Abstract: In this paper, the average heat transfer characteristics
for a cross flow cylinder of 16 mm diameter in a vertical pipe has
been studied for single-phase flow (water/oil) and multicomponent
(non-boiling) flow (water-air, water-oil, oil-air and water-oil-air). The
cylinder is uniformly heated by electrical heater placed at the centre
of the element. The results show that the values of average heat
transfer coefficients for water are around four times the values for oil
flow. Introducing air as a second phase with water has very little
effect on heat transfer rate, while the heat transfer increased by 70%
in case of oil. For water–oil flow, the heat transfer coefficient values
are reflecting the percentage of water up to 50%, but increasing the
water more than 50% leads to a sharp increase in the heat transfer
coefficients to become close to the values of pure water. The
enhancement of heat transfer by mixing two phases may be attributed
to the changes in flow structure near to cylinder surface which lead to
thinner boundary layer and higher turbulence. For three-phase flow,
the heat transfer coefficients for all cases fall within the limit of
single-phase flow of water and oil and are very close to pure water
values. The net effect of the turbulence augmentation due to the
introduction of air and the attenuation due to the introduction of oil
leads to a thinner boundary layer of oil over the cylinder surface
covered by a mixture of water and air bubbles.
Abstract: Finite Element Models (FEMs) are widely used in order to study and predict the dynamic properties of structures and usually, the prediction can be obtained with much more accuracy in the case of a single component than in the case of assemblies. Especially for structural dynamics studies, in the low and middle frequency range, most complex FEMs can be seen as assemblies made by linear components joined together at interfaces. From a modelling and computational point of view, these types of joints can be seen as localized sources of stiffness and damping and can be modelled as lumped spring/damper elements, most of time, characterized by nonlinear constitutive laws. On the other side, most of FE programs are able to run nonlinear analysis in time-domain. They treat the whole structure as nonlinear, even if there is one nonlinear degree of freedom (DOF) out of thousands of linear ones, making the analysis unnecessarily expensive from a computational point of view. In this work, a methodology in order to obtain the nonlinear frequency response of structures, whose nonlinearities can be considered as localized sources, is presented. The work extends the well-known Structural Dynamic Modification Method (SDMM) to a nonlinear set of modifications, and allows getting the Nonlinear Frequency Response Functions (NLFRFs), through an ‘updating’ process of the Linear Frequency Response Functions (LFRFs). A brief summary of the analytical concepts is given, starting from the linear formulation and understanding what the implications of the nonlinear one, are. The response of the system is formulated in both: time and frequency domain. First the Modal Database is extracted and the linear response is calculated. Secondly the nonlinear response is obtained thru the NL SDMM, by updating the underlying linear behavior of the system. The methodology, implemented in MATLAB, has been successfully applied to estimate the nonlinear frequency response of two systems. The first one is a two DOFs spring-mass-damper system, and the second example takes into account a full aircraft FE Model. In spite of the different levels of complexity, both examples show the reliability and effectiveness of the method. The results highlight a feasible and robust procedure, which allows a quick estimation of the effect of localized nonlinearities on the dynamic behavior. The method is particularly powerful when most of the FE Model can be considered as acting linearly and the nonlinear behavior is restricted to few degrees of freedom. The procedure is very attractive from a computational point of view because the FEM needs to be run just once, which allows faster nonlinear sensitivity analysis and easier implementation of optimization procedures for the calibration of nonlinear models.
Abstract: Ionic liquids are finding a wide range of applications from reaction media to separations and materials processing. In these applications, Vapor–Liquid equilibrium (VLE) is the most important one. VLE for six systems at 353 K and activity coefficients at infinite dilution [(γ)_i^∞] for various solutes (alkanes, alkenes, cycloalkanes, cycloalkenes, aromatics, alcohols, ketones, esters, ethers, and water) in the ionic liquids (1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide [EMIM][BTI], 1-hexyl-3-methyl imidazolium bis (trifluoromethylsulfonyl) imide [HMIM][BTI], 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [OMIM][BTI], and 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide [BMPYR][BTI]) have been used to train neural networks in the temperature range from (303 to 333) K. Densities of the ionic liquids, Hildebrant constant of substances, and temperature were selected as input of neural networks. The networks with different hidden layers were examined. Networks with seven neurons in one hidden layer have minimum error and good agreement with experimental data.
Abstract: In this paper, we propose a new method for threedimensional
object indexing based on D.A.M.C-S.H.C descriptor
(Direct and Analytical Method for Calculating the Spherical
Harmonics Coefficients). For this end, we propose a direct
calculation of the coefficients of spherical harmonics with perfect
precision. The aims of the method are to minimize, the processing
time on the 3D objects database and the searching time of similar
objects to a request object.
Firstly we start by defining the new descriptor using a new
division of 3-D object in a sphere. Then we define a new distance
which will be tested and prove his efficiency in the search for similar
objects in the database in which we have objects with very various
and important size.
Abstract: In this paper, we propose a method for three-dimensional
(3-D)-model indexing based on defining a new
descriptor, which we call new descriptor using spherical harmonics.
The purpose of the method is to minimize, the processing time on the
database of objects models and the searching time of similar objects
to request object.
Firstly we start by defining the new descriptor using a new
division of 3-D object in a sphere. Then we define a new distance
which will be used in the search for similar objects in the database.
Abstract: Heavy rare earth (HRE) oxalate concentrates were
prepared from the Egyptian crude monazite sand (graded about 47%).
The concentrates were specified quantitatively for their constituents
of individual rare earth elements using ion chromatograph (IC) and
qualitatively by scanning electron microscope (SEM) for the other
major constituents. The 1st concentrate was composed of 10.5%
HREE where 7.25% of them represented yttrium. The 2nd concentrate
contained about 41.7% LREE, 17.5% HREE and 13.6% Th. The
LREE involved 18.3% Ce, 10.5% La and 8% Nd while the HREE
were 8.7% Y, 3.5% Gd and 2.9% Dy. The 3rd concentrate was
containing about 8.0% LREE (3.7% Ce, 2.0% La and 1.5% Nd),
10.2% HREE (6.4% yttrium and 2.0% Dy) and 2.1% uranium. The
final concentrate comprised 0.84% uranium beside iron, chromium
and traces of REE.
Abstract: Free vibration analysis of a gabled frame with elastic support and semi-rigid connections is performed by using a program in OpenSees software. Natural frequencies and mode shape details of frame are obtained for two states, which are semi-rigid connections and elastic supports, separately. The members of this structure are analyzed as a prismatic nonlinear beam-column element in software. The mass of structure is considered as two equal lumped masses at the head of two columns in horizontal and vertical directions. Note that the degree of freedom, allocated to all nodes, is equal to three. Furthermore, the mode shapes of frame are achieved. Conclusively, the effects of connections and supports flexibility on the natural frequencies and mode shapes of structure are investigated.
Abstract: Rapid industrialization has led to increased disposal of heavy metals into the environment. Activated carbon adsorption has proven to be an effective process for the removal of trace metal contaminants from aqueous media. This paper was investigated chromium adsorption efficiency by commercial activated carbon. The sorption studied as a function of activated carbon particle size, dose of activated carbon and initial pH of solution. Adsorption tests for the effects of these factors were designed with Taguchi approach. According to the Taguchi parameter design methodology, L9 orthogonal array was used. Analysis of experimental results showed that, the most influential factor was initial pH of solution. The optimum conditions for chromium adsorption by activated carbons were found to be as follows: initial feed pH 6, adsorbent particle size 0.412 mm and activated carbon dose 6 g/l. Under these conditions, nearly %100 of chromium ions was adsorbed by activated carbon after 2 hours.
Abstract: Monitoring is essential to assessing the effectiveness of air pollution control actions. The goal of the air quality information system is through monitoring, to keep authorities, major polluters and the public informed on the short and long-term changes in air quality, thereby helping to raise awareness. Mathematical models are the best tools available for the prediction of the air quality management. The main objective of the work was to apply a Model that predicts the concentration levels of different pollutants at any instant of time. In this study, distribution of air pollutants concentration such as nitrogen dioxides (NO2), sulphur dioxides (SO2) and total suspended particulates (TSP) of industries are determined by using Gaussian model. Besides that, the effect of wind speed and its direction on the pollutant concentration within the affected area were evaluated. In order to determine the efficiency and percentage of error in the modeling, validation process of data was done. Sampling of air quality was conducted in getting existing air quality around a factory and the concentrations of pollutants in a plume were inversely proportional to wind velocity. The resultant ground level concentrations were then compared to the quality standards to determine if there could be a negative impact on health. This study concludes that concentration of pollutants can be significantly predicted using Gaussian Model. The data base management is developed for the air data of Hubli-Dharwad region.
Abstract: In this article we research on the drivers’ behavior at intersections. Some significant behaviors are chosen and designed a questionnaire which was about 2 pages. In this questionnaire, samples were being asked to answer by checking the box. The answers have been from always to never. This questionnaire related to our selection’s behaviors. Finally it has been resulted that most of aggressive behaviors were being common in them. Also it has been suggested some solutions for each of them.
Abstract: Proton transfer and hydrogen bonding are two aspects
of the chemistry of hydrogen that respectively govern the behaviour
and structure of many molecules, both simple and complex. All the
theoretical enol and keto conformations of 1,3-diphenyl-1,3-
propandion known as dibenzoylmethane (DBM), have been
investigated by means of atoms in molecules (AIM) theory. It was
found that the most stable conformers are those stabilized by
hydrogen bridges.The aim of the present paper is a thorough
conformational analysis of DBM (with special attention on chelated
cis-enol conformers) in order to obtain detailed information on the
geometrical parameters, relative stabilities and rotational motion of
the phenyl groups. It is also important to estimate the barrier height
for ptoton transfer and hydrogen bond strength, which are the main
factors governing conformational stability.
Abstract: In this article, we discuss project-based learning in the context of a wheel garden as an instructional tool in science and mathematics education. A wheel garden provides multiple opportunities to teach across the curriculum, to integrate disciplines, and to promote community involvement. Grounded in the theoretical framework of constructivism, the wheel garden provides a multidisciplined educational tool that provides a hands-on, non-traditional arena for learning. We will examine some of the cultural, art, science, and mathematics connections made with this project.
Abstract: Implemented 5-bit 125-MS/s successive
approximation register (SAR) analog to digital converter (ADC) on
FPGA is presented in this paper.The design and modeling of a high
performance SAR analog to digital converter are based on monotonic
capacitor switching procedure algorithm .Spartan 3 FPGA is chosen
for implementing SAR analog to digital converter algorithm. SAR
VHDL program writes in Xilinx and modelsim uses for showing
results.
Abstract: It is known that symmetric encryption algorithms are
fast and easy to implement in hardware. Also elliptic curves have
proved to be a good choice for building encryption system. Although
most of the symmetric systems have been broken, we can create a
hybrid system that has the same properties of the symmetric
encryption systems and in the same time, it has the strength of
elliptic curves in encryption. As DES algorithm is considered the
core of all successive symmetric encryption systems, we modified
DES using elliptic curves and built a new DES algorithm that is hard
to be broken and will be the core for all other symmetric systems.
Abstract: The effect of the rotational speed and axial torque on
the diagnostics of tapered rolling element bearing defects was
investigated. The accelerometer was mounted on the bearing housing
and connected to Sound and Vibration Analyzer (SVAN 958) and
was used to measure the accelerations from the bearing housing. The
data obtained from the bearing was processed to detect damage of the
bearing using statistical tools and the results were subsequently
analyzed to see if bearing damage had been captured. From this study
it can be seen that damage is more evident when the bearing is
loaded. Also, at the incipient stage of damage the crest factor and
kurtosis values are high but as time progresses the crest factors and
kurtosis values decrease whereas the peak and RMS values are low at
the incipient stage but increase with damage.