Abstract: We have developed a new computer program in
Fortran 90, in order to obtain numerical solutions of a system
of Relativistic Magnetohydrodynamics partial differential equations
with predetermined gravitation (GRMHD), capable of simulating
the formation of relativistic jets from the accretion disk of matter
up to his ejection. Initially we carried out a study on numerical
methods of unidimensional Finite Volume, namely Lax-Friedrichs,
Lax-Wendroff, Nessyahu-Tadmor method and Godunov methods
dependent on Riemann problems, applied to equations Euler in
order to verify their main features and make comparisons among
those methods. It was then implemented the method of Finite
Volume Centered of Nessyahu-Tadmor, a numerical schemes that
has a formulation free and without dimensional separation of
Riemann problem solvers, even in two or more spatial dimensions,
at this point, already applied in equations GRMHD. Finally, the
Nessyahu-Tadmor method was possible to obtain stable numerical
solutions - without spurious oscillations or excessive dissipation -
from the magnetized accretion disk process in rotation with respect
to a central black hole (BH) Schwarzschild and immersed in a
magnetosphere, for the ejection of matter in the form of jet over a
distance of fourteen times the radius of the BH, a record in terms
of astrophysical simulation of this kind. Also in our simulations,
we managed to get substructures jets. A great advantage obtained
was that, with the our code, we got simulate GRMHD equations in
a simple personal computer.
Abstract: Laplace transformations have wide applications in
engineering and sciences. All previous studies of modified Laplace
transformations depend on differential equation with initial
conditions. The purpose of our paper is to solve the linear differential
equations (not initial value problem) and then find the general
solution (not particular) via the Laplace transformations without
needed any initial condition. The study involves both types of
differential equations, ordinary and partial.
Abstract: Self-compacting concrete (SCC) developed in Japan
in the late 80s has enabled the construction industry to reduce
demand on the resources, improve the work condition and also
reduce the impact of environment by elimination of the need for
compaction. Fuzzy logic (FL) approaches has recently been used to
model some of the human activities in many areas of civil
engineering applications. Especially from these systems in the model
experimental studies, very good results have been obtained. In the
present study, a model for predicting compressive strength of SCC
containing various proportions of fly ash, as partial replacement of
cement has been developed by using Fuzzy Inference System (FIS).
For the purpose of building this model, a database of experimental
data were gathered from the literature and used for training and
testing the model. The used data as the inputs of fuzzy logic models
are arranged in a format of five parameters that cover the total binder
content, fly ash replacement percentage, water content,
superplasticizer and age of specimens. The training and testing results
in the fuzzy logic model have shown a strong potential for predicting
the compressive strength of SCC containing fly ash in the considered
range.
Abstract: Adapting quickly to environmental dynamism is
essential for an organization to develop outsourcing strategic and
management in order to sustain competitive advantage. This research
used the Partial Least Squares Structural Equation Modeling (PLSSEM)
tool to investigate the factors of environmental dynamism
impact on the strategic outsourcing success among electrical and
electronic manufacturing industries in outsourcing management.
Statistical results confirm that the inclusion of customer demand,
technological change, and competition level as a new combination
concept of environmental dynamism, has positive effects on
outsourcing success. Additionally, this research demonstrates the
acceptability of PLS-SEM as a statistical analysis to furnish a better
understanding of environmental dynamism in outsourcing
management in Malaysia. A practical finding contributes to
academics and practitioners in the field of outsourcing management.
Abstract: Nations are still finding it quite difficult to win mega
sport competitions despite the major contribution of sport to society
in terms of social and economic development, personal health, and in
education. Even though the world of sports has been transformed into
a huge global economy, it is important to note that the first step of
sport is usually its introduction to children at school through physical
education or PE. In other words, nations who do not win mega sport
competitions also suffer from a weak and neglected PE system. This
problem of the neglect of PE systems is the main motivation of this
research aimed at examining the factors affecting the perceived
awareness of physical education teachers on the ICTs that are
adoptable for the teaching and learning of physical education. Two
types of research objectives will materialize this aim: relevant
theories will be identified in relation to the analysis of the perceived
ICT awareness of PE teachers and subsequent models will be
compiled and designed from existing literature; the empirical testing
of such theories and models will also be achieved through the survey
of PE teachers from the Camperdown magisterial district of the
KwaZulu-Natal province of South Africa. The main hypothesis at the
heart of this study is the relationship between the demographics of PE
teachers, their behavior both as individuals and as social entities, and
their perceived awareness of the ICTs that are adoptable for PE, as
postulated by existing literature; except that this study categorizes
human behavior under performance expectancy, computer attitude,
and social influence. This hypothesis was partially confirmed by the
survey conducted by this research in the sense that performance
expectancy and teachers’ age, gender, computer usage, and class size
were found to be the only factors affecting their awareness of ICTs
for physical education.
Abstract: A noble low NOx combustion technology, based on
partial oxidation combustion concept in a fuel rich combustion zone, is
successfully applied in this research. The burner is designed such that
a portion of fuel is heated and pre-vaporized in the furnace then
injected into a fuel rich combustion zone so that a partial oxidation
reaction occurs. The effects of equivalence ratio, thermal load, and
fuel distribution ratio on the emissions of NOx and CO are
experimentally investigated. This newly developed combustion
technology showed very low NOx emission level, about 12 ppm, when
light oil is used as a fuel.
Abstract: In the present work, hydrogen gas sensor of modest
sensitivity utilizing functionalized multiwalled carbon nanotubes
partially decorated with tin oxide nanoparticles (F-MWCNTs/SnO2)
has been fabricated. This sensing material was characterized by
scanning electron microscopy (SEM). In addition, a remarkable
finding was that the F-MWCNTs/SnO2 sensor shows good sensitivity
as compared to F-MWCNTs for low concentration (0.05-1% by
volume) of H2 gas. The fabricated sensors show complete resistance
recovery and good repeatability when exposed to H2 gas at the room
temperature conditions.
Abstract: This study proposes the transformation of nonlinear
Magnetic Levitation System into linear one, via state and feedback
transformations using explicit algorithm. This algorithm allows
computing explicitly the linearizing state coordinates and feedback
for any nonlinear control system, which is feedback linearizable,
without solving the Partial Differential Equations. The algorithm is
performed using a maximum of N-1 steps where N being the
dimension of the system.
Abstract: reliability-based methodology for the assessment
and evaluation of reinforced concrete (R/C) structural elements of
concrete structures is presented herein. The results of the reliability
analysis and assessment for R/C structural elements were verified by
the results obtained through deterministic methods. The outcomes of
the reliability-based analysis were compared against currently
adopted safety limits that are incorporated in the reliability indices
β’s, according to international standards and codes. The methodology
is based on probabilistic analysis using reliability concepts and
statistics of the main random variables that are relevant to the subject
matter, and for which they are to be used in the performance-function
equation(s) associated with the structural elements under study.
These methodology techniques can result in reliability index β, which
is commonly known as the reliability index or reliability measure
value that can be utilized to assess and evaluate the safety, human
risk, and functionality of the structural component. Also, these
methods can result in revised partial safety factor values for certain
target reliability indices that can be used for the purpose of
redesigning the R/C elements of the building and in which they could
assist in considering some other remedial actions to improve the
safety and functionality of the member.
Abstract: This paper presents a new method to design nonlinear
feedback linearization controller for PEMFCs (Polymer Electrolyte
Membrane Fuel Cells). A nonlinear controller is designed based on
nonlinear model to prolong the stack life of PEMFCs. Since it is
known that large deviations between hydrogen and oxygen partial
pressures can cause severe membrane damage in the fuel cell,
feedback linearization is applied to the PEMFC system so that the
deviation can be kept as small as possible during disturbances or load
variations. To obtain an accurate feedback linearization controller,
tuning the linear parameters are always important. So in proposed
study NSGA (Non-Dominated Sorting Genetic Algorithm)-II method
was used to tune the designed controller in aim to decrease the
controller tracking error. The simulation result showed that the
proposed method tuned the controller efficiently.
Abstract: Nowadays, the amounts of companies which tend to
have an Enterprise Resource Planning (ERP) application are
increasing. Although ERP projects are expensive, time consuming,
and complex, there are some successful experiences. These days,
developing countries are striving to implement ERP projects
successfully; however, there are many obstacles. Therefore, these
projects would be failed or partially failed. This paper concerns the
implementation of a successful ERP implementation, IFS, in Iran at
Dana Geophysics Company (DGC). After a short review of ERP and
ERP market in Iran, we propose a three phases deployment
methodology (phase 1: Preparation and Business Process
Management (BPM) phase 2: implementation and phase 3: testing,
golive-1 (pilot) and golive-2 (final)). Then, we present five guidelines
(Project Management, Change Management, Business Process
Management (BPM), Training& Knowledge Management, and
Technical Management), which were chose as work streams. In this
case study we present lessons learned in Project management and
Business process Management.
Abstract: The reduction of greenhouse gases emissions is highly
discussed ecological theme at present. In addition to power industry
also main production sectors of binders, i.e. cement, air and hydraulic
lime are very sensitive to these questions. One of the possibilities
how CO2 emissions can be reduced directly at clinker burnout is
represented by partial substitution of lime with a material containing
limy ions at absence of carbonate group. Fluidised fly ash is one of
such potential raw materials where CaO can be found free and also
bound in anhydrite, CaSO4. At application of FBC (fluidized bed
combustion) fly ash with approximate 20% CaO content and its
dosing ratio to high percent lime 1:2, corresponding stechiometrically
to the preparation of raw material powder, approximately 0,37 t CO2
per 1 ton of one-component cement would be released at clinker
burnout compared to 0,46 t CO2 when orthodox raw materials are
used. The reduction of CO2 emissions thus could reach even 20%.
Abstract: The paper a summary of the results of concretes with
partial substitution of natural aggregates with recycled concrete is
solved. Design formulas of the concretes were characterised with 20,
40 and 60% substitution of natural 8-16mm fraction aggregates with
a selected recycled concrete of analogous coarse fractions. With the
product samples an evaluation of coarse fraction aggregates influence
on fresh concrete consistency and concrete strength in time was
carried out. The results of concretes with aggregates substitution will
be compared to reference formula containing only the fractions of
natural aggregates.
Abstract: This study aims to examine the role of career
advancement and job security as predictors of employee commitment
to their organization. Data was collected from 580 frontline
employees attached to two departments of 29 luxury hotels in
Peninsular Malaysia. Statistical results using Partial Least Squares
technique provided support for the proposed hypotheses. In view of
the findings, theoretical and practical implications are discussed.
Abstract: A theoretical study has been presented to describe the boundary layer flow and heat transfer on an exponentially shrinking sheet with a variable wall temperature and suction, in the presence of magnetic field. The governing nonlinear partial differential equations are converted into ordinary differential equations by similarity transformation, which are then solved numerically using the shooting method. Results for the skin friction coefficient, local Nusselt number, velocity profiles as well as temperature profiles are presented through graphs and tables for several sets of values of the parameters. The effects of the governing parameters on the flow and heat transfer characteristics are thoroughly examined.
Abstract: In this paper, we present a new maintenance model
for a partially observable system subject to two failure modes,
namely a catastrophic failure and a failure due to the system
degradation. The system is subject to condition monitoring and the
degradation process is described by a hidden Markov model. A
cost-optimal Bayesian control policy is developed for maintaining
the system. The control problem is formulated in the semi-Markov
decision process framework. An effective computational algorithm is
developed, illustrated by a numerical example.
Abstract: The mixed convection stagnation point flow toward a vertical plate is investigated. The external flow impinges normal to the heated plate and the surface temperature is assumed to vary linearly with the distance from the stagnation point. The governing partial differential equations are transformed into a set of ordinary differential equations, which are then solved numerically using MATLAB routine boundary value problem solver bvp4c. Numerical results show that dual solutions are possible for a certain range of the mixed convection parameter. A stability analysis is performed to determine which solution is linearly stable and physically realizable.
Abstract: In this paper, we apply the Exp-function method to
Rosenau-Kawahara and Rosenau-KdV equations. Rosenau-Kawahara
equation is the combination of the Rosenau and standard Kawahara
equations and Rosenau-KdV equation is the combination of the
Rosenau and standard KdV equations. These equations are nonlinear
partial differential equations (NPDE) which play an important role
in mathematical physics. Exp-function method is easy, succinct and
powerful to implement to nonlinear partial differential equations
arising in mathematical physics. We mainly try to present an
application of Exp-function method and offer solutions for common
errors wich occur during some of the recent works.
Abstract: Partial shadowing is one of the problems that are always faced in terrestrial applications of solar photovoltaic (PV). The effects of partial shadow on the energy yield of conventional mono-crystalline and multi-crystalline PV modules have been researched for a long time. With deployment of new thin-film solar PV modules in the market, it is important to understand the performance of new PV modules operating under the partial shadow in the tropical zone. This paper addresses the impacts of different partial shadowing on the operating characteristics of four different types of solar PV modules that include multi-crystalline, amorphous thin-film, CdTe thin-film and CIGS thin-film PV modules.
Abstract: A continuous time model of the interaction between
crop insect pests and naturally beneficial pest enemies is created
using a set of simultaneous, non-linear, ordinary differential
equations incorporating natural death rates based on the Weibull
distribution. The crop pest is present in all its life-cycle stages of:
egg, larva, pupa and adult. The beneficial insects, parasitoid wasps,
may be present in either or all parasitized: eggs, larva and pupa.
Population modelling is used to estimate the quantity of the natural
pest enemies that should be introduced into the pest infested
environment to suppress the pest population density to an
economically acceptable level within a prescribed number of days.
The results obtained illustrate the effect of different combinations of
parasitoid wasps, using the Pascal distribution to estimate their
success in parasitizing different pest developmental stages, to deliver
pest control to a sustainable level. Effective control, within a
prescribed number of days, is established by the deployment of two
or all three species of wasps, which partially destroy pest: egg, larvae
and pupae stages. The selected scenarios demonstrate effective
sustainable control of the pest in less than thirty days.