Showing 32 results for Ashkan
Volume 0, Issue 0 (In press 2023)
Abstract
Urban growth boundaries are considered one of the key tools for controlling and managing the physical development of metropolitan areas. Uncontrolled and unplanned expansion in these regions has become a major challenge for urban and regional planners and managers, as this process leads to the destruction of agricultural lands and natural resources. The aim of this research is to simulate and assess future changes in growth boundaries in the Isfahan metropolitan area with the goal of preserving environmental resources and controlling physical expansion. In this regard, by adopting a positivist approach that follows an analytical and measurement-driven process, satellite imagery was utilized to assess changes in the physical expansion of the Isfahan metropolitan area. Artificial neural networks and machine learning algorithms were employed to predict the extent of future physical growth, and the projected growth boundaries were delineated. The research findings indicate that the Isfahan metropolitan area has experienced significant uncontrolled expansion, particularly in terms of physical development, over recent decades, and the reduction of agricultural and natural lands has become one of its major challenges. Based on the conducted simulations, the proposed growth boundaries can serve as an effective tool for managing and planning urban-regional development and preventing further degradation of natural resources and lands.
Volume 4, Issue 1 (6-2015)
Abstract
Oxidative stability of oils, fats and fatty food products can be affected by many factors such as oxygen, light, heat, metal ions and enzymes used and finally it brings about oxidative corruption. This study has been done to survey the role of Dorema aucheri extract in oxidative stability of fish oil (under microwave heating) and comparising that with BHT synthetic antioxidant. Concentrations of 250 and 500 ppm extracts of Dorema auchri and BHT 200 ppm were added to fish oil and a fish oil sample without the addition of antioxidant was considered as control, Then they were sampled after putting in microwave at time periods 0, 3, 6, 9, and 12 minutes. Chemical oxidative indicators (peroxide, free fatty acids and thiobarbituric acid) were surveyed. According to the results, in all times putting in microwave the amount of peroxide, free fatty acids and thiobarbituric acid in the treatments that contained extract, were lower than the control treatment, but were higher than the treatment that contained BHT. A significant difference wasn't seen among the treatment that contained 250 ppm of extract and the treatment that contained BHT (p>0/05). According to the results, because of significant difference of samples contained extract with control sample and the lack of significant difference sample containd 250 ppm extract with BHT, it would be expected that Dorema aucheri extract as antioxidant can be used in food industry in maintenace of fish oil.
Volume 5, Issue 1 (6-2016)
Abstract
Silver nanoparticles (AgNPs) are widely used in consumer products mainly due to their antimicrobial action. The rapid increase in the use of nanoparticles has driven more attention to their possible ecotoxicological effects. In this study: first, acute effects of colloidal AgNPs during embryonic stage of Persian sturgeon and Starry sturgeon were investigated and then in Starry sturgeon, their short-term effects during early life stages (before active feeding commences) were analyzed. Based on the obtained results from the acute toxicity tests, AgNPs induced a dose-dependent toxicity in both species during early life stages. The short-term toxicity test was performed using 0, 0.025, 0.05 and 0.1 mg/l of colloidal AgNPs. Silver accumulation in larvae exposed to 0.1 mg/l AgNPs was recorded significantly higher than the control treatment (P<0.05). However, the obtained survival rate data did not indicate any significant differences among treatments.
Volume 5, Issue 3 (2015 2015)
Abstract
Spatial continuity particularly continuity between inside and outside is a concept that man always was looking forward to express it in architecture. It is a trait for expanding a restricted area and relating the spaces to other adjacent spaces in order to have more physical-visual or intellectual-moral motions. Although the boundaries of spaces create spatial order and specify the quality of space, on the other hand, one another trait of architecture is continuity which leads to dynamism and motion. A continuous space is opposite to a closed and interrupted one, so in such spaces there is a spatial locomotion towards horizontal and vertical axis. These motions cause transparency and mobility towards the bulk of materials such as walls and columns in a way that the paths of moving or the directions of the sight are continuous. In the field of architectural expressions, continuity has several types and in this case, one of the categories can be noticed. This classification include four cases such as Historical, Cultural–social, Natural and Spatial continuity. Any of them has its definition, but in what follows, the spatial continuity will be described in detail. Spatial continuity can be studied in four states: First, the interior and exterior; in this case, besides the continuity makes perspective expansion, it inspires the concept of «being inside». The user requires both inside and outside spaces, and also the ability to move between these two spaces. Therefore, the architect should visualize and form inside and outside as a unit concept. Second case, between two interior spaces; flexible interior space, diversity and maximize capacity of space can be achieved in this way. Third, in an interior; this kind of continuity is more understood in a large enclosed space such as a church or a mosque. The fourth state, in the space outside the building; in open spaces or urban spaces can be observed. Any interior space may have continuation in six axes. Spatial continuity can be established through some architectural features, these factors include: Transparent layers; the most important factor to create continuity between two spaces. Transparency can be made by embedding the openings, doors and windows. Axis; axis represent the directions and correlate different elements to each other. In other words, axes connect spaces like a string. Although axes can be defined in various ways, two directions are often stronger than the others because the orientation of human kind is based on the horizontal and vertical direction. Rhythm and Repetition; the most important and most tangible factors that can represent spatial continuity are rhythm and repetition. Continuation and repetition are the basis of continuity. Continuation of surfaces; shared elements between the two spaces arouses a sense of continuity to the spectator. Continuity will be well understood when the surfaces of the floor, wall or ceiling of a space stretches to another space. Intermediate space; intermediate space (the third space) is one of the main factors of continuity and sequencing of architectural elements. Although this item separate two spaces, it causes the continuation without any separation between them. In each ancient and modern architecture, new methods can be observed, trying to show spatial continuity. In modern age, progress in technology and release of Classic principals (norms) caused the best type of continuity. Modern architects reduced the confliction of inside and outside and ignored the role of walls as separator elements by eliminating the boundaries of interior space. Modern architecture incorporated inside and outside to let them form one unique continuous space, without any difference between interior and exterior space. Spatial continuity in modern architecture: In modern architecture a continuous space is created by eliminating or neglecting the role of walls (separators). Therefore, there is no difference remains between inside and outside. The boundaries have become smooth, so visual continuity and accordingly, spatial continuity arises. In other words the walls lose their existence and permanency, the conflict of inside and outside is eliminated therefore the meaning of inside is weakened. The same as universal architecture, there are some rules in ancient Iranian architecture to represent spatial continuity, however mentioning the spiritual and moral sides of continuity. Iranian architectural space include three categories from the primitive time: closed, covered and open spaces. These three mainsubspaces define the whole space. Room, as a closed space, porch (Ivan) as a semi closed one and the yard as an open space. Iranian architects always try to track the continuity between these three items in their design process. They have attempted to pass the user through the space unimpeded, promoting the idea of transparency, lightness and spatial continuity, by reducing the bulk of mass and increasing the space. Iranian architectural space can be thought of as a wavy space. Conjunction with unlimited space is created through the light and perspective expansion, and space expansion between the components. Continuity through these spaces were shown spreading natural lights, and the extension of the sceneries and perspectives. Iranian architects tried to reduce the material mass of the building body in order to achieve transparency and spiritual lightness. In this essay we are intending to study the level of effect of traditional Iranian architecture on contemporary Iranian architecture and the level of effect of modern architecture on it, and finally we will make a comparison between them. For this review, a descriptive–analytic observation is set that the criteria of comparison are the factors of spatial continuity of Iranian and modern architecture. For each architectural Style, factors that represent continuity is listed, mentioning that any of these factors can be used in which state, relating the inside and outside. So this will assort results in a set of tables for each Style. A number of public buildings, built during 50 decade till now is selected for analyzing the factors in each group. Four of them will be expounded. At last the results can be observed in a detailed table, along with, a diagram represents the percentage of each factor’s participation in indicating spatial continuity in both Iranian and modern architecture.
Volume 5, Issue 10 (Fall & Winter 2019)
Abstract
One of the greatest difficulties Quran translators have been faced with is rendering those verses in which, at least on the surface, material, anthropomorphic qualities have been attributed to Allah. Given the wealth of theological dimensions of the concepts relating to God, this challenging area, which has always been the center of attention and diverse opinions by philosophers, theologists, and exegetes, can have direct implications for Quran translation. The present study has been aimed at investigating English and Persian translations of those Quranic verses containing the terms “Yad [Hand]” and “Sāq [Shin]” in connection with God so as to find out how they have been dealt with in under the influence of the translators’ dominant theological conceptions. To this end, all the verses containing these words were extracted and then their rendition in 18 English and 12 Persian translations was scrutinized. The results indicated that in 79% of the cases, an anthropomorphic translation has been produced while in the remaining 21%, a non-anthropomorphic translation has been opted for. In addition, an interesting difference found between the English and Persian translations with regard to their preference for (non-)anthropomorphism in the translation of such verses. These findings suggest that the dominant theological conceptions of the translator, as well as those of the receiving community, play a considerable part in the process of decision-making when faced with such challenging parts of the text.
Volume 9, Issue 2 (Spring 2018)
Abstract
Aims: In recent years, magnetotactic bacteria and their magnetic nanoparticles (magnetosomes) were considered in different fields of science, including medicine, biotechnology, and nanobiotechnology due to their novel and unique magnetic properties. The present study was performed with the aim of evaluating the effect of temperature and reducing agent on labeling of magnetosomes with 188Re and biodistribution of labeled magnetic nanoparticles.
Materials and Methods: In this experimental study, Alphaproteobacterium MTB-KTN90 and sonication extraction method were used for the extraction of magnetic nanoparticles. After bacterial lysis, the magnetic nanoparticles produced by electron microscope were investigated and tin (II) chloride, as reducing agent, was used to check the labeling efficiency and rats were used to examine the biodistribution of the labeled magnetosomes.
Findings: The highest efficiency in magnetosome labeling experiments was 11100kBq in the initial activity, which decreased with increasing activity. The increase in temperature did not have much effect on increasing the labeling efficiency. The labeling value in the absence of a reducing agent was 721.5kBq, while at a concentration of 2mg of this agent, the labeling value increased to 10745.91kBq. After the injection of magnetosomes through the sublingual vein of the rat, the magnetosomes accumulated in the liver.
Conclusion: Magnetosomes extracted from Alphaproteobacterium MTB-KTN90 have a high potential for labeling by 188Re. Increasing temperature does not affect the labeling efficiency, but tin (II) chloride is a very important factor in optimizing the labeling efficiency, and the highest accumulation of magnetosomes labeled with 188Re after injection is in the liver of the rat.
Volume 9, Issue 4 (Number 4 - 2007)
Abstract
Eight genotypes of spring safflower (Carthamus tinctorius L.) were evaluated for several physiological traits under stress and non-stress water regimes. Data were analyzed using principal factor analysis. The factor analysis technique extracted six factors under non-stress conditions. Six factors explained about 80% of the total variation, and only 40% of the variance was accounted for by the first two factors. Factors I and II were identified as water consumption, and water balance capacity, respectively. Similarly, seven factors were extracted under stress conditions, and 34% of the total variation was accounted for by the first two factors. Factors I and II were described as water conservation, and water holding capacity, respectively. Important physiological criteria were recognized by Fac-tors I and II in two experiments. Ultimately, initial water content (at stem elongation and grain filling stages), canopy temperature (at stem elongation and flowering stages), and leaf water potential (at flowering stage) under non-stress conditions, and canopy tempera-ture (at all stages), leaf area index (at stem elongation), and rate of water loss from ex-cised leaf (at grain filling) were the best criteria for screening suitable genotypes under the afore mentioned conditions.
Volume 9, Issue 4 (Fall 2023)
Abstract
Aims: This study aimed to investigate persistent symptoms of coronavirus disease 2019 (COVID-19) patients admitted to a general tertiary teaching hospital during a 9-month follow-up period.
Materials & Methods: In this study, 400 hospitalized COVID-19 patients in Iran were studied, among them 78 RT-qPCR positive cases were identified from February 19 to March 18, 2020. After excluding readmitted and deceased patients, 75 cases underwent in-hospital follow-up. Out-of-hospital follow-up was done for 57 living patients, of whom four cases were unreachable, and five cases died after discharge. The remaining 48 participants were followed up for nine months, and their symptoms and complaints were checked by regular visits to the infectious disease clinic and telephone calls via a checklist designed by the authors.
Findings: The mean age of RT-qPCR positive hospitalized patients was 54.64 ± 17.42 years, and 38.7% of them were female. Overall, five (10.4%) patients complained of dyspnea, three (6.2%) patients of olfactory nerve complications, three (6.2%) patients of persistent fatigue, and two (4.2%) patients of prolonged cough up to the end of the follow-up period. New-onset symptoms were reported in five (10.4%) patients; in most of them (4 out of 5), these symptoms were neurological (urinary retention, tremor with ataxia, distraction, and insomnia).
Conclusion: A large proportion of patients who recover from COVID-19 infection experience prolonged symptoms. Further investigations should be done to provid more data on the underlying causes and risk factors of developing these post-COVID conditions.
Volume 10, Issue 3 (9-2021)
Abstract
The aim of this study was to investigate the effect of adding protein concentrate of Bream (Abramis Brama) on chemical properties, texture, color and sensory evaluation of pasta. The fillets were cooked in boiling water for 10 minutes, then minced using a meat grinder. The minced fish was dried at 60 C for 24 hours in an oven and powdered with a grinder. Pasta was prepared with different percentages of FPC (0, 5%, 7.5%, 10%, 15% and 20%). Chemical properties (energy, carbohydrate), tissue tests (hardness, adhesion and resilience), color tests (b, a, L) and sensory evaluation were evaluated. The results showed that by adding fish protein concentrate, the amount of pasta carbohydrate decreased compared to the control sample. In contrast, with increasing fish protein concentrate in pasta, the amount of energy increased significantly (p <0.05). The highest energy content was observed in the pasta containing 20% FPC and the lowest energy content in the control sample. The addition of FPC did not cause any adverse changes in the color of the pasta. The amount of yellow and redness of the pasta increased with the addition of FPC. The amount of pasta patency increased with the addition of fish protein concentrate. The color, taste, chewability, elasticity, odor, filament appearance, adhesion, hardness and overall evaluation of pasta with 7.5% FPC was better than others. Regarding the texture, color and sensory characteristics of the pasta, it can be concluded that the pasta containing 7.5% fish protein concentrate had better characteristics than other samples.
Volume 12, Issue 47 (7-2015)
Abstract
Apple fruit is one of the most worthy garden Product with high nutritional Value and its production in Iran makes more job and Exchange technology. From different apple Non-destructive quality control methods, machine vision technology achieves the more speed, quality, greater productivity and higher valuation for the product. Usually, apple bruise overlaps with Peduncle and in these causes, serious problems of recognition for quality sorting occurs. In this research work it was tried to work out this problem and to increase the sorting systems performance precision. In order to accomplish this, two separate algorithms based on color to identify bruise and pedicle was designed in Matlab. It was achieved 97.14% accuracy for the bruise algorithm and 100% accuracy for the pedicle algorithm. Then with integration of these two algorithms, an algorithm was achieved with 94.29% accuracy. Further experiments to investigate the possibility of increasing the accuracy in detecting bruise with time maintenance was performed by the bruise algorithm. The results indicate that the bruise detection quality by this algorithm gradually increased and after two to three days it reaches the desired consistency. Another algorithm with special properties of bruise and pedicle pictures shape such as roundness value, ratio of area to Perimeter square and also coefficient of variation (cv) of distances of spaced points on the edge from center of gravity of picture was designed. Then bruise and pedicle were distinguished from each other with an accuracy of 100% with this algorithm along with the ANN which it proving the importance of using these techniques, combined with machine vision techniques to increase the accuracy of sorting machines performance.
Volume 13, Issue 0 (kongore 94- 2015)
Abstract
Volume 13, Issue 4 (11-2024)
Abstract
The indirect application of silver nanoparticles (AgNPs) in controlling the common fungal infection during the incubation period of Persian sturgeon -saprolegniasis - was investigated in this research. Filters containing 0.2%, 0.5% and 1% of AgNPs in two states without agent and with aminopropyltriethoxysilane (APTES) coupling agent along with the control treatment (without filter) were the treatments investigated in the present study. The results showed that in the first 48 hours of incubation, which corresponds to embryonic growth before the start of neurulation, despite the start of contaminating the water in the incubators with Saprolegnia fungus, fungal infection was not seen in any of the investigated treatments. The results of measuring the amount of silver released from the studied filters at the end of the first 12 hours of incubation showed that the amounts of silver released in the water in the treatments of 1% AgNP filters without APTES and with APTES were significantly higher than other filters containing AgNPs. This trend was repeated at the next sampling rounds (48 and 96 hours) with the difference that the release rate was significantly higher only in the 1% AgNP-APTES filter treatment. In the treatment of AgNP-APTES filters, the percentage of hatching showed a significant increase compared to the control filter treatment.
Volume 13, Issue 7 (10-2013)
Abstract
In this article, effect of axial angle of injection nozzles on the flow field structure in a Low-Pressure vortex tube has been investigated by computational fluid dynamics (CFD) techniques. Numerical results of compressible and turbulent flows are derived by using the standard k-ε turbulence model. The dimensions of studied vortex tubes are kept the same for all models and the performance of machine is studied under 6 different axial angles (β) of nozzles. Achieving to a minimum cold exit temperature is the main goal of this numerical research. Our investigation shows that utilizing this kind of nozzle changes the energy separation and flow characteristic. Considering total pressure of cold flow, a new parameter, ξ is defined and results shows that changing the amount of ξ can affect the cold exit temperature directly. Finally, some results of the CFD models are validated by the available experimental data which show reasonable agreement.
Volume 13, Issue 13 (First Special Issue 2014)
Abstract
In this study a feed forward back propagation artificial neural network (ANN) model was established to predict Vickers microhardness in aluminum-alumina nanocomposites which have been synthesized by mechanical alloying and hot pressing. Volume percent of reinforcement, size of nanoparticles, force in microhardness test; and mechanical alloying parameters, such as time, ball to powder ratio (BPR) and speed of ball mill were used as the inputs and Vickers microhardness as the output of the model. Effective parameters in training such as learning rate, hidden layers and number of neurons, were determined by trail and error due to amount and percentage of errors. Regression analysis in train, validation and test stages; and mean squared error were used to verify the performance of neural network. Average error of predicted results was 2.67% or 2.25 Vickers. Also mean squared error for validation data was 7.76. As can be expected, ANN methods reduce the expenses of experimental investigations, by predicting the optimum parameters.
Volume 13, Issue 15 (Third Special Issue 2014)
Abstract
Nanostructured (Al-8wt%Zn-3wt%Mg) alloy was synthesized by simultaneous fracture and cold welding mechanisms in mechanical alloying with initial elemental powders and subsequently, this alloy was applied as matrix to fabricate Al/Short glass fiber nanocomposite in 1, 3 and 5 percent of glass fibers. The resulting powders were consolidated under 400 MPa at 380 °C in cylindrical die to produce consolidated nanocomposites. Relative density of samples reduced with increasing the percentage of glass fibers and this trend was more intense from 3 to 5 percent. Also compressive strength and hardness were investigated for these samples in different percent of glass fiber. The results showed that strength and hardness were enhanced with increasing glass fiber but decrease of mechanical properties was observed in 5 percent due to reducing in relative density. Compressive strength was compared between nanocomposite with pure Al and Al alloy matrix, and results show more reinforcement in Al based sample.
Volume 15, Issue 4 (6-2015)
Abstract
One of the most important challenges in the field of structural health monitoring and non-destructive testing is to assess some features of damages in structures, like the shape of damaged region. To reconstruct the shape of damage there are different methods in tomography. Already, researchers have used two general types of shape reconstruction techniques: transform based methods and algebraic reconstruction methods. Both methods suffer from some disadvantages like high sensitivity to incomplete data sets, bulky and expensive scanning hardware or low image resolution. In this work, a novel method to find the shape of damage via polygon reconstruction technique in tomography using the Radon transform is introduced. In this technique, damaged region is approximated by a polygon which the number of its sides is chosen arbitrarily, and the aim is to find this polygon’s vertices. To achieve this goal, an aluminum plate with a triangular hole as the damage was modeled in software. Then beams of guided Lamb wave were propagated toward the damaged region using arrays of piezoelectric transducers in just a few numbers of angles. Finally the polygon’s vertices were determined by processing the reflected signals from the damaged region. The results confirmed the efficiency of the proposed method.
Volume 15, Issue 6 (8-2015)
Abstract
In this article constitutive equations on dynamic behavior of off- axis polymer matrix composites in different strain rates were investigated. Using the Hill Anisotropy and assumptions governing in fiber composites, a model was developed to express the dynamic behavior of polymer matrix composites. Using the flow rules and effective stress and assumptions in fiber composites like non plastic behavior of composites in fiber direction, the Hill parameters were omitted and reduced to one namely a_66 parameter. This model was called2D one- Parameter Plastic Model (also it can be developed for 3D composite layers). This model was developed for off axis composites as well. For each composite with different fiber directions, effective stress- effective strain was introduced. With choosing the right value for parameter a_66 by try and error, all the stress- strain curves were collapsed in to one single curve. Using this model and the experimental static and quasi- static results gathered from different authors (in range of〖 0.01s〗^(-1)), a viscoplastic model was obtained which can predict the polymer composite respond both in static and high strain rate tests (between 400 s^(-1) and 700s^(-1)). Constant parameters in high strain rates in this model were calculated through extrapolating the data in the static test rang. The accuracy of this model was investigated and approved by Split Hopkinson Pressure Bar test. The results showed that the visco plastic model can predict the dynamic respond of composite fibers in high strain rates very well.
Volume 15, Issue 85 (3-2019)
Abstract
Due to increasing the importance of natural antioxidants because of their positive effects on human health and enhancing preservation of food products, and on the other hand, some unexplained effects of synthetic antioxidants, using and replacing of natural antioxidants is considered widely nowadays. The purpose of this study was to identify the potentials of Ferulla Persica extract as a native and novel source of antioxidants and polyphenols. In this research, the optimization of extraction conditions from the leaf of Ferulla Persica was studied by response surface methodology (RSM) at 3 temperature levels (20, 40 and 60 °C), three time levels (2, 3 and 4 hours) and three levels of water to ethanol ratio (50, 75 and 100%). RSM was used to evaluate the effect of different optimization processes on extraction efficiency, antioxidant activity and total phenolic content. Based on the results of optimization, a second-order polynomial model was designed to optimize the extraction conditions as the best model. the optimum conditions of extraction were in the solvent ratio of 79.58% at 20 °C during 2 hours. In these conditions, the optimum point has yield of 17.61%, EC50 equal to 87.20 (μg/ml) and TPC of 140428.0 (mg GAE/g).
Volume 16, Issue 4 (6-2016)
Abstract
In this work steady flow of fluid in shell and coiled tube heat exchangers has been simulated then analyzed. Effect of pitch, coil’s diameter, tube’s diameter, shell’s diameter, coil’s height, shell’s height and Reynolds number on the friction factor of coil side has been investigated using numerical method. Forty cases have been analyzed in numerical work. The working fluid of both sides is water which its viscosity and thermal conductivity were assumed to be dependent on temperature. The standard K-έ model was used for turbulence. Results indicate the diameter of the coil is the most effective geometrical parameter on the friction factor of the coil side so that by remaining other parameters constant, if the coil’s diameter increases 60%, the friction factor will decrease 30.6%. Also by remaining other parameters constant if the tube’s diameter is doubled the friction factor of the coil side will increase 16.5%, if the shell’s diameter is doubled the friction factor of the coil side will increase 11.7% while the effect of other geometrical parameters on the friction factor of the coil side is much less than the effect of coil’s diameter, tube’s diameter and shell’s height. Also a correlation has been proposed for prediction of the friction factor of the coil side that contains the effect of all defined geometrical parameters in addition to Reynolds number. This correlation is applicable for wide range of Reynolds number (2700< Re< 38000) and has been compared with the correlations proposed in previous works.
Volume 16, Issue 11 (1-2017)
Abstract
In this paper, using both linear and nonlinear identification methods based on iterative and recursive least-square, the performance of a backstepping control system of a quadrotor in the presence of uncertainties is improved. At first, the dynamic model of a quadrotor is introduced and descriptive equations are presented in an appropriate state-space in order to design a controller based on backstepping method. Then the backstepping controller is designed using virtual controller for trajectory tracking. In this control system, the control performance is not satisfying because of the physical uncertainties existed in quadrotor. Consequently, an online identification method is introduced and used to improve the performance of the controller. In this regard, some parameters, which are linear in the model structure, are identified by least square error technique and iterative least square method is used for identifying other parameters.The results indicate that the steady-state error is decreased and the ability of tracking of a desired trajectory in the presence of uncertainties is increased. Furthermore, the result demonstrate the stabilization of roll and pitch angles, while, the method prevents the vibration of control forces.