Abstract: Semiconductor materials with coatings have a wide range of applications in MEMS and NEMS. This work uses transfermatrix method for calculating the radiative properties. Dopped silicon is used and the coherent formulation is applied. The Drude model for the optical constants of doped silicon is employed. Results showed that for the visible wavelengths, more emittance occurs in greater concentrations and the reflectance decreases as the concentration increases. In these wavelengths, transmittance is negligible. Donars and acceptors act similar in visible wavelengths. The effect of wave interference can be understood by plotting the spectral properties such as reflectance or transmittance of a thin dielectric film versus the film thickness and analyzing the oscillations of properties due to constructive and destructive interferences. But this effect has not been shown at visible wavelengths. At room temperature, the scattering process is dominated by lattice scattering for lightly doped silicon, and the impurity scattering becomes important for heavily doped silicon when the dopant concentration exceeds1018cm-3 .
Abstract: The increasing competitiveness in manufacturing
industry is forcing manufacturers to seek effective processing
schedules. The paper presents an optimization manufacture
scheduling approach for dependent details processing with given
processing sequences and times on multiple machines. By defining
decision variables as start and end moments of details processing it is
possible to use straightforward variables restrictions to satisfy
different technological requirements and to formulate easy to
understand and solve optimization tasks for multiple numbers of
details and machines. A case study example is solved for seven base
moldings for CNC metalworking machines processed on five
different machines with given processing order among details and
machines and known processing time-s duration. As a result of linear
optimization task solution the optimal manufacturing schedule
minimizing the overall processing time is obtained. The
manufacturing schedule defines the moments of moldings delivery
thus minimizing storage costs and provides mounting due-time
satisfaction. The proposed optimization approach is based on real
manufacturing plant problem. Different processing schedules variants
for different technological restrictions were defined and implemented
in the practice of Bulgarian company RAIS Ltd. The proposed
approach could be generalized for other job shop scheduling
problems for different applications.
Abstract: This present paper proposes the modified Elastic Strip
method for mobile robot to avoid obstacles with a real time system in
an uncertain environment. The method deals with the problem of
robot in driving from an initial position to a target position based on
elastic force and potential field force. To avoid the obstacles, the
robot has to modify the trajectory based on signal received from the
sensor system in the sampling times. It was evident that with the
combination of Modification Elastic strip and Pseudomedian filter to
process the nonlinear data from sensor uncertainties in the data
received from the sensor system can be reduced. The simulations and
experiments of these methods were carried out.
Abstract: A glider is in essence an unpowered vehicle and in this project we designed and built an oceanic glider, designed to operate underwater. This Glider was designed to collect ocean data such as temperature, pressure and (in future measures physical dimensions of the operating environment) and output this data to an external source. Development of the Oceanic Glider required research into various actuation systems that control buoyancy, pitch and yaw and the dynamics of these systems. It also involved the design and manufacture of the Glider and the design and implementation of a controller that enabled the Glider to navigate and move in an appropriate manner.
Abstract: This paper deals with a new way for designing
external fixators applied in traumatology and orthopaedics. These
fixators can be applied in the treatment of open and unstable
fractures or for lengthening human or animal bones etc. The new
design is based on the development of Ilizarov and other techniques
(i.e. shape and weight optimalization based on composite materials,
application of smart materials, nanotechnology, low x-ray absorption,
antibacterial protection, patient's comfort, reduction in the duration
of the surgical treatment, and cost).
Abstract: The purpose of this study was to explore the complex
flow structure a novel active-type micromixer that based on concept of
Wankle-type rotor. The characteristics of this micromixer are two
folds; a rapid mixing of reagents in a limited space due to the
generation of multiple vortices and a graduate increment in dynamic
pressure as the mixed reagents is delivered to the output ports.
Present micro-mixer is consisted of a rotor with shape of triangle
column, a blending chamber and several inlet and outlet ports. The
geometry of blending chamber is designed to make the rotor can be
freely internal rotated with a constant eccentricity ratio. When the
shape of the blending chamber and the rotor are fixed, the effects of
rotating speed of rotor and the relative locations of ports on the mixing
efficiency are numerical studied. The governing equations are
unsteady, two-dimensional incompressible Navier-Stokes equation
and the working fluid is the water. The species concentration equation
is also solved to reveal the mass transfer process of reagents in various
regions then to evaluate the mixing efficiency.
The dynamic mesh technique was implemented to model the
dynamic volume shrinkage and expansion of three individual
sub-regions of blending chamber when the rotor conducted a complete
rotating cycle. Six types of ports configuration on the mixing
efficiency are considered in a range of Reynolds number from 10 to
300. The rapid mixing process was accomplished with the multiple
vortex structures within a tiny space due to the equilibrium of shear
force, viscous force and inertial force. Results showed that the highest
mixing efficiency could be attained in the following conditions: two
inlet and two outlet ports configuration, that is an included angle of 60
degrees between two inlets and an included angle of 120 degrees
between inlet and outlet ports when Re=10.
Abstract: A manufacturing inventory model with shortages with
carrying cost, shortage cost, setup cost and demand quantity as
imprecise numbers, instead of real numbers, namely interval number
is considered here. First, a brief survey of the existing works on
comparing and ranking any two interval numbers on the real line
is presented. A common algorithm for the optimum production
quantity (Economic lot-size) per cycle of a single product (so as
to minimize the total average cost) is developed which works well
on interval number optimization under consideration. Finally, the
designed algorithm is illustrated with numerical example.
Abstract: This paper presents a hybrid fuzzy-PD plus PID
(HFPP) controller and its application to steam distillation process for
essential oil extraction system. Steam temperature is one of the most
significant parameters that can influence the composition of essential
oil yield. Due to parameter variations and changes in operation
conditions during distillation, a robust steam temperature controller becomes nontrivial to avoid the degradation of essential oil quality.
Initially, the PRBS input is triggered to the system and output of steam temperature is modeled using ARX model structure. The
parameter estimation and tuning method is adopted by simulation
using HFPP controller scheme. The effectiveness and robustness of
proposed controller technique is validated by real time
implementation to the system. The performance of HFPP using 25 and 49 fuzzy rules is compared. The experimental result demonstrates the proposed HFPP using 49 fuzzy rules achieves a
better, consistent and robust controller compared to PID when considering the test on tracking the set point and the effects due to disturbance.
Abstract: In this paper, we investigate the strategic stochastic air traffic flow management problem which seeks to balance airspace capacity and demand under weather disruptions. The goal is to reduce the need for myopic tactical decisions that do not account for probabilistic knowledge about the NAS near-future states. We present and discuss a scenario-based modeling approach based on a time-space stochastic process to depict weather disruption occurrences in the NAS. A solution framework is also proposed along with a distributed implementation aimed at overcoming scalability problems. Issues related to this implementation are also discussed.
Abstract: In this paper, a one-dimensional numerical approach is
used to study the effect of applying electrohydrodynamics on the
temperature and species mass fraction profiles along the microcombustor.
Premixed mixture is H2-Air with a multi-step chemistry
(9 species and 19 reactions). In the micro-scale combustion because
of the increasing ratio of area-to-volume, thermal and radical
quenching mechanisms are important. Also, there is a significant heat
loss from the combustor walls. By inserting a number of electrodes
into micro-combustor and applying high voltage to them corona
discharge occurs. This leads in moving of induced ions toward
natural molecules and colliding with them. So this phenomenon
causes the movement of the molecules and reattaches the flow to the
walls. It increases the velocity near the walls that reduces the wall
boundary layer. Consequently, applying electrohydrodynamics
mechanism can enhance the temperature profile in the microcombustor.
Ultimately, it prevents the flame quenching in microcombustor.
Abstract: This paper discuss the separation of the miscible
liquids by means of fractional distillation. For complete separation of
liquids, the process of heating, condensation, separation and storage
is done automatically to achieve the objective. PIC micro-controller
has been used to control each and every process of the work. The
controller also controls the storage process by activating and deactivating
the conveyors. The liquids are heated which on reaching
their respective boiling points evaporate and enter the condensation
chamber where they convert into liquid. The liquids are then directed
to their respective tanks by means of stepper motor which moves in
three directions, each movement into different tank. The tank on
filling sends the signal to controller which then opens the solenoid
valves. The tank is emptied into the beakers below the nozzle. As the
beaker filled, the nozzle closes and the conveyors come into
operation. The filled beaker is replaced by an empty beaker from
behind. The work can be used in oil industries, chemical industries
and paint industries.
Abstract: This paper presents a numerical analysis of the
performance of a five-bladed Darrieus vertical-axis water turbine,
based on the NACA 0025 blade profile, for both bare and shrouded
configurations. A complete campaign of 2-D simulations, performed
for several values of tip speed ratio and based on RANS unsteady
calculations, has been performed to obtain the rotor torque and power
curves. Also the effect of a NACA-shaped central hydrofoil has been
investigated, with the aim of evaluating the impact of a solid
blockage on the performance of the shrouded rotor configuration.
The beneficial effect of the shroud on rotor overall performances
has clearly been evidenced, while the adoption of the central
hydrofoil has proved to be detrimental, being the resulting flow slow
down (due to the presence of the obstacle) much higher with respect
to the flow acceleration (due to the solid blockage effect).
Abstract: In this paper, the full state feedback controllers
capable of regulating and tracking the speed trajectory are presented.
A fourth order nonlinear mean value model of a 448 kW turbocharged
diesel engine published earlier is used for the purpose.
For designing controllers, the nonlinear model is linearized and
represented in state-space form. Full state feedback controllers
capable of meeting varying speed demands of drivers are presented.
Main focus here is to investigate sensitivity of the controller to the
perturbations in the parameters of the original nonlinear model.
Suggested controller is shown to be highly insensitive to the
parameter variations. This indicates that the controller is likely
perform with same accuracy even after significant wear and tear of
engine due to its use for years.
Abstract: This study compares three meta heuristics to minimize makespan (Cmax) for Hybrid Flow Shop (HFS) Scheduling Problem with Parallel Machines. This problem is known to be NP-Hard. This study proposes three algorithms among improvement heuristic searches which are: Genetic Algorithm (GA), Simulated Annealing (SA), and Tabu Search (TS). SA and TS are known as deterministic improvement heuristic search. GA is known as stochastic improvement heuristic search. A comprehensive comparison from these three improvement heuristic searches is presented. The results for the experiments conducted show that TS is effective and efficient to solve HFS scheduling problems.
Abstract: This paper presents modeling and optimization of two NP-hard problems in flexible manufacturing system (FMS), part type selection problem and loading problem. Due to the complexity and extent of the problems, the paper was split into two parts. The first part of the papers has discussed the modeling of the problems and showed how the real coded genetic algorithms (RCGA) can be applied to solve the problems. This second part discusses the effectiveness of the RCGA which uses an array of real numbers as chromosome representation. The novel proposed chromosome representation produces only feasible solutions which minimize a computational time needed by GA to push its population toward feasible search space or repair infeasible chromosomes. The proposed RCGA improves the FMS performance by considering two objectives, maximizing system throughput and maintaining the balance of the system (minimizing system unbalance). The resulted objective values are compared to the optimum values produced by branch-and-bound method. The experiments show that the proposed RCGA could reach near optimum solutions in a reasonable amount of time.
Abstract: Active Vibration Control (AVC) is an important
problem in structures. One of the ways to tackle this problem is to
make the structure smart, adaptive and self-controlling. The objective
of active vibration control is to reduce the vibration of a system by
automatic modification of the system-s structural response. This
paper features the modeling and design of a Periodic Output
Feedback (POF) control technique for the active vibration control of
a flexible Timoshenko cantilever beam for a multivariable case with
2 inputs and 2 outputs by retaining the first 2 dominant vibratory
modes using the smart structure concept. The entire structure is
modeled in state space form using the concept of piezoelectric
theory, Timoshenko beam theory, Finite Element Method (FEM) and
the state space techniques. Simulations are performed in MATLAB.
The effect of placing the sensor / actuator at 2 finite element
locations along the length of the beam is observed. The open loop
responses, closed loop responses and the tip displacements with and
without the controller are obtained and the performance of the smart
system is evaluated for active vibration control.
Abstract: A numerical simulation of micro Poiseuille flow has
performed for rarefied and compressible flow at slip flow regimes.
The wall roughness is simulated in two cases with triangular
microelements and random micro peaks distributed on wall surfaces
to study the effects of roughness shape and distribution on flow field.
Two values of Mach and Knudsen numbers have used to investigate
the effects of rarefaction as well as compressibility. The numerical
results have also checked with available theoretical and experimental
relations and good agreements has achieved. High influence of
roughness shape can be seen for both compressible and
incompressible rarefied flows. In addition it is found that rarefaction
has more significant effect on flow field in microchannels with
higher relative roughness. It is also found that compressibility has
more significant effects on Poiseuille number when relative
roughness increases.
Abstract: A model of vortex wake is suggested to determine the
induced power during animal hovering flight. The wake is modeled
by a series of equi-spaced rigid rectangular vortex plates, positioned
horizontally and moving vertically downwards with identical speeds;
each plate is generated during powering of the functionally wing
stroke. The vortex representation of the wake considered in the
current theory allows a considerable loss of momentum to occur. The
current approach accords well with the nature of the wingbeat since it
considers the unsteadiness in the wake as an important fluid
dynamical characteristic. Induced power in hovering is calculated as
the aerodynamic power required to generate the vortex wake system.
Specific mean induced power to mean wing tip velocity ratio is
determined by solely the normal spacing parameter (f) for a given
wing stroke amplitude. The current theory gives much higher specific
induced power estimate than anticipated by classical methods.
Abstract: This paper presents kinematic and dynamic analysis of a novel 8-DOF hybrid robot manipulator. The hybrid robot manipulator under consideration consists of a parallel robot which
is followed by a serial mechanism. The parallel mechanism has three translational DOF, and the serial mechanism has five DOF so that the overall degree of freedom is eight. The introduced
manipulator has a wide workspace and a high capability to reduce
the actuating energy. The inverse and forward kinematic solutions are described in closed form. The theoretical results are verified by
a numerical example. Inverse dynamic analysis of the robot is presented by utilizing the Iterative Newton-Euler and Lagrange dynamic formulation methods. Finally, for performing a multi-step
arc welding process, results have indicated that the introduced manipulator is highly capable of reducing the actuating energy.
Abstract: Algae-based fuel are considered a promising sources
of clean energy, and because it has many advantages over traditional
biofuel, research and business ventures have driven into developing
and producing Algal-biofuel. But its production stages create a cost
structure that it is not competitive with traditional fuels. Therefore,
cost becomes the main obstacle in commercial production purpose.
However, the present research which aims at using cost structure
model, and designed MS-Dose program, to investigate the a mount of
production cost and determined the parameter had great effect on it,
second to measured the amount of contribution rate of algae in
process the pollution by capturing Co2 from air . The result generated
from the model shows that the production cost of biomass is between
$0.137 /kg for 100 ha and $0.132 /kg for 500 ha which was less than
cost of other studies, while gallon costs between $3.4 - 3.5, more
than traditional sources of oil about $1 ,which regarded as a rate of
contribution of algal in capturing CO2 from air.