Abstract: This paper presents effects of the mean operating
pressure on the optimal operating frequency based on temperature
differences across stack ends in a thermoacoustic refrigerator. In
addition to the length of the resonance tube, components of the
thermoacoustic refrigerator have an influence on the operating
frequency due to their acoustic properties, i.e., absorptivity,
reflectivity and transmissivity. The interference of waves incurs and
distorts the original frequency generated by the driver so that the
optimal operating frequency differs from the designs. These acoustic
properties are not parameters in the designs and be very complicated
to infer their responses. A prototype thermoacoustic refrigerator is
constructed and used to investigate its optimal operating frequency
compared to the design at various operating pressures. Helium and air
are used as working fluids during the experiments. The results
indicate that the optimal operating frequency of the prototype
thermoacoustic refrigerator using helium is at 6 bar and 490Hz or
approximately 20% away from the design frequency. The optimal
operating frequency at other mean pressures differs from the design
in an unpredictable manner, however, the optimal operating
frequency and pressure can be identified by testing.
Abstract: A cyclostationary Gaussian linearization method is
formulated for investigating the time average response of nonlinear
system under sinusoidal signal and white noise excitation. The
quantitative measure of cyclostationary mean, variance, spectrum of
mean amplitude, and mean power spectral density of noise are
analyzed. The qualitative response behavior of stochastic jump and
bifurcation are investigated. The validity of the present approach in
predicting the quantitative and qualitative statistical responses is
supported by utilizing Monte Carlo simulations. The present analysis
without imposing restrictive analytical conditions can be directly
derived by solving non-linear algebraic equations. The analytical
solution gives reliable quantitative and qualitative prediction of mean
and noise response for the Duffing system subjected to both sinusoidal
signal and white noise excitation.
Abstract: In this paper, a direct power control (DPC)
strategies have been investigated in order to control a high
power AC/DC converter with time variable load. This converter
is composed of a three level three phase neutral point clamped
(NPC) converter as rectifier and an H-bridge four quadrant
current control converter. In the high power application,
controller not only must adjust the desire outputs but also
decrease the level of distortions which are injected to the network
from the converter. Regarding to this reason and nonlinearity
of the power electronic converter, the conventional controllers
cannot achieve appropriate responses. In this research, the
precise mathematical analysis has been employed to design the
appropriate controller in order to control the time variable
load. A DPC controller has been proposed and simulated using
Matlab/ Simulink. In order to verify the simulation result, a real
time simulator- OPAL-RT- has been employed. In this paper,
the dynamic response and stability of the high power NPC
with variable load has been investigated and compared with
conventional types using a real time simulator. The results proved
that the DPC controller is more stable and has more precise
outputs in comparison with conventional controller.
Abstract: This paper examines the effect of the volatility of oil
prices on food price in South Africa using monthly data covering the
period 2002:01 to 2014:09. Food price is measured by the South
African consumer price index for food while oil price is proxied by
the Brent crude oil. The study employs the GARCH-in-mean VAR
model, which allows the investigation of the effect of a negative and
positive shock in oil price volatility on food price. The model also
allows the oil price uncertainty to be measured as the conditional
standard deviation of a one-step-ahead forecast error of the change in
oil price. The results show that oil price uncertainty has a positive
and significant effect on food price in South Africa. The responses of
food price to a positive and negative oil price shocks is asymmetric.
Abstract: The explosion of the World Wide Web and the
electronic trend of university teaching have transformed the learning
style to become more learner-centered, which has popularized the
digital delivery of mediated lectures as an alternative or an adjunct to
traditional lectures. Despite its potential and popularity, virtual
lectures have not been adopted yet in Jordanian universities. This
research aimed to fill this gap by studying the factors that influence
students’ willingness to accept virtual lectures in one Jordanian
University. A quantitative approach was followed, by obtaining 216
survey responses and statistically applying the UTAUT model with
some modifications. Results revealed that performance expectancy,
effort expectancy, social influences, and self-efficacy could
significantly influence students’ attitudes towards virtual lectures.
Additionally, Facilitating conditions and attitudes towards virtual
lectures were found with significant influence on students’ intention
to take virtual lectures. Research implications and future work were
specified afterwards.
Abstract: The capability of CNC gantry milling machines in
manufacturing long components has caused the expanded use of such
machines. On the other hand, the machines’ gantry rigidity can
reduce under severe loads or vibration during operation. Indeed, the
quality of machining is dependent on the machine’s dynamic
behavior throughout the operating process. For this reason, these
types of machines have always been used widely and are not
efficient. Therefore, they can usually be employed for rough
machining and may not produce adequate surface finishing. In this
paper, a CNC gantry milling machine with the potential to produce
good surface finish has been designed and analyzed. The lowest
natural frequency of this machine is 202 Hz corresponding to 12000
rpm at all motion amplitudes with a full range of suitable frequency
responses. Meanwhile, the maximum deformation under dead loads
for the gantry machine is 0.565*m, indicating that this machine tool
is capable of producing higher product quality.
Abstract: Over the years, it has been extensively established that
the practice of assuming a structure being fixed at base, leads to gross
errors in evaluation of its overall response due to dynamic loadings
and overestimations in design. The extent of these errors depends on
a number of variables; soil type being one of the major factor. This
paper studies the effect of Soil Structure Interaction (SSI) on multistorey
buildings with varying under-laying soil types after proper
validation of the effect of SSI. Analysis for soft, stiff and very stiff
base soils has been carried out, using a powerful Finite Element
Method (FEM) software package ANSYS v14.5. Results lead to
some very important conclusions regarding time period, deflection
and acceleration responses.
Abstract: We are facing serious problems related to long-term
depopulation and an aging society with a falling birth rate in Japan. In
this situation, we are suffering from a shortfall in human resources as
well as a shortage of workforce in rural regions. In addition, we are
struggling with a protracted economic slump and excess concentration
of population in the Tokyo Metropolitan area. It is an urgent national
issue to consider how to live in this country and what kind of structure
of society and administration policy is needed. It is necessary to clarify
people’s desire for their way of living and social assistance to be
provided. The aim of this study is to clarify the characteristics of
regional issues and the degree of their seriousness in local
municipalities of Japan. We conducted a questionnaire survey about
regional agenda in all local municipalities in Japan. We obtained
responses concerning the degree of seriousness of regional issues and
degree of importance of policies. Based on the data gathered from the
survey, it is apparent that many local municipalities are facing an
aging population and declining population. We constructed a model to
analyze factors for declining population. Using the model, it was
clarified that a population’s age structure, job opportunities and
income level affect the decline of population. In addition, we showed
the way of the evaluation of state of local municipality.
Abstract: This paper analyzes the political and economic issues
that people with disabilities face related to globalization; how people
with disabilities have been adapting globalization and surviving under
worldwide competition system. It explains that economic
globalization exacerbates inequality and deprivation of people with
disabilities. The rising tide of neo-liberal welfare policies emphasized
efficiency, downsized social expenditure for people with disabilities,
excluded people with disabilities against labor market, and shifted
them from welfare system to nothing. However, there have been
people with disabilities' political responses to globalization, which are
characterized by a global network of people with disabilities as well as
participation to global governance. Their resistance can be seen as an
attempt to tackle the problems that economic globalization has
produced. It is necessary paradigm shift of disability policy from
dependency represented by disability benefits to independency
represented by labor market policies for people with disabilities.
Abstract: This paper addresses the issue of the autonomous
mobile robot (AMR) navigation task based on the hybrid control
modes. The novel hybrid control mode, based on multi-sensors
information by using the fuzzy approach, has been presented in this
research. The system operates in real time, is robust, enables the robot
to operate with imprecise knowledge, and takes into account the
physical limitations of the environment in which the robot moves,
obtaining satisfactory responses for a large number of different
situations. An experiment is simulated and carried out with a pioneer
mobile robot. From the experimental results, the effectiveness and
usefulness of the proposed AMR obstacle avoidance and navigation
scheme are confirmed. The experimental results show the feasibility,
and the control system has improved the navigation accuracy. The
implementation of the controller is robust, has a low execution time,
and allows an easy design and tuning of the fuzzy knowledge base.
Abstract: This paper presents Finite Element Method (FEM) for
analyzing the internal responses generated in thin rectangular plates
with various edge conditions and rigidity conditions. Comparison has
been made between the FEM (ANSYS software) results for
displacement, stresses and moments generated with and without the
consideration of hole in plate and different aspect ratios. In the end
comparison for responses in plain and composite square plates has
been studied.
Abstract: The seismic responses of steel buildings with semirigid
post-tensioned connections (PC) are estimated and compared
with those of steel buildings with typical rigid (welded) connections
(RC). The comparison is made in terms of global and local response
parameters. The results indicate that the seismic responses in terms of
interstory shears, roof displacements, axial load and bending
moments are smaller for the buildings with PC connection. The
difference is larger for global than for local parameters, which in turn
varies from one column location to another. The reason for this
improved behavior is that the buildings with PC dissipate more
hysteretic energy than those with RC. In addition, unlike the case of
buildings with WC, for the PC structures the hysteretic energy is
mostly dissipated at the connections, which implies that structural
damage in beams and columns is not significant. According to these
results, steel buildings with PC are a viable option in high seismicity
areas because of their smaller response and self-centering connection
capacity as well as the fact that brittle failure is avoided.
Abstract: Although there had been a many studies that shows
the impact of air pollution on physical health, comparatively less was
known of human behavioral responses and annoyance impacts.
Annoyance caused by air pollution is a public health problem because
it can be an ambient stressor causing stress and disease and can affect
quality of life. The objective of this work is to evaluate the
annoyance caused by air pollution in two different industrialized
urban areas, Dunkirk (France) and Vitoria (Brazil). The populations
of these cities often report feeling annoyed by dust. Surveys were
conducted, and the collected data were analyzed using statistical
analyses. The results show that sociodemographic variables,
importance of air quality, perceived industrial risk, perceived air
pollution and occurrence of health problems play important roles in
the perceived annoyance. These results show the existence of a
common problem in geographically distant areas and allow
stakeholders to develop prevention strategies.
Abstract: A quartz crystal microbalance (QCM) nanosensor was developed to detect lysozyme enzyme by functionalizing its gold surface with the attachment of poly(methacroyl-L-phenylalanine) (PMAPA) nanoparticles. PMAPA was chosen as a hydrophobic matrix. The hydrophobic nanoparticles were synthesized by micro-emulsion polymerization method. Hydrophobic QCM nanosensor was tested for real time detection of lysozyme enzyme from aqueous solution. The kinetic and affinity studies were determined by using lysozyme solutions with different concentrations. The responses related with mass (Δm) and frequency (Δf) shifts were used to evaluate adsorption properties.
Abstract: In this study, we have focused our attention on
combining of molecular imprinting into nanofilms and QCM
nanosensor approaches and producing QCM nanosensor for anti-
CCP, chosen as model protein, using anti-CCP imprinted nanofilms.
The nonimprinted nanosensor was also prepared to evaluate the
selectivity of the imprinted nanosensor. Anti-CCP imprinted QCM
nanosensor was tested for real time detection of anti-CCP from
aqueous solution. The kinetic and affinity studies were determined by
using anti-CCP solutions with different concentrations. The
responses related with mass shifts (%m) and frequency shifts (%f)
were used to evaluate adsorption properties. To show the selectivity
of the anti-CCP imprinted QCM nanosensor, competitive adsorption
of anti-CCP and IgM was investigated. The results indicate that anti-
CCP imprinted QCM nanosensor has higher adsorption capabilities
for anti-CCP than for IgM, due to selective cavities in the polymer
structure.
Abstract: Physics Education Research (PER) results have shown
that students do not achieve the expected level of competency in
understanding the concepts of different domains of Physics learning
when taught by the traditional teaching methods, the concepts of
Electricity and Magnetism (E&M) being one among them.
Simulation being one of the valuable instructional tools renders an
opportunity to visualize varied experiences with such concepts.
Considering the electric force concept which requires extensive use
of vector representations, we report here the outcome of the research
results pertaining to the student understanding of this concept and the
role of simulation in using vector representation. The simulation
platform provides a positive impact on the use of vector
representation.
The first stage of this study involves eliciting and analyzing
student responses to questions that probe their understanding of the
concept of electrostatic force and this is followed by four stages of
student interviews as they use the interactive simulations of electric
force in one dimension. Student responses to the questions are
recorded in real time using electronic pad. A validation test interview
is conducted to evaluate students' understanding of the electric force
concept after using interactive simulation. Results indicate lack of
procedural knowledge of the vector representation. The study
emphasizes the need for the choice of appropriate simulation and
mode of induction for learning.
Abstract: The present study was carried out to evaluate the
effect of different levels of dietary seed and extract of Harmal
(Peganum harmala L.) on immunity of broiler chicks. A total of 350
one-day old broiler chicks (Ross 308) were randomly allocated to
five dietary treatments with four replicates pen of 14 birds each.
Dietary treatments consisted of control, 1 and 2 g/kg Harmal seed in
diet, 100 and 200 mg/L Harmal seed extract in water. Broilers
received dietary treatments from 1 to 42 d. Two birds from each pen
were randomly weighed and sacrificed at 42 d of age, the relative
weight of lymphoid organs (bursa of Fabercius and spleen) to live
weight were calculated. Antibody titers against Newcastle and
influenza viruses and sheep red blood cell were measured at 30 d of
age. Results showed that the relative weights of lymphoid organs
were not affected by dietary treatments. Furthermore, antibody titer
against Newcastle and influenza viruses as well as sheep red blood
cell antigen were significantly (P
Abstract: This paper investigates the activity of the rectus
femoris (RF) and biceps femoris (BF) in healthy subjects during salat
(prostration) and specific exercise (squat exercise) using
electromyography (EMG). A group of undergraduates aged between
19 to 25 years voluntarily participated in this study. The myoelectric
activity of the muscles were recorded and analyzed. The finding
indicated that there were contractions of the muscles during the salat
and exercise with almost same EMG’s level. From the result,
Wilcoxon’s Rank Sum test showed significant difference between
prostration and squat exercise (p
Abstract: Welfare may be considered to be a subjective
experience; it has a biological function that is related to the fitness
and survival of the animal accordingly, researches have suggested
that welfare is compromised when the animal's evolutionary fitness is
reduced. This study was carried out to explain the effect of some
managerial stressors as handling and restraint on behavioral patterns
and biochemical parameters of rats. A total of 24 (12 males & 12
females) Sprague-Dawley rats (12 months & 150-180g) were allotted
into 3 groups, handled group (4 male & 4 female), restrained group (4
male & 4 female) and control group (4 males & 4 females).
The obtained results revealed that time spent feeding, drinking,
movement and cage exploration frequencies increased significantly in
handled rats than other groups, while lying time and licking increased
significantly in restrained rats than handled and controls. Moreover,
social behavior decreased in both stressed groups than control.
Triglycerides were significantly increased in handled rats than
other groups, while total lipid, total protein and globulin significantly
increased in both treated groups than control. Corticosterone
increased in restrained and handled rats than control ones. Moreover,
there was an increment in packed cell volume significantly in
restrained rats than others. These deducted that if we want to study
the effect of stress on animal welfare it is necessary to study the
effect of such stressors on animal’s behavior and physiological
responses.
Abstract: Over the last few decades, oilfield service rolling
equipment has significantly increased in weight, primarily because of
emissions regulations, which require larger/heavier engines, larger
cooling systems, and emissions after-treatment systems, in some
cases, etc. Larger engines cause more vibration and shock loads,
leading to failure of electronics and control systems.
If the vibrating frequency of the engine matches the system
frequency, high resonance is observed on structural parts and mounts.
One such existing automated control equipment system comprising
wire rope mounts used for mounting computers was designed
approximately 12 years ago. This includes the use of an industrialgrade
computer to control the system operation. The original
computer had a smaller, lighter enclosure. After a few years, a newer
computer version was introduced, which was 10 lbm heavier. Some
failures of internal computer parts have been documented for cases in
which the old mounts were used. Because of the added weight, there
is a possibility of having the two brackets impact each other under
off-road conditions, which causes a high shock input to the computer
parts. This added failure mode requires validating the existing mount
design to suit the new heavy-weight computer.
This paper discusses the modal finite element method (FEM)
analysis and experimental modal analysis conducted to study the
effects of vibration on the wire rope mounts and the computer. The
existing mount was modelled in ANSYS software, and resultant
mode shapes and frequencies were obtained. The experimental modal
analysis was conducted, and actual frequency responses were
observed and recorded.
Results clearly revealed that at resonance frequency, the brackets
were colliding and potentially causing damage to computer parts. To
solve this issue, spring mounts of different stiffness were modeled in
ANSYS software, and the resonant frequency was determined.
Increasing the stiffness of the system increased the resonant
frequency zone away from the frequency window at which the engine
showed heavy vibrations or resonance. After multiple iterations in
ANSYS software, the stiffness of the spring mount was finalized,
which was again experimentally validated.