Abstract: When designing satellites, one of the major issues aside for designing its primary subsystems is to devise its thermal. The thermal management of satellites requires solving different sets of issues with regards to modelling. If the satellite is well conditioned all other parts of the satellite will have higher temperature no matter what. The main issue of thermal modelling for satellite design is really making sure that all the other points of the satellite will be within the temperature limits they are designed. The insertion of power electronics in aerospace technologies is becoming widespread and the modern electronic systems used in space must be reliable and efficient with thermal management unaffected by outer space constraints. Many advanced thermal management techniques have been developed in recent years that have application in high power electronic systems. This paper presents a Three-Dimensional Modal Transmission Line Matrix (3D-TLM) implementation of transient heat flow in space power electronics. In such kind of components heat dissipation and good thermal management are essential. Simulation provides the cheapest tool to investigate all aspects of power handling. The 3DTLM has been successful in modeling heat diffusion problems and has proven to be efficient in terms of stability and complex geometry. The results show a three-dimensional visualisation of self-heating phenomena in the device affected by outer space constraints, and will presents possible approaches for increasing the heat dissipation capability of the power modules.
Abstract: This paper presents a model for the characterization
and selection of beeswaxes for use as base substitute tissue for the
manufacture of objects suitable for external radiotherapy using
megavoltage photon beams. The model of characterization was
divided into three distinct stages: 1) verification of aspects related to
the origin of the beeswax, the bee species, the flora in the vicinity of
the beehives and procedures to detect adulterations; 2) evaluation of
physical and chemical properties; and 3) evaluation of beam
attenuation capacity. The chemical composition of the beeswax
evaluated in this study was similar to other simulators commonly
used in radiotherapy. The behavior of the mass attenuation coefficient
in the radiotherapy energy range was comparable to other simulators.
The proposed model is efficient and enables convenient assessment
of the use of any particular beeswax as a base substitute tissue for
radiotherapy.
Abstract: Organizations are supposed to be systems and
consequently require defining the notion of equilibrium within.
However, organizations comprise people and unavoidably entail their
irrational aspects. Then, the question is what is the organizational
equilibrium and equilibrating mechanisms considering these aspects.
Hence, some arguments are provided here to conceptualize human
unconsciousness, irrationalities and consequent uncertainties within
organizations in the form of a system of psychic dynamism. The
assumption is this dynamism maintains the psychic balance of the
organization through a psychodynamic point of view. The resultant
conceptualization expected to promote the understanding of such
aspects in different organizational settings by hypothesizing
organizational equilibration from this perspective. As a result, the
main expectation is, if it is known that how the organization
equilibrates in this sense, we can explain and deal with such
irrationalities and unconsciousness by rational and, of course
conscious, planning and accomplishing.
Abstract: An alternative iterative computational procedure is
proposed for internal normal ball loads calculation in statically
loaded single-row, angular-contact ball bearings, subjected to a
known thrust load, which is applied in the inner ring at the geometric
bearing center line. An accurate method for curvature radii at
contacts with inner and outer raceways in the direction of the motion
is used. Numerical aspects of the iterative procedure are discussed.
Numerical examples results for a 218 angular-contact ball bearing
have been compared with those from the literature. Twenty figures
are presented showing the geometrical features, the behavior of the
convergence variables and the following parameters as functions of
the thrust load: normal ball loads, contact angle, distance between
curvature centers, and normal ball and axial deflections.
Abstract: Campus sustainability is the goal of a university striving for sustainable development. This study found that of 17 popular approaches, two comprehensive campus sustainability assessment frameworks were developed in the context of Sustainability in Higher Education (SHE), and used by many university campuses around the world. Sustainability Tracking Assessment and Rating Systems (STARS) and the Campus Sustainability Assessment Framework (CSAF) approaches are more comprehensive than others. Therefore, the researchers examined aspects and elements used by CSAF and STARS in the approach to develop a campus sustainability assessment framework for Universiti Kebangsaan Malaysia (UKM). Documents analysis found that CSAF and STARS do not focus on physical development, especially the construction industry, as key elements of campus sustainability assessment. This finding is in accordance with the Sustainable UKM Programme which consists of three main components of sustainable community, ecosystem and physical development.
Abstract: This work aims to describe the process of developing
services and applications of seamless communication within a
Telecom Italia long-term research project, which takes as central aim
the design of a wearable communication device. In particular, the
objective was to design a wrist phone integrated into everyday life of
people in full transparency. The methodology used to design the
wristwatch was developed through several subsequent steps also
involving the Personas Layering Framework. The data collected in
this phases have been very useful for designing an improved version
of the first two concepts of wrist phone going to change aspects
related to the four critical points expressed by the users.
Abstract: The aim of this paper is to study in depth some methodological aspects of social interventation, focusing on desirable passage from social maternage method to peer advocacy method. For this purpose, we intend analyze social and organizative components, that affect operator's professional action and that are part of his psychological environment, besides the physical and social one. In fact, operator's interventation should not be limited to a pure supply of techniques, nor to take shape as improvised action, but “full of good purposes".
Abstract: Walking as a type of non-motorized transportation has
various social, economical and environmental privileges. Also, today
different aspects of sustainable development have been emphasized
and promotion of sustainable transportation modes has been
considered according to this approach. Therefore, the objective of
this research is exploring the circumstance of relationship between
walking and sustainable urban transportation.For writing this article,
the most important resources related to the traits of walking have
been surveyed via a documentary method and after explaining the
concept of sustainable transportation and its indicators, benefiting
from the viewpoints of transportation experts of Tehran, as the capital
and greatest city of Iran, different modes of urban transportation have
been compared in proportion to each criterion and to each other and
have been analyzed according to AHP method. The results of this
study indicate that walking is the most sustainable mode of inner city
transportation.
Abstract: This preliminary study attempts to see if a learning
environment influences instructor’s teaching strategies and learners’
in-class activities in a foreign language class at a university in Japan.
The class under study was conducted in a computer room, while the
majority of classes of the same course were offered in traditional
classrooms without computers. The study also sees if the unplanned
blended learning environment, enhanced, or worked against, in
achieving course goals, by paying close attention to in-class artefacts,
such as computers. In the macro-level analysis, the course syllabus
and weekly itinerary of the course were looked at; and in the microlevel
analysis, nonhuman actors in their environments were named
and analyzed to see how they influenced the learners’ task processes.
The result indicated that students were heavily influenced by the
presence of computers, which lead them to disregard some aspects of
intended learning objectives.
Abstract: To support user mobility for a wireless network new mechanisms are needed and are fundamental, such as paging, location updating, routing, and handover. Also an important key feature is mobile QoS offered by the WATM. Several ATM network protocols should be updated to implement mobility management and to maintain the already ATM QoS over wireless ATM networks. A survey of the various schemes and types of handover is provided. Handover procedure allows guarantee the terminal connection reestablishment when it moves between areas covered by different base stations. It is useful to satisfy user radio link transfer without interrupting a connection. However, failure to offer efficient solutions will result in handover important packet loss, severe delays and degradation of QoS offered to the applications. This paper reviews the requirements, characteristics and open issues of wireless ATM, particularly with regard to handover. It introduces key aspects of WATM and mobility extensions, which are added in the fixed ATM network. We propose a flexible approach for handover management that will minimize the QoS deterioration. Functional entities of this flexible approach are discussed in order to achieve minimum impact on the connection quality when a MT crosses the BS.
Abstract: Due to the fast development of technology, the
competition of technological products is turbulent; therefore, it is
important to understand the market trend, consumers- demand and
preferences. As the smartphones are prevalent, the main purpose of
this paper is to utilize Analytic Hierarchy Process (AHP) to analyze
consumer-s purchase evaluation factors of smartphones. Through the
AHP expert questionnaire, the smartphones- main functions are
classified as “user interface", “mobile commerce functions",
“hardware and software specifications", “entertainment functions" and
“appearance and design", five aspects to analyze the weights. Then
four evaluation criteria are evaluated under each aspect to rank the
weights. Based on an analysis of data shows that consumers consider
when purchase factors are “hardware and software specifications",
“user interface", “appearance and design", “mobile commerce
functions" and “entertainment functions" in sequence. The “hardware
and software specifications" aspect obtains the weight of 33.18%; it is
the most important factor that consumers are taken into account. In
addition, the most important evaluation criteria are central processing
unit, operating system, touch screen, and battery function in sequence.
The results of the study can be adopted as reference data for mobile
phone manufacturers in the future on the design and marketing
strategy to satisfy the voice of customer.
Abstract: The mobile users with Laptops need to have an
efficient access to i.e. their home personal data or to the Internet from
any place in the world, regardless of their location or point of
attachment, especially while roaming outside the home subnet. An
efficient interpretation of packet losses problem that is encountered
from this roaming is to the centric of all aspects in this work, to be
over-highlighted. The main previous works, such as BER-systems,
Amigos, and ns-2 implementation that are considered to be in
conjunction with that problem under study are reviewed and
discussed. Their drawbacks and limitations, of stopping only at
monitoring, and not to provide an actual solution for eliminating or
even restricting these losses, are mentioned. Besides that, the
framework around which we built a Triple-R sequence as a costeffective
solution to eliminate the packet losses and bridge the gap
between subnets, an area that until now has been largely neglected, is
presented. The results show that, in addition to the high bit error rate
of wireless mobile networks, mainly the low efficiency of mobile-IP
registration procedure is a direct cause of these packet losses.
Furthermore, the output of packet losses interpretation resulted an
illustrated triangle of the registration process. This triangle should be
further researched and analyzed in our future work.
Abstract: The article touches upon questions of information security in Russian Economy. It covers theoretical bases of information security and causes of its development. The theory is proved by the analysis of business activities and the main tendencies of information security development. Perm region has been chosen as the bases for the analysis, being the fastestdeveloping region that uses methods of information security in managing it economy. As a result of the study the authors of the given article have formulated their own vision of the problem of information security in various branches of economy and stated prospects of information security development and its growing role in Russian economy
Abstract: FW4 is a newly developed hot die material widely
used in Forging Dies manufacturing. The right selection of the
machining conditions is one of the most important aspects to take
into consideration in the Electrical Discharge Machining (EDM) of
FW4. In this paper an attempt has been made to develop
mathematical models for relating the Material Removal Rate (MRR),
Tool Wear Ratio (TWR) and surface roughness (Ra) to machining
parameters (current, pulse-on time and voltage). Furthermore, a study
was carried out to analyze the effects of machining parameters in
respect of listed technological characteristics. The results of analysis
of variance (ANOVA) indicate that the proposed mathematical
models, can adequately describe the performance within the limits of
the factors being studied.
Abstract: Integral Abutment Bridges (IAB) are defined as
simple or multiple span bridges in which the bridge deck is cast
monolithically with the abutment walls. This kind of bridges are
becoming very popular due to different aspects such as good
response under seismic loading, low initial costs, elimination of
bearings, and less maintenance. However the main issue related to
the analysis of this type of structures is dealing with soil-structure
interaction of the abutment walls and the supporting piles. Various
soil constitutive models have been used in studies of soil-structure
interaction in this kind of structures by researchers. This paper is an
effort to review the implementation of various finite elements model
which explicitly incorporates the nonlinear soil and linear structural
response considering various soil constitutive models and finite
element mesh.
Abstract: After the development of the Internet a suitable
discipline for trading goods electronically has been emerged.
However, this type of markets is not still mature enough in order to
become independent and get closer to seller/buyer-s needs.
Furthermore, the buyable and sellable goods in these markets still
don-t have essential standards for being well-defined. In this paper,
we will present a model for development of a market which can
contain goods with variable definitions and we will also investigate
its characteristics. Besides, by noticing the fact that people have
different discriminations, it-s figured out that the significance of each
attribute of a specific product may vary from different people-s view
points. Consequently we-ll present a model for weighting and
accordingly different people-s view points could be satisfied. These
two aspects will be discussed completely throughout this paper.
Abstract: The objective of this research was to study influence
parameters affecting to mechanical property of austenitic stainless
steel grade 304 (AISI 304) with Gas Metal Arc Welding (GMAW).
The research was applying factorial design experiment, which have
following interested parameters: welding current at 80, 90, and 100
Amps, welding speeds at 250, 300, and 350 mm/min, and shield gas
of 75% Ar + 25% CO2, 70% Ar + 25% CO2 + 5% O2 and 69.5% Ar +
25% CO2 + 5% O2 + 0.5% He gas. The study was done in following
aspects: ultimate tensile strength and elongation. A research study of
ultimate tensile strength found that main factor effect, which had the
highest strength to AISI 304 welding was shield gas of 70% Ar +
25% CO2 + 5% O2 at average of 954.81 N/mm2. Result of the highest
elongation was showed significantly different at interaction effect
between shield gas of 69.5%Ar+25%CO2+5%O2+.5%He and
welding speed at 250 mm/min at 47.94%.
Abstract: This paper was to study the clothes dryer using waste
heat from a split type air conditioner with a capacity of 12,648 btu/h.
The drying chamber had a minimum cross section area with the size
of 0.5 x 1.0 m2. The chamber was constructed by sailcloth and was
inside folded with aluminium foil. Then, it was connected to the
condensing unit of an air conditioner. The experiment was carried out
in two aspects which were the clothes drying with and without
auxiliary fan unit. The results showed that the drying rate of clothes
in the chamber installed with and without auxiliary fan unit were
2.26 and 1.1 kg/h, respectively. In case of the chamber installed with
a auxiliary fan unit, the additional power of 0.011 kWh was
consumed and the drying rate was higher than that of clothes drying
without auxiliary fan unit. Without auxiliary fan unit installation, no
energy was required but there was a portion of hot air leaks away
through the punctured holes at the wall of the drying chamber, hence
the drying rate was dropped below. The drying rate of clothes drying
using waste heat was higher than natural indoor drying and
commercial dryer which their drying rate were 0.17 and 1.9 kg/h,
respectively. It was noted that the COP of the air conditioner did not
change during the operating of clothes drying.
Abstract: This paper focuses on the development of bond graph
dynamic model of the mechanical dynamics of an excavating mechanism
previously designed to be used with small tractors, which are
fabricated in the Engineering Workshops of Jomo Kenyatta University
of Agriculture and Technology. To develop a mechanical dynamics
model of the manipulator, forward recursive equations similar to
those applied in iterative Newton-Euler method were used to obtain
kinematic relationships between the time rates of joint variables
and the generalized cartesian velocities for the centroids of the
links. Representing the obtained kinematic relationships in bondgraphic
form, while considering the link weights and momenta as
the elements led to a detailed bond graph model of the manipulator.
The bond graph method was found to reduce significantly the number
of recursive computations performed on a 3 DOF manipulator for a
mechanical dynamic model to result, hence indicating that bond graph
method is more computationally efficient than the Newton-Euler
method in developing dynamic models of 3 DOF planar manipulators.
The model was verified by comparing the joint torque expressions
of a two link planar manipulator to those obtained using Newton-
Euler and Lagrangian methods as analyzed in robotic textbooks. The
expressions were found to agree indicating that the model captures
the aspects of rigid body dynamics of the manipulator. Based on
the model developed, actuator sizing and valve sizing methodologies
were developed and used to obtain the optimal sizes of the pistons
and spool valve ports respectively. It was found that using the pump
with the sized flow rate capacity, the engine of the tractor is able to
power the excavating mechanism in digging a sandy-loom soil.
Abstract: Tasks of an application program of an embedded system are managed by the scheduler of a real-time operating system
(RTOS). Most RTOSs adopt just fixed priority scheduling, which is not optimal in all cases. Some applications require earliest deadline
first (EDF) scheduling, which is an optimal scheduling algorithm.
In order to develop an efficient real-time embedded system, the
scheduling algorithm of the RTOS should be selectable. The paper presents a method to customize the scheduler using aspectoriented
programming. We define aspects to replace the fixed priority scheduling mechanism of an OSEK OS with an EDF scheduling
mechanism. By using the aspects, we can customize the scheduler
without modifying the original source code. We have applied the
aspects to an OSEK OS and get a customized operating system with
EDF scheduling. The evaluation results show that the overhead of
aspect-oriented programming is small enough.