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Showing 7 results for Pakdel
Feasibility study and design of hydraulic hybrid powertrain system for a refuse truck

Volume 14, Issue 15 (Third Special Issue 2015)
Abstract
The aim of this study is to feasibility study and design of hydraulic hybrid power train system for refuse truck in order to regenerate and store kinetic energy and reuse it for supplying propulsion power of vehicle. The hydraulic hybrid propulsion system includes a conventional internal combustion engine, a hydraulic pump/motor and also the accumulators as the energy storage device. Here, the parallel configuration has been chosen for implementing this powertrain. At first part of the paper, regarding the unique driving trends of refuse trucks, a driving cycle for refuse truck in Tehran has been extracted to improve the reliability of the designed powertrain. Also, AXOR 1828, one of the trucks used as the refuse vehicles in Tehran, has been chosen as the based vehicle. The driving cycle is extracted by performing observations on the based vehicle operation during several days. In the second part of the paper, the components of hydraulic hybrid powertrain have been designed to recuperate as much kinetic energy as possible in the refuse truck driving cycle. The initial computations show 17 percent reduction in fuel consumption of the refuse truck.
Accuracy of Real-time Ultrasonography in Assessing Carcass Traits in Torki-Ghashghaii Sheep

Volume 16, Issue 4 (7-2014)
Abstract
The possibility of in vivo carcass trait prediction using the ultrasound measurements obtained between 12th and 13th ribs was studied. Attention was paid to several carcass traits such as carcass backfat thickness (CBFT), carcass longissimus dorsi muscle (CLMA) and carcass weight (HCW). Also, the effects of the flock, as the fixed effects, and body weight (BW), as covariate, on these traits were considered. The study was carried out on 99 lamb of Torki-Ghashghaii breed from 4 flocks. BW had significant effects (P< 0.001) on HCW, Fat-tail, CBFT, and CLMA, but had no significant effect on carcass longissimus dorsi muscle depth (CLMD) and width (CLMW). The flock had a significant effect (P< 0.0001) on HCW and CBFT, only. The correlations between ultrasound and carcass measurements, before and after adjustment for flock effect, ranged between (0.27 to 0.80) and (0.22 to 0.78), respectively. Estimates of CBFT, CLMW, CLMD and CLMA based on the corresponding ultrasound measurements explained 49%, 29%, 59%, and 64% of their variation, respectively. BW explained 57% variation of HCW and only 12% variation of Fat-tail. The introduction of two or three ultrasound measurements by stepwise procedure in the multiple regression equations improved the explanation of variation for all traits by 0.01 up to 0.13. The results indicate that ultrasound has potential for carcass traits prediction in live Torki-Ghashghaii sheep.
Application of Fe3O4/Silica hybrid nanofluid as working fluid of direct absorption solar collector

Volume 18, Issue 2 (4-2018)
Abstract
In this study, the performance of direct absorption solar collector is experimentally investigated using Fe3O4/Silica hybrid nanofluid based on deionized water. First, stability of prepared nanofluids is considered using spectral absorbency method. Then, spectrophotometry method is used for measuring optical properties of nanofluids. A prototype of this new type of collector was built with applicability for solar water heating systems. The procedure of EN 12975-2 standard was used for testing the thermal performance of the collector. Results show that collector efficiency is enhanced by nanofluid concentration, so that collector maximum efficiency is 73.9%, 79.8% and 83.7%using nanofluid with concentration of 500 ppm, 1000 ppm and 2000 ppm, respec/tively. This vaule is 63% using the base fluid as working fluid. Regarding very low volume fractions of nanofluids used in direct absorption solar collectors, the viscosity of the base fluid experience insignificant increase, therefore, pumping power will not increase significsantly. Such increase in efficiency show that direct absorption solar collector performance using hybrid nanofluid is much better than that of using the water at the same operating conditions. Application of stable hybrid nanofluid results in higher conversion efficiency of solar energy to useful energy.
Numerical simulation of the effect of waves on the vortex formed in the vertical intake

Volume 19, Issue 5 (12-2019)
Abstract
The formation of a vortex at the mouth of power plant intake is one of the unfavorable hydraulic phenomena that occur during dewatering of dams. More precisely, the formation of vortex flows in the openings of the intake disturbs the proper functioning of the intake structure. vortices cause problems such as oscillating in the system, reducing turbine output, increasing hydraulic losses in the intake openings, entering the air and particles into the intake pipe and eventually reducing its efficiency. In recent years, various scholars have conducted extensive studies on the phenomenon of vortex. In the meantime, research has been carried out experimentally using mechanical devices and less attention has been paid to the natural phenomena existing on the level of reservoirs of dams and their impact on the vortex. One of the most important natural phenomena that occurs in the reservoir of dams is the waves that can affect the vortex. In this research, with the aim of investigating the effect of waves on the vortex, numerical simulation of waves in the openings of vertical intake has been studied in various vortex formation conditions. In this regard, three class of vortices A, B and C were simulated in numerical model and the results were investigated after dealing with waves. To simulate the flow in the vertical intake, the model designed by Sun and Liu was used. This model is designed in a cylindrical shape with four rectangular inlets, with a vertical intake located at the center and end of the cylinder. In the present study, the model was studied in three-dimensional and two-phase mode, so that numerical simulation of vortex and wave can be investigated with this approach. In order to reduce the computational time to solve the equations, Euler's method was chosen and the turbulence was simulated using the LES model in STAR-CCM Software. After sensitivity analysis, 3 mm grid dimensions were selected. For computational mesh domain, a Cartesian coordinate was used and the free surface was considered using the VOF method. Accordingly, after formation of three classes of vortices A, B and C in the numerical model, three waves with a/d ratio of 2.6%, 1.3% and 0.3% were generated and the effect of their collisions on vortices was analyzed. The amplitudes of the waves are determined in relative proportions of the reservoir water's height and are not far from reality. The results showed that the waves reduced the components of tangential, radial and axial velocity. According to the results, the maximum component of the tangential velocity at the time of the presence of waves is reduced by about 14%, 19% and 23%, respectively, in the class A, B, and C vortices. The radial velocity component is also reduced by about 9%, 13% and 18% for the A, B, and C vortices, respectively. The maximum axial velocity was also reduced to 26%, 13%, and 23% for class A, B, and C vortices, respectively. According to the simulation results, the decrease rate with decrease decreasing wave amplitude, which means that smaller waves can lower the velocity components and thus weaken the vortex flow.
Investigation of effect bracing in the performance and progressive collapse of steel tall building including long-span entrance and removed column under lateral loading

Volume 21, Issue 3 (5-2021)
Abstract 
One of the most important points of interest for designers in the construction of the tall building is to create a large entrance to the lower floors of the building. The need for such large openings is mainly due to architectural issues such as high traffic congestion, aesthetics, and parking. Creating these large openings, if accompanied by the removal of a column, connects the issue with other structural issues such as the effect of the Construction sequence, progressive collapse, loads during execution, and the presence or absence of auxiliary supports (temporary piles) and making the problem more complex. In this study, 36 regular structures of 10, 20, and 30 floors with a height of 40 to 120 meters were considered with the Moment resistance frame system in the ETABS software. The Iranian National Building Code part 6 has been used for load gravity of structures and the Iranian standard No. 2800 has been used for calculation and loading of earthquake lateral loads. After spectral dynamic analysis and Pushover analysis of the mentioned structures, their behavior was examined from the structural point of view and the effect of using bracing in one to four upper floors of the removed column. In the studied structures, the changes in the process of plastic hinges formation, structural performance level, Demand- Capacity ratio (DCR) of structural elements, period of the first mode, and drift in case of exterior (non-corner) column removal were evaluated. The effect of elimination on the exterior column to create a large entrance to the building on the probability of progressive collapse of the 10-story steel structure was also studied. The results showed that the use of braces to strengthen the large span beam is a convenient and economical solution. In particular, the V braces show better performance compared to the Chevron brace, if the number of braced floors above the desired span is before the inflection point of the building. Because when the braces enter the area adjacent to the inflection point of the building, due to the low ductility in the pressure, with failure in the pressure, they reduce the level of performance of the building. The first plastic hinge at any performance level starts from the inflection point and as a result, the use of low ductility elements in these areas reduces the ductility of the structure. Structures with V brace in most cases have smaller elements than structures with Chevron braces and are more economical.  Structures that are reinforced only by increasing the dimensions of the beam and column sections and without adding bracing have more strength than structures with bracing. However, in this case, the dimensions of a large number of sections compared to the braced structures in some cases increase several times, and therefore this increase in strength will be accompanied by a large increase in cost. The results of pushover analysis and performance-based design showed that if the structure is designed from the beginning according to the common code design, assuming the absence of columns, the structure does not experience a reduction in performance and is generally better than to use braces with higher ductility.

Stabilization and optimization of doogh powder using some hydrocolloids: Production and characterization

Volume 23, Issue 5 (9-2021)
Abstract

Doogh, a favorite acidic dairy drink, usually sufferd from low stability and swelling due to microbial activation, protein aggregation and consequently phase separation which happens at low pH. In this study optimization of doogh powder production stabilized by pectin and tragacanth was performed using response surface methodology for selection of appropriate hydrocolloid and processing condition. The results showed that the quality of doogh powder strongly depends upon the spray drying temperature and type of hydrocolloid addition. Optimum operating conditions were found to be an inlet air temperature of 122 ºC and stabilization using tragacanth, under which moisture content, bulk density, solubility, Carr index, serum separation, color (L factor), pH, Hausner ratio, and porosity were 5%, 0.31%, 88%, 37, 65%, 89, 4.33, 1.59% and 73.5%, respectively.  Evaluation of sensory attributes (color, odor, flavor, consistency, and total acceptance) confirmed that there was no significant difference (p>0.05) between dried doogh powder produced in optimized conditions and freshly prepared sample.


Investigating the Concept of Paradise in Iranian Mythology and Rituals

Volume 29, Issue 2 (6-2022)
Abstract
“Paradise” is one of the concepts common between myths and religions. This paper uses an analytical-descriptive method to study the concept of Paradise, the origin of which is different in religions, and there is existence of commonalities of this aspect. The existing similarities and shared view of the Paradise indicate the conceptual commonality of this word in rituals. The religion of Islam uses the Paradise in the form of the word “Ferdows” and considers it as a reward for the pious and righteous. In other religions, too, the high-frequency of Paradise in religious books suggests a broader concept of it. In other words, its purpose is to be close to God and the Creator of the universe to achieve immortality. Mythical man, by imitating the gods who are immortal, wants to join eternity and open the wings to the infinite world and immortality from destruction in the immortal universe. He has tried to build a utopia on Earth and his image of the Paradise that bears a complete resemblance to the worldly Paradise. The Paradise-like cities imitated from the heavenly ones and built on Earth were analyzed in this paper. Examples of the mythical heroes of Shahnameh who tried to build Paradise on the Earth were mentioned.
 
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