voltage
disturbances mitigation as well as reactive power compensation.
Dynamic Voltage Restorer (DVR) which is the most efficient and
effective modern custom power device can provide the most
commercial solution to solve several problems of power quality in
distribution networks. This paper deals with analysis and simulation
technique of DVR based on instantaneous power theory which is a
quick control to detect signals. The main purpose of this work is to
remove three important disturbances including voltage sags/swells
and flicker. Simulation of the proposed method was carried out on
two sample systems by using Matlab software environment and the
results of simulation show that the proposed method is able to
provide desirable power quality in the presence of wide range of
disturbances.
Abstract: Corrosion of concrete sewer pipes induced by
sulphuric acid attack is a recognised problem worldwide, which is not
only an attribute of countries with hot climate conditions as thought
before. The significance of this problem is by far only realised when
the pipe collapses causing surface flooding and other severe
consequences. To change the existing post-reactive attitude of
managing companies, easy to use and robust models are required to
be developed which currently lack reliable data to be correctly
calibrated. This paper focuses on laboratory experiments of
establishing concrete pipe corrosion rate by submerging samples in to
0.5pH sulphuric acid solution for 56 days under 10ºC, 20ºC and 30ºC
temperature regimes. The result showed that at very early stage of the
corrosion process the samples gained overall mass, at 30ºC the
corrosion progressed quicker than for other temperature regimes,
however with time the corrosion level for 10ºC and 20ºC regimes
tended towards those at 30ºC. Overall, at these conditions the
corrosion rates of 10 mm/year, 13,5 mm/year and 17 mm/year were
observed.
Abstract: The potential neuroprotective effect of Phyllantus
nuriri against Fe2+ and sodium nitroprusside (SNP) induced oxidative
stress in mitochondria of rats brain was evaluated. Cellular viability
was assessed by MTT reduction, reactive oxygen species (ROS)
generation was measured using the probe 2,7-dichlorofluoresce
indiacetate (DCFH-DA). Glutathione content was measured using
dithionitrobenzoic acid (DTNB). Fe2+ (10μM) and SNP (5μM)
significantly decreased mitochondrial activity, assessed by MTT
reduction assay, in a dose-dependent manner, this occurred in parallel
with increased glutathione oxidation, ROS production and lipid
peroxidation end-products (thiobarbituric acid reactive substances,
TBARS). The co-incubation with methanolic extract of Phyllantus
nuriri (10-200 μg/ml) reduced the disruption of mitochondrial
activity, gluthathione oxidation, ROS production as well as the
increase in TBARS levels caused by both Fe2+ and SNP in a dose
dependent manner. HPLC analysis of the extract revealed the
presence of gallic acid (20.540.01), caffeic acid (7.930.02), rutin
(25.310.05), quercetin (31.280.03) and kaemferol (14.360.01).
This result suggests that these phytochemicals account for the
protective actions of P. niruri against Fe2+ and SNP -induced
oxidative stress. Our results show that P. nuriri consist important
bioactive molecules in the search for an improved therapy against the
deleterious effects of Fe2+, an intrinsic producer of reactive oxygen
species (ROS), that leads to neuronal oxidative stress and
neurodegeneration.