Abstract: Although water only takes a little percentage in the total mass of soil, it indeed plays an important role to the strength of structure. Moisture transfer can be carried out by many different mechanisms which may involve heat and mass transfer, thermodynamic phase change, and the interplay of various forces such as viscous, buoyancy, and capillary forces. The continuum models are not well suited for describing those phenomena in which the connectivity of the pore space or the fracture network, or that of a fluid phase, plays a major role. However, Lattice Boltzmann methods (LBMs) are especially well suited to simulate flows around complex geometries. Lattice Boltzmann methods were initially invented for solving fluid flows. Recently, fluid with multicomponent and phase change is also included in the equations. By comparing the numerical result with experimental result, the Lattice Boltzmann methods with phase change will be optimized.
Abstract: In this paper we evaluated the efficacy of
photodynamic treatment of infected wounds on pig animal model by
diffuse reflectance spectrometry. The study was conducted on fifteen
wounds contaminated with Staphylococcus aureus bacteria that were
incubated for 30 min with methylene blue solution (c = 3.3 x 10-3 M)
and exposed to laser radiations (λ = 670 nm, P = 15 mW) for 15 min.
The efficiency of photodynamic inactivation of bacteria was
evaluated by microbiological exams and diffuse reflectance
spectrometry. The results of the microbiological exams showed that
the bacterial concentration has decreased from 6.93±0.138
logCFU/ml to 3.12±0.108 logCFU/ml. The spectral examination
showed that the diffuse reflectance of wounds contaminated with
Staphylococcus aureus has decreased from 5.06±0.036 % to
3.36±0.025 %. In conclusion, photodynamic therapy is an effective
method for the treatment of infected wounds and there is a correlation
between the CFU count and diffuse reflectance.
Abstract: The growing importance of sustainability in corporate
policies represents a great opportunity for workers to gain more
consideration, with great benefits to their well being. Sustainable
work is believed to be one which improves the organization-s
performance and fosters professional development as well as
workers- health. In a multiple case study based on document
research, information was sought about work activities and their
sustainability or corporate social responsibility (CSR) policies, as
disseminated by corporations. All the companies devoted attention to
work activities and delivered a good amount of information about
them. Nevertheless, the information presented was generic; all the
actions developed were top-down and there was no information about
the impact of changes aimed at sustainability on the workers-
activities. It was found that the companies seemed to be at an early
stage. In the future, they need to show more commitment through
concrete goals: they must be aware that workers contribute directly to
the corporations- sustainability. This would allow room for
Ergonomics and Work Psychodynamics to be incorporated and to be
useful for both companies and society, so as to promote and ensure
work sustainability.
Abstract: The aim of the work presented here was to either use
existing forest dynamic simulation models or calibrate a new one
both within the SYMFOR framework with the purpose of examining
changes in stand level basal area and functional composition in
response to selective logging considering trees > 10 cm d.b.h for two
areas of undisturbed Amazonian non flooded tropical forest in Brazil
and one in Peru. Model biological realism was evaluated for forest in
the undisturbed and selectively logged state and it was concluded that
forest dynamics were realistically represented. Results of the logging
simulation experiments showed that in relation to undisturbed forest
simulation subject to no form of harvesting intervention there was a
significant amount of change over a 90 year simulation period that
was positively proportional to the intensity of logging. Areas which
had in the dynamic equilibrium of undisturbed forest a greater
proportion of a specific ecological guild of trees known as the light
hardwoods (LHW’s) seemed to respond more favorably in terms of
less deviation but only within a specific range of baseline forest
composition beyond which compositional diversity became more
important. These finds are in line partially with practical management
experience and partiality basic systematics theory respectively.
Abstract: Software maintenance, which involves making enhancements, modifications and corrections to existing software systems, consumes more than half of developer time. Specification comprehensibility plays an important role in software maintenance as it permits the understanding of the system properties more easily and quickly. The use of formal notation such as B increases a specification-s precision and consistency. However, the notation is regarded as being difficult to comprehend. Semi-formal notation such as the Unified Modelling Language (UML) is perceived as more accessible but it lacks formality. Perhaps by combining both notations could produce a specification that is not only accurate and consistent but also accessible to users. This paper presents an experiment conducted on a model that integrates the use of both UML and B notations, namely UML-B, versus a B model alone. The objective of the experiment was to evaluate the comprehensibility of a UML-B model compared to a traditional B model. The measurement used in the experiment focused on the efficiency in performing the comprehension tasks. The experiment employed a cross-over design and was conducted on forty-one subjects, including undergraduate and masters students. The results show that the notation used in the UML-B model is more comprehensible than the B model.
Abstract: Using a force balanced translational-radial dynamics,
phase space of the moving single bubble sonoluminescence (m-
SBSL) in 85% wt sulfuric acid has been numerically calculated. This
phase space is compared with that of single bubble sonoluminescence
(SBSL) in pure water which has been calculated by using the mere
radial dynamics. It is shown that in 85% wt sulfuric acid, in a general
agreement with experiment, the bubble-s positional instability
threshold lays under the shape instability threshold. At the onset of
spatial instability of moving sonoluminescing (SL) bubble in 85%
wt sulfuric acid, temporal effects of the hydrodynamic force on the
bubble translational-radial dynamics have been investigated. The
appearance of non-zero history force on the moving SL bubble is
because of proper condition which was produced by high viscosity of
acid. Around the moving bubble collapse due to the rapid contraction
of the bubble wall, the inertial based added mass force overcomes the
viscous based history force and induces acceleration on the bubble
translational motion.
Abstract: Polyurethanes (PURs) are very versatile polymeric
materials with a wide range of physical and chemical properties.
PURs have desirable properties such as high abrasion resistance, tear
strength, shock absorption, flexibility and elasticity. Although they
have relatively poor thermal stability, this can be improved by using
treated clay. Polyurethane/clay nanocomposites have been
synthesized from renewable sources. A polyol for the production of
polyurethane by reaction with an isocyanate was obtained by the
synthesis of palm oil-based oleic acid with glycerol. Dodecylbenzene
sulfonic acid (DBSA) was used as catalyst and emulsifier. The
unmodified clay (kunipia-F) was treated with cetyltrimethyl
ammonium bromide (CTAB-mont) and octadodecylamine (ODAmont).
The d-spacing in CTAB-mont and ODA-mont were 1.571 nm
and 1.798 nm respectively and larger than that of the pure-mont
(1.142 nm). The organoclay was completely intercalated in the
polyurethane, as confirmed by a wide angle x-ray diffraction
(WAXD) pattern.
The results showed that adding clay demonstrated better thermal
stability in comparison with the virgin polyurethane. Onset
degradation of pure PU is at 200oC, and is lower than that of the
CTAB-mont PU and ODA-mont PU which takes place at about
318oC and 330oC, respectively. The mechanical properties (including
the dynamic mechanical properties) of pure polyurethane (PU) and
PU/clay nanocomposites, were measured. The modified organoclay
had a remarkably beneficial effect on the strength and elongation at
break of the nanocomposites, which both increased with increasing
clay content with the increase of the tensile strength of more than
214% and 267% by the addition of only 5 wt% of the
montmorillonite CTAB-mont PU and ODA-mont PU, respectively.
Abstract: Genetic algorithms (GAs) have been widely used for
global optimization problems. The GA performance depends highly
on the choice of the search space for each parameter to be optimized.
Often, this choice is a problem-based experience. The search space
being a set of potential solutions may contain the global optimum
and/or other local optimums. A bad choice of this search space
results in poor solutions. In this paper, our approach consists in
extending the search space boundaries during the GA optimization,
only when it is required. This leads to more diversification of GA
population by new solutions that were not available with fixed search
space boundaries. So, these dynamic search spaces can improve the
GA optimization performances. The proposed approach is applied to
power system stabilizer optimization for multimachine power system
(16-generator and 68-bus). The obtained results are evaluated and
compared with those obtained by ordinary GAs. Eigenvalue analysis
and nonlinear system simulation results show the effectiveness of the
proposed approach to damp out the electromechanical oscillation and
enhance the global system stability.
Abstract: In this paper, a new dependable algorithm based on an adaptation of the standard variational iteration method (VIM) is used for analyzing the transition from steady convection to chaos for lowto-intermediate Rayleigh numbers convection in porous media. The solution trajectories show the transition from steady convection to chaos that occurs at a slightly subcritical value of Rayleigh number, the critical value being associated with the loss of linear stability of the steady convection solution. The VIM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions to the considered model and other dynamical systems. We shall call this technique as the piecewise VIM. Numerical comparisons between the piecewise VIM and the classical fourth-order Runge–Kutta (RK4) numerical solutions reveal that the proposed technique is a promising tool for the nonlinear chaotic and nonchaotic systems.
Abstract: Dual bell nozzle is a promising one among the altitude
adaptation nozzle concepts, which offer increased nozzle
performance in rocket engines. Its advantage is the simplicity it offers
due to the absence of any additional mechanical device or movable
parts. Hence it offers reliability along with improved nozzle
performance as demanded by future launch vehicles. Among other
issues, the flow transition to the extension nozzle of a dual bell
nozzle is one of the major issues being studied in the development of
dual bell nozzle. A parameter named over-expansion factor, which
controls the value of the wall inflection angle, has been reported to
have substantial influence in this transition process. This paper
studies, through CFD and cold flow experiments, the effect of overexpansion
factor on flow transition in dual bell nozzles.
Abstract: This paper addresses linear quadratic regulation (LQR)
for variable speed variable pitch wind turbines. Because of the
inherent nonlinearity of wind turbine, a set of operating conditions is
identified and then a LQR controller is designed for each operating
point. The feedback controller gains are then interpolated linearly to
get control law for the entire operating region. Besides, the
aerodynamic torque and effective wind speed are estimated online to
get the gain-scheduling variable for implementing the controller. The
potential of the method is verified through simulation with the help of
MATLAB/Simulink and GH Bladed. The performance and
mechanical load when using LQR are also compared with that when
using PI controller.
Abstract: Multi criteria decision analysis (MDCA) covers both
data and experience. It is very common to solve the problems with
many parameters and uncertainties. GIS supported solutions improve
and speed up the decision process. Weighted grading as a MDCA
method is employed for solving the geotechnical problems. In this
study, geotechnical parameters namely soil type; SPT (N) blow
number, shear wave velocity (Vs) and depth of underground water
level (DUWL) have been engaged in MDCA and GIS. In terms of
geotechnical aspects, the settlement suitability of the municipal area
was analyzed by the method. MDCA results were compatible with
the geotechnical observations and experience. The method can be
employed in geotechnical oriented microzoning studies if the criteria
are well evaluated.
Abstract: The paper presents the design of a mini-UAV attitude
controller using the backstepping method. Starting from the nonlinear
dynamic equations of the mini-UAV, by using the backstepping
method, the author of this paper obtained the expressions of the
elevator, rudder and aileron deflections, which stabilize the UAV, at
each moment, to the desired values of the attitude angles. The attitude
controller controls the attitude angles, the angular rates, the angular
accelerations and other variables that describe the UAV longitudinal
and lateral motions. To design the nonlinear controller, by using the
backstepping technique, the nonlinear equations and the Lyapunov
analysis have been directly used. The designed controller has been
implemented in Matlab/Simulink environment and its effectiveness
has been tested with a campaign of numerical simulations using data
from the UAV flight tests. The obtained results are very good and
they are better than the ones found in previous works.
Abstract: The overriding goal of software engineering is to
provide a high quality system, application or a product. To achieve
this goal, software engineers must apply effective methods coupled
with modern tools within the context of a mature software process
[2]. In addition, it is also must to assure that high quality is realized.
Although many quality measures can be collected at the project
levels, the important measures are errors and defects. Deriving a
quality measure for reusable components has proven to be
challenging task now a days. The results obtained from the study are
based on the empirical evidence of reuse practices, as emerged from
the analysis of industrial projects. Both large and small companies,
working in a variety of business domains, and using object-oriented
and procedural development approaches contributed towards this
study. This paper proposes a quality metric that provides benefit at
both project and process level, namely defect removal efficiency
(DRE).
Abstract: One of the most important parts of a cement factory is
the cement rotary kiln which plays a key role in quality and quantity of produced cement. In this part, the physical exertion and bilateral
movement of air and materials, together with chemical reactions take
place. Thus, this system has immensely complex and nonlinear dynamic equations. These equations have not worked out yet. Only
in exceptional case; however, a large number of the involved parameter were crossed out and an approximation model was
presented instead. This issue caused many problems for designing a
cement rotary kiln controller. In this paper, we presented nonlinear predictor and simulator models for a real cement rotary kiln by using
nonlinear identification technique on the Locally Linear Neuro-
Fuzzy (LLNF) model. For the first time, a simulator model as well as
a predictor one with a precise fifteen minute prediction horizon for a
cement rotary kiln is presented. These models are trained by
LOLIMOT algorithm which is an incremental tree-structure
algorithm. At the end, the characteristics of these models are expressed. Furthermore, we presented the pros and cons of these
models. The data collected from White Saveh Cement Company is used for modeling.
Abstract: Inventory decisional environment of short life-cycle
products is full of uncertainties arising from randomness and
fuzziness of input parameters like customer demand requiring
modeling under hybrid uncertainty. Prior inventory models
incorporating fuzzy demand have unfortunately ignored stochastic
variation of demand. This paper determines an unambiguous optimal
order quantity from a set of n fuzzy observations in a newsvendor
inventory setting in presence of fuzzy random variable demand
capturing both fuzzy perception and randomness of customer
demand. The stress of this paper is in providing solution procedure
that attains optimality in two steps with demand information
availability in linguistic phrases leading to fuzziness along with
stochastic variation. The first step of solution procedure identifies
and prefers one best fuzzy opinion out of all expert opinions and the
second step determines optimal order quantity from the selected
event that maximizes profit. The model and solution procedure is
illustrated with a numerical example.
Abstract: In this article, the authors reviewed and analyzed the survey materials similarities ornament proto-Turkic and northern Indians. The study examined the materials scientists - geneticists, archaeologists, anthropologists. Numerous studies of scientists from different directions once again prove the relevance of the topic. The authors approached the subject from an artistic side. The study authors have made the appropriate conclusions. This publication is based on the proceedings of the investigation.
Abstract: The quality of a machined surface is becoming more and more important to justify the increasing demands of sophisticated component performance, longevity, and reliability. Usually, any machining operation leaves its own characteristic evidence on the machined surface in the form of finely spaced micro irregularities (surface roughness) left by the associated indeterministic characteristics of the different elements of the system: tool-machineworkpart- cutting parameters. However, one of the most influential sources in machining affecting surface roughness is the instantaneous state of tool edge. The main objective of the current work is to relate the in-process immeasurable cutting edge deformation and surface roughness to a more reliable easy-to-measure force signals using a robust non-linear time-dependent modeling regression techniques. Time-dependent modeling is beneficial when modern machining systems, such as adaptive control techniques are considered, where the state of the machined surface and the health of the cutting edge are monitored, assessed and controlled online using realtime information provided by the variability encountered in the measured force signals. Correlation between wear propagation and roughness variation is developed throughout the different edge lifetimes. The surface roughness is further evaluated in the light of the variation in both the static and the dynamic force signals. Consistent correlation is found between surface roughness variation and tool wear progress within its initial and constant regions. At the first few seconds of cutting, expected and well known trend of the effect of the cutting parameters is observed. Surface roughness is positively influenced by the level of the feed rate and negatively by the cutting speed. As cutting continues, roughness is affected, to different extents, by the rather localized wear modes either on the tool nose or on its flank areas. Moreover, it seems that roughness varies as wear attitude transfers from one mode to another and, in general, it is shown that it is improved as wear increases but with possible corresponding workpart dimensional inaccuracy. The dynamic force signals are found reasonably sensitive to simulate either the progressive or the random modes of tool edge deformation. While the frictional force components, feeding and radial, are found informative regarding progressive wear modes, the vertical (power) components is found more representative carrier to system instability resulting from the edge-s random deformation.
Abstract: Ovshinsky initiated scientific research in the field of
amorphous and disordered materials that continues to this day. The
Ovshinsky Effect where the resistance of thin GST films is
significantly reduced upon the application of low voltage is of
fundamental importance in phase-change - random access memory
(PC-RAM) devices.GST stands for GdSbTe chalcogenide type
glasses.However, the Ovshinsky Effect is not without controversy.
Ovshinsky thought the resistance of GST films is reduced by the
redistribution of charge carriers; whereas, others at that time including
many PC-RAM researchers today argue that the GST resistance
changes because the GST amorphous state is transformed to the
crystalline state by melting, the heat supplied by external heaters. In
this controversy, quantum mechanics (QM) asserts the heat capacity of
GST films vanishes, and therefore melting cannot occur as the heat
supplied cannot be conserved by an increase in GST film
temperature.By precluding melting, QM re-opens the controversy
between the melting and charge carrier mechanisms. Supporting
analysis is presented to show that instead of increasing GST film
temperature, conservation proceeds by the QED induced creation of
photons within the GST film, the QED photons confined by TIR. QED
stands for quantum electrodynamics and TIR for total internal
reflection. The TIR confinement of QED photons is enhanced by the
fact the absorbedheat energy absorbed in the GST film is concentrated
in the TIR mode because of their high surface to volume ratio. The
QED photons having Planck energy beyond the ultraviolet produce
excitons by the photoelectric effect, the electrons and holes of which
reduce the GST film resistance.
Abstract: Unsteady magnetohydrodynamics (MHD) boundary
layer flow and heat transfer over a continuously stretching surface in
the presence of radiation is examined. By similarity transformation,
the governing partial differential equations are transformed to a set of
ordinary differential equations. Numerical solutions are obtained by
employing the Runge-Kutta-Fehlberg method scheme with shooting
technique in Maple software environment. The effects of
unsteadiness parameter, radiation parameter, magnetic parameter and
Prandtl number on the heat transfer characteristics are obtained and
discussed. It is found that the heat transfer rate at the surface
increases as the Prandtl number and unsteadiness parameter increase
but decreases with magnetic and radiation parameter.