Abstract: A semi-active control strategy for suspension
systems of passenger cars is presented employing
Magnetorheological (MR) dampers. The vehicle is modeled with
seven DOFs including the, roll pitch and bounce of car body, and
the vertical motion of the four tires. In order to design an optimal
controller based on the actuator constraints, a Linear-Quadratic
Regulator (LQR) is designed. The design procedure of the LQR
consists of selecting two weighting matrices to minimize the energy
of the control system. This paper presents a hybrid optimization
procedure which is a combination of gradient-based and
evolutionary algorithms to choose the weighting matrices with
regards to the actuator constraint. The optimization algorithm is
defined based on maximum comfort and actuator constraints. It is
noted that utilizing the present control algorithm may significantly
reduce the vibration response of the passenger car, thus, providing
a comfortable ride.
Abstract: In this paper, we proposed a new routing protocol for
Unmanned Aerial Vehicles (UAVs) that equipped with directional
antenna. We named this protocol Directional Optimized Link State
Routing Protocol (DOLSR). This protocol is based on the well
known protocol that is called Optimized Link State Routing Protocol
(OLSR). We focused in our protocol on the multipoint relay (MPR)
concept which is the most important feature of this protocol. We
developed a heuristic that allows DOLSR protocol to minimize
the number of the multipoint relays. With this new protocol the
number of overhead packets will be reduced and the End-to-End
delay of the network will also be minimized. We showed through
simulation that our protocol outperformed Optimized Link State
Routing Protocol, Dynamic Source Routing (DSR) protocol and Ad-
Hoc On demand Distance Vector (AODV) routing protocol in
reducing the End-to-End delay and enhancing the overall
throughput. Our evaluation of the previous protocols was based
on the OPNET network simulation tool.
Abstract: Facility location problem involves locating a facility
to optimize some performance measures. Location of a public facility
to serve the community, such as a fire station, significantly affects its
service quality. Main objective in locating a fire station is to
minimize the response time, which is the time duration between
receiving a call and reaching the place of incident. In metropolitan
areas, fire vehicles need to cross highways and other traffic obstacles
through some obstacle-overcoming points which delay the response
time. In this paper, fire station location problem is analyzed.
Simulation models are developed for the location problems which
involve obstacles. Particular case problems are analyzed and the
results are presented.
Abstract: We address the balancing problem of transfer lines in
this paper to find the optimal line balancing that minimizes the nonproductive
time. We focus on the tool change time and face
orientation change time both of which influence the makespane. We
consider machine capacity limitations and technological constraints
associated with the manufacturing process of auto cylinder heads.
The problem is represented by a mixed integer programming model
that aims at distributing the design features to workstations and
sequencing the machining processes at a minimum non-productive
time. The proposed model is solved by an algorithm established using
linearization schemes and Benders- decomposition approach. The
experiments show the efficiency of the algorithm in reaching the
exact solution of small and medium problem instances at reasonable
time.
Abstract: Double-diffusive steady convection in a partially
porous cavity with partially permeable walls and under the combined
buoyancy effects of thermal and mass diffusion was analysed
numerically using finite volume method.
The top wall is well insulated and impermeable while the bottom
surface is partially well insulated and impermeable and partially
submitted to constant temperature T1 and concentration C1. Constant
equal temperature T2 and concentration C2 are imposed along the
vertical surfaces of the enclosure. Mass suction/injection and
injection/suction are respectively considered at the bottom of the
porous centred partition and at one of the vertical walls.
Heat and mass transfer characteristics as streamlines and average
Nusselt numbers and Sherwood numbers were discussed for different
values of buoyancy ratio, Rayleigh number, and injection/suction
coefficient.
It is especially noted that increasing the injection factor
disadvantages the exchanges in the case of the injection while the
transfer is augmented in case of suction. On the other hand, a critical
value of the buoyancy ratio was highlighted for which heat and mass
transfers are minimized.
Abstract: In this paper we present a novel technique for data
hiding in binary document images. We use the concept of entropy in
order to identify document specific least distortive areas throughout
the binary document image. The document image is treated as any
other image and the proposed method utilizes the standard document
characteristics for the embedding process. Proposed method
minimizes perceptual distortion due to embedding and allows
watermark extraction without the requirement of any side information
at the decoder end.
Abstract: In the last decades, the problem of perforation
damage has been considered as the major factor for the
reduction of oil productivity. Underbalance perforation is
considered as one of the best means to minimize or overcome
this problem. By maintaining wellbore pressure lower than
formation pressure, perforation damage could be minimize or
eliminated. This can be achieved by the use of nontraditional
lightweight completion fluid. This paper presents the effect of
natural clay in formulating nontraditional completion fluid to
ensure successful perforation job and increase of production
rate. Natural clay is used as homogenizing agent to create a
stable and non-damaging low-density completion fluid.
Results indicate that the addition of natural clay dramatically
increase the stability of the final fluids. In addition, field test
has shown that the application of nontraditional completion
fluid increases oil production by three folds.
Abstract: The paper presents the virtual model of the active
suspension system used for improving the dynamic behavior of a
motor vehicle. The study is focused on the design of the control
system, the purpose being to minimize the effect of the road
disturbances (which are considered as perturbations for the control
system). The analysis is performed for a quarter-car model, which
corresponds to the suspension system of the front wheel, by using the
DFC (Design for Control) software solution EASY5 (Engineering
Analysis Systems) of MSC Software. The controller, which is a PIDbased
device, is designed through a parametric optimization with the
Matrix Algebra Tool (MAT), considering the gain factors as design
variables, while the design objective is to minimize the overshoot of
the indicial response.
Abstract: In this paper smooth trajectories are computed in the Lie group SO(2, 1) as a motion planning problem by assigning a Frenet frame to the rigid body system to optimize the cost function of the elastic energy which is spent to track a timelike curve in Minkowski space. A method is proposed to solve a motion planning problem that minimize the integral of the square norm of Darboux vector of a timelike curve. This method uses the coordinate free Maximum Principle of Optimal control and results in the theory of integrable Hamiltonian systems. The presence of several conversed quantities inherent in these Hamiltonian systems aids in the explicit computation of the rigid body motions.
Abstract: As the air traffic increases at a hub airport, some
flights cannot land or depart at their preferred target time. This event
happens because the airport runways become occupied to near their
capacity. It results in extra costs for both passengers and airlines
because of the loss of connecting flights or more waiting, more fuel
consumption, rescheduling crew members, etc. Hence, devising an
appropriate scheduling method that determines a suitable runway and
time for each flight in order to efficiently use the hub capacity and
minimize the related costs is of great importance. In this paper, we
present a mixed-integer zero-one model for scheduling a set of mixed
landing and departing flights (despite of most previous studies
considered only landings). According to the fact that the flight cost is
strongly affected by the level of airline, we consider different airline
categories in our model. This model presents a single objective
minimizing the total sum of three terms, namely 1) the weighted
deviation from targets, 2) the scheduled time of the last flight (i.e.,
makespan), and 3) the unbalancing the workload on runways. We
solve 10 simulated instances of different sizes up to 30 flights and 4
runways. Optimal solutions are obtained in a reasonable time, which
are satisfactory in comparison with the traditional rule, namely First-
Come-First-Serve (FCFS) that is far apart from optimality in most
cases.
Abstract: In this paper, the Tabu search algorithm is used to
solve a transportation problem which consists of determining the
shortest routes with the appropriate vehicle capacity to facilitate the
travel of the students attending the University of Mauritius. The aim
of this work is to minimize the total cost of the distance travelled by
the vehicles in serving all the customers. An initial solution is
obtained by the TOUR algorithm which basically constructs a giant
tour containing all the customers and partitions it in an optimal way
so as to produce a set of feasible routes. The Tabu search algorithm
then makes use of a search procedure, a swapping procedure and the
intensification and diversification mechanism to find the best set of
feasible routes.
Abstract: Coated tool inserts can be considered as the backbone
of machining processes due to their wear and heat resistance.
However, defects of coating can degrade the integrity of these inserts
and the number of these defects should be minimized or eliminated if
possible. Recently, the advancement of coating processes and
analytical tools open a new era for optimizing the coating tools.
First, an overview is given regarding coating technology for cutting
tool inserts. Testing techniques for coating layers properties, as well
as the various coating defects and their assessment are also surveyed.
Second, it is introduced an experimental approach to examine the
possible coating defects and flaws of worn multicoated carbide
inserts using two important techniques namely scanning electron
microscopy and atomic force microscopy. Finally, it is
recommended a simple procedure for investigating manufacturing
defects and flaws of worn inserts.
Abstract: One of the criteria in production scheduling is Make
Span, minimizing this criteria causes more efficiently use of the
resources specially machinery and manpower. By assigning some
budget to some of the operations the operation time of these activities
reduces and affects the total completion time of all the operations
(Make Span). In this paper this issue is practiced in parallel flow
shops. At first we convert parallel flow shop to a network model and
by using a linear programming approach it is identified in order to
minimize make span (the completion time of the network) which
activities (operations) are better to absorb the predetermined and
limited budget. Minimizing the total completion time of all the
activities in the network is equivalent to minimizing make span in
production scheduling.
Abstract: With Power system movement toward restructuring along with factors such as life environment pollution, problems of transmission expansion and with advancement in construction technology of small generation units, it is expected that small units like wind turbines, fuel cells, photovoltaic, ... that most of the time connect to the distribution networks play a very essential role in electric power industry. With increase in developing usage of small generation units, management of distribution networks should be reviewed. The target of this paper is to present a new method for optimal management of active and reactive power in distribution networks with regard to costs pertaining to various types of dispersed generations, capacitors and cost of electric energy achieved from network. In other words, in this method it-s endeavored to select optimal sources of active and reactive power generation and controlling equipments such as dispersed generations, capacitors, under load tapchanger transformers and substations in a way that firstly costs in relation to them are minimized and secondly technical and physical constraints are regarded. Because the optimal management of distribution networks is an optimization problem with continuous and discrete variables, the new evolutionary method based on Ant Colony Algorithm has been applied. The simulation results of the method tested on two cases containing 23 and 34 buses exist and will be shown at later sections.
Abstract: Silver nano-particles have been used for antibacterial
purpose and it is also believed to have removal of odorous compounds,
oxidation capacity as a metal catalyst. In this study, silver
nano-particles in nano sizes (5-30 nm) were prepared on the surface of
NaHCO3, the supporting material, using a sputtering method that
provided high silver content and minimized conglomerating problems
observed in the common AgNO3 photo-deposition method. The silver
nano-particles were dispersed by dissolving Ag-NaHCO3 into water,
and the dispersed silver nano-particles in the aqueous phase were
applied to remove inorganic odor compounds, H2S, in a scrubbing
reactor. Hydrogen sulfide in the gas phase was rapidly removed by the
silver nano-particles, and the concentration of sulfate (SO4
2-) ion
increased with time due to the oxidation reaction by silver as a
catalyst. Consequently, the experimental results demonstrated that the
silver nano-particles in the aqueous solution can be successfully
applied to remove odorous compounds without adding additional
energy sources and producing any harmful byproducts
Abstract: The article describes a case study on one of Czech
Republic-s manufacturing middle size enterprises (ME), where due to
the European financial crisis, production lines had to be redesigned
and optimized in order to minimize the total costs of the production
of goods. It is considered an optimization problem of minimizing the
total cost of the work load, according to the costs of the possible
locations of the workplaces, with an application of the Greedy
algorithm and a partial analogy to a Set Packing Problem. The
displacement of working tables in a company should be as a one-toone
monotone increasing function in order for the total costs of
production of the goods to be at minimum. We use a heuristic
approach with greedy algorithm for solving this linear optimization
problem, regardless the possible greediness which may appear and
we apply it in a Czech ME.
Abstract: Scheduling of diversified service requests in
distributed computing is a critical design issue. Cloud is a type of
parallel and distributed system consisting of a collection of
interconnected and virtual computers. It is not only the clusters and
grid but also it comprises of next generation data centers. The paper
proposes an initial heuristic algorithm to apply modified ant colony
optimization approach for the diversified service allocation and
scheduling mechanism in cloud paradigm. The proposed optimization
method is aimed to minimize the scheduling throughput to service all
the diversified requests according to the different resource allocator
available under cloud computing environment.
Abstract: This paper presents an optimization technique to economic load dispatch (ELD) problems with considering the daily load patterns and generator constraints using a particle swarm optimization (PSO). The objective is to minimize the fuel cost. The optimization problem is subject to system constraints consisting of power balance and generation output of each units. The application of a constriction factor into PSO is a useful strategy to ensure convergence of the particle swarm algorithm. The proposed method is able to determine, the output power generation for all of the power generation units, so that the total constraint cost function is minimized. The performance of the developed methodology is demonstrated by case studies in test system of fifteen-generation units. The results show that the proposed algorithm scan give the minimum total cost of generation while satisfying all the constraints and benefiting greatly from saving in power loss reduction
Abstract: When the profile information of an existing road is
missing or not up-to-date and the parameters of the vertical
alignment are needed for engineering analysis, the engineer has to recreate
the geometric design features of the road alignment using
collected profile data. The profile data may be collected using
traditional surveying methods, global positioning systems, or digital
imagery. This paper develops a method that estimates the parameters
of the geometric features that best characterize the existing vertical
alignments in terms of tangents and the expressions of the curve, that
may be symmetrical, asymmetrical, reverse, and complex vertical
curves. The method is implemented using an Excel-based
optimization method that minimizes the differences between the
observed profile and the profiles estimated from the equations of the
vertical curve. The method uses a 'wireframe' representation of the
profile that makes the proposed method applicable to all types of
vertical curves. A secondary contribution of this paper is to introduce
the properties of the equal-arc asymmetrical curve that has been
recently developed in the highway geometric design field.
Abstract: In this paper, real-coded genetic algorithm (RCGA) optimization technique has been applied for large-scale linear dynamic multi-input-multi-output (MIMO) system. The method is based on error minimization technique where the integral square error between the transient responses of original and reduced order models has been minimized by RCGA. The reduction procedure is simple computer oriented and the approach is comparable in quality with the other well-known reduction techniques. Also, the proposed method guarantees stability of the reduced model if the original high-order MIMO system is stable. The proposed approach of MIMO system order reduction is illustrated with the help of an example and the results are compared with the recently published other well-known reduction techniques to show its superiority.