Abstract: The paper presents a practical three-phase PWM
inverter suitable for low voltage, low rating energy efficient systems.
The work in the paper is conducted with the view to establishing the
significance of the loss contribution from the PWM inverter in the
determination of the complete losses of a photovoltaic (PV) arraypowered
induction motor drive water pumping system. Losses
investigated include; conduction and switching loss of the devices
and gate drive losses. It is found that the PWM inverter operates at a
reasonable variable efficiency that does not fall below 92%
depending on the load. The results between the simulated and
experimental results for the system with or without a maximum
power tracker (MPT) compares very well, within an acceptable range
of 2% margin.
Abstract: In this paper 3D FEM analysis was carried out on
double lap bonded joint with composite adherents subjected to
dynamic shear. The adherents are made of Carbon/Epoxy while the
adhesive is epoxy Araldite 2031. The maximum average shear stress
and the stress homogeneity in the adhesive layer were examined.
Three fibers textures were considered: UD; 2.5D and 3D with same
volume fiber then a parametric study based on changing the thickness
and the type of fibers texture in 2.5D was accomplished. Moreover,
adherents’ dissimilarity was also investigated. It was found that the
main parameter influencing the behavior is the longitudinal stiffness
of the adherents. An increase in the adherents’ longitudinal stiffness
induces an increase in the maximum average shear stress in the
adhesive layer and an improvement in the shear stress homogeneity
within the joint. No remarkable improvement was observed for
dissimilar adherents.
Abstract: Polycyclic aromatic hydrocarbons (PAHs) are formed
during the pyrolysis of scrap tyres to produce tyre pyrolytic oil
(TPO). Due to carcinogenic, mutagenic, and toxic properties PAHs
are priority pollutants. Hence it is essential to remove PAHs from
TPO before utilising TPO as a petroleum fuel alternative (to run the
engine). Agricultural wastes have promising future to be utilized as
biosorbent due to their cost effectiveness, abundant availability, high
biosorption capacity and renewability. Various low cost adsorbents
were prepared from natural sources. Uptake of PAHs present in tyre
pyrolytic oil was investigated using various low-cost adsorbents of
natural origin including sawdust (shisham), coconut fiber, neem bark,
chitin, activated charcoal. Adsorption experiments of different PAHs
viz. naphthalene, acenaphthalene, biphenyl and anthracene have been
carried out at ambient temperature (25°C) and at pH 7. It was
observed that for any given PAH, the adsorption capacity increases
with the lignin content. Freundlich constant Kf and 1/n have been
evaluated and it was found that the adsorption isotherms of PAHs
were in agreement with a Freundlich model, while the uptake
capacity of PAHs followed the order: activated charcoal> saw dust
(shisham) > coconut fiber > chitin. The partition coefficients in
acetone-water, and the adsorption constants at equilibrium, could be
linearly correlated with octanol–water partition coefficients. It is
observed that natural adsorbents are good alternative for PAHs
removal. Sawdust of Dalbergia sissoo, a by-product of sawmills was
found to be a promising adsorbent for the removal of PAHs present in
TPO. It is observed that adsorbents studied were comparable to those
of some conventional adsorbents.
Abstract: Living today in turbulent business environment forces
companies to distinguish from each other, securing sustainable
competitive growth and competitive advantage. The best possible
solution is to invest (effort and financial resources) within
companies’ different practices of human resource management
(HRM), more specifically in employees’ knowledge, skills and
abilities. Applying this approach companies will create enviable level
of human capital securing its economic growth. Employees become
human capital for their employers at the moment when they
contribute with their own knowledge and abilities in creating material
and non-material value of the company. The main aim of this
research is to explore the relations between human capital
investments and business excellence of Croatian companies.
Furthermore, the differences in the level of human capital
investments with regard to several companies’ characteristics (e.g.
size of the company, ownership and type of the industry) are
investigated.
Abstract: Constructing a portfolio of investments is one of the
most significant financial decisions facing individuals and
institutions. In accordance with the modern portfolio theory
maximization of return at minimal risk should be the investment goal
of any successful investor. In addition, the costs incurred when
setting up a new portfolio or rebalancing an existing portfolio must
be included in any realistic analysis.
In this paper rebalancing an investment portfolio in the presence of
transaction costs on the Croatian capital market is analyzed. The
model applied in the paper is an extension of the standard portfolio
mean-variance optimization model in which transaction costs are
incurred to rebalance an investment portfolio. This model allows
different costs for different securities, and different costs for buying
and selling. In order to find efficient portfolio, using this model, first,
the solution of quadratic programming problem of similar size to the
Markowitz model, and then the solution of a linear programming
problem have to be found. Furthermore, in the paper the impact of
transaction costs on the efficient frontier is investigated. Moreover, it
is shown that global minimum variance portfolio on the efficient
frontier always has the same level of the risk regardless of the amount
of transaction costs. Although efficient frontier position depends of
both transaction costs amount and initial portfolio it can be concluded
that extreme right portfolio on the efficient frontier always contains
only one stock with the highest expected return and the highest risk.
Abstract: This study aims to investigate the possibility of crime
prevention through CCTV by analyzing the appropriateness of the
CCTV location, whether it is installed in the hotspot of crime-prone
areas, and exploring the crime prevention effect and transition effect.
The real crime and CCTV locations of case city were converted into
the spatial data by using GIS. The data was analyzed by hotspot
analysis and weighted displacement quotient (WDQ). As study
methods, it analyzed existing relevant studies for identifying the trends
of CCTV and crime studies based on big data from 1800 to 2014 and
understanding the relation between CCTV and crime. Second, it
investigated the current situation of nationwide CCTVs and analyzed
the guidelines of CCTV installation and operation to draw attention to
the problems and indicating points of CCTV use. Third, it investigated
the crime occurrence in case areas and the current situation of CCTV
installation in the spatial aspects, and analyzed the appropriateness and
effectiveness of CCTV installation to suggest a rational installation of
CCTV and the strategic direction of crime prevention. The results
demonstrate that there was no significant effect in the installation of
CCTV on crime prevention in the case area. This indicates that CCTV
should be installed and managed in a more scientific way reflecting
local crime situations. In terms of CCTV, the methods of spatial
analysis such as GIS, which can evaluate the installation effect, and the
methods of economic analysis like cost-benefit analysis should be
developed. In addition, these methods should be distributed to local
governments across the nation for the appropriate installation of
CCTV and operation. This study intended to find a design guideline of
the optimum CCTV installation. In this regard, this study is
meaningful in that it will contribute to the creation of a safe city.
Abstract: The Cone Penetration Test (CPT) is a common in-situ
test which generally investigates a much greater volume of soil more
quickly than possible from sampling and laboratory tests. Therefore,
it has the potential to realize both cost savings and assessment of soil
properties rapidly and continuously. The principle objective of this
paper is to demonstrate the feasibility and efficiency of using
artificial neural networks (ANNs) to predict the soil angle of internal
friction (Φ) and the soil modulus of elasticity (E) from CPT results
considering the uncertainties and non-linearities of the soil. In
addition, ANNs are used to study the influence of different
parameters and recommend which parameters should be included as
input parameters to improve the prediction. Neural networks discover
relationships in the input data sets through the iterative presentation
of the data and intrinsic mapping characteristics of neural topologies.
General Regression Neural Network (GRNN) is one of the powerful
neural network architectures which is utilized in this study. A large
amount of field and experimental data including CPT results, plate
load tests, direct shear box, grain size distribution and calculated data
of overburden pressure was obtained from a large project in the
United Arab Emirates. This data was used for the training and the
validation of the neural network. A comparison was made between
the obtained results from the ANN's approach, and some common
traditional correlations that predict Φ and E from CPT results with
respect to the actual results of the collected data. The results show
that the ANN is a very powerful tool. Very good agreement was
obtained between estimated results from ANN and actual measured
results with comparison to other correlations available in the
literature. The study recommends some easily available parameters
that should be included in the estimation of the soil properties to
improve the prediction models. It is shown that the use of friction
ration in the estimation of Φ and the use of fines content in the
estimation of E considerable improve the prediction models.
Abstract: Concrete is found to undergo degradation when
subjected to elevated temperatures and loose substantial amount of its
strength. The loss of strength in concrete is mainly attributed to
decomposition of C-S-H and release of physically and chemically
bound water, which begins when the exposure temperature exceeds
100°C. When such a concrete comes in contact with moisture, the
cement paste is found rehydrate and considerable amount of strength
lost is found to recover. This paper presents results of an
experimental program carried out to investigate the effect of recuring
on strength gain of OPC concrete specimens subjected to elevated
temperatures from 200°C to 800°C, which were subjected to
retention time of two hours and four hours at the designated
temperature. Strength recoveries for concrete subjected to 7
designated elevated temperatures are compared. It is found that the
efficacy of recuring as a measure of strength recovery reduces with
increase in exposure temperature.
Abstract: The object of the present paper is to investigate several
general families of bilinear and bilateral generating functions with
different argument for the Gauss’ hypergeometric polynomials.
Abstract: The detection of the polymer melt state during
manufacture process is regarded as an efficient way to control the
molded part quality in advance. Online monitoring rheological
property of polymer melt during processing procedure provides an
approach to understand the melt state immediately. Rheological
property reflects the polymer melt state at different processing
parameters and is very important in injection molding process
especially. An approach that demonstrates how to calculate
rheological property of polymer melt through in-process
measurement, using injection molding as an example, is proposed in
this study. The system consists of two sensors and a data acquisition
module can process the measured data, which are used for the
calculation of rheological properties of polymer melt. The rheological
properties of polymer melt discussed in this study include shear rate
and viscosity which are investigated with respect to injection speed
and melt temperature. The results show that the effect of injection
speed on the rheological properties is apparent, especially for high
melt temperature and should be considered for precision molding
process.
Abstract: Nic Pizzolatto’s True Detective offers profound
mythological and philosophical ramblings for audiences with literary
sensibilities. An American Sothern Gothic with its Bayon landscape
of the Gulf Coast of Louisiana, where two detectives Rustin Cohle
and Martin Hart begin investigating the isolated murder of Dora
Lange, only to discover an entrenched network of perversion and
corruption, offers an existential outlook. The proposed research paper
shall attempt to investigate the pervasive themes of gothic and
existentialism in the music of the first season of the series.
Abstract: This study presents the moisture variations of
unbound layers from April 2012 to January 2014 in the Interstate 40
(I-40) pavement section in New Mexico. Three moisture probes were
installed at different layers inside the pavement which measure the
continuous moisture variations of the unbound layers. Data show that
the moisture contents of unbound layers are typically constant
throughout the day and month unless there is rainfall. Moisture
contents of all unbound layers change with rainfall. Change in ground
water table may affect the moisture content of unbound layers which
has not been investigated in this study. In addition, the Level 3
predictions of moisture contents using the Pavement Mechanistic-
Empirical (ME) Design software were compared and found quite
reasonable. However, results presented in the current study may not
be applicable for pavement in other regions.
Abstract: The work studied the effect of germination on
proximate, phenol and flavonoid content and antioxidant activities
(AOA) of African Yam been (AYB). Germination was done in
controlled dark chamber (100% RH, 28oC). The proximate, phenol
and flavonoid content and antioxidant activities before and after
germination were investigated. The crude protein, moisture, and
crude fiber content of germinated AYB were significantly higher
(P
Abstract: It is likely that robots will cross the boundaries of
industry into households over the next decades. With demographic
challenges worldwide, the future ageing populations will require the
introduction of assistive technologies capable of providing, care,
human dignity and quality of life through the aging process. Robotics
technology has a high potential for being used in the areas of social
and healthcare by promoting a wide range of activities such as
entertainment, companionship, supervision or cognitive and physical
assistance. However such close Human Robotics Interaction (HRI)
encompass a rich set of ethical scenarios that need to be addressed
before Socially Assistive Robots (SARs) reach the global markets.
Such interactions with robots may seem a worthy goal for many
technical/financial reasons but inevitably require close attention to
the ethical dimensions of such interactions. This article investigates
the current HRI benchmark of social success. It revises it according
to the ethical principles of beneficence, non-maleficence and justice
aligned with social care ethos. An extension of such benchmark is
proposed based on an empirical study of HRIs conducted with elderly
groups.
Abstract: Fluid viscous damping systems are well suited for
many air vehicles subjected to shock and vibration. These damping
system work with the principle of viscous fluid throttling through the
orifice to create huge pressure difference between compression and
rebound chamber and obtain the required damping force. One
application of such systems is its use in aircraft door system to
counteract the door’s velocity and safely stop it. In exigency
situations like crash or emergency landing where the door doesn’t
open easily, possibly due to unusually tilting of fuselage or some
obstacles or intrusion of debris obstruction to move the parts of the
door, such system can be combined with other systems to provide
needed force to forcefully open the door and also securely stop it
simultaneously within the required time i.e. less than 8 seconds. In
the present study, a hydraulic system called snubber along with other
systems like actuator, gas bottle assembly which together known as
emergency power assist system (EPAS) is designed, built and
experimentally studied to check the magnitude of angular velocity,
damping force and time required to effectively open the door.
Whenever needed, the gas pressure from the bottle is released to
actuate the actuator and at the same time pull the snubber’s piston to
operate the emergency opening of the door. Such EPAS installed in
the suspension arm of the aircraft door is studied explicitly changing
parameters like orifice size, oil level, oil viscosity and bypass valve
gap and its spring of the snubber at varying temperature to generate
the optimum design case. Comparative analysis of the EPAS at
several cases is done and conclusions are made. It is found that
during emergency condition, the system opening time and angular
velocity, when snubber with 0.3mm piston and shaft orifice and
bypass valve gap of 0.5 mm with its original spring is used, shows
significant improvement over the old ones.
Abstract: Organic Rankine Cycle (ORC) is the most commonly used method for recovering energy from small sources of heat. The investigation of the ORC in supercritical condition is a new research area as it has a potential to generate high power and thermal efficiency in a waste heat recovery system. This paper presents a steady state ORC model in supercritical condition and its simulations with a real engine’s exhaust data. The key component of ORC, evaporator, is modelled using finite volume method, modelling of all other components of the waste heat recovery system such as pump, expander and condenser are also presented. The aim of this paper is to investigate the effects of mass flow rate and evaporator outlet temperature on the efficiency of the waste heat recovery process. Additionally, the necessity of maintaining an optimum evaporator outlet temperature is also investigated. Simulation results show that modification of mass flow rate is the key to changing the operating temperature at the evaporator outlet.
Abstract: The paper deals with the problems of the actual
behavior, failure mechanism and load-carrying capacity of the special
bolt connection developed and intended for the assembly connections
of truss main girders of perspective railway temporary steel bridges.
Within the framework of this problem solution, several types of
structural details of assembly joints have been considered as the
conceptual structural design. Based on the preliminary evaluation of
advantages or disadvantages of these ones, in principle two basic
structural configurations – so-called “tooth” and “splice-plate”
connections have been selected for the subsequent detailed
investigation. This investigation is mainly based on the experimental
verification of the actual behavior, strain and failure mechanism and
corresponding strength of the connection, and on its numerical
modeling using FEM. This paper is focused only on the cyclic
loading (fatigue) tests results of “splice-plate” connections and their
evaluation, which have already been finished. Simultaneously with
the fatigue tests, the static loading tests have been realized too, but
these ones, as well as FEM numerical modeling, are not the subject of
this paper.
Abstract: In this article a comparison was made between Cu and
TiO2 supported catalysts on activated carbon for ozone
decomposition reaction. The activated carbon support in the case of
TiO2/AC sample was prepared by physicochemical pyrolysis and for
Cu/AC samples the supports are chemically modified carbons. The
prepared catalysts were synthesized by impregnation method. The
samples were annealed in two different regimes- in air and under
vacuum. To examine adsorption efficiency of the samples BET
method was used. All investigated catalysts supported on chemically
modified carbons have higher specific surface area compared to the
specific surface area of TiO2 supported catalysts, varying in the range
590÷620 m2/g. The method of synthesis of the precursors had
influenced catalytic activity.
Abstract: Based on the experimental data, the impact of
resistance and reactance of the winding, as well as the magnetic
permeability of the magnetic circuit steel material on the value of the
electromotive force of the induction converter is investigated. The
obtained results allow estimating the main technological spreads and
determining the maximum level of the electromotive force change.
By the method of experiment planning, the expression of a
polynomial for the electromotive force which can be used to estimate
the adequacy of mathematical models to be used at the investigation
and design of induction converters is obtained.
Abstract: Sound exposure effects have been investigated by
broadcasting a group of broilers with sound of Quran verses (Group
B) whereas the other group is the control broilers (Group C). The
growth rate comparisons in terms of weight and raw meat texture
measured by shear force have been investigated. Twenty-seven
broilers were randomly selected from each group on Day 24 and
weight measurement was carried out every week till the harvest day
(Day 39).Group B showed a higher mean weight on Day 24 (1.441 ±
0.013 kg) than Group C. Significant difference in the weight on Day
39 existed for Group B compared to Group C (p < 0.05). However,
there was no significant (p >0.05) difference of shear force in the
same muscles (breast and drumstick raw meat) of both groups but the
shear force of the breast meat for Group B and C broilers was lower
(p < 0.05) than that of their drumstick meat. Thus, broadcasting the
sound of Quran verses in the coop can be applied to improve the
growth rate of broilers for producing better quality poultry.