Abstract: In this paper, we presented a Multi-Objective Random
Drift Particle Swarm Optimization algorithm (MORDPSO-CD) based
on RDPSO and crowding distance sorting to improve the convergence
and distribution with less computation cost. MORDPSO-CD makes
the most of RDPSO to approach the true Pareto optimal solutions
fast. We adopt the crowding distance sorting technique to update and
maintain the archived optimal solutions. Introducing the crowding
distance technique into MORDPSO can make the leader particles
find the true Pareto solution ultimately. The simulation results reveal
that the proposed algorithm has better convergence and distribution.
Abstract: Hybrid propulsion combines beneficial properties of both solid and liquid rockets, such as multiple restarts, throttability as well as simplicity and reduced costs. A nitrous oxide (N2O)/paraffin-based hybrid rocket engine demonstrator is currently under development at the Italian Aerospace Research Center (CIRA) within the national research program HYPROB, funded by the Italian Ministry of Research. Nitrous oxide belongs to the class of self-pressurizing propellants that exhibit a high vapor pressure at standard ambient temperature. This peculiar feature makes those fluids very attractive for space rocket applications because it avoids the use of complex pressurization systems, leading to great benefits in terms of weight savings and reliability. To avoid feed-system-coupled instabilities, the phase change is required to occur through the injectors. In this regard, the oxidizer is stored in liquid condition while target chamber pressures are designed to lie below vapor pressure. The consequent cavitation and flash vaporization constitute a remarkably complex phenomenology that arises great modelling challenges. Thus, it is clear that the design of the injection system is fundamental for the full exploitation of hybrid rocket engine throttability. The Analytical Hierarchy Process has been used to select the injection architecture as best compromise among different design criteria such as functionality, technology innovation and cost. The impossibility to use engineering simplified relations for the dimensioning of the injectors led to the needs of applying a numerical approach based on OpenFOAM®. The numerical tool has been validated with selected experimental data from literature. Quantitative, as well as qualitative comparisons are performed in terms of mass flow rate and pressure drop across the injector for several operating conditions. The results show satisfactory agreement with the experimental data. Modeling assumptions, together with their impact on numerical predictions are discussed in the paper. Once assessed the reliability of the numerical tool, the injection plate has been designed and sized to guarantee the required amount of oxidizer in the combustion chamber and therefore to assure high combustion efficiency. To this purpose, the plate has been designed with multiple injectors whose number and diameter have been selected in order to reach the requested mass flow rate for the two operating conditions of maximum and minimum thrust. The overall design has been finally verified through three-dimensional computations in cavitating non-reacting conditions and it has been verified that the proposed design solution is able to guarantee the requested values of mass flow rates.
Abstract: During aircraft maintenance scheduling, operator calculates the budget of the maintenance. Usually, this calculation includes only the costs that are directly related to the maintenance process such as cost of labor, material, and equipment. In some cases, overhead cost is also included. However, in some of those, downtime cost is neglected claiming that grounding is a natural fact of maintenance; therefore, it is not considered as part of the analytical decision-making process. Based on the normalized data, we introduce downtime cost with its monetary value and add its seasonal character. We envision that the rest of the model, which works together with the downtime cost, could be checked with the real life cases, through the review of MRO cost and airline spending in the particular and scheduled maintenance events.
Abstract: This paper describes the use of by-products as
adsorbents for removing heavy metals from aqueous effluent
solutions. Products of almond skin, walnut shell, saw dust, rice bran
and egg shell were evaluated as metal ion adsorbents in aqueous
solutions. A comparative study was done with commercial adsorbents
like ion exchange resins and activated carbon too. Batch experiments
were investigated to determine the affinity of all of biomasses for,
Cd(ΙΙ), Cr(ΙΙΙ), Ni(ΙΙ), and Pb(ΙΙ) metal ions at pH 5. The rate of
metal ion removal in the synthetic wastewater by the biomass was
evaluated by measuring final concentration of synthetic wastewater.
At a concentration of metal ion (50 mg/L), egg shell adsorbed high
levels (98.6 – 99.7%) of Pb(ΙΙ) and Cr(ΙΙΙ) and walnut shell adsorbed
high levels (35.3 – 65.4%) of Ni(ΙΙ) and Cd(ΙΙ). In this study, it has
been shown that by-products were excellent adsorbents for removal
of toxic ions from wastewater with efficiency comparable to
commercially available adsorbents, but at a reduced cost. Also
statistical studies using Independent Sample t Test and ANOVA Oneway
for statistical comparison between various elements adsorption
showed that there isn’t a significant difference in some elements
adsorption percentage by by-products and commercial adsorbents.
Abstract: Gas lift optimization is becoming more important now a day in petroleum industry. A proper lift optimization can reduce the operating cost, increase the net present value (NPV) and maximize the recovery from the asset. A widely accepted definition of gas lift optimization is to obtain the maximum output under specified operating conditions. In addition, gas lift, a costly and indispensable means to recover oil from high depth reservoir entails solving the gas lift optimization problems. Gas lift optimization is a continuous process; there are two levels of production optimization. The total field optimization involves optimizing the surface facilities and the injection rate that can be achieved by standard tools softwares. Well level optimization can be achieved by optimizing the well parameters such as point of injection, injection rate, and injection pressure. All these aspects have been investigated and presented in this study by using experimental data and PROSPER simulation program. The results show that the well head pressure has a large influence on the gas lift performance and also proved that smart gas lift valve can be used to improve gas lift performance by controlling gas injection from down hole. Obtaining the optimum gas injection rate is important because excessive gas injection reduces production rate and consequently increases the operation cost.
Abstract: The problem of construction material waste remains unresolved, as a significant percentage of the materials delivered to some project sites end up as waste which might result in additional project cost. Cost overrun is a problem which affects 90% of the completed projects in the world. The argument on how to eliminate it has been on-going for the past 70 years, but there is neither substantial improvement nor significant solution for mitigating its detrimental effects. Research evidence has proposed various construction cost overruns and material-waste management approaches; nonetheless, these studies failed to give a clear indication on the framework and the equation for managing construction material waste and cost overruns. Hence, this research aims to develop a conceptual framework and a mathematical equation for managing material waste and cost overrun in the construction industry. The paper adopts the desktop methodological approach. This involves comparing the causes of material waste and those of cost overruns from the literature to determine the possible relationship. The review revealed a relationship between material waste and cost overrun that; increase in material waste would result to a corresponding increase in the amount of cost overrun at both the pre-contract and the post contract stages of a project. It was found from the equation that achieving an effective construction material waste management must ensure a “Good Quality-of-Planning, Estimating, and Design Management” and a “Good Quality- of-Construction, Procurement and Site Management”; a decrease in “Design Complexity” which would reduce “Material Waste” and subsequently reduce the amount of cost overrun by 86.74%. The conceptual framework and the mathematical equation developed in this study are recommended to the professionals of the construction industry.
Abstract: The purpose of this paper is to study and compare two maximum power point tracking (MPPT) algorithms in a photovoltaic simulation system and also show a simulation study of maximum power point tracking (MPPT) for photovoltaic systems using perturb and observe algorithm and Incremental conductance algorithm. Maximum power point tracking (MPPT) plays an important role in photovoltaic systems because it maximize the power output from a PV system for a given set of conditions, and therefore maximize the array efficiency and minimize the overall system cost. Since the maximum power point (MPP) varies, based on the irradiation and cell temperature, appropriate algorithms must be utilized to track the (MPP) and maintain the operation of the system in it. MATLAB/Simulink is used to establish a model of photovoltaic system with (MPPT) function. This system is developed by combining the models established of solar PV module and DC-DC Boost converter. The system is simulated under different climate conditions. Simulation results show that the photovoltaic simulation system can track the maximum power point accurately.
Abstract: The cumulative costs for O&M may represent as
much as 65%-90% of the turbine's investment cost. Nowadays the
cost effectiveness concept becomes a decision-making and
technology evaluation metric. The cost of energy metric accounts for
the effect replacement cost and unscheduled maintenance cost
parameters. One key of the proposed approach is the idea of
maintaining the WTs which can be captured via use of a finite state
Markov chain. Such a model can be embedded within a probabilistic
operation and maintenance simulation reflecting the action to be
done. In this paper, an approach of estimating the cost of O&M is
presented. The finite state Markov model is used for decision
problems with number of determined periods (life cycle) to predict
the cost according to various options of maintenance.
Abstract: Voltage level must be raised in order to deliver the
produced energy to the consumption zones with less loss and less
cost. Power transformers used to raise or lower voltage are important
parts of the energy transmission system. Power transformers used in
switchgear and power generation plants stay in human's intensive
habitat zones as a result of expanding cities. Accordingly, noise
levels produced by power transformers have begun more and more
important and they have established itself as one of the research field.
In this research, the noise cause on transformers has been
investigated, it's causes has been examined and noise measurement
techniques have been introduced. Examples of transformer noise test
results are submitted and precautions to be taken were discussed for
the purpose of decreasing of the noise which will occurred by
transformers.
Abstract: The study of the aerodynamics related to the
improvement in the acting of airplanes and automobiles with the
objective of being reduced the effect of the attrition of the air on
structures, providing larger speeds and smaller consumption of fuel.
The application of the knowledge of the aerodynamics not more
limits to the aeronautical and automobile industries. Therefore, this
research aims to design and construction of a wind tunnel to perform
aerodynamic analysis in bodies of cars, seeking greater efficiency.
Therefore, this research aims to design and construction of a wind
tunnel to perform aerodynamic analysis in bodies of cars, seeking
greater efficiency. For this, a methodology for wind tunnel type
selection is designed to be built, taking into account the various
existing configurations in which chose to build an open circuit tunnel,
due to the lower complexity of construction and installation;
operational simplicity and low cost. The guidelines for the project
were teaching: the layer that limits study and analyze specimens with
different geometries. For the variation of pressure in the test, section
of a switched gauge used a pitot tube. Thus, it was possible to obtain
quantitative and qualitative results, which proved to be satisfactory.
Abstract: Journal bearings used in IC engines are prone to premature
failures and are likely to fail earlier than the rated life due to
highly impulsive and unstable operating conditions and frequent
starts/stops. Vibration signature extraction and wear debris analysis
techniques are prevalent in industry for condition monitoring of
rotary machinery. However, both techniques involve a great deal of
technical expertise, time, and cost. Limited literature is available on
the application of these techniques for fault detection in reciprocating
machinery, due to the complex nature of impact forces that
confounds the extraction of fault signals for vibration-based analysis
and wear prediction. In present study, a simulation model was developed to investigate
the bearing wear behaviour, resulting because of different operating
conditions, to complement the vibration analysis. In current
simulation, the dynamics of the engine was established first, based on
which the hydrodynamic journal bearing forces were evaluated by
numerical solution of the Reynold’s equation. In addition, the
essential outputs of interest in this study, critical to determine wear
rates are the tangential velocity and oil film thickness between the
journals and bearing sleeve, which if not maintained appropriately,
have a detrimental effect on the bearing performance. Archard’s wear prediction model was used in the simulation to
calculate the wear rate of bearings with specific location information
as all determinative parameters were obtained with reference to crank
rotation. Oil film thickness obtained from the model was used as a
criterion to determine if the lubrication is sufficient to prevent contact
between the journal and bearing thus causing accelerated wear. A
limiting value of 1 μm was used as the minimum oil film thickness
needed to prevent contact. The increased wear rate with growing
severity of operating conditions is analogous and comparable to the
rise in amplitude of the squared envelope of the referenced vibration
signals. Thus on one hand, the developed model demonstrated its
capability to explain wear behaviour and on the other hand it also
helps to establish a co-relation between wear based and vibration
based analysis. Therefore, the model provides a cost effective and
quick approach to predict the impending wear in IC engine bearings
under various operating conditions.
Abstract: Customer’ needs, quality, and value creation while
reducing costs through supply chain management provides challenges
and opportunities for companies and researchers. In the light of these
challenges, modern ideas must contribute to counter these challenges
and exploit opportunities. Therefore, this paper discusses the impact
of the quality cost on revenue sharing as a most important incentive
to configure business networks. This paper develops the quality cost approach to align with the
modern era. It develops a model to measure quality costs which
might enable firms to manage revenue sharing in a supply chain. The
developed model includes five categories; besides the well-known
four categories (namely prevention costs, appraisal costs, internal
failure costs, and external failure costs), a new category has been
developed in this research as a new vision of the relationship between
quality costs and innovations in industry. This new category is
Recycle Cost. This paper also examines whether such quality costs in
supply chains influence the revenue sharing between partners. Using the author's quality cost model, the relationship between
quality costs and revenue sharing among partners is examined using a
case study in an Egyptian manufacturing company which is a part of
a supply chain. This paper argues that the revenue-sharing proportion
allocated to supplier increases as the recycle cost of supplier
increases, and the revenue-sharing proportion allocated to
manufacturer increases as the prevention and appraisal costs increase,
as well as the failure costs, the recycle costs of manufacturer, and the
recycle costs of suppliers decrease. However, the results present
surprising findings. The purposes of this study are developing quality cost approach
and understanding the relationships between quality costs and
revenue sharing in supply chains. Therefore, the present study
contributes to theory and practice by explaining how the cost of
recycling can be combined in quality cost model to better
understanding the revenue sharing among partners in supply chains.
Abstract: In order to utilize results from global climate models,
dynamical and statistical downscaling techniques have been
developed. For dynamical downscaling, usually a limited area
numerical model is used, with associated high computational cost.
This research proposes dynamic equation for specific space-time
regional climate downscaling from the Educational Global Climate
Model (EdGCM) for Southeast Asia. The equation is for surface air
temperature. This equation provides downscaling values of surface
air temperature at any specific location and time without running a
regional climate model. In the proposed equations, surface air
temperature is approximated from ground temperature, sensible heat
flux and 2m wind speed. Results from the application of the equation
show that the errors from the proposed equations are less than the
errors for direct interpolation from EdGCM.
Abstract: This research was conducted in an automotive company in Indonesia to overcome the problem of high logistics cost. The problem causes high of additional truck delivery. From the breakdown of the problem, chosen one route, which has the highest gap value, namely for RE-04. Research methodology will be started from calculating the ideal condition, making simulation, calculating the ideal logistic cost, and proposing an improvement. From the calculation of the ideal condition, box arrangement was done on the truck has efficiency with three trucks delivery per day. Route simulation making uses Tecnomatix Plant Simulation software as a visualization for the company about how the system is occurred on route RE-04 in ideal condition. The last step is proposing improvements on the area of route RE-04. The route arrangement is done by Saving Method and sequence of each supplier with the Nearest Neighbor. The results of the proposed improvements are three new route groups, where was expected to decrease logistics cost and increase the average of the truck efficiency per day.
Abstract: Digital reference service is when a traditional library
reference service is provided electronically. In most cases users do
not get full satisfaction from using digital reference service due to
variety of reasons. This paper discusses the formal specification of
web services applications for digital reference services (WSDRS).
WSDRS is an informal model that claims to reduce the problems of
digital reference services in libraries. It uses web services technology
to provide efficient digital way of satisfying users’ need in the
reference section of libraries. Informal model is in natural language
which is inconsistent and ambiguous that may cause difficulties to the
developers of the system. In order to solve this problem we decided
to convert the informal specifications into formal specifications. This
is supposed to reduce the overall development time and cost. We use
Z language to develop the formal model and verify it with Z/EVES
theorem prover tool.
Abstract: In recent years, new techniques for solving complex
problems in engineering are proposed. One of these techniques is
JPSO algorithm. With innovative changes in the nature of the jump
algorithm JPSO, it is possible to construct a graph-based solution
with a new algorithm called G-JPSO. In this paper, a new algorithm
to solve the optimal control problem Fletcher-Powell and optimal
control of pumps in water distribution network was evaluated.
Optimal control of pumps comprise of optimum timetable operation
(status on and off) for each of the pumps at the desired time interval.
Maximum number of status on and off for each pumps imposed to the
objective function as another constraint. To determine the optimal
operation of pumps, a model-based optimization-simulation
algorithm was developed based on G-JPSO and JPSO algorithms.
The proposed algorithm results were compared well with the ant
colony algorithm, genetic and JPSO results. This shows the
robustness of proposed algorithm in finding near optimum solutions
with reasonable computational cost.
Abstract: This paper reports the viability of developing Zn-27Al
alloy matrix hybrid composites reinforced with alumina, graphite and
fly ash (solid waste bye product of coal in thermal power plants).
This research work was aimed at developing low cost-high
performance Zn-27Al matrix composite with low density. Alumina
particulates (Al2O3), graphite added with 0, 2, 3, 4 and 5 wt% fly ash
were utilized to prepare 10wt% reinforcing phase with Zn-27Al alloy
as matrix using two-step stir casting method. Density measurement,
estimated percentage porosity, tensile testing, micro hardness
measurement and optical microscopy were used to assess the
performance of the composites produced. The results show that the
hardness, ultimate tensile strength, and percent elongation of the
hybrid composites decrease with increase in fly ash content. The
maximum decrease in hardness and ultimate tensile strength of
13.72% and 15.25% respectively were observed for composite grade
containing 5wt% fly ash. The percentage elongation of composite
sample without fly ash is 8.9% which is comparable with that of the
sample containing 2wt% fly ash with percentage elongation of 8.8%.
The fracture toughness of the fly ash containing composites was
however superior to those of composites without fly ash with 5wt%
fly ash containing composite exhibiting the highest fracture
toughness. The results show that fly ash can be utilized as
complementary reinforcement in ZA-27 alloy matrix composite to
reduce cost.
Abstract: This research studies the joint production,
maintenance and subcontracting control policy for an unreliable
deteriorating manufacturing system. Production activities are
controlled by a derivation of the Hedging Point Policy, and given that
the system is subject to deterioration, it reduces progressively its
capacity to satisfy product demand. Multiple deterioration effects are
considered, reflected mainly in the quality of the parts produced and
the reliability of the machine. Subcontracting is available as support
to satisfy product demand; also, overhaul maintenance can be
conducted to reduce the effects of deterioration. The main objective
of the research is to determine simultaneously the production,
maintenance and subcontracting rate, which minimize the total,
incurred cost. A stochastic dynamic programming model is
developed and solved through a simulation-based approach
composed of statistical analysis and optimization with the response
surface methodology. The obtained results highlight the strong
interactions between production, deterioration and quality, which
justify the development of an integrated model. A numerical example
and a sensitivity analysis are presented to validate our results.
Abstract: Carefully scheduling the operations of pumps can be
resulted to significant energy savings. Schedules can be defined
either implicit, in terms of other elements of the network such as tank
levels, or explicit by specifying the time during which each pump is
on/off. In this study, two new explicit representations based on timecontrolled
triggers were analyzed, where the maximum number of
pump switches was established beforehand, and the schedule may
contain fewer switches than the maximum. The optimal operation of
pumping stations was determined using a Jumping Particle Swarm
Optimization (JPSO) algorithm to achieve the minimum energy cost.
The model integrates JPSO optimizer and EPANET hydraulic
network solver. The optimal pump operation schedule of VanZyl
water distribution system was determined using the proposed model
and compared with those from Genetic and Ant Colony algorithms.
The results indicate that the proposed model utilizing the JPSO
algorithm is a versatile management model for the operation of realworld
water distribution system.
Abstract: The localization information is crucial for the
operation of WSN. There are principally two types of localization
algorithms. The Range-based localization algorithm has strict
requirements on hardware, thus is expensive to be implemented in
practice. The Range-free localization algorithm reduces the hardware
cost. However, it can only achieve high accuracy in ideal scenarios.
In this paper, we locate unknown nodes by incorporating the
advantages of these two types of methods. The proposed algorithm
makes the unknown nodes select the nearest anchor using the
Received Signal Strength Indicator (RSSI) and choose two other
anchors which are the most accurate to achieve the estimated
location. Our algorithm improves the localization accuracy compared
with previous algorithms, which has been demonstrated by the
simulating results.