Abstract: Titanium alloys like the modern alloy Ti 6Al 2Sn 4Zr 6Mo (Ti-6246) combine excellent specific mechanical properties and corrosion resistance. On the other hand,due to their material characteristics, machining of these alloys is difficult to perform. The aim of the current study is the analyses of wear mechanisms of coated cemented carbide tools applied in orthogonal cutting experiments of Ti-6246 alloy. Round bars were machined with standard coated tools in dry conditions on a CNC latheusing a wide range of cutting speeds and cutting depths. Tool wear mechanisms were afterwards investigated by means of stereo microscopy, optical microscopy, confocal microscopy and scanning electron microscopy. Wear mechanisms included fracture of the tool tip (total failure) and abrasion. Specific wear features like crater wear, micro cracks and built-up edgeformation appeared depending of the mechanical and thermal conditions generated in the workpiece surface by the cutting action.
Abstract: Biological evolution has generated a rich variety of
successful solutions; from nature, optimized strategies can be
inspired. One interesting example is the ant colonies, which are able
to exhibit a collective intelligence, still that their dynamic is simple.
The emergence of different patterns depends on the pheromone trail,
leaved by the foragers. It serves as positive feedback mechanism for
sharing information.
In this paper, we use the dynamic of TASEP as a model of
interaction at a low level of the collective environment in the ant-s
traffic flow. This work consists of modifying the movement rules of
particles “ants" belonging to the TASEP model, so that it adopts with
the natural movement of ants. Therefore, as to respect the constraints
of having no more than one particle per a given site, and in order to
avoid collision within a bidirectional circulation, we suggested two
strategies: decease strategy and waiting strategy. As a third work
stage, this is devoted to the study of these two proposed strategies-
stability. As a final work stage, we applied the first strategy to the
whole environment, in order to get to the emergence of traffic flow,
which is a way of learning.
Abstract: In this paper, a parametric experimental study for producing paving blocks using fine and coarse waste glass is presented. Some of the physical and mechanical properties of paving blocks having various levels of fine glass (FG) and coarse glass (CG) replacements with fine aggregate (FA) are investigated. The test results show that the replacement of FG by FA at level of 20% by weight has a significant effect on the compressive strength, flexural strength, splitting tensile strength and abrasion resistance of the paving blocks as compared with the control sample because of puzzolanic nature of FG. The compressive strength, flexural strength, splitting tensile strength and abrasion resistance of the paving block samples in the FG replacement level of 20% are 69%, 90%, 47% and 15 % higher as compared with the control sample respectively. It is reported in the earlier works the replacement of FG by FA at level of 20% by weight suppress the alkali-silica reaction (ASR) in the concrete. The test results show that the FG at level of 20% has a potential to be used in the production of paving blocks. The beneficial effect on these properties of CG replacement with FA is little as compared with FG.
Abstract: The hydrodynamic and thermal lattice Boltzmann
methods are applied to investigate the turbulent convective heat
transfer in the wavy channel flows. In this study, the turbulent
phenomena are modeling by large-eddy simulations with the
Smagorinsky model. As a benchmark, the laminar and turbulent
backward-facing step flows are simulated first. The results give good
agreement with other numerical and experimental data. For wavy
channel flows, the distribution of Nusselt number and the skin-friction
coefficients are calculated to evaluate the heat transfer effect and the
drag force. It indicates that the vortices at the trough would affect the
magnitude of drag and weaken the heat convection effects on the wavy
surface. In turbulent cases, if the amplitude of the wavy boundary is
large enough, the secondary vortices would be generated at troughs
and contribute to the heat convection. Finally, the effects of different
Re on the turbulent transport phenomena are discussed.
Abstract: Wireless Sensor Network is widely used in electronics. Wireless sensor networks are now used in many applications including military, environmental, healthcare applications, home automation and traffic control. We will study one area of wireless sensor networks, which is the routing protocol. Routing protocols are needed to send data between sensor nodes and the base station. In this paper, we will discuss two routing protocols, such as datacentric and hierarchical routing protocol. We will show the output of the protocols using the NS-2 simulator. This paper will compare the simulation output of the two routing protocol using Nam. We will simulate using Xgraph to find the throughput and delay of the protocol.
Abstract: In this paper, by applying Mawhin-s continuation theorem of coincidence degree theory, we study the existence of almost periodic solutions for neural multi-delay logarithmic population model and obtain one sufficient condition for the existence of positive almost periodic solution for the above equation. An example is employed to illustrate our result.
Abstract: The stab resistance performance of newly developed
fabric composites composed of hexagonal paper honeycombs, filled
with shear thickening fluid (STF), and woven Kevlar® fabric or
UHMPE was investigated in this study. The STF was prepared by
dispersing submicron SiO2 particles into polyethylene glycol (PEG).
Our results indicate that the STF-Kevlar composite possessed lower
penetration depth than that of neat Kevlar. In other words, the
STF-Kevlar composite can attain the same energy level in
stab-resistance test with fewer layers of Kevlar fabrics than that of the
neat Kevlar fabrics. It also indicates that STF can be used for the
fabrication of flexible body armors and can provide improved
protection against stab threats. We found that the stab resistance of the
STF-Kevlar composite increases with the increase of SiO2
concentration in STF. Moreover, the silica particles functionalized
with silane coupling agent can further improve the stab resistance.
Abstract: This paper presents an approach which is based on the
use of supervised feed forward neural network, namely multilayer
perceptron (MLP) neural network and finite element method (FEM)
to solve the inverse problem of parameters identification. The
approach is used to identify unknown parameters of ferromagnetic
materials. The methodology used in this study consists in the
simulation of a large number of parameters in a material under test,
using the finite element method (FEM). Both variations in relative
magnetic permeability and electrical conductivity of the material
under test are considered. Then, the obtained results are used to
generate a set of vectors for the training of MLP neural network.
Finally, the obtained neural network is used to evaluate a group of
new materials, simulated by the FEM, but not belonging to the
original dataset. Noisy data, added to the probe measurements is used
to enhance the robustness of the method. The reached results
demonstrate the efficiency of the proposed approach, and encourage
future works on this subject.
Abstract: In this paper, we suggest new product-type estimators for the population mean of the variable of interest exploiting the first or the third quartile of the auxiliary variable. We obtain mean square error equations and the bias for the estimators. We study the properties of these estimators using simple random sampling (SRS) and ranked set sampling (RSS) methods. It is found that, SRS and RSS produce approximately unbiased estimators of the population mean. However, the RSS estimators are more efficient than those obtained using SRS based on the same number of measured units for all values of the correlation coefficient.
Abstract: In this paper, we study the cooperative communications where multiple cognitive radio (CR) transmit-receive pairs competitive maximize their own throughputs. In CR networks, the influences of primary users and the spectrum availability are usually different among CR users. Due to the existence of multiple relay nodes and the different spectrum availability, each CR transmit-receive pair should not only select the relay node but also choose the appropriate channel. For this distributed problem, we propose a game theoretic framework to formulate this problem and we apply a regret-matching learning algorithm which is leading to correlated equilibrium. We further formulate a modified regret-matching learning algorithm which is fully distributed and only use the local information of each CR transmit-receive pair. This modified algorithm is more practical and suitable for the cooperative communications in CR network. Simulation results show the algorithm convergence and the modified learning algorithm can achieve comparable performance to the original regretmatching learning algorithm.
Abstract: The improvement of quality of life is the main visible
integrated indicator of state well-being. More and more states pay
attention to define and to achieve social standards of quality of life as
social-economic strategy of development. These standards are
determinate by state features, complex of needs and interests of
individual, family and society.
It still remains in open question: “What is middle class" in
contemporary Kazakhstan. Appearance of new social standards of
quality of life is important indicator of its successful establishment.
The middle class as agent of social, politic and economic reforms
promotes to improve the quality of life of the country. But if consider
a low and a middle stratums of middle class, we can see that high
social expectations and real achievements are still significantly
different.
The article relies on the sociological data, collected during of
search of household-s standards of living in Almaty city and Almaty
region, and case-study of cottage city “Jana Kuat".
Abstract: The aim of the study was to investigate whether there
is the promotion of product ecodesign measures as a result of
adopting ISO 14001 certification in manufacturing companies in the
Republic of Slovenia. Companies gave the most of their product
development attention to waste and energy reduction during
manufacturing process and reduction of material consumption per
unit of product. Regarding the importance of different ecodesign
criteria reduction of material consumption per unit of product was
reported as the most important criterion. Less attention is paid to endof-
life issues considering recycling or packaging. Most
manufacturing enterprises considered ISO 14001 standard as a very
useful tool or at least a useful tool helping them to accelerate and
establish product ecodesign activities. Two most frequently
considered ecodesign drivers are increased competitive advantage
and legal requirements and two most important barriers are high
development costs and insufficient market demand.
Abstract: This paper proposes the study of a robust control of
the doubly fed induction generator (DFIG) used in a wind energy
production. The proposed control is based on the linear active
disturbance rejection control (ADRC) and it is applied to the control
currents rotor of the DFIG, the DC bus voltage and active and
reactive power exchanged between the DFIG and the network. The
system under study and the proposed control are simulated using
MATLAB/SIMULINK.
Abstract: Study is on the vibration of thin cylindrical shells made of a functionally gradient material (FGM) composed of stainless steel and nickel is presented. The effects of the FGM configuration are studied by studying the frequencies of FG cylindrical shells. In this case FG cylindrical shell has Nickel on its inner surface and stainless steel on its outer surface. The study is carried out based on third order shear deformation shell theory. The objective is to study the natural frequencies, the influence of constituent volume fractions and the effects of configurations of the constituent materials on the frequencies. The properties are graded in the thickness direction according to the volume fraction power-law distribution. Results are presented on the frequency characteristics, the influence of the constituent various volume fractions on the frequencies.
Abstract: An epidemiological cross sectional study was
undertaken in Yaoundé in 2002 and updated in 2005. Focused on
health within the city, the objectives were to measure diarrheal
prevalence and to identify the risk factors associated with them.
Results of microbiological examinations have revealed an urban
average prevalence rate of 14.5%. Access to basic services in the
living environment appears to be an important risk factor for
diarrheas. Statistical and spatial analyses conducted have revealed
that prevalence of diarrheal diseases vary among the two main types
of settlement (informal and planned). More importantly, this study
shows that, diarrhea prevalence rates (notably bacterial and parasitic
diarrheas) vary according to the sub- category of settlements. The
study draws a number of theoretical and policy implications for
researchers and policy decision makers.
Abstract: The accomplished study is based on the appointment
and identification of ageing effects and according to this absorption
of moisture of aircraft cabin components over the life-cycle. In the
first step of the study ceiling panels from same age and from the
same aircraft cabin have been examined according to weight changes
depending on the position in the aircraft cabin. In the second step of
the study different aged ceiling panels have been examined
concerning deflection, weight changes and the acoustic sound
transmission loss. To prove the assumption of water absorption
within the study and with the theoretical background from literature
and scientific papers, an older test panel was exposed extreme
thermal conditions (humidity and temperature) within a climate
chamber to show that there is a general ingress of water to cabin
components and that this ingress of water leads to the change of
different mechanical properties.
Abstract: Electrophoretic motion of a liquid droplet within an
uncharged cylindrical pore is investigated theoretically in this study. It
is found that the boundary effect in terms of the reduction of droplet
mobility (droplet velocity per unit strength of the applied electric field)
is very significant when the double layer surrounding the droplet is
thick, and diminishes as it gets very thin. Moreover, the viscosity ratio
of the ambient fluid to the internal one, σ, is a crucial factor in
determining its electrophoretic behavior. The boundary effect is less
significant as the viscosity ratio gets high. Up to 70% mobility
reduction is observed when this ratio is low (σ = 0.01), whereas only
40% reduction when it is high (σ = 100). The results of this study can
be utilized in various fields of biotechnology, such as a biosensor or a
lab-on-a-chip device.
Abstract: The purpose of this study is to examine employee assessments of the usefulness/value of different types of information available to those employees during the process of organizational assimilation. Participants in the study were 247 “new" employees at Bangkok Bank. Bangkok Bank considers employees whose length of stay with the bank has been less than 18 months as new employees. Questionnaires were administered to all of the Bank-s new employees to obtain the data for this study. Repeated measures analysis was used to analyze the data. The data were summed and coded by using Statistical Package for Social Science. Newcomers indicate that social information is the most useful information, followed by job (technical, referent, and appraisal information), political, normative, and organizational information. Essentially, social, job, and political information are evaluated by newcomers as highly useful, while normative and organizational information are rated as moderately useful.
Abstract: In an effort to understand the preliminary effects of aerodynamic stress on alveolar epithelial cells, we developed a multifluidic cell culture platform capable of supporting alveolar cultures at an air-liquid interface under constant air flow and exposure to varying pressure stimuli on the apical side while providing nourishment on the basolateral plane. Our current study involved utilizing the platform to study the effect of basement membrane coating and addition of dexamethasone on cellular response to pressure in A549 and H441 alveolar epithelial cells.
Abstract: The design of a gravity dam is performed through an
interactive process involving a preliminary layout of the structure
followed by a stability and stress analysis. This study presents a
method to define the optimal top width of gravity dam with genetic
algorithm. To solve the optimization task (minimize the cost of the
dam), an optimization routine based on genetic algorithms (GAs) was
implemented into an Excel spreadsheet. It was found to perform well
and GA parameters were optimized in a parametric study. Using the
parameters found in the parametric study, the top width of gravity
dam optimization was performed and compared to a gradient-based
optimization method (classic method). The accuracy of the results
was within close proximity. In optimum dam cross section, the ratio
of is dam base to dam height is almost equal to 0.85, and ratio of dam
top width to dam height is almost equal to 0.13. The computerized
methodology may provide the help for computation of the optimal
top width for a wide range of height of a gravity dam.