Abstract: The main emphasis of metallurgists has been to process the materials to obtain the balanced mechanical properties for the given application. One of the processing routes to alter the properties is heat treatment. Nearly 90% of the structural applications are related to the medium carbon an alloyed steels and hence are regarded as structural steels. The major requirement in the conventional steel is to improve workability, toughness, hardness and grain refinement. In this view, it is proposed to study the mechanical and tribological properties of unalloyed structural (AISI 1140) steel with different thermal (heat) treatments like annealing, normalizing, tempering and hardening and compared with as brought (cold worked) specimen. All heat treatments are carried out in atmospheric condition. Hardening treatment improves hardness of the material, a marginal decrease in hardness value with improved ductility is observed in tempering. Annealing and normalizing improve ductility of the specimen. Normalized specimen shows ultimate ductility. Hardened specimen shows highest wear resistance in the initial period of slide wear where as above 25KM of sliding distance, as brought steel dominates the hardened specimen. Both mild and severe wear regions are observed. Microstructural analysis shows the existence of pearlitic structure in normalized specimen, lath martensitic structure in hardened, pearlitic, ferritic structure in annealed specimen.
Abstract: Solar energy is not only sustainable but also a clean
alternative to be used as source of high temperature heat for many
processes and power generation. However, the major drawback of
solar energy is its transient nature. Especially in solar
thermochemical processing, it is crucial to maintain constant or semiconstant
temperatures inside the solar reactor. In our laboratory, we
have developed a mechanism allowing us to achieve semi-constant
temperature inside the solar reactor. In this paper, we introduce the
concept along with some updated designs and provide the optical
analysis of the concept under various incoming flux.
Abstract: In this paper, the techniques for estimating the
residual stress in high velocity oxy fuel thermal spray coatings have
been discussed and compared. The development trend and the last
investigation have been studied. It is seemed that the there is not
effective study on the effect of the peening action in HVOF
analytically and numerically.
Abstract: Studies have shown that the SnAgCu solder family has been widely used as a replacement for conventional Sn-Pb solders. An attractive approach is by introducing alloying additives (rare earth elements (RE), Zn, Co, Fe, Ni, Sb) into the SnAgCu solder, which helps in refining the microstructure also improving the mechanical and wetting properties of the solder. The present work focuses on the effect of additions of 0.5% Ce and Fe into Sn-3.0Ag-0.5Cu solder, in attempt to reduce the intermetallic compound (IMC) growth and reflow properties of the solder on Cu and Ni (P) surface finish, as well as effects thermal aging on the formation of intermetallic compound (IMC) on different surface finish. Excessive intermetallic compound growth may effect the interface and solder joint due to the brittle nature of the intermetallic compounds. Thus, by introducing alloying elements, IMC layer thickness can be decrease, resulting in better joint and solder reliability.
Abstract: In this paper, the optimum weight and cost of a laminated composite plate is seeked, while it undergoes the heaviest load prior to a complete failure. Various failure criteria are defined for such structures in the literature. In this work, the Tsai-Hill theory is used as the failure criterion. The theory of analysis was based on the Classical Lamination Theory (CLT). A newly type of Genetic Algorithm (GA) as an optimization technique with a direct use of real variables was employed. Yet, since the optimization via GAs is a long process, and the major time is consumed through the analysis, Radial Basis Function Neural Networks (RBFNN) was employed in predicting the output from the analysis. Thus, the process of optimization will be carried out through a hybrid neuro-GA environment, and the procedure will be carried out until a predicted optimum solution is achieved.
Abstract: Extraction of laccase produced by L. polychrous in an
aqueous two-phase system, composed of polyethylene glycol and
phosphate salt at pH 7.0 and 250C was investigated. The effect of
PEG molecular weight, PEG concentration and phosphate
concentration was determined. Laccase preferentially partitioned to
the top phase. Good extraction of laccase to the top phase was
observed with PEG 4000. The optimum system was found in the
system containing 12% w/w PEG 4000 and 16% w/w phosphate salt
with KE of 88.3, purification factor of 3.0-fold and 99.1% yield.
Some properties of the enzyme such as thermal stability, effect of
heavy metal ions and kinetic constants were also presented in this
work. The thermal stability decreased sharply with high temperature
above 60 0C. The enzyme was inhibited by Cd2+, Pb2+, Zn2+ and
Cu2+. The Vmax and Km values of the enzyme were 74.70
μmol/min/ml and 9.066 mM respectively.
Abstract: wind catchers have been served as a cooling system, used to provide acceptable ventilation by means of renewable energy of wind. In the present study, the city of Yazd in arid climate is selected as case study. From the architecture point of view, learning about wind catchers in this study is done by means of field surveys. Research method for selection of the case is based on random form, and analytical method. Wind catcher typology and knowledge of relationship governing the wind catcher's architecture were those measures that are taken for the first time. 53 wind catchers were analyzed. The typology of the wind-catchers is done by the physical analyzing, patterns and common concepts as incorporated in them. How the architecture of wind catcher can influence their operations by analyzing thermal behavior are the archetypes of selected wind catchers. Calculating fluids dynamics science, fluent software and numerical analysis are used in this study as the most accurate analytical approach. The results obtained from these analyses show the formal specifications of wind catchers with optimum operation in Yazd. The knowledge obtained from the optimum model could be used for design and construction of wind catchers with more improved operation
Abstract: This study describes a micro device integrated with
multi-chamber for polymerase chain reaction (PCR) with different
annealing temperatures. The device consists of the reaction
polydimethylsiloxane (PDMS) chip, a cover glass chip, and is
equipped with cartridge heaters, fans, and thermocouples for
temperature control. In this prototype, commercial software is utilized
to determine the geometric and operational parameters those are
responsible for creating the denaturation, annealing, and extension
temperatures within the chip. Two cartridge heaters are placed at two
sides of the chip and maintained at two different temperatures to
achieve a thermal gradient on the chip during the annealing step. The
temperatures on the chip surface are measured via an infrared imager.
Some thermocouples inserted into the reaction chambers are used to
obtain the transient temperature profiles of the reaction chambers
during several thermal cycles. The experimental temperatures
compared to the simulated results show a similar trend. This work
should be interesting to persons involved in the high-temperature
based reactions and genomics or cell analysis.
Abstract: This paper is concerned with propagation of thermoelastic longitudinal vibrations of an infinite circular cylinder, in the context of the linear theory of generalized thermoelasticity with two relaxation time parameters (Green and Lindsay theory). Three displacement potential functions are introduced to uncouple the equations of motion. The frequency equation, by using the traction free boundary conditions, is given in the form of a determinant involving Bessel functions. The roots of the frequency equation give the value of the characteristic circular frequency as function of the wave number. These roots, which correspond to various modes, are numerically computed and presented graphically for different values of the thermal relaxation times. It is found that the influences of the thermal relaxation times on the amplitudes of the elastic and thermal waves are remarkable. Also, it is shown in this study that the propagation of thermoelastic longitudinal vibrations based on the generalized thermoelasticity can differ significantly compared with the results under the classical formulation. A comparison of the results for the case with no thermal effects shows well agreement with some of the corresponding earlier results.
Abstract: Titanium oxide films with different morphologies have for the first time been fabricated through hydrothermal reactions between a titanium substrate and iodine powder in water or ethanol. SEM revealed that iodine supported titanium (Ti-I2) surface shows different morphologies with variable treatment conditions. The mean surface roughness (Ra) was increased in the different groups. Use of surfactant has a role to increase the roughness of the film. The surface roughness was in the range of 0.15 μm-0.42 μm. Furthermore, the electrochemical examinations showed that the Ti-I2 surface fabricated in alcoholic medium has high corrosion resistance than in aqueous medium.
Abstract: In this paper, we have compared the performance of a Turbo and Trellis coded optical code division multiple access (OCDMA) system. The comparison of the two codes has been accomplished by employing optical orthogonal codes (OOCs). The Bit Error Rate (BER) performances have been compared by varying the code weights of address codes employed by the system. We have considered the effects of optical multiple access interference (OMAI), thermal noise and avalanche photodiode (APD) detector noise. Analysis has been carried out for the system with and without double optical hard limiter (DHL). From the simulation results it is observed that a better and distinct comparison can be drawn between the performance of Trellis and Turbo coded systems, at lower code weights of optical orthogonal codes for a fixed number of users. The BER performance of the Turbo coded system is found to be better than the Trellis coded system for all code weights that have been considered for the simulation. Nevertheless, the Trellis coded OCDMA system is found to be better than the uncoded OCDMA system. Trellis coded OCDMA can be used in systems where decoding time has to be kept low, bandwidth is limited and high reliability is not a crucial factor as in local area networks. Also the system hardware is less complex in comparison to the Turbo coded system. Trellis coded OCDMA system can be used without significant modification of the existing chipsets. Turbo-coded OCDMA can however be employed in systems where high reliability is needed and bandwidth is not a limiting factor.
Abstract: Energy generated by the force of water in hydropower
can provide a more sustainable, non-polluting alternative to fossil
fuels, along with other renewable sources of energy, such as wind,
solar and tidal power, bio energy and geothermal energy. Small scale
hydroelectricity in Iran is well suited for “off-grid" rural electricity
applications, while other renewable energy sources, such as wind,
solar and biomass, can be beneficially used as fuel for pumping
groundwater for drinking and small scale irrigation in remote rural
areas or small villages. Small Hydro Power plants in Iran have very
low operating and maintenance costs because they consume no fossil
or nuclear fuel and do not involve high temperature processes. The
equipment is relatively simple to operate and maintain. Hydropower
equipment can adjust rapidly to load changes. The extended
equipment life provides significant economic advantages. Some
hydroelectric plants installed 100 years ago still operate reliably. The
Polkolo river is located on Karun basin at southwest of Iran. Situation
and conditions of Polkolo river are evaluated for construction of
small hydropower in this article. The topographical conditions and
the existence of permanent water from springs provide the suitability
to install hydroelectric power plants on the river Polkolo. The
cascade plant consists of 9 power plants connected with each other
and is having the total head as 1100m and discharge about 2.5cubic
meter per second. The annual production of energy is 105.5 million
kwh.
Abstract: In this paper, the steady-state temperature of a sample 500 KW two rotor one stator Non-slotted axial flux permanent magnet motor is calculated using the finite element simulator software package. Due to the high temperature in various parts of the machine, especially at stator winding, a cooling system is designed for the motor and the temperature is recalculated. The results show that the temperature obtained for the parts is within the permissible range.
Abstract: In this paper, a novel method using Bees Algorithm is proposed to determine the optimal allocation of FACTS devices for maximizing the Available Transfer Capability (ATC) of power transactions between source and sink areas in the deregulated power system. The algorithm simultaneously searches the FACTS location, FACTS parameters and FACTS types. Two types of FACTS are simulated in this study namely Thyristor Controlled Series Compensator (TCSC) and Static Var Compensator (SVC). A Repeated Power Flow with FACTS devices including ATC is used to evaluate the feasible ATC value within real and reactive power generation limits, line thermal limits, voltage limits and FACTS operation limits. An IEEE30 bus system is used to demonstrate the effectiveness of the algorithm as an optimization tool to enhance ATC. A Genetic Algorithm technique is used for validation purposes. The results clearly indicate that the introduction of FACTS devices in a right combination of location and parameters could enhance ATC and Bees Algorithm can be efficiently used for this kind of nonlinear integer optimization.
Abstract: Auckland has a temperate climate with comfortable
warm, dry summers and mild, wet winters. An Auckland school
normally does not need air conditioning for cooling during the
summer and only need heating during the winter. The space hating
energy is the major portion of winter school energy consumption and
the winter energy consumption is major portion of annual school
energy consumption. School building thermal design should focus
on the winter thermal performance for reducing the space heating
energy. A number of Auckland schools- design data and energy
consumption data are used for this study. This pilot study
investigates the relationships between their energy consumption data
and school building design data to improve future school design for
energy efficiency.
Abstract: Combustion, emission and performance
characterization of a single cylinder diesel engine using methanol
diesel blends was carried out. The blends were 5% (v/v) methanol in
diesel (MD05) and 10% (v/v) methanol in diesel (MD10). The
problem of solubility of methanol and diesel was addressed by an
agitator placed inside the fuel tank to prevent phase separation. The
results indicated that total combustion duration was reduced by15.8%
for MD05 and 31.27% for MD10compared to the baseline data.
Ignition delay was increased with increasing methanol volume
fraction in the test fuel. Total cyclic heat release was reduced by
1.5% for MD05 and 6.7% for MD10 as compared to diesel baseline.
Emissions of carbon monoxide, hydrocarbons along with smoke were
reduced and that of nitrogen oxides were increased with rising
methanol contents in the test fuel. Full load brake thermal efficiency
was marginally reduced with increased methanol composition in the
blend.
Abstract: Municipal solid waste (MSW) comprises of a wide
range of heterogeneous materials generated by individual, household
or organization and may include food waste, garden wastes, papers,
textiles, rubbers, plastics, glass, ceramics, metals, wood wastes,
construction wastes but it is not limited to the above mentioned
fractions. The most common Municipal Solid Waste pretreatment
method in use is thermal pretreatment (incineration) and Mechanical
Biological pretreatment. This paper presents an overview of these
two pretreatment methods describing their benefits and laboratory
scale reactors that simulate landfill conditions were constructed in
order to compare emissions in terms of biogas production and
leachate contamination between untreated Municipal Solid Waste and
Mechanical Biological Pretreated waste. The findings of this study
showed that Mechanical Biological pretreatment of waste reduces the
emission level of waste and the benefit over the landfilling of
untreated waste is significant.
Abstract: Arc welding is an important joining process widely used in many industrial applications including production of automobile, ships structures and metal tanks. In welding process, the moving electrode causes highly non-uniform temperature distribution that leads to residual stresses and different deviations, especially buckling distortions in thin plates. In order to control the deviations and increase the quality of welded plates, a fixture can be used as a practical and low cost method with high efficiency. In this study, a coupled thermo-mechanical finite element model is coded in the software ANSYS to simulate the behavior of thin plates located by a 3-2-1 positioning system during the welding process. Computational results are compared with recent similar works to validate the finite element models. The agreement between the result of proposed model and other reported data proves that finite element modeling can accurately predict the behavior of welded thin plates.
Abstract: A novel physico-chemical route to produce few layer graphene nanoribbons with atomically smooth edges is reported, via acid treatment (H2SO4:HNO3) followed by characteristic thermal shock processes involving extremely cold substances. Samples were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy. This method demonstrates the importance of having the nanotubes open ended for an efficient uniform unzipping along the nanotube axis. The average dimensions of these nanoribbons are approximately ca. 210 nm wide and consist of few layers, as observed by transmission electron microscopy. The produced nanoribbons exhibit different chiralities, as observed by high resolution transmission electron microscopy. This method is able to provide graphene nanoribbons with atomically smooth edges which could be used in various applications including sensors, gas adsorption materials, composite fillers, among others.
Abstract: Studying literature theme in the fields of tourism and
sustainable development and its importance in today world and their
criteria in architecture, here in this article we will also study the area
where the selected site is located; beside the Aab-Ask Village located
in Larijan region in Mazandaran province on the way to Haraz – one
of the tourism routes of Iran. After these studies by analyzing the
site, its strong potentials – such as mineral water springs (hot
springs), geothermal, landscapes and ideal climate - as a tourist
attraction spot in the region, and considering sustainable
development criteria – with regard to limits and available facilities –
a plan was offered that could change the region to provide the needs
of local people and in addition change it to a place where tourism
services is offered to the visitors and make it an acceptable sample of
stable building in Iran. Finally the reason to make design for this
complex is recovery of natural and historical values of Aab-Ask area
regarding development and sustainable architecture criteria in the
form of a functional sample which can be a suitable place to fulfill
this goal for having lots of strong points in attracting cultural and
sustainable tourist.