Abstract: This work presents a numerical model developed to
simulate the dynamics and vibrations of a multistage tractor gearbox.
The effect of time varying mesh stiffness, time varying frictional
torque on the gear teeth, lateral and torsional flexibility of the shafts
and flexibility of the bearings were included in the model. The model
was developed by using the Lagrangian method, and it was applied to
study the effect of three design variables on the vibration and stress
levels on the gears. The first design variable, module, had little effect
on the vibration levels but a higher module resulted to higher bending
stress levels. The second design variable, pressure angle, had little
effect on the vibration levels, but had a strong effect on the stress
levels on the pinion of a high reduction ratio gear pair. A pressure
angle of 25o resulted to lower stress levels for a pinion with 14 teeth
than a pressure angle of 20o. The third design variable, contact ratio,
had a very strong effect on both the vibration levels and bending
stress levels. Increasing the contact ratio to 2.0 reduced both the
vibration levels and bending stress levels significantly. For the gear
train design used in this study, a module of 2.5 and contact ratio of
2.0 for the various meshes was found to yield the best combination
of low vibration levels and low bending stresses. The model can
therefore be used as a tool for obtaining the optimum gear design
parameters for a given multistage spur gear train.
Abstract: Group contribution methods such as the UNIFAC are
of major interest to researchers and engineers involved synthesis,
feasibility studies, design and optimization of separation processes as
well as other applications of industrial use. Reliable knowledge of
the phase equilibrium behavior is crucial for the prediction of the fate
of the chemical in the environment and other applications. The
objective of this study was to predict the solubility of selected
volatile organic compounds (VOCs) in glycol polymers and
biodiesel. Measurements can be expensive and time consuming,
hence the need for thermodynamic models. The results obtained in
this study for the infinite dilution activity coefficients compare very
well those published in literature obtained through measurements. It
is suggested that in preliminary design or feasibility studies of
absorption systems for the abatement of volatile organic compounds,
prediction procedures should be implemented while accurate fluid
phase equilibrium data should be obtained from experiment.
Abstract: There is an urgent need to conserve the biological diversity of the Nigerian Environment for the future and present generation in the face of current energy resources development. This paper gives an in-depth analysis of the impact of oil and gas activities on the biological diversity of the Nigerian Niger Delta area and its consequences on the sustainable development of the host communities as it relates to their social, economic and environmental issues, particularly on the womenfolk who are the key managers of environmental resources. Also reviewed is the frustration of these communities that is reflected in unending conflicts.
Abstract: The evolution of ICT has changed all sections of society and these changes have been creating an irreversible impact on higher education institutions, which are expected to adopt innovative technologies in their teaching practices. As theorical framework this study select Rogers theory of innovation diffusion which is widely used to illustrate how technologies move from a localized invented to a widespread evolution on organizational practices. Based on descriptive statistical data collected in a European higher education institution three years longitudinal study was conducted for analyzing and discussion the different stages of a LMS adoption process. Results show that ICT integration in higher education is not progressively successful and a linear process and multiple aspects must be taken into account.
Abstract: Friction Stir Welding (FSW) is a solid state welding
process invented and patented by The Welding Institute (TWI) in the
United Kingdom in 1991 for butt and lap welding of metals and plastics. This paper highlights the benefits of friction stir welding
process as an energy efficient and a green technology process in the
field of welding. Compared to the other conventional welding processes, its benefits, typical applications and its use in joining
similar and dissimilar materials are also presented.
Abstract: The effects of global warming on India vary from the
submergence of low-lying islands and coastal lands to the melting of
glaciers in the Indian Himalayas, threatening the volumetric flow rate
of many of the most important rivers of India and South Asia. In
India, such effects are projected to impact millions of lives. As a
result of ongoing climate change, the climate of India has become
increasingly volatile over the past several decades; this trend is
expected to continue.
Climate change is one of the most important global environmental
challenges, with implications for food production, water supply,
health, energy, etc. Addressing climate change requires a good
scientific understanding as well as coordinated action at national and
global level. The climate change issue is part of the larger challenge
of sustainable development. As a result, climate policies can be more
effective when consistently embedded within broader strategies
designed to make national and regional development paths more
sustainable. The impact of climate variability and change, climate
policy responses, and associated socio-economic development will
affect the ability of countries to achieve sustainable development
goals.
A very well calibrated Soil and Water Assessment Tool (R2 =
0.9968, NSE = 0.91) was exercised over the Khatra sub basin of the
Kangsabati River watershed in Bankura district of West Bengal,
India, in order to evaluate projected parameters for agricultural
activities. Evapotranspiration, Transmission Losses, Potential
Evapotranspiration and Lateral Flow to reach are evaluated from the
years 2041-2050 in order to generate a picture for sustainable
development of the river basin and its inhabitants.
India has a significant stake in scientific advancement as well as
an international understanding to promote mitigation and adaptation.
This requires improved scientific understanding, capacity building,
networking and broad consultation processes. This paper is a
commitment towards the planning, management and development of
the water resources of the Kangsabati River by presenting detailed
future scenarios of the Kangsabati river basin, Khatra sub basin, over
the mentioned time period.
India-s economy and societal infrastructures are finely tuned to the
remarkable stability of the Indian monsoon, with the consequence
that vulnerability to small changes in monsoon rainfall is very high.
In 2002 the monsoon rains failed during July, causing profound loss
of agricultural production with a drop of over 3% in India-s GDP.
Neither the prolonged break in the monsoon nor the seasonal rainfall
deficit was predicted. While the general features of monsoon
variability and change are fairly well-documented, the causal
mechanisms and the role of regional ecosystems in modulating the
changes are still not clear. Current climate models are very poor at
modelling the Asian monsoon: this is a challenging and critical
region where the ocean, atmosphere, land surface and mountains all
interact. The impact of climate change on regional ecosystems is
likewise unknown. The potential for the monsoon to become more
volatile has major implications for India itself and for economies
worldwide. Knowledge of future variability of the monsoon system,
particularly in the context of global climate change, is of great
concern for regional water and food security.
The major findings of this paper were that of all the chosen
projected parameters, transmission losses, soil water content,
potential evapotranspiration, evapotranspiration and lateral flow to
reach, display an increasing trend over the time period of years 2041-
2050.
Abstract: Most neural network (NN) models of human category learning use a gradient-based learning method, which assumes that locally-optimal changes are made to model parameters on each learning trial. This method tends to under predict variability in individual-level cognitive processes. In addition many recent models of human category learning have been criticized for not being able to replicate rapid changes in categorization accuracy and attention processes observed in empirical studies. In this paper we introduce stochastic learning algorithms for NN models of human category learning and show that use of the algorithms can result in (a) rapid changes in accuracy and attention allocation, and (b) different learning trajectories and more realistic variability at the individual-level.
Abstract: Circular tubes have been widely used as structural
members in engineering application. Therefore, its collapse behavior
has been studied for many decades, focusing on its energy absorption
characteristics. In order to predict the collapse behavior of members,
one could rely on the use of finite element codes or experiments.
These tools are helpful and high accuracy but costly and require
extensive running time. Therefore, an approximating model of tubes
collapse mechanism is an alternative for early step of design. This
paper is also aimed to develop a closed-form solution of thin-walled
circular tube subjected to bending. It has extended the Elchalakani et
al.-s model (Int. J. Mech. Sci.2002; 44:1117-1143) to include the
rate of energy dissipation of rolling hinge in the circumferential
direction. The 3-D geometrical collapse mechanism was analyzed by
adding the oblique hinge lines along the longitudinal tube within the
length of plastically deforming zone. The model was based on the
principal of energy rate conservation. Therefore, the rates of internal
energy dissipation were calculated for each hinge lines which are
defined in term of velocity field. Inextensional deformation and
perfect plastic material behavior was assumed in the derivation of
deformation energy rate. The analytical result was compared with
experimental result. The experiment was conducted with a number of
tubes having various D/t ratios. Good agreement between analytical
and experiment was achieved.
Abstract: In recent years, the underground water sources in
southern Taiwan have become salinized because of saltwater
intrusions. This study explores the adsorption characteristics of
activated carbon on salinizing inorganic salts using isothermal
adsorption experiments and provides a model analysis. The
temperature range for the isothermal adsorption experiments ranged
between 5 to 45 ℃, and the amount adsorbed varied between 28.21 to
33.87 mg/g. All experimental data of adsorption can be fitted to both
the Langmuir and the Freundlich models. The thermodynamic
parameters for per chlorate onto granular activated carbon were
calculated as -0.99 to -1.11 kcal/mol for DG°, -0.6 kcal/mol for DH°,
and 1.21 to 1.84 kcal/mol for DS°. This shows that the adsorption
process of granular activated carbon is spontaneously exothermic. The
observation of adsorption behaviors under low ionic strength, low pH
values, and low temperatures is beneficial to the adsorption removal of
perchlorate with granular activated carbon.
Abstract: The present work describes a computational study of
aerodynamic characteristics of GLC305 airfoil clean and with 16.7
min ice shape (rime 212) and 22.5 min ice shape (glaze 944).The
performance of turbulence models SA, Kε, Kω Std, and Kω SST
model are observed against experimental flow fields at different
Mach numbers 0.12, 0.21, 0.28 in a range of Reynolds numbers
3x106, 6x106, and 10.5x106 on clean and iced aircraft airfoil
GLC305. Numerical predictions include lift, drag and pitching
moment coefficients at different Mach numbers and at different angle
of attacks were done. Accuracy of solutions with respect to the
effects of turbulence models, variation of Mach number, initial
conditions, grid resolution and grid spacing near the wall made the
study much sensitive. Navier Stokes equation based computational
technique is used. Results are very close to the experimental results.
It has seen that SA and SST models are more efficient than Kε and
Kω standard in under study problem.
Abstract: This paper makes a contribution to the on-going
debate on conceptualization and lexicalization of cutting and
breaking (C&B) verbs by discussing data from Telugu, a language of
India belonging to the Dravidian family. Five Telugu native speakers-
verbalizations of agentive actions depicted in 43 short video-clips
were analyzed. It was noted that verbalization of C&B events in
Telugu requires formal units such as simple lexical verbs, explicator
compound verbs, and other complex verb forms. The properties of
the objects involved, the kind of instruments used, and the manner of
action had differential influence on the lexicalization patterns.
Further, it was noted that all the complex verb forms encode 'result'
and 'cause' sub-events in that order. Due to the polysemy associated
with some of the verb forms, our data does not support the
straightforward bipartition of this semantic domain.
Abstract: This paper explains the cause of nonlinearity in floor
attenuation hither to left unexplained. The performance degradation
occurring in air interface for GSM signals is quantitatively analysed
using the concept of Radiating Columns of buildings. The signal
levels were measured using Wireless Network Optimising Drive Test
Tool (E6474A of Agilent Technologies). The measurements were
taken in reflected signal environment under usual fading conditions
on actual GSM signals radiated from base stations. A mathematical
model is derived from the measurements to predict the GSM signal
levels in different floors. It was applied on three buildings and found
that the predicted signal levels deviated from the measured levels
with in +/- 2 dB for all floors. It is more accurate than the prediction
models based on Floor Attenuation Factor. It can be used for
planning proper indoor coverage in multi storey buildings.
Abstract: In pressure vessels contain hydrogen, the role of
hydrogen will be important because of hydrogen cracking problem. It
is difficult to predict what is happened in metallurgical field spite of a
lot of studies have been searched. The main role in controlling the
mass diffusion as driving force is related to stress. In this study, finite
element analysis is implemented to estimate material-s behavior
associated with hydrogen embrittlement. For this purpose, one model
of a pressure vessel is introduced that it has definite boundary and
initial conditions. In fact, finite element is employed to solve the
sequentially coupled mass diffusion with stress near a crack front in a
pressure vessel. Modeling simulation intergrarnular fracture of AISI
4135 steel due to hydrogen is investigated. So, distribution of
hydrogen and stress are obtained and they indicate that their
maximum amounts occur near the crack front. This phenomenon is
happened exactly the region between elastic and plastic field.
Therefore, hydrogen is highly mobile and can diffuse through crystal
lattice so that this zone is potential to trap high volume of hydrogen.
Consequently, crack growth and fast fracture will be happened.
Abstract: The use of technology is increasingly adopted to
support flexible learning in Higher Education institutions. The
adoption of more sophisticated technologies offers a broad range of
facilities for communication and resource sharing, thereby creating a
flexible learning environment that facilitates and even encourages
students not to physically attend classes. However this emerging
trend seems to contradict class attendance requirements within
universities, inevitably leading to a dilemma between amending
traditional regulations and creating new policies for the higher
education institutions. This study presents an investigation into
student engagement in a technology enhanced/driven flexible
environment along with its relationship to attainment. We propose an
approach to modelling engagement from different perspectives in
terms of indicators and then consider what impact these indicators
have on student academic performance. We have carried out a case
study on the relation between attendance and attainment in a flexible
environment. Although our preliminary results show attendance is
quantitatively correlated with successful student development and
learning outcomes, our results also indicate there is a cohort that did
not follow such a pattern. Nevertheless the preliminary results could
provide an insight into pilot studies in the wider deployment of new
technology to support flexible learning.
Abstract: The machining of Carbon Fiber Reinforced Plastics
has come to constitute a significant challenge for many fields of
industry. The resulting surface finish of machined parts is of primary
concern for several reasons, including contact quality and impact on
the assembly. Therefore, the characterization and prediction of
roughness based on machining parameters are crucial for costeffective
operations. In this study, a PCD tool comprised of two
straight flutes was used to trim 32-ply carbon fiber laminates in a bid
to analyze the effects of the feed rate and the cutting speed on the
surface roughness. The results show that while the speed has but a
slight impact on the surface finish, the feed rate for its part affects it
strongly. A detailed study was also conducted on the effect of fiber
orientation on surface roughness, for quasi-isotropic laminates used
in aerospace. The resulting roughness profiles for the four-ply
orientation lay-up were compared, and it was found that fiber angle is
a critical parameter relating to surface roughness. One of the four
orientations studied led to very poor surface finishes, and
characteristic roughness profiles were identified and found to only
relate to the ply orientations of multilayer carbon fiber laminates.
Abstract: The paper presents a comparative performance of the
models developed to predict 28 days compressive strengths using
neural network techniques for data taken from literature (ANN-I) and
data developed experimentally for SCC containing bottom ash as
partial replacement of fine aggregates (ANN-II). The data used in the
models are arranged in the format of six and eight input parameters
that cover the contents of cement, sand, coarse aggregate, fly ash as
partial replacement of cement, bottom ash as partial replacement of
sand, water and water/powder ratio, superplasticizer dosage and an
output parameter that is 28-days compressive strength and
compressive strengths at 7 days, 28 days, 90 days and 365 days,
respectively for ANN-I and ANN-II. The importance of different
input parameters is also given for predicting the strengths at various
ages using neural network. The model developed from literature data
could be easily extended to the experimental data, with bottom ash as
partial replacement of sand with some modifications.
Abstract: The Cluster Dimension of a network is defined as, which is the minimum cardinality of a subset S of the set of nodes having the property that for any two distinct nodes x and y, there exist the node Si, s2 (need not be distinct) in S such that ld(x,s1) — d(y, s1)1 > 1 and d(x,s2) < d(x,$) for all s E S — {s2}. In this paper, strictly non overlap¬ping clusters are constructed. The concept of LandMarks for Unique Addressing and Clustering (LMUAC) routing scheme is developed. With the help of LMUAC routing scheme, It is shown that path length (upper bound)PLN,d < PLD, Maximum memory space requirement for the networkMSLmuAc(Az) < MSEmuAc < MSH3L < MSric and Maximum Link utilization factor MLLMUAC(i=3) < MLLMUAC(z03) < M Lc
Abstract: Foodborne Salmonella infections have become a
major problem world wide. Salmonellosis transmitted from fish are
quite common. Established quality control measures exist for export
oriented fish, none exists for fish consumed locally. This study aimed
at characterization of Salmonella isolated from Nile tilapia . The
study was carried out in selected beaches along L. Victoria in
Western Kenya between March and June 2007. One hundred and
twenty fish specimens were collected. Salmonella isolates were
confirmed using serotyping, biochemical testing in addition to malic
acid dehydrogenase (mdh) and fliC gene sequencing. Twenty
Salmonella isolates were confirmed by mdh gene sequencing. Nine
(9) were S. enterica serotype typhimurium, four (4) were S. enterica
Serotype, enteritidis and seven (7) were S. enterica serotype typhi.
Nile tilapia have a role in transmission of Salmonellosis in the study
area, poor sanitation was a major cause of pollution at the beach
inshore waters.
Abstract: Due to their high power-to-weight ratio and low cost, pneumatic actuators are attractive for robotics and automation applications; however, achieving fast and accurate control of their position have been known as a complex control problem. The paper presents a methodology for obtaining controllers that achieve high position accuracy and preserve the closed-loop characteristics over a broad operating range. Experimentation with a number of conventional (or "classical") three-term controllers shows that, as repeated operations accumulate, the characteristics of the pneumatic actuator change requiring frequent re-tuning of the controller parameters (PID gains). Furthermore, three-term controllers are found to perform poorly in recovering the closed-loop system after the application of load or other external disturbances. The key reason for these problems lies in the non-linear exchange of energy inside the cylinder relating, in particular, to the complex friction forces that develop on the piston-wall interface. In order to overcome this problem but still remain within the boundaries of classical control methods, we designed an auto selective classicaql controller so that the system performance would benefit from all three control gains (KP, Kd, Ki) according to system requirements and the characteristics of each type of controller. This challenging experimentation took place for consistent performance in the face of modelling imprecision and disturbances. In the work presented, a selective PID controller is presented for an experimental rig comprising an air cylinder driven by a variable-opening pneumatic valve and equipped with position and pressure sensors. The paper reports on tests carried out to investigate the capability of this specific controller to achieve consistent control performance under, repeated operations and other changes in operating conditions.
Abstract: Most of the collision warning systems currently
available in the automotive market are mainly designed to warn
against imminent rear-end and lane-changing collisions. No collision
warning system is commercially available to warn against imminent
turning collisions at intersections, especially for left-turn collisions
when a driver attempts to make a left-turn at either a signalized or
non-signalized intersection, conflicting with the path of other
approaching vehicles traveling on the opposite-direction traffic
stream. One of the major factors that lead to left-turn collisions is the
human error and misjudgment of the driver of the turning vehicle
when perceiving the speed and acceleration of other vehicles
traveling on the opposite-direction traffic stream; therefore, using a
properly-designed collision warning system will likely reduce, or
even eliminate, this type of collisions by reducing human error. This
paper introduces perceptual framework for a proposed collision
warning system that can detect imminent left-turn collisions at
intersections. The system utilizes a commercially-available detection
sensor (either a radar sensor or a laser detector) to detect approaching
vehicles traveling on the opposite-direction traffic stream and
calculate their speeds and acceleration rates to estimate the time-tocollision
and compare that time to the time required for the turning
vehicle to clear the intersection. When calculating the time required
for the turning vehicle to clear the intersection, consideration is given
to the perception-reaction time of the driver of the turning vehicle,
which is the time required by the driver to perceive the message
given by the warning system and react to it by engaging the throttle.
A regression model was developed to estimate perception-reaction
time based on age and gender of the driver of the host vehicle.
Desired acceleration rate selected by the driver of the turning vehicle,
when making the left-turn movement, is another human factor that is
considered by the system. Another regression model was developed
to estimate the acceleration rate selected by the driver of the turning
vehicle based on driver-s age and gender as well as on the location
and speed of the nearest approaching vehicle along with the
maximum acceleration rate provided by the mechanical
characteristics of the turning vehicle. By comparing time-to-collision
with the time required for the turning vehicle to clear the intersection,
the system displays a message to the driver of the turning vehicle
when departure is safe. An application example is provided to
illustrate the logic algorithm of the proposed system.