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: The main aim of the presented experiments is to
improve behaviour of sandwich structures under dynamic loading,
such as crash or explosion. This paper describes experimental
investigation on the response of new advanced materials to low and
high velocity load. Blast wave energy absorbers were designed using
two types of porous lightweight raw particle materials based on
expanded glass and ceramics with dimensions of 0.5-1 mm,
combined with polymeric binder. The effect of binder amount on the
static and dynamic properties of designed materials was observed.
Prism shaped specimens were prepared and loaded to obtain physicomechanical
parameters – bulk density, compressive and flexural
strength under quasistatic load, the dynamic response was determined
using Split Hopkinson Pressure bar apparatus. Numerical
investigation of the material behaviour in sandwich structure was
performed using implicit/explicit solver LS-Dyna. As the last step,
the developed material was used as the interlayer of blast resistant
litter bin, and it´s functionality was verified by real field blast tests.
Abstract: The purpose of the present work was to develop an
innovative food product with nutritional properties as well as
appealing organoleptic qualities. The product, a jam, was prepared
with the beans’ cooking water combined with fresh apple or carrot,
without the addition of any conservatives. Three different jams were
produced: bean and carrot, bean and apple and bean, apple and
cinnamon. The developed products underwent a sensorial analysis
that revealed that the bean, apple and cinnamon jam was globally
better accepted. However, with this study, the consumers determined
that the bean and carrot jam had the most attractive color and the
bean and apple jam the better consistency. Additionally, it was
possible to analyze the jams for their chemical components, namely
fat, fiber, protein, sugars and antioxidant activity. The obtained
results showed that the bean and carrot jam had the highest lipid
content, while the bean, apple and cinnamon jam had the highest
fiber content, when compared to the other two jams. Regarding the
sugar content, both jams with apple revealed similar sugar values,
which were higher than the sugar content of the bean and carrot jam.
The antioxidant activity was on average 10 mg TE/g.
Abstract: In this paper we present the efficient parallel
implementation of elastoplastic problems based on the TFETI (Total
Finite Element Tearing and Interconnecting) domain decomposition
method. This approach allow us to use parallel solution and compute
this nonlinear problem on the supercomputers and decrease the
solution time and compute problems with millions of DOFs. In
our approach we consider an associated elastoplastic model with
the von Mises plastic criterion and the combination of linear
isotropic-kinematic hardening law. This model is discretized by
the implicit Euler method in time and by the finite element
method in space. We consider the system of nonlinear equations
with a strongly semismooth and strongly monotone operator. The
semismooth Newton method is applied to solve this nonlinear
system. Corresponding linearized problems arising in the Newton
iterations are solved in parallel by the above mentioned TFETI. The
implementation of this problem is realized in our in-house MatSol
packages developed in MatLab.
Abstract: Power Regeneration in Refrigeration Plant concept
has been analyzed and has been shown to be capable of saving about
25% power in Cryogenic Plants with the Power Regeneration System
(PRS) running under nominal conditions. The innovative component
Compressor Expander Group (CEG) based on turbomachinery has
been designed and built modifying CETT compressor and expander,
both selected for optimum plant performance. Experiments have
shown the good response of the turbomachines to run with R404a as
working fluid. Power saving up to 12% under PRS derated conditions
(50% loading) has been demonstrated. Such experiments allowed
predicting a power saving up to 25% under CEG full load.
Abstract: The paper describes the OAS role in dispute
resolution. The authors make an attempt to identify a general pattern
of the OAS activities within the peaceful settlement of interstate
conflicts, in the beginning of 21st century, as well as to analyze some
features of Honduras–Belize, Nicaragua–Honduras, Honduras–El
Salvador, Costa-Rica–Nicaragua, Colombia–Ecuador cases.
Abstract: In this work, we begin with the presentation of the
Tθ family of usual similarity measures concerning multidimensional
binary data. Subsequently, some properties of these measures are
proposed. Finally the impact of the use of different inter-elements
measures on the results of the Agglomerative Hierarchical Clustering
Methods is studied.
Abstract: In this paper we consider the equation of motion for
the F (R, T) gravity on their property of conformal invariance. It
is shown that in the general case, such a theory is not conformal
invariant. Studied special cases for the functions v and u in which
can appear properties of the theory. Also we consider cosmological
aspects F (R, T) theory of gravity, having considered particular case
F (R, T) = μR+νT^2. Showed that in this case there is a nonlinear
dependence of the parameter equation of state from time to time,
which affects its evolution.
Abstract: Using the pseudopotential technique the Sagdeev
potential equation has been derived in a plasma consisting of twotemperature
nonisothermal electrons, negatively charged dust grains
and warm positive ions. The study shows that the presence of
nonisothermal two-temperature electrons and charged dust grains
have significant effects on the excitation and structure of the ionacoustic
double layers in the model plasma under consideration. Only
compressive type double layer is obtained in the present plasma
model. The double layer solution has also been obtained by including
higher order nonlinearity and nonisothermality, which is shown to
modify the amplitude and deform the shape of the double layer.
Abstract: Theory of interpretation of electromagnetic fields studied in the electrical prospecting with direct current is mainly developed for the case of a horizontal surface observation. However in practice we often have to work in difficult terrain surface. Conducting interpretation without the influence of topography can cause non-existent anomalies on sections. This raises the problem of studying the impact of different shapes of ground surface relief on the results of electrical prospecting's research. This research examines the numerical solutions of the direct problem of electrical prospecting for two-dimensional and three-dimensional media, taking into account the terrain. The problem is solved using the method of integral equations. The density of secondary currents on the relief surface is obtained.
Abstract: In the present work, fly ash geopolymer based
composites including polyester (PES) waste were studied. Specimens
of three compositions were prepared: (a) fly ash geopolymer with 5%
PES waste; (b) fly ash geopolymer mortar with 5% PES waste; (c) fly
ash geopolymer mortar with 6.25% PES waste. Compressive and
bending strength measurements, water absorption test and
determination of thermal conductivity coefficient were performed.
The results showed that the addition of sand in a mixture of
geopolymer with 5% PES content led to higher compressive strength,
while it increased water absorption and reduced thermal conductivity
coefficient. The increase of PES addition in geopolymer mortars
resulted in a more dense structure, indicated by the increase of
strength and thermal conductivity and the decrease of water
absorption.
Abstract: The present work describes the implementation of the
Enhanced Collaborative Optimization (ECO) multilevel architecture
with a gradient-based optimization algorithm with the aim of
performing a multidisciplinary design optimization of a generic
unmanned aerial vehicle with morphing technologies. The concepts
of weighting coefficient and dynamic compatibility parameter are
presented for the ECO architecture. A routine that calculates the
aircraft performance for the user defined mission profile and vehicle’s
performance requirements has been implemented using low fidelity
models for the aerodynamics, stability, propulsion, weight, balance
and flight performance. A benchmarking case study for evaluating
the advantage of using a variable span wing within the optimization
methodology developed is presented.
Abstract: Advances in the use of health care technology have
resulted in increased adverse events (AEs) related to the use of
medical devices. The study focused on the existing reporting systems.
This study was conducted in a tertiary care public sector hospital.
Devices included Syringe infusion pumps, Cardiac monitors, Pulse
oximeters, Ventilators and Defibrillators. A total of 211 respondents
were recruited. Interviews were held with 30 key informants. Medical
records were scrutinized. Relevant statistical tests were used.
Resident doctors reported maximum frequency of AEs, followed
by nurses; and least by consultants. A significant association was
found between the cadre of health care personnel and awareness that
the patients and bystanders have a risk of sustaining AE. Awareness
regarding reporting of AEs was low, and it was generally done
verbally. Other critical findings are discussed in the light of the
barriers to reporting, reasons for non-compliance, recording system,
and so on.
Abstract: Exact solution of an unsteady flow of elastico-viscous
fluid through a porous media in a tube of ellipsoidal cross section
under the influence of constant pressure gradient has been obtained in
this paper. Initially, the flow is generated by a constant pressure
gradient. After attaining the steady state, the pressure gradient is
suddenly withdrawn and the resulting fluid motion in a tube of
ellipsoidal cross section by taking into account of the porosity factor
of the bounding surface is investigated. The problem is solved in twostages
the first stage is a steady motion in tube under the influence of
a constant pressure gradient, the second stage concern with an
unsteady motion. The problem is solved employing separation of
variables technique. The results are expressed in terms of a nondimensional
porosity parameter (K) and elastico-viscosity parameter
(β), which depends on the Non-Newtonian coefficient. The flow
parameters are found to be identical with that of Newtonian case as
elastic-viscosity parameter tends to zero and porosity tends to
infinity. It is seen that the effect of elastico-viscosity parameter and
the porosity parameter of the bounding surface has significant effect
on the velocity parameter.
Abstract: This paper presents circuit models to analyze the
conducted susceptibility of multiconductor shielded cables in
frequency domains using Branin’s method, which is referred to as the
method of characteristics. These models, which can be used directly
in the time and frequency domains, take into account the presence of
both the transfer impedance and admittance. The conducted
susceptibility is studied by using an injection current on the cable
shield as the source. Two examples are studied; a coaxial shielded
cable and shielded cables with two parallel wires (i.e., twinax cables).
This shield has an asymmetry (one slot on the side). Results obtained
by these models are in good agreement with those obtained by other
methods.
Abstract: This study aimed to identify the alignment of
understanding and assessment practices among secondary school
teachers. The study was carried out using quantitative descriptive
study. The sample consisted of 164 teachers who taught Form 1 and 2
from 11 secondary schools in the district of North Kinta, Perak,
Malaysia. Data were obtained from 164 respondents who answered
Expectation Alignment Understanding and Practices of School
Assessment (PEKDAPS) questionnaire. The data were analysed
using SPSS 17.0+. The Cronbach’s alpha value obtained through
PEKDAPS questionnaire pilot study was 0.86. The results showed
that teachers' performance in PEKDAPS based on the mean value
was less than 3, which means that perfect alignment does not occur
between the understanding and practices of school assessment. Two
major PEKDAPS sub-constructs of articulation across grade and age
and usability of the system were higher than the moderate alignment
of the understanding and practices of school assessment (Min=2.0).
The content focused of PEKDAPs sub-constructs which showed
lower than the moderate alignment of the understanding and practices
of school assessment (Min=2.0). Another two PEKDAPS subconstructs
of transparency and fairness and the pedagogical
implications showed moderate alignment (2.0). The implications of
the study is that teachers need to fully understand the importance of
alignment among components of assessment, learning and teaching
and learning objectives as strategies to achieve quality assessment
process.
Abstract: This paper discusses the design and analysis of a
hybrid PV-Fuel cell energy system destined to power a DC load. The
system is composed of a photovoltaic array, a fuel cell, an
electrolyzer and a hydrogen tank. HOMER software is used in this
study to calculate the optimum capacities of the power system
components that their combination allows an efficient use of solar
resource to cover the hourly load needs. The optimal system sizing
allows establishing the right balance between the daily electrical
energy produced by the power system and the daily electrical energy
consumed by the DC load using a 28 KW PV array, a 7.5 KW fuel
cell, a 40KW electrolyzer and a 270 Kg hydrogen tank. The variation
of powers involved into the DC bus of the hybrid PV-fuel cell system
has been computed and analyzed for each hour over one year: the
output powers of the PV array and the fuel cell, the input power of
the elctrolyzer system and the DC primary load. Equally, the annual
variation of stored hydrogen produced by the electrolyzer has been
assessed. The PV array contributes in the power system with 82%
whereas the fuel cell produces 18%. 38% of the total energy
consumption belongs to the DC primary load while the rest goes to
the electrolyzer.
Abstract: The article deals with modelling of the fire
pragmatism in the area of military management and its experimental
verification. Potential approaches are based on the synergy of
mathematical and theoretical ideas, operational and tactical
requirements and the military decision-making process. This issue
has taken on importance in recent times, particularly with the
increasing trend of digitized battlefield, the development of C4ISR
systems and intention to streamline the command and control process
at the lowest levels of command. From fundamental and
philosophical point of view, these new approaches seek to
significantly upgrade and enhance the decision-making process of the
tactical commanders.
Abstract: Urban Search and Rescue (USAR) is a functional
capability that has been developed to allow the United Kingdom Fire
and Rescue Service to deal with ‘major incidents’ primarily involving
structural collapse. The nature of the work undertaken by USAR
means that staying out of a damaged or collapsed building structure is
not usually an option for search and rescue personnel. As a result
there is always a risk that they themselves could become victims. For
this paper, a systematic and investigative review using desk research
was undertaken to explore the role which structural engineering can
play in assisting search and rescue personnel to conduct structural
assessments when in the field. The focus is on how search and rescue
personnel can assess damaged and collapsed building structures, not
just in terms of structural damage that may been countered, but also
in relation to structural stability. Natural disasters, accidental
emergencies, acts of terrorism and other extreme events can vary
significantly in nature and ferocity, and can cause a wide variety of
damage to building structures. It is not possible or, even realistic, to
provide search and rescue personnel with definitive guidelines and
procedures to assess damaged and collapsed building structures as
there are too many variables to consider. However, understanding
what implications damage may have upon the structural stability of a
building structure will enable search and rescue personnel to better judge
and quantify risk from a life-safety standpoint. It is intended that this
will allow search and rescue personnel to make informed decisions
and ensure every effort is made to mitigate risk, so that they
themselves do not become victims.
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.