Abstract: Nowadays, energy dissipation devices are commonly
used in structures. High rate of energy absorption during earthquakes
is the benefit of using such devices, which results in damage
reduction of structural elements, specifically columns. The hysteretic
damping capacity of energy dissipation devices is the key point that it
may adversely make analysis and design process complicated. This
effect may be generally represented by Equivalent Viscous Damping
(EVD). The equivalent viscous damping might be obtained from the
expected hysteretic behavior regarding to the design or maximum
considered displacement of a structure. In this paper, the hysteretic
damping coefficient of a steel Moment Resisting Frame (MRF),
which its performance is enhanced by a Buckling Restrained Brace
(BRB) system has been evaluated. Having foresight of damping
fraction between BRB and MRF is inevitable for seismic design
procedures like Direct Displacement-Based Design (DDBD) method.
This paper presents an approach to calculate the damping fraction for
such systems by carrying out the dynamic nonlinear time history
analysis (NTHA) under harmonic loading, which is tuned to the
natural system frequency. Two MRF structures, one equipped with
BRB and the other without BRB are simultaneously studied.
Extensive analysis shows that proportion of each system damping
fraction may be calculated by its shear story portion. In this way,
contribution of each BRB in the floors and their general contribution
in the structural performance may be clearly recognized, in advance.
Abstract: Anammox is a novel and promising technology that has changed the traditional concept of biological nitrogen removal. The process facilitates direct oxidation of ammonical nitrogen under anaerobic conditions with nitrite as an electron acceptor without addition of external carbon sources. The present study investigated the feasibility of Anammox Hybrid Reactor (AHR) combining the dual advantages of suspended and attached growth media for biodegradation of ammonical nitrogen in wastewater. Experimental unit consisted of 4 nos. of 5L capacity AHR inoculated with mixed seed culture containing anoxic and activated sludge (1:1). The process was established by feeding the reactors with synthetic wastewater containing NH4-H and NO2-N in the ratio 1:1 at HRT (hydraulic retention time) of 1 day. The reactors were gradually acclimated to higher ammonium concentration till it attained pseudo steady state removal at a total nitrogen concentration of 1200 mg/l. During this period, the performance of the AHR was monitored at twelve different HRTs varying from 0.25-3.0 d with increasing NLR from 0.4 to 4.8 kg N/m3d. AHR demonstrated significantly higher nitrogen removal (95.1%) at optimal HRT of 1 day. Filter media in AHR contributed an additional 27.2% ammonium removal in addition to 72% reduction in the sludge washout rate. This may be attributed to the functional mechanism of filter media which acts as a mechanical sieve and reduces the sludge washout rate many folds. This enhances the biomass retention capacity of the reactor by 25%, which is the key parameter for successful operation of high rate bioreactors. The effluent nitrate concentration, which is one of the bottlenecks of anammox process was also minimised significantly (42.3-52.3 mg/L). Process kinetics was evaluated using first order and Grau-second order models. The first-order substrate removal rate constant was found as 13.0 d-1. Model validation revealed that Grau second order model was more precise and predicted effluent nitrogen concentration with least error (1.84±10%). A new mathematical model based on mass balance was developed to predict N2 gas in AHR. The mass balance model derived from total nitrogen dictated significantly higher correlation (R2=0.986) and predicted N2 gas with least error of precision (0.12±8.49%). SEM study of biomass indicated the presence of heterogeneous population of cocci and rod shaped bacteria of average diameter varying from 1.2-1.5 mm. Owing to enhanced NRE coupled with meagre production of effluent nitrate and its ability to retain high biomass, AHR proved to be the most competitive reactor configuration for dealing with nitrogen laden wastewater.
Abstract: This study examined the mental health and behavioral
problems in early adolescence with the instrument of Achenbach
System of Empirically Based Assessment (ASEBA). The purpose of
the study was stratified sampling method was used to collect data
from 1975 participants. Multiple regression models and hierarchical
regression models were applied to examine the relations between the
background variables and internalizing problems, and the ones
between students’ performance and internalizing problems. The
results indicated that several background variables as predictors could
significantly predict the anxious/depressed problem; reading and
social study scores could significantly predict the anxious/depressed
problem. However the class as a hierarchical macro factor did not
indicate the significant effect. In brief, the majority of these models
represented that the background variables, behaviors and academic
performance were significantly related to the anxious/depressed
problem.
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: In this study, an Artificial Neural Network (ANN)
analytical method has been developed for analyzing earthquake
performances of the Reinforced Concrete (RC) buildings. 66 RC
buildings with four to ten storeys were subjected to performance
analysis according to the parameters which are the existing material,
loading and geometrical characteristics of the buildings. The selected
parameters have been thought to be effective on the performance of
RC buildings. In the performance analyses stage of the study, level of
performance possible to be shown by these buildings in case of an
earthquake was determined on the basis of the 4-grade performance
levels specified in Turkish Earthquake Code-2007 (TEC-2007). After
obtaining the 4-grade performance level, selected 23 parameters of
each building have been matched with the performance level. In this
stage, ANN-based fast evaluation algorithm mentioned above made
an economic and rapid evaluation of four to ten storey RC buildings.
According to the study, the prediction accuracy of ANN has been
found about 74%.
Abstract: Fiber Reinforced Polymer (FRP) is a composite material with exceptional properties that are capable to replace conventional steel reinforcement in reinforced and pre-stressed concrete structures. However, the main obstacle for their wide use in pre-stressed concrete application is the anchorage system. Due to the weakness of FRP in the transverse direction, the pre-stressing capacity of FRP bars are limited. This paper investigates the modification of the conventional wedge anchorage system to be used for stressing of FRP bars in pre-stressed applications. Epoxy adhesive material with glass FRP (GFRP) bars and conventional steel wedge were used in this paper. The GFRP bars are encased with epoxy at the anchor zone and the wedge system was used in pull-out test. The results showed a loading capacity of 47.6 kN which is 69% of the bar ultimate capacity. Additionally, nylon wedge was made with the same dimensions of the steel wedge and tested for GFRP bars without epoxy layer. The nylon wedge showed a loading capacity of 19.7 kN which is only 28.5% of the ultimate bar capacity.
Abstract: In an attempt to investigate the performance of single
basin solar still for climate conditions of Ludhiana a single basin
solar still was designed, fabricated and tested. The energy balance
equations for various parts of the still are solved by Gauss-Seidel
iteration method. Computer model was made and experimentally
validated. The validated computer model was used to estimate the
annual distillation yield and performance ratio of the still for
Ludhiana. The Theoretical and experimental distillation yield were
4318.79 ml and 3850 ml respectively for the typical day. The
predicted distillation yield was 12.5% higher than the experimental
yield. The annual distillation yield per square metre aperture area and
annual performance ratio for single basin solar still is 1095 litres and
0.43 respectively. The payback period for micro-stepped solar still is
2.5 years.
Abstract: The present study aims to investigate the performance
of Moringa oleifera seed extract as natural coagulant in clarification
of secondary wastewater treatment plant (MWWTP) located in East
of Algiers, Algeria. Coagulation flocculation performance of
Moringa oleifera was evaluated through supernatant residual
turbidity after jar test trials. Various influence parameters namely
Moringa oleifera dosage and pH have been considered. Tests on
Reghaia wastewater, having 129 NTU of initial turbidity, showed a
removal of 69.45% of residual turbidity with only 1.5 mg/l of
Moringa oleifera. This sufficient removal capability encourages the
use of this bioflocculant for treatment of turbid waters. Indeed,
Moringa oleifera which is a natural resource available locally (South
of Algeria) coupled to the non-toxicity, biocompatibility and
biodegradability, may be a very interesting alternative to the
conventional coagulants used so far.
Abstract: This study was carried out for an underground subway station at Seoul Metro, Korea. The optimal set-points of the ventilation control system are determined every 3 hours, then, the ventilation controller adjusts the ventilation fan speed according to the optimal set-point changes. Compared to manual ventilation system which is operated irrespective of the OAQ, the IDP-based ventilation control system saves 3.7% of the energy consumption. Compared to the fixed set-point controller which is operated irrespective of the IAQ diurnal variation, the IDP-based controller shows better performance with a 2% decrease in energy consumption, maintaining the comfortable IAQ range inside the station.
Abstract: The present research investigated whether gender
differences affect performance in a simple math quiz in statistics
course. Participants of this study comprised a sample of 567 statistics
students in two different universities in Lebanon. Data were collected
through a simple math quiz. Analysis of quantitative data indicated
that there wasn’t a significant difference in math performance
between males and females. The results suggest that improvements in
student performance may depend on improved mastery of basic
algebra especially for females. The implications of these findings and
further recommendations were discussed.
Abstract: Passive control methods can be utilized to build
earthquake resistant structures, and also to strengthen the vulnerable
ones. In this paper, we studied the effect of this system in increasing
the ductility and energy dissipation and also modeled the behavior of
this type of eccentric bracing, and compared the hysteresis diagram
of the modeled samples with the laboratory samples. We studied
several samples of frames with vertical shear-links in order to assess
the behavior of this type of eccentric bracing. Each of these samples
was modeled in finite element software ANSYS 9.0, and was
analyzed under the static cyclic loading. It was found that vertical
shear-links have a more stable hysteresis loops. Another analysis
showed that using honeycomb beams as the horizontal beam along
with steel reinforcement has no negative effect on the hysteresis
behavior of the sample.
Abstract: This paper proposes that in the course of evolution
pitch structure became a human specific tool of communication the
function of which is to induce emotional states such as uncertainty
and cohesion. By the means of eliciting these emotions during
collective music performance people are able to unconsciously give
cues concerning social acceptance. This is probably one of the
reasons why in all cultures people collectively perform tonal music. It
is also suggested that tonal pitch structure had been invented socially
before it became an evolutionary innovation of hominines. It means
that a predisposition to tonally organize pitches evolved by the means
of ‘Baldwin effect’ – a process in which natural selection transforms
the learned response of an organism into the instinctive response. In
the proposed, hypothetical evolutionary scenario of the emergence of
tonal pitch structure social forces such as a need for closer
cooperation play the crucial role.
Abstract: Multiple-input multiple-output (MIMO) radar has
received increasing attention in recent years. MIMO radar has many
advantages over conventional phased array radar such as target
detection,resolution enhancement, and interference suppression. In
this paper, the results are presented from a simulation study of MIMO
uniformly-spaced linear array (ULA) antennas. The performance is
investigated under varied parameters, including varied array size,
pseudo random (PN) sequence length, number of snapshots, and
signal to noise ratio (SNR). The results of MIMO are compared to a
traditional array antenna.
Abstract: In this paper numerical studies have been carried out
to examine the pre-ignition flow features of high-performance solid
propellant rocket motors with two different port geometries but with
same propellant loading density. Numerical computations have been
carried out using a validated 3D, unsteady, 2nd-order implicit, SST k-
ω turbulence model. In the numerical study, a fully implicit finite
volume scheme of the compressible, Reynolds-Averaged, Navier-
Stokes equations is employed. We have observed from the numerical
results that in solid rocket motors with highly loaded propellants
having divergent port geometry the hot igniter gases can create preignition
pressure oscillations leading to thrust oscillations due to the
flow unsteadiness and recirculation. We have also observed that the
igniter temperature fluctuations are diminished rapidly thereby
reaching the steady state value faster in the case of solid propellant
rocket motors with convergent port than the divergent port
irrespective of the igniter total pressure. We have concluded that the
prudent selection of the port geometry, without altering the propellant
loading density, for damping the total temperature fluctuations within
the motor is a meaningful objective for the suppression and control of
instability and/or thrust oscillations often observed in solid propellant
rocket motors with non-uniform port geometry.
Abstract: Concrete is strong in compression however weak in
tension. The tensile strength as well as ductile property of concrete
could be improved by addition of short dispersed fibers. Polyethylene
terephthalate (PET) fiber obtained from hand cutting or mechanical
slitting of plastic sheets generally used as discrete reinforcement in
substitution of steel fiber. PET fiber obtained from the former process
is in the form of straight slit sheet pattern that impart weaker
mechanical bonding behavior in the concrete matrix. To improve the
limitation of straight slit sheet fiber the present study considered two
additional geometry of fiber namely (a) flattened end slit sheet and
(b) deformed slit sheet. The mix for plain concrete was design for a
compressive strength of 25 MPa at 28 days curing time with a watercement
ratio of 0.5. Cylindrical and beam specimens with 0.5% fibers
volume fraction and without fibers were cast to investigate the
influence of geometry on the mechanical properties of concrete. The
performance parameters mainly studied include flexural strength,
splitting tensile strength, compressive strength and ultrasonic pulse
velocity (UPV). Test results show that geometry of fiber has a
marginal effect on the workability of concrete. However, it plays a
significant role in achieving a good compressive and tensile strength
of concrete. Further, significant improvement in term of flexural and
energy dissipation capacity were observed from other fibers as
compared to the straight slit sheet pattern. Also, the inclusion of PET
fiber improved the ability in absorbing energy in the post-cracking
state of the specimen as well as no significant porous structures.
Abstract: Electrohydraulic servo system have been used in
industry in a wide number of applications. Its dynamics are highly
nonlinear and also have large extent of model uncertainties and
external disturbances. In this paper, a robust back-stepping control
(RBSC) scheme is proposed to overcome the problem of disturbances
and system uncertainties effectively and to improve the tracking
performance of EHS systems. In order to implement the proposed
control scheme, the system uncertainties in EHS systems are
considered as total leakage coefficient and effective oil volume. In
addition, in order to obtain the virtual controls for stabilizing system,
the update rule for the system uncertainty term is induced by
the Lyapunov control function (LCF). To verify the performance and
robustness of the proposed control system, computer simulation of
the proposed control system using Matlab/Simulink Software
is executed. From the computer simulation, it was found that the
RBSC system produces the desired tracking performance and has
robustness to the disturbances and system uncertainties of EHS
systems.
Abstract: The teaching of computer programming for beginners
has been generally considered as a difficult and challenging task.
Several methodologies and research tools have been developed,
however, the difficulty of teaching still remains. Our work integrates
the state of the art in teaching programming with game software and
further provides metrics for the evaluation of student performance in
a collaborative activity of playing games. This paper aims to present a
multi-agent system architecture to be incorporated to the educational
collaborative game software for teaching programming that monitors,
evaluates and encourages collaboration by the participants. A
literature review has been made on the concepts of Collaborative
Learning, Multi-agents systems, collaborative games and techniques
to teach programming using these concepts simultaneously.
Abstract: The Multiple Intelligences theory characterizes human
intelligence as a multifaceted entity that exists in all human beings
with varying degrees. The most important contribution of this theory
to the field of English Language Teaching (ELT) is its role in
identifying individual differences and designing more learnercentered
programs. The present study aims at investigating the
relationship between different elements of multiple intelligence and
grammar scores. To this end, 63 female Iranian EFL learner selected
from among intermediate students participated in the study. The
instruments employed were a Nelson English language test, Michigan
Grammar Test, and Teele Inventory for Multiple Intelligences
(TIMI). The results of Pearson Product-Moment Correlation revealed
a significant positive correlation between grammatical accuracy and
linguistic as well as interpersonal intelligence. The results of
Stepwise Multiple Regression indicated that linguistic intelligence
contributed to the prediction of grammatical accuracy.
Abstract: As smartphones are equipped with various sensors,
there have been many studies focused on using these sensors to create
valuable applications. Human activity recognition is one such
application motivated by various welfare applications, such as the
support for the elderly, measurement of calorie consumption, lifestyle
and exercise patterns analyses, and so on. One of the challenges one
faces when using smartphone sensors for activity recognition is that
the number of sensors should be minimized to save battery power. In
this paper, we show that a fairly accurate classifier can be built that
can distinguish ten different activities by using only a single sensor
data, i.e., the smartphone accelerometer data. The approach that we
adopt to deal with this twelve-class problem uses various methods.
The features used for classifying these activities include not only the
magnitude of acceleration vector at each time point, but also the
maximum, the minimum, and the standard deviation of vector
magnitude within a time window. The experiments compared the
performance of four kinds of basic multi-class classifiers and the
performance of four kinds of ensemble learning methods based on
three kinds of basic multi-class classifiers. The results show that
while the method with the highest accuracy is ECOC based on
Random forest.
Abstract: These days, the industrial trend is moving away from heavy and bulky passive components to power converter systems that use more and more semiconductor elements. Also, it is difficult to connect the traditional converters to the high and medium voltage. For these reasons, a new family of multilevel inverters has appeared as a solution for working with higher voltage levels. Different modulation topologies like Sinusoidal Pulse Width Modulation (SPWM), Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) are available for multilevel inverters. In this work, different hybrid modulation techniques which are combination of fundamental frequency modulation and multilevel sinusoidal-modulation are compared. The main characteristic of these modulations are reduction of switching losses with good harmonic performance and balanced power loss dissipation among the device. The proposed hybrid modulation schemes are developed and simulated in Matlab/Simulink for cascaded H-bridge inverter. The results validate the applicability of the proposed schemes for cascaded multilevel inverter.