Abstract: Generation system reliability assessment is an
important task which can be performed using deterministic or
probabilistic techniques. The probabilistic approaches have
significant advantages over the deterministic methods. However,
more complicated modeling is required by the probabilistic
approaches. Power generation model is a basic requirement for this
assessment. One form of the generation models is the well known
capacity outage probability table (COPT). Different analytical
techniques have been used to construct the COPT. These approaches
require considerable mathematical modeling of the generating units.
The unit-s models are combined to build the COPT which will add
more burdens on the process of creating the COPT. Decimal to
Binary Conversion (DBC) technique is widely and commonly applied
in electronic systems and computing This paper proposes a novel
utilization of the DBC to create the COPT without engaging in
analytical modeling or time consuming simulations. The simple
binary representation , “0 " and “1 " is used to model the states o f
generating units. The proposed technique is proven to be an effective
approach to build the generation model.
Abstract: Post-anthesis drought stress is the most important
problem affecting wheat production in dryland fields, specially in
Mediterranean regions. The main objective of this research was to
evaluate drought tolerance indices in dryland wheat genotypes under
post-anthesis drought stress. The research was including two different
experiments. In each experiment, twenty dryland bread wheat
genotypes were sown in a randomized complete blocks design
(RCBD) with three replications. One of experiments belonged to
rain-fed conditions (post-anthesis drought stress) and other
experiment was under non-stress conditions (with supplemental
irrigation). Different drought tolerance indices include Stress
Tolerance (Tol), Mean Productivity (MP), Geometric Mean
Productivity (GMP), Stress Susceptibility Index (SSI), Stress
Tolerance Index (STI), Harmonic Mean (HAM), Yield Index (YI)
and Yield Stability Index (YSI) were evaluate based on grain yield
under rain-fed (Ys) and supplemental irrigation (Yp) environments.
G10 and G12 were the most tolerant genotypes based on TOL and
SSI. But, based on MP, GMP, STI, HAM and YI indices, G1 and G2
were selected. STI, GMP and MP indices had high correlation with
grain yield under rain-fed and supplementary irrigation conditions
and were recognized as appropriate indices to identify genotypes with
high grain yield and low sensitivity to drought stress environments.
Abstract: We assert here that there might be some factors that
influence professional identity construction at the university/higher
education stage. In accord, we propose a conceptual framework of
intervening factors in professional identity construction at university
from a literature review and preliminary data from a qualitative pilot
study using focus groups. This model identifies several factors that
might influence university students- professional identity
construction and group them into categories. In turn, we describe
how these factors might contribute in strengthening or weakening
their professional identity. Finally, we discuss the implications of
strengthening students- PI for the university, individuals and
organizations and we provide a roadmap for future empirical work in
this area.
Abstract: Thrombosis can be life threatening, necessitating therefore its instant treatment. Hydergine, a nootropic agent is used as a cognition enhancer in stroke patients but relatively little is known about its anti-thrombolytic effect. To investigate this aspect, in vivo and ex vivo experiments were designed and conducted. Three groups of rats were injected 1.5mg, 3.0mg and 4.5mg hydergine intraperitonealy with and without prior exposure to fresh plasma. Positive and negative controls were run in parallel. Animals were sacrificed after 1.5hrs and BT, CT, PT, INR, APTT, plasma calcium levels were estimated. For ex vivo analyses, each 1ml blood aspirated was exposed to 0.1mg, 0.2mg, 0.3mg dose of hydergine with parallel controls. Parameters analyzed were as above. Statistical analysis was through one-way ANOVA. Dunken-s and Tukey-s tests provided intra-group variance. BT, CT, PT, INR and APTT increased while calcium levels dropped significantly (P
Abstract: This work presents a numerical model developed to
simulate the dynamics and vibrations of a multistage tractor gearbox.
The effect of time varying mesh stiffness, time varying frictional
torque on the gear teeth, lateral and torsional flexibility of the shafts
and flexibility of the bearings were included in the model. The model
was developed by using the Lagrangian method, and it was applied to
study the effect of three design variables on the vibration and stress
levels on the gears. The first design variable, module, had little effect
on the vibration levels but a higher module resulted to higher bending
stress levels. The second design variable, pressure angle, had little
effect on the vibration levels, but had a strong effect on the stress
levels on the pinion of a high reduction ratio gear pair. A pressure
angle of 25o resulted to lower stress levels for a pinion with 14 teeth
than a pressure angle of 20o. The third design variable, contact ratio,
had a very strong effect on both the vibration levels and bending
stress levels. Increasing the contact ratio to 2.0 reduced both the
vibration levels and bending stress levels significantly. For the gear
train design used in this study, a module of 2.5 and contact ratio of
2.0 for the various meshes was found to yield the best combination
of low vibration levels and low bending stresses. The model can
therefore be used as a tool for obtaining the optimum gear design
parameters for a given multistage spur gear train.
Abstract: Optimal routing in communication networks is a
major issue to be solved. In this paper, the application of Tabu Search
(TS) in the optimum routing problem where the aim is to minimize
the computational time and improvement of quality of the solution in
the communication have been addressed. The goal is to minimize the
average delays in the communication. The effectiveness of Tabu
Search method is shown by the results of simulation to solve the
shortest path problem. Through this approach computational cost can
be reduced.
Abstract: This paper presents the climatic range calculations for
comfort evaporative cooling for Tehran. In this study the minimum
climatic conditions required to achieve an appropriate comfort zone
will be presented.
Physiologically uncomfortable conditions in arid climates are
mainly caused by the extreme heat and dryness. Direct evaporative
cooling adds moisture to the air stream until the air stream is close to
saturation. The dry bulb temperature is reduced, while the wet bulb
temperature stays the same. Evaporative cooling is economical,
effective, environmentally friendly, and healthy.
Comfort cooling by direct evaporative cooling (passive or fan
forced) in the 35. 41 N (such as Tehran) latitude requires design
wet-bulb temperature not over 25.4 C. Evaporative cooling outside
this limit cannot achieve the required 26.7 ET, and is recommended
for relief cooling only.
Abstract: In this paper, genetic algorithm (GA) opmization technique is applied to design Flexible AC Transmission System (FACTS)-based damping controllers. Two types of controller structures, namely a proportional-integral (PI) and a lead-lag (LL) are considered. The design problem of the proposed controllers is formulated as an optimization problem and GA is employed to search for optimal controller parameters. By minimizing the time-domain based objective function, in which the deviation in the oscillatory rotor speed of the generator is involved; stability performance of the system is improved. The proposed controllers are tested on a weakly connected power system subjected to different disturbances. The non-linear simulation results are presented to show the effectiveness of the proposed controller and their ability to provide efficient damping of low frequency oscillations. It is also observed that the proposed SSSC-based controllers improve greatly the voltage profile of the system under severe disturbances. Further, the dynamic performances of both the PI and LL structured FACTS-controller are analyzed at different loading conditions and under various disturbance condition as well as under unbalanced fault conditions..
Abstract: The paper presents the Romanian realities and perspectives from the point of view of reaching the sustainable development model in the context of the recent accession to the European Union, based on the analysis of the indicators listed in the EU Sustainable Development Strategy. The analysis of the economic-social potential for sustainable development and of the environment aspects show that the objectives stipulated in the renewed EU Sustainable Development Strategy of 2006 can be reached, but an extra effort must be put-in in order to overcome the existing substantial gaps in several areas in relation to the developed countries of the EU. The paper-s conclusions show that even if sustainable development is not an easy target to reach in Romania, there are resources and a growing potential, which can lead to sustainable development if used rationally.
Abstract: In this paper, Fabless Prototyping Methodology is
introduced for the design and analysis of MEMS devices.
Conventionally Finite Element Analysis (FEA) is performed before
system level simulation. In our proposed methodology, system level
simulation is performed earlier than FEA as it is computationally less
extensive and low cost. System level simulations are based on
equivalent behavioral models of MEMS device. Electrostatic
actuation based MEMS Microgripper is chosen as case study to
implement this methodology. This paper addresses the behavioral
model development and simulation of actuator part of an
electrostatically actuated Microgripper. Simulation results show that
the actuator part of Microgripper works efficiently for a voltage range
of 0-45V with the corresponding jaw displacement of 0-4.5425μm.
With some minor changes in design, this range can be enhanced to
15μm at 85V.
Abstract: This study proposes novel hybrid social network analysis and collaborative filtering approach to enhance the performance of recommender systems. The proposed model selects subgroups of users in Internet community through social network analysis (SNA), and then performs clustering analysis using the information about subgroups. Finally, it makes recommendations using cluster-indexing CF based on the clustering results. This study tries to use the cores in subgroups as an initial seed for a conventional clustering algorithm. This model chooses five cores which have the highest value of degree centrality from SNA, and then performs clustering analysis by using the cores as initial centroids (cluster centers). Then, the model amplifies the impact of friends in social network in the process of cluster-indexing CF.
Abstract: Incremental forming is a complex forming process with
continuously local cumulative deformation taking place during its
process, and springback that forming quality affected by would occur.
The springback evaluation method based on forming error
compensation also was proposed, which it can be defined as the
difference between theory and the actual amount of compensation
along the measured direction. According to forming error
compensation evaluation method, experiments was designed and
implemented. And from the results that obtained it can be show, the
magnitude of springback average (δE) of formed parts was very small,
and the forming precision could be significantly improved by adopting
compensation method. Based on double tensile stress state in the main
deformation area, a hypothesis that there is little springback be arisen
by bending behavior on the formed parts that was proposed.
Abstract: This paper mainly proposes an efficient modified
particle swarm optimization (MPSO) method, to identify a slidercrank
mechanism driven by a field-oriented PM synchronous motor.
In system identification, we adopt the MPSO method to find
parameters of the slider-crank mechanism. This new algorithm is
added with “distance" term in the traditional PSO-s fitness function to
avoid converging to a local optimum. It is found that the comparisons
of numerical simulations and experimental results prove that the
MPSO identification method for the slider-crank mechanism is
feasible.
Abstract: The leisure boatbuilding industry has tight profit margins that demand that boats are created to a high quality but with low cost. This requirement means reduced design times combined with increased use of design for production can lead to large benefits. The evolutionary nature of the boatbuilding industry can lead to a large usage of previous vessels in new designs. With the increase in automated tools for concurrent engineering within structural design it is important that these tools can reuse this information while subsequently feeding this to designers. The ability to accurately gather this materials and parts data is also a key component to these tools. This paper therefore aims to develop an architecture made up of neural networks and databases to feed information effectively to the designers based on previous design experience.
Abstract: To achieve reliable solutions, today-s numerical and
experimental activities need developing more accurate methods and
utilizing expensive facilities, respectfully in microchannels. The analytical
study can be considered as an alternative approach to alleviate
the preceding difficulties. Among the analytical solutions, those with
high robustness and low complexities are certainly more attractive.
The perturbation theory has been used by many researchers to analyze
microflows. In present work, a compressible microflow with constant
heat flux boundary condition is analyzed. The flow is assumed to be
fully developed and steady. The Mach and Reynolds numbers are also
assumed to be very small. For this case, the creeping phenomenon
may have some effect on the velocity profile. To achieve robustness
solution it is assumed that the flow is quasi-isothermal. In this study,
the creeping term which appears in the slip boundary condition
is formulated by different mathematical formulas. The difference
between this work and the previous ones is that the creeping term
is taken into account and presented in non-dimensionalized form.
The results obtained from perturbation theory are presented based
on four non-dimensionalized parameters including the Reynolds,
Mach, Prandtl and Brinkman numbers. The axial velocity, normal
velocity and pressure profiles are obtained. Solutions for velocities
and pressure for two cases with different Br numbers are compared
with each other and the results show that the effect of creeping
phenomenon on the velocity profile becomes more important when
Br number is less than O(ε).
Abstract: New theory for functionally graded (FG) shell based on expansion of the equations of elasticity for functionally graded materials (GFMs) into Legendre polynomials series has been developed. Stress and strain tensors, vectors of displacements, traction and body forces have been expanded into Legendre polynomials series in a thickness coordinate. In the same way functions that describe functionally graded relations has been also expanded. Thereby all equations of elasticity including Hook-s law have been transformed to corresponding equations for Fourier coefficients. Then system of differential equations in term of displacements and boundary conditions for Fourier coefficients has been obtained. Cases of the first and second approximations have been considered in more details. For obtained boundary-value problems solution finite element (FE) has been used of Numerical calculations have been done with Comsol Multiphysics and Matlab.
Abstract: A Finite Volume method based on Characteristic Fluxes for compressible fluids is developed. An explicit cell-centered resolution is adopted, where second and third order accuracy is provided by using two different MUSCL schemes with Minmod, Sweby or Superbee limiters for the hyperbolic part. Few different times integrator is used and be describe in this paper. Resolution is performed on a generic unstructured Cartesian grid, where solid boundaries are handled by a Cut-Cell method. Interfaces are explicitely advected in a non-diffusive way, ensuring local mass conservation. An improved cell cutting has been developed to handle boundaries of arbitrary geometrical complexity. Instead of using a polygon clipping algorithm, we use the Voxel traversal algorithm coupled with a local floodfill scanline to intersect 2D or 3D boundary surface meshes with the fixed Cartesian grid. Small cells stability problem near the boundaries is solved using a fully conservative merging method. Inflow and outflow conditions are also implemented in the model. The solver is validated on 2D academic test cases, such as the flow past a cylinder. The latter test cases are performed both in the frame of the body and in a fixed frame where the body is moving across the mesh. Adaptive Cartesian grid is provided by Paramesh without complex geometries for the moment.
Abstract: Group contribution methods such as the UNIFAC are
of major interest to researchers and engineers involved synthesis,
feasibility studies, design and optimization of separation processes as
well as other applications of industrial use. Reliable knowledge of
the phase equilibrium behavior is crucial for the prediction of the fate
of the chemical in the environment and other applications. The
objective of this study was to predict the solubility of selected
volatile organic compounds (VOCs) in glycol polymers and
biodiesel. Measurements can be expensive and time consuming,
hence the need for thermodynamic models. The results obtained in
this study for the infinite dilution activity coefficients compare very
well those published in literature obtained through measurements. It
is suggested that in preliminary design or feasibility studies of
absorption systems for the abatement of volatile organic compounds,
prediction procedures should be implemented while accurate fluid
phase equilibrium data should be obtained from experiment.
Abstract: The aim of this study is to compare the innovativeness, risk taking, and focusing on opportunity of the nurse managers and nurses. The data are collected from nurse managers and nurses in Ondokuz Mayıs University, Faculty of Medicine Hospital and Karadeniz Technical University, Faculty of Medicine Hospital. The study sample consisted of 151 participants, 76 nurse managers (50.3%) and 75 nurses (49.7%). All participants have been assessed by Participant Information Form and Corporate Entrepreneurship Scale. In data analysis, independent t-test has applied. The results show that there are significant differences between nurse managers and nurses on innovativeness (t = 2.42, p < 0.05), risk taking (t = 3.62, p < 0.01), and focusing on opportunity (t = 2.16, p < 0.05). Consequently, it can be said that nurse managers have more innovativeness than nurses and tend to take more risks and focus more on opportunities.
Abstract: In this study, single nozzle method used for
electrospinning technique which composite polymer solution with
cellulose nanowiskers (CNW) was treated by ultrasonic sonificator
have been compared with coaxial (double) nozzle method, in terms of
mechanical, thermal and morphological properties of composite
nanofiber. The effect of water content in composite polymer solution
on properties of nanofiber has also been examined. It has been seen
that single nozzle method which polymer solution does not contain
water has better results than that of coaxial method, in terms of
mechanical, thermal and morphological properties of nanofiber.
However, it is necessary to make an optimization study on setting
condition of ultrasonic treatment to get better dispersion of CNW in
composite nanofiber and to get better mechanical and thermal
properties