Abstract: The storage of thermal energy as a latent heat of phase
change material (PCM) has created considerable interest among
researchers in recent times. Here, an attempt is made to carry out
numerical investigations to analyze the performance of latent heat
storage units (LHSU) employing phase change material. The
mathematical model developed is based on an enthalpy formulation.
Freezing time of PCM packed in three different shaped containers
viz. rectangular, cylindrical and cylindrical shell is compared. The
model is validated with the results available in the literature. Results
show that for the same mass of PCM and surface area of heat
transfer, cylindrical shell container takes the least time for freezing
the PCM and this geometric effect is more pronounced with an
increase in the thickness of the shell than that of length of the shell.
Abstract: Electromagnetic flow meter by measuring the varying of magnetic flux, which is related to the velocity of conductive flow, can measure the rate of fluids very carefully and precisely. Electromagnetic flow meter operation is based on famous Faraday's second Law. In these equipments, the constant magnetostatic field is produced by electromagnet (winding around the tube) outside of pipe and inducting voltage that is due to conductive liquid flow is measured by electrodes located on two end side of the pipe wall. In this research, we consider to 2-dimensional mathematical model that can be solved by numerical finite difference (FD) solution approach to calculate induction potential between electrodes. The fundamental concept to design the electromagnetic flow meter, exciting winding and simulations are come out by using MATLAB and PDE-Tool software. In the last stage, simulations results will be shown for improvement and accuracy of technical provision.
Abstract: A mathematical model based on a mass and energy
balance for the combustion in a cement rotary kiln was developed.
The model was used to investigate the impact of replacing about
45 % of the primary coal energy by different alternative fuels.
Refuse derived fuel, waste wood, solid hazardous waste and liquid
hazardous waste were used in the modeling. The results showed that
in order to keep the kiln temperature unchanged, and thereby
maintain the required clinker quality, the production capacity had to
be reduced by 1-15 %, depending on the fuel type. The reason for the
reduction is increased exhaust gas flow rates caused by the fuel
characteristics. The model, which has been successfully validated in a
full-scale experiment, was also used to show that the negative impact
on the production capacity can be avoided if a relatively small part of
the combustion air is replaced by pure oxygen.
Abstract: This paper presents the system identification by
physical-s law method and designs the controller for the Azimuth
Angle Control of the Platform of the Multi-Launcher Rocket System
(MLRS) by Root Locus technique. The plant mathematical model
was approximated using MATLAB for simulation and analyze the
system. The controller proposes the implementation of PID
Controller using Programmable Logic Control (PLC) for control the
plant. PID Controllers are widely applicable in industrial sectors and
can be set up easily and operate optimally for enhanced productivity,
improved quality and reduce maintenance requirement. The results
from simulation and experiments show that the proposed a PID
Controller to control the elevation angle that has superior control
performance by the setting time less than 12 sec, the rise time less
than 1.6 sec., and zero steady state. Furthermore, the system has a
high over shoot that will be continue development.
Abstract: The paper deals with the possibilities of modelling
vapour propagation of explosive substances in the FLUENT
software. With regard to very low tensions of explosive substance
vapours the experiment has been verified as exemplified by
mononitrotoluene. Either constant or time variable meteorological
conditions have been used for calculation. Further, it has been
verified that the eluent source may be time-dependent and may reflect
a real situation or the liberation rate may be constant. The execution
of the experiment as well as evaluation were clear and it could also
be used for modelling vapour and aerosol propagation of selected
explosive substances in the atmospheric boundary layer.
Abstract: For many industrial applications plate heat
exchangers are demonstrating a large superiority over the
other types of heat exchangers. The efficiency of such a
device depends on numerous factors the effect of which needs
to be analysed and accurately evaluated.
In this paper we present a theoretical analysis of a cocurrent
plate heat exchanger and the results of its numerical
simulation.
Knowing the hot and the cold fluid streams inlet temperatures,
the respective heat capacities mCp
and the value of the
overall heat transfer coefficient, a 1-D mathematical model
based on the steady flow energy balance for a differential
length of the device is developed resulting in a set of N first
order differential equations with boundary conditions where N
is the number of channels.For specific heat exchanger
geometry and operational parameters, the problem is
numerically solved using the shooting method.
The simulation allows the prediction of the temperature
map in the heat exchanger and hence, the evaluation of its
performances. A parametric analysis is performed to evaluate
the influence of the R-parameter on the e-NTU values. For
practical purposes effectiveness-NTU graphs are elaborated
for specific heat exchanger geometry and different operating
conditions.
Abstract: Malaria is a serious, acute and chronic relapsing
infection to humans. It is characterized by periodic attacks of chills,
fever, nausea, vomiting, back pain, increased sweating anemia,
splenomegaly (enlargement of the spleen) and often-fatal
complications.The malaria disease is caused by the multiplication of
protozoa parasite of the genus Plasmodium. Malaria in humans is due
to 4 types of malaria parasites such that Plasmodium falciparum,
Plasmodium vivax, Plasmodium malariae and Plasmodium ovale.
P.vivax malaria differs from P. falciparum malaria in that a person
suffering from P. vivax malaria can experience relapses of the
disease. Between the relapses, the malaria parasite will remain
dormant in the liver of the patient, leading to the patient being
classified as being in the dormant class. A mathematical model for
the transmission of P. vivax is developed in which the human
population is divided into four classes, the susceptible, the infected,
the dormant and the recovered. In this paper, we formulate the
dynamical model of P. vivax malaria to see the distribution of this
disease at the district level.
Abstract: To calculate the temperature distribution of the slab in
a hot rolled reheating furnace a mathematical model has been
developed by considering the thermal radiation in the furnace and
transient conduction in the slab. The furnace is modeled as radiating
medium with spatially varying temperature. Radiative heat flux within
the furnace including the effect of furnace walls, combustion gases,
skid beams and buttons is calculated using the FVM and is applied as
the boundary condition of the transient conduction equation of the
slab. After determining the slab emissivity by comparison between
simulation and experimental work, variation of heating characteristics
in the slab is investigated in the case of changing furnace temperature
with various time and the slab residence time is optimized with this
evaluation.
Abstract: In this study, we are interested in the economic lot
scheduling problem (ELSP) that considers manufacturing of the
serviceable products and remanufacturing of the reworked products. In
this paper, we formulate a mathematical model for the ELSP with
reworks using the basic period approach. In order to solve this
problem, we propose a search algorithm to find the cyclic multiplier ki
of each product that can be cyclically produced for every ki basic
periods. This research also uses two heuristics to search for the optimal
production sequence of all lots and the optimal time length of the basic
period so as to minimize the average total cost. This research uses a
numerical example to show the effectiveness of our approach.
Abstract: Temperature is one of the most principle factors affects aquaculture system. It can cause stress and mortality or superior environment for growth and reproduction. This paper presents the control of pond water temperature using artificial intelligence technique. The water temperature is very important parameter for shrimp growth. The required temperature for optimal growth is 34oC, if temperature increase up to 38oC it cause death of the shrimp, so it is important to control water temperature. Solar thermal water heating system is designed to supply an aquaculture pond with the required hot water in Mersa Matruh in Egypt. Neural networks are massively parallel processors that have the ability to learn patterns through a training experience. Because of this feature, they are often well suited for modeling complex and non-linear processes such as those commonly found in the heating system. Artificial neural network is proposed to control water temperature due to Artificial intelligence (AI) techniques are becoming useful as alternate approaches to conventional techniques. They have been used to solve complicated practical problems. Moreover this paper introduces a complete mathematical modeling and MATLAB SIMULINK model for the aquaculture system. The simulation results indicate that, the control unit success in keeping water temperature constant at the desired temperature by controlling the hot water flow rate.
Abstract: In this study we propose a novel monitor hydraulic
automatic gauge control (HAGC) system based on fuzzy feedforward
controller. This is used in the development of cold rolling
mill automation system to improve the quality of cold strip. According to features/ properties of entry steel strip like its average
yield stress, width of strip, and desired exit thickness, this controller realizes the compensation for the exit thickness error. The traditional methods of adjusting the roller position, can-t tolerate the variance in
the entry steel strip. The proposed method uses a mathematical model
of the system together with the expert knowledge to perform this adjustment while minimizing the effect of the stated problem. In
order to improve the speed of the controller in rejecting disturbances
introduced by entry strip thickness variations, expert knowledge is added as a feed-forward term to the HAGC system. Simulation
results for the application of the proposed controller to a real cold mill show that the exit strip quality is highly improved.
Abstract: Thermal-driven refrigeration systems have attracted increasing research and development interest in recent years. These systems do not cause ozone depletion and can reduce demand on electricity. The main objective of this work is to perform theoretical analyses of a thermal-driven refrigeration system using a new sorbent-sorptive pair as the working pair. The active component of sorbent is sodium thiocyanate (NaSCN). Ammonia (NH3) is chosen as sorptive. Based on the thermodynamic properties of the working solution, a mathematical model is introduced to analyze the system characteristics and performance. The results are used to compare with other thermal-driven refrigeration systems. It is shown that the advantages provided by this system over other absorption units include lower generator and evaporator temperatures, a higher coefficient of performance (COP). The COP is about 10 percent higher than the ones for the NH3-H2O system working at the same conditions.
Abstract: Mathematical models can be used to describe the
dynamics of the spread of infectious disease between susceptibles
and infectious populations. Dengue fever is a re-emerging disease in
the tropical and subtropical regions of the world. Its incidence has
increased fourfold since 1970 and outbreaks are now reported quite
frequently from many parts of the world. In dengue endemic regions,
more cases of dengue infection in pregnancy and infancy are being
found due to the increasing incidence. It has been reported that
dengue infection was vertically transmitted to the infants. Primary
dengue infection is associated with mild to high fever, headache,
muscle pain and skin rash. Immune response includes IgM antibodies
produced by the 5th day of symptoms and persist for 30-60 days. IgG
antibodies appear on the 14th day and persist for life. Secondary
infections often result in high fever and in many cases with
hemorrhagic events and circulatory failure. In the present paper, a
mathematical model is proposed to simulate the succession of dengue
disease transmission in pregnancy and infancy. Stability analysis of
the equilibrium points is carried out and a simulation is given for the
different sets of parameter. Moreover, the bifurcation diagrams of our
model are discussed. The controlling of this disease in infant cases is
introduced in the term of the threshold condition.
Abstract: There are various solutions for improving existing overhead line systems with the general purpose of increasing their limited capacity. The capacity reserve of the existing overhead lines is an important problem that must be considered from different aspects. The paper contains a comparative analysis of the mechanical and thermal limitations of an existing overhead line based on certain calculation conditions characterizing the examined variants. The methodology of the proposed estimation of the permissible conductor temperature and maximum load current is described in detail. The transmission line model consists of specific information of an existing overhead line of the Latvian power network. The main purpose of the simulation tasks is to find an additional capacity reserve by using accurate mathematical models. The results of the obtained data are presented.
Abstract: This paper evaluates the performance of a novel
algorithm for tracking of a mobile node, interms of execution time
and root mean square error (RMSE). Particle Filter algorithm is used
to track the mobile node, however a new technique in particle filter
algorithm is also proposed to reduce the execution time. The
stationary points were calculated through trilateration and finally by
averaging the number of points collected for a specific time, whereas
tracking is done through trilateration as well as particle filter
algorithm. Wi-Fi signal is used to get initial guess of the position of
mobile node in x-y coordinates system. Commercially available
software “Wireless Mon" was used to read the WiFi signal strength
from the WiFi card. Visual Cµ version 6 was used to interact with
this software to read only the required data from the log-file
generated by “Wireless Mon" software. Results are evaluated through
mathematical modeling and MATLAB simulation.
Abstract: As there has been a recognizable transition in
automotive industry from mass production to mass customization,
automobile manufacturers and their suppliers have been seeking ways
for more flexible and efficient processes. Eventually, modular
production is currently being applied to manage the changing orders of
the industry. In this paper, two different modular assembly line
concepts were studied: conveyor line and box assembly line.
Mathematical model for two assembly line concepts were developed
and their production line efficiency were compared as a performance
measure to improve their assembly line balancing.
Abstract: Worldwide conventional resources of fossil fuel are depleting very fast due to large scale increase in use of transport vehicles every year, therefore consumption rate of oil in transport sector alone has gone very high. In view of this, the major thrust has now been laid upon the search of alternative energy source and also for cost effective energy conversion system. The air converted into compressed form by non conventional or conventional methods can be utilized as potential working fluid for producing shaft work in the air turbine and thus offering the capability of being a zero pollution energy source. This paper deals with the mathematical modeling and performance evaluation of a small capacity compressed air driven vaned type novel air turbine. Effect of expansion action and steady flow work in the air turbine at high admission air pressure of 6 bar, for varying injection to vane angles ratios 0.2-1.6, at the interval of 0.2 and at different vane angles such as 30o, 45o, 51.4o, 60o, 72o, 90o, and 120o for 12, 8, 7, 6, 5, 4 and 3 vanes respectively at speed of rotation 2500 rpm, has been quantified and analyzed here. Study shows that the expansion power has major contribution to total power, whereas the contribution of flow work output has been found varying only up to 19.4%. It is also concluded that for variation of injection to vane angle ratios from 0.2 to 1.2, the optimal power output is seen at vane angle 90o (4 vanes) and for 1.4 to 1.6 ratios, the optimal total power is observed at vane angle 72o (5 vanes). Thus in the vaned type novel air turbine the optimum shaft power output is developed when rotor contains 4-5 vanes for almost all situations of injection to vane angle ratios from 0.2 to 1.6.
Abstract: In the forming of ceramic materials the plasticity
concept is commonly used. This term is related to a particular
mechanical behavior when clay is mixed with water. A plastic
ceramic material shows a permanent strain without rupture
when a compressive load produces a shear stress that exceeds
the material-s yield strength. For a plastic ceramic body it
observes a measurable elastic behavior before the yield
strength and when the applied load is removed. In this work, a
mathematical model was developed from applied concepts of
the plasticity theory by using the stress/strain diagram under
compression.
Abstract: Calcium [Ca2+] dynamics is studied as a potential form
of neuron excitability that can control many irregular processes like
metabolism, secretion etc. Ca2+ ion enters presynaptic terminal and
increases the synaptic strength and thus triggers the neurotransmitter
release. The modeling and analysis of calcium dynamics in neuron
cell becomes necessary for deeper understanding of the processes
involved. A mathematical model has been developed for cylindrical
shaped neuron cell by incorporating physiological parameters like
buffer, diffusion coefficient, and association rate. Appropriate initial
and boundary conditions have been framed. The closed form solution
has been developed in terms of modified Bessel function. A computer
program has been developed in MATLAB 7.11 for the whole
approach.
Abstract: In this paper, an analytical approach is used to study the coupled lateral-torsional vibrations of laminated composite beam. It is known that in such structures due to the fibers orientation in various layers, any lateral displacement will produce a twisting moment. This phenomenon is modeled by the bending-twisting material coupling rigidity and its main feature is the coupling of lateral and torsional vibrations. In addition to the material coupling, the effects of shear deformation and rotary inertia are taken into account in the definition of the potential and kinetic energies. Then, the governing differential equations are derived using the Hamilton-s principle and the mathematical model matches the Timoshenko beam model when neglecting the effect of bending-twisting rigidity. The equations of motion which form a system of three coupled PDEs are solved analytically to study the free vibrations of the beam in lateral and rotational modes due to the bending, as well as the torsional mode caused by twisting. The analytic solution is carried out in three steps: 1) assuming synchronous motion for the kinematic variables which are the lateral, rotational and torsional displacements, 2) solving the ensuing eigenvalue problem which contains three coupled second order ODEs and 3) imposing different boundary conditions related to combinations of simply, clamped and free end conditions. The resulting natural frequencies and mode shapes are compared with similar results in the literature and good agreement is achieved.