Search results for: Hossein Molavi Vardanjani

Authors: Hossein Arfaeinia, Azam Nadali, Zahra Asadgol, Mohammad Fahiminia

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Indoor and outdoor particulate matters (PM) were monitored in 20 residential buildings in a two-part study. In part I, the levels of indoor and outdoor PM₁₀, PM₂.₅ and PM₁ was measured using real time GRIMM dust monitors. In part II, the effect of negative air ions (NAIs) method was investigated on the reduction of indoor concentration of PM in these residential buildings. Hourly average concentration and standard deviation (SD) of PM₁₀ in indoor and outdoor at residential buildings were 90.1 ± 33.5 and 63.5 ± 27.4 µg/ m3, respectively. Indoor and outdoor concentrations of PM₂.₅ in residential buildings were 49.5 ± 18.2 and 39.4± 18.1 µg/ m3 and for PM₁ the concentrations were 6.5 ± 10.1and 4.3 ± 7.7 µg/ m3, respectively. Indoor/outdoor (I/O) ratios and concentrations of all size fractions of PM were strongly correlated with wind speed and temperature whereas a good relationship was not observed between humidity and I/O ratios of PM. We estimated that nearly 71.47 % of PM₁₀, 79.86 % of PM₂.₅ and of 61.25 % of PM₁ in indoor of residential buildings can be removed by negative air ions.

Keywords: particle matter (PM), indoor air, negative air ions (NAIs), residential building

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Authors: Hossein Mostafavi

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A diversity of biological activities and pharmaceutical uses have been attributed to gallic acid derivatives such as antibacterial, anticancer, anti inflammatory. A series of gallic acid derivatives were synthesized, and their structure was confirmed by FT-IR, HNMR, CNMR, elemental analysis. In vitro biological activity of compounds was determined against Proteus vulgaris ATCC 7829, Escherichia coli ATCC 25922, as (Gram-negative) bacteria and bacillus cereus ATCC 11778, Staphylococus aureus ATCC 6538 as (Gram-positive) bacteria. Antibacterial susceptibility tests were done by use of the paper disc diffusion method on Mueller Hinton agar (Merck). Chloramiphenicol, Penicilline, Streptomycin and Tetracycline were standard reference antibiotics. The zone of inhibition against bacteria was measured after 24 hours at 37 °C. Compounds 3, 4, 5 were the main antibacterial compounds against Gram-negative bacteria but not Gram-positive.

Keywords: gallic acid derivatives, antibacterial, antibiotics, inhibition

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Authors: Sajjad Rostami-Sani, Mojtaba Valinataj, Amir-Hossein Khojir-Angasi

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The cache has an important role in the reduction of access delay between a processor and memory in high-performance embedded systems. In these systems, the energy consumption is one of the most important concerns, and it will become more important with smaller processor feature sizes and higher frequencies. Meanwhile, the cache system dissipates a significant portion of energy compared to the other components of a processor. There are some elements that can affect the energy consumption of the cache such as replacement policy and degree of associativity. Due to these points, it can be inferred that selecting an appropriate configuration for the cache is a crucial part of designing a system. In this paper, we investigate the effect of different cache replacement policies on both cache’s performance and energy consumption. Furthermore, the impact of different Instruction Set Architectures (ISAs) on cache’s performance and energy consumption has been investigated.

Keywords: energy consumption, replacement policy, instruction set architecture, multicore processor

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Authors: Kasra HosseinMostofi, Mohamadamin Oyar Hossein, Reza Mehdizadeh Anvigh

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BIM is an innovative concept for the majority of firms operating in industry. BIM offers a new paradigm to design, construct, operate, and maintain a facility. However, even with the most conscientious use, stakeholders can run into trouble during its implementation on a project or within an organization. At times, project stakeholders are unaware of the challenges that they can face with the implementation at the project level or an organizational level. Therefore, the study aimed to identify and compile barriers associated with the BIM implementation at the project and organizational level, as per the literature. Despite the fact that innumerable advantageous involved in exploiting BIM, there are some barriers to implement it properly. These barriers have been proved as impediments for academicians and members of construction team project to take the maximum advantage of its utilization. Although some research has been conducted to identify these barriers regarding BIM implementation in construction industry, more research is needed to be carried out among academicians to identify these barriers in institutions, and most importantly, to make suggestions for eliminating these obstacles.

Keywords: building information modelling, construction, design and construction, designers

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Authors: Karim Hamidi Machekposhti, Hossein Sedghi

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This study was designed to find the best-fit probability distribution of annual rainfall based on 50 years sample (1966-2015) in the Karkheh river basin at Iran using six probability distributions: Normal, 2-Parameter Log Normal, 3-Parameter Log Normal, Pearson Type 3, Log Pearson Type 3 and Gumbel distribution. The best fit probability distribution was selected using Stormwater Management and Design Aid (SMADA) software and based on the Residual Sum of Squares (R.S.S) between observed and estimated values Based on the R.S.S values of fit tests, the Log Pearson Type 3 and then Pearson Type 3 distributions were found to be the best-fit probability distribution at the Jelogir Majin and Pole Zal rainfall gauging station. The annual values of expected rainfall were calculated using the best fit probability distributions and can be used by hydrologists and design engineers in future research at studied region and other region in the world.

Keywords: Log Pearson Type 3, SMADA, rainfall, Karkheh River

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Authors: Seyed Abolhasan Naeini, Mohammad Hossein Zade

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This article is an attempt to present a numerically study of the behaviour of an eccentrically loaded circular footing resting on sand to determine ‎its ultimate bearing capacity. A surface circular footing of diameter 12 cm (D) was used as ‎shallow foundation. For this purpose, three dimensional models consist of foundation, and medium sandy soil was modelled by ABAQUS software. Bearing capacity of footing was evaluated and the ‎effects of the load eccentricity on bearing capacity, its settlement, and modulus of subgrade reaction were studied. Three different values of load eccentricity with equal space from inside the core on the core boundary and outside the core boundary, which were respectively e=0.75, 1.5, and 2.25 cm, were considered. The results show that by increasing the load eccentricity, the ultimate load and the ‎modulus of subgrade reaction decreased.

Keywords: circular foundation, sand, eccentric loading, modulus of subgrade reaction

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Authors: Amirreza Kosari, Hossein Maghsoudi, Malahat Givar

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In this study, the three-dimensional optimal path planning of a flying robot for Terrain Following / Terrain Avoidance (TF/TA) purposes using Direct Collocation has been investigated. To this purpose, firstly, the appropriate equations of motion representing the flying robot translational movement have been described. The three-dimensional optimal path planning of the flying vehicle in terrain following/terrain avoidance maneuver is formulated as an optimal control problem. The terrain profile, as the main allowable height constraint has been modeled using Fractal Generation Method. The resulting optimal control problem is discretized by applying Direct Collocation numerical technique, and then transformed into a Nonlinear Programming Problem (NLP). The efficacy of the proposed method is demonstrated by extensive simulations, and in particular, it is verified that this approach could produce a solution satisfying almost all performance and environmental constraints encountering a low-level flying maneuver

Keywords: path planning, terrain following, optimal control, nonlinear programming

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Authors: Shahin Mirshekari, Mohammadreza Moradi, Hossein Jafari, Mehdi Jafari, Mohammad Ensaf

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This research employs Gaussian Process Regression (GPR) with an ensemble kernel, integrating Exponential Squared, Revised Matern, and Rational Quadratic kernels to analyze pharmaceutical sales data. Bayesian optimization was used to identify optimal kernel weights: 0.76 for Exponential Squared, 0.21 for Revised Matern, and 0.13 for Rational Quadratic. The ensemble kernel demonstrated superior performance in predictive accuracy, achieving an R² score near 1.0, and significantly lower values in MSE, MAE, and RMSE. These findings highlight the efficacy of ensemble kernels in GPR for predictive analytics in complex pharmaceutical sales datasets.

Keywords: Gaussian process regression, ensemble kernels, bayesian optimization, pharmaceutical sales analysis, time series forecasting, data analysis

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Authors: Samaneh Rahimirshnani, Hossein Jafari

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In this paper, we consider fluid queueing processes fed by an isonormal Gaussian process. We study the correlation structure of the queueing process and the rate of convergence of the running supremum in the queueing process. The Malliavin calculus techniques are applied to obtain relations that show the workload process inherits the dependence properties of the input process. As examples, we consider two isonormal Gaussian processes, the sub-fractional Brownian motion (SFBM) and the fractional Brownian motion (FBM). For these examples, we obtain upper bounds for the covariance function of the queueing process and its rate of convergence to zero. We also discover that the rate of convergence of the queueing process is related to the structure of the covariance function of the input process.

Keywords: queue length process, Malliavin calculus, covariance function, fractional Brownian motion, sub-fractional Brownian motion

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Authors: Majid Mokhtari, Masoud Bahrami Alamdarlo, Babak Nazari, Hossein Zakerinya, Mehdi Salehi

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In this study, microstructure, macro, and microhardness of phases for three grades of cast iron rolls with modified chemical composition using a light microscope (OM) and electron microscopy (SEM) were investigated. The grades were chosen from Chodan Sazan Manufacturing Co. (CSROLL) productions for finishing stands of hot strip mills. The percentage of residual austenite was determined with a ferrite scope magnetic device. Thermal susceptibility testing was also measured. The results show the best oxidation resistance at high temperatures is graphitic high chromium white cast iron alloy. In order to evaluate the final properties of these grades in rolling lines, the results of the Pin on Disk abrasion test showed the superiority of the abrasive behavior of the white chromium graphite cast iron alloy grade sample at the same hardness compared to conventional alloy grades and the enhanced grades.

Keywords: hot roller, wear, behavior, microstructure

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Authors: Mohammadhadi Mirmohammadi, Reza Safian, Hossein Haddad

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This paper presents an innovative solution for complex multi-objective optimization problem which is a part of efforts toward maximizing rolling mill throughput and minimizing processing costs in tandem cold rolling. This computational intelligence based optimization has been applied to the rolling schedules of tandem cold rolling mill. This method involves the combination of two derivative-free optimization procedures in the form of nested loops. The first optimization loop is based on Improving Hit and Run method which focus on balance of power, force and reduction distribution in rolling schedules. The second loop is a real-coded genetic algorithm based optimization procedure which optimizes energy consumption and productivity. An experimental result of application to five stand tandem cold rolling mill is presented.

Keywords: derivative-free optimization, Improving Hit and Run method, real-coded genetic algorithm, rolling schedules of tandem cold rolling mill

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Authors: Khaled Abou-El-Hossein

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The presentation will address the features of two IR convex lenses that have been manufactured using an ultra-high precision machining centre based on single-point diamond turning. The lenses are made from silicon and germanium with a radius of curvature of 500 mm. Because of the brittle nature of silicon and germanium, machining parameters were selected in such a way that ductile regime was achieved. The cutting speed was 800 rpm while the feed rate and depth cut were 20 mm/min and 20 um, respectively. Although both materials comprise a mono-crystalline microstructure and are quite similar in terms of optical properties, machining of silicon was accompanied with more difficulties in terms of form accuracy compared to germanium machining. The P-V error of the silicon profile was 0.222 um while it was only 0.055 um for the germanium lens. This could be attributed to the accelerated wear that takes place on the tool edge when turning mono-crystalline silicon. Currently, we are using other ranges of the machining parameters in order to determine their optimal range that could yield satisfactory performance in terms of form accuracy when fabricating silicon lenses.

Keywords: diamond turning, optical surfaces, precision machining, surface roughness

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Authors: Negin Parsamanesh, Saman Ameri-Mahabadi, Ali Nikfar, Mojdeh Mansouri, Hossein Chiti, Gita Fatemi Abhari

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Duchenne muscular dystrophy (DMD) is a severe progressive X-linked neuromuscular illness that affects movement through mutations in dystrophin gene. The mutation leads to insufficient, lack of or dysfunction of dystrophin. The cause of DMD was determined in an Iranian family. Exome sequencing was carried out along with a complete physical examination of the family. In silico methods were applied to find the alteration in the protein structure. The homozygous variant in DMD gene (NM-004006.2) was defined as c.2732-2733delTT (p.Phe911CysfsX8) in exon 21. In addition, phylogenetic conservation study of the human dystrophin protein sequence revealed that phenylalanine 911 is one of the evolutionarily conserved amino acids. In conclusion, our study indicated a new deletion in the DMD gene in the affected family. This deletion with an X-linked inheritance pattern is new in Iran. These findings could facilitate genetic counseling for this family and other patients in the future.

Keywords: duchenne muscular dystrophy, whole exome sequencing, iran, metabolic syndrome

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Authors: Hossein Kabir, Mojtaba Sadeghi

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Nowadays, high-strength concrete is an integral element of a variety of high-rise buildings. On the other hand, finding a suitable aggregate size distribution is a great concern; hence, the concrete mix proportion is presented that has no coarse aggregate, which still withstands enough desirable strength. Nano Reactive Silica sand powder concrete (NRSSPC) is a type of concrete with no coarse material in its own composition. In this concrete, the only aggregate found in the mix design is silica sand powder with a size less than 150 mm that is infinitesimally small regarding the normal concrete. The research aim is to find the compressive strength of this particular concrete under the applied different conditions of curing and consolidation to compare the approaches. In this study, the young concrete specimens were compacted with a pressing or vibrating process. It is worthwhile to mention that in order to show the influence of temperature in the curing process, the concrete specimen was cured either in 20 ⁰C lime water or autoclaved in 90 ⁰C oven.

Keywords: reactive silica sand powder concrete (RSSPC), consolidation, compressive strength, normal curing, thermal accelerated curing

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Authors: Ava Salmanpour, Hanieh Saeedi, Payam Rouhi, Elahe Hamzeil, Shima Alimohammadi, Siamak Hossein Khalaj, Mohammad Asadian

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Software-defined network (SDN) is a network architecture designed to control network using software application in a central manner. This ability enables remote control of the whole network regardless of the network technology. In fact, in this architecture network intelligence is separated from physical infrastructure, it means that required network components can be implemented virtually using software applications. Today, power networks are characterized by a high range of complexity with a large number of intelligent devices, processing both huge amounts of data and important information. Therefore, reliable and secure communication networks are required. SDNs are the best choice to meet this issue. In this paper, SDN networks capabilities and characteristics will be reviewed and different basic controllers will be compared. The importance of using SDNs to escalate efficiency and reliability in utility power networks is going to be discussed and the comparison between the SDN-based power networks and traditional networks will be explained.

Keywords: software-defined network, SDNs, utility network, open flow, communication, gas and electricity, controller

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Authors: Yasaman Tohidi, Shidvash Vakilipour, Saeed Ebadi Tavallaee, Shahin Vakilipoor Takaloo, Hossein Amiri

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The numerical modeling is performed to study the effects of N₂ addition to the fuel stream on the flame structure and temperature distribution of methane-air swirl diffusion flames with different swirl intensities. The Open source Field Operation and Manipulation (OpenFOAM) has been utilized as the computational tool. Flamelet approach along with modified k-ε model is employed to model the flame characteristics.  The results indicate that the presence of N₂ in the fuel stream leads to the flame temperature reduction. By increasing of swirl intensity, the flame structure changes significantly. The flame has a conical shape in low swirl intensity; however, it has an hour glass-shape with a shorter length in high swirl intensity. The effects of N₂ dilution decrease the flame length in all swirl intensities; however, the rate of reduction is more noticeable in low swirl intensity.

Keywords: swirl diffusion flame, N2 dilution, OpenFOAM, swirl intensity

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Authors: Fatemeh Alsadat Miri, Morteza Ehsani, Hossein Ali Khonakdar, Behjat Kavyani

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This paper studies the effect of nano glass flakes on morphology, dynamic-mechanical properties, and crystallization behavior of poly (ethylene terephthalate) (PET). The concentration of nano glass flakes was varied from 0.5, 1, 2, and 3% wt of the total formulation. Scanning electron microscopy (SEM) micrographs showed the poor distribution of nano-glass flake particles in PET, as well as low adhesion of particles to the polymer matrix. According to differential scanning calorimetry (DSC), the crystallization rate and crystallization temperature of PET were increased by the addition of nano glass flakes. The crystallization rate of PET was increased from 31.41% to 34.25% by the incorporation of 1%wt of nano glass flakes. Based on the results of the dynamic-mechanical analysis, the storage modulus of PET gets increased by adding nano glass flakes, especially below glass transition temperature (Tg). The glass transition of PET did not change remarkably with the addition of nano glass flakes. Moreover, the use of nano glass flakes reduced the impact strength of PET.

Keywords: PET, nano glass flakes, morphology, crystallization

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Authors: A. Hossein Madadi-Najafabadi, Masoud Nasiri

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The discrete element method is a powerful technique for numerical modeling the flow of granular materials such as direct reduced iron. It would enable us to study processes and equipment related to the production and handling of the material. However, the characteristics and properties of the granules have to be adjusted precisely to achieve reliable results in a DEM simulation. The main properties for DEM simulation are size distribution, density, Young's modulus, Poisson's ratio and the contact coefficients of restitution, rolling friction and sliding friction. In the present paper, the mentioned properties are determined for DEM simulation of DRI pellets. A reliable DEM simulation would contribute to optimizing the handling system of DRIs in an iron-making plant. Among the mentioned properties, Young's modulus is the most important parameter, which is usually hard to get for particulate solids. Here, an especial method is utilized to precisely determine this parameter for DRI.

Keywords: discrete element method, direct reduced iron, simulation parameters, granular material

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Authors: Hossein Kheirollahi, Yunhua Luo

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Studying stress and strain trends in the femur and recognizing femur failure mechanism is very important for preventing hip fracture in the elderly. The aim of this study was to identify high stress and strain regions in the femur during normal walking and falling to find the mechanical behavior and failure mechanism of the femur. We developed a finite element model of the femur from the subject’s quantitative computed tomography (QCT) image and used it to identify potentially high stress and strain regions during the single-leg stance and the sideways fall. It was found that fracture may initiate from the superior region of femoral neck and propagate to the inferior region during a high impact force such as sideways fall. The results of this study showed that the femur bone is more sensitive to strain than stress which indicates the effect of strain, in addition to effect of stress, should be considered for failure analysis.

Keywords: finite element analysis, hip fracture, strain, stress

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Authors: Negin Binesh, Mohammad Hossein Niksokhan, Amin Sarang

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Best Management Practices (BMPs) are considered as one of the most important structural adaptive measures to climate change and urban development challenges in recent decades. However, not every location is appropriate for applying BMPs in the watersheds. In this paper, location prioritization of two kinds of BMPs was done: Pourous pavement and Detention pond. West Flood-Diversion (WFD) catchment in northern parts of Tehran, Iran, was considered as the case study. The methodology includes integrating the results of Storm Water Management Model (SWMM) into Fuzzy Analytic Hierarchy Process (FAHP) method using Geographic Information System (GIS). The results indicate that mostly suburban areas of the watershed in northern parts are appropriate for applying detention basin, and downstream high-density urban areas are more suitable for using permeable pavement.

Keywords: adaptive measures, BMPs, location prioritization, urban flooding

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Authors: Samaneh Sadat Fattahi Massoom, Hossein Salimi Bajestani

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The study examines loneliness and depression in students who regularly care for themselves after school (latchkey students) in Mashhad and compares them with parent supervised students using a causal-comparative research method. The 270 participants, aged 7 -13, were selected using convenience and cluster random-assignment sampling. Independent t-test results showed significant differences between loneliness (-4.32, p ≤ 0.05) and depression (-3.02, p ≤0.05) among latchkey and non-latchkey students. Using the Pearson correlation test, significant correlation between depression and loneliness among latchkey students was also discovered (r=0.59, p ≤ 0.05). However, regarding non latchkey students, no significant difference between loneliness and depression was observed (r= 0.02. p ≥ 0.05). Multiple regression results also showed that depression variance can be determined by gender (22%) and loneliness (34%). The findings of this study, specifically the significant difference between latchkey and non-latchkey children regarding feelings of loneliness and depression, carries clear implications for parents. It can be concluded that mothers who spend most of their time working out of the house and devoid their children of their presence in the home may cause some form of mental distress like loneliness and depression. Moreover, gender differences affect the degree of these psychological disorders.

Keywords: loneliness, depression, self-care students, latchkey and non-latchkey students, gender

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Authors: Anahita Yarahmadi, Nazanin Mahboobi, Nahid Sadat Rahmatpour Nori, Mohammad Hossein Bijeh Keshavarzi, Mohammad Javad Shakori

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This research aimed at considering biological fertilizer effect and chemical fertilizer on the quantitative characteristics of Sweet wormwood (Artemisia annua L.), an experiment was carried out in factorial design in completely randomized design with 4 replications in an experimental greenhouse which was located in Tehran. Experimental treatment involved chemical fertilizers (Nitrogen, Phosphorus) in4 levels and biological fertilizers in 4 levels (control, Nitroxin, Bio-phosphorus and Vemricompost). Results showed that using biological fertilizers and increasing different levels of chemical fertilizers (N, P) had significant effects on all the characteristics. Considering means comparison showed that biological fertilizers lead to significant enhancement on all the characteristics and among biological fertilizers, Vermicompost treatment has the most effect. Considering means comparison tables of different levels of chemical fertilizer have been found that (N80P80) had the most increase on characteristics.

Keywords: Artemisia annua L, bio-fertilizer, chemical fertilizer, vermicompost

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Authors: Seyed Hossein Alavi, Farshad Ghazalian, Soghra Jamshidi

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The present study was done with the purpose of considering mental health and general purpose of describing and comparing depression level of athlete and non-athlete male students educational year of 2012 Research method in this study in proportion to the selective title, descriptive method is causative – comparative. Research samples were selected randomly from B.A students of different fields including 500 students. Average mean of research samples was between 20 to 25 years. Data collection tool is questionnaire of depression measurement of Aroun Beck (B.D.I) that analyzes and measures 21 aspects of depression in 6 ranges. Operation related to analysis of statistical data to extraction of results was done by SPSS software. To extraction of research obtained by comparison of depression level mean, show that the hypothesis of the research (H_1) based on the existence of the significance scientific difference was supported and showed that there’s a significance difference between depression level of athlete male students in comparison with depression level of non-athlete male students. Thus, depression level of athlete male students was lower in comparison with depression level of non-athlete male students.

Keywords: depression, athlete students, non-athlete students

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Authors: Marjan Heidarian Dehkordi, Hossein Allahyari, Bruce Parker, Reza Talaee-Hassanlouei

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The Western flower thrips, Frankliniella occidentalis Priesner (Thysanoptera: Thripidae), is a significant pest of many economically important crops. This study evaluated the functional responses, prey-stage preferences and mutual interference of Amblyseius swirskii Anthias-Henriot (Acari: Phytoseiidae) with F. occidentalis as the host under laboratory conditions. The predator species showed no prey stage preference for either prey 1st or 2nd instar. Logistic regression analysis suggested Type II (convex) functional response for the predator species. Consequently, the per capita searching efficiency decreased significantly from 1.2425 to -7.4987 as predator densities increased from 2 to 8. The findings from this study could help select better biological control agents for effective control of F. occidentalis and other pests in vegetable production.

Keywords: biological control, functional responses, mutual interference, prey-stage preferences

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Authors: Mohamed Khallaf, Hossein M Rizeei

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Simulating wind pattern behavior over proposed urban features is critical in the early stage of the conceptual design of both architectural and urban disciplines. However, it is typically not possible for designers to explore the impact of wind flow profiles across new urban developments due to a lack of real data and inaccurate estimation of building parameters. Modeling the details of existing and proposed urban features and testing them against wind flows is the missing part of the conceptual design puzzle where architectural and urban discipline can focus. This research aims to develop a spatial decision-support design method utilizing LiDAR, GIS, and performance-based wind simulation technology to mitigate wind-related hazards on a design by simulating alternative design scenarios at the pedestrian level prior to its implementation in Sydney, Australia. The result of the experiment demonstrates the capability of the proposed framework to improve pedestrian comfort in relation to wind profile.

Keywords: spatial decision-support design, performance-based wind simulation, LiDAR, GIS

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Authors: Shatirah Akib, Hossein Basser, Hojat Karami, Afshin Jahangirzadeh

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Bridge piers which are constructed in the track of high water rivers cause some variations in the flow patterns. This variation mostly is a result of the changes in river sections. Decreasing the river section, bridge piers significantly impress the flow patterns. Once the flow approaches the piers, the stream lines change their order, causing the appearance of different flow patterns around the bridge piers. New flow patterns are created following the geometry and the other technical characteristics of the piers. One of the most significant consequences of this event is the scour generated around the bridge piers which threatens the safety of the structure. In order to determine the properties of scour holes, to find maximum depth of the scour is an important factor. In this manuscript a numerical simulation of the scour around Marand-Soofian route bridge piers has been carried out via SSIIM 2.0 Software and the amount of maximum scour has been achieved subsequently. Eventually the methods for retrofitting of bridge piers against scours and also the methods for decreasing the amount of scour have been offered.

Keywords: scour, bridge pier, numerical simulation, SSIIM 2.0

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Authors: Misagh Irandoost Shahrestani, Hossein Shokouhmand, Mohammad Kalteh, Behrang Hasanpour

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In this paper, nanofluid conjugate heat transfer through a microtube with viscous dissipation effect is investigated numerically. The fluid flow is considered as a laminar regime. A constant heat flux is applied on the microtube outer wall and the two ends of its wall are considered adiabatic. Conjugate heat transfer problem is solved and investigated for this geometry. It is shown that viscous dissipation effect which is induced by shear stresses can not be neglected in microtubes. Viscous heating behaves as an energy source in the fluid and affects the temperature distribution. The effect of Reynolds number, particle volume fraction and the nanoparticles diameter on the energy source are investigated and an attempt on establishing suitable equations for assessing the value of the energy source based on Re, Dp and Φ is performed and they are depicted as 3D diagrams. Finally, the significance of viscous dissipation and the influence of these parameters on convective heat transfer coefficient are studied.

Keywords: convective heat transfer coefficient, heat transfer, microtube, nanofluid, viscous dissipation

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Authors: Hossein Keshtkar, Ali Nasiri Toosi

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With the growing concerns about gasoline environmental pollution and also the need for a more widely available fuel source, natural gas is finding its way to the automotive engines. But before this could happen industrially, simulations of natural gas direct injection need to take place to maximize and optimize power output. KIVA is one of the most powerful tools when it comes to engine simulation. Widely accepted by both researchers and the industry, KIVA an open-source code, offers great in-depth simulation and analyzation. KIVA can compute complex phenomena’s which can occur inside the chamber before, whilst and after ignition. One downside to KIVA, is its in-capability of simulating gaseous injections, making it useful for only liquidized fuel. In this study, we developed a numerical code, to enable the simulation of gaseous injection within the KIVA code. By introducing our code as a subroutine, we modified the original KIVA program. To ensure the correct application of gaseous fuel injection using our modified KIVA code, we simulated two different cases and compared them with their experimental data. We concluded our modified version of KIVA’s simulation results came in very close to those measured experimentally.

Keywords: gaseous injections, KIVA, natural gas direct injection, numerical code, simulation

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Authors: Hossein Mardani, Neil Buchanan, Robert Cahill, Vincent Fusco

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In this paper, we study the input impedance characteristics of axial mode helical antennas to find an effective way for matching it to 50 Ω. The study is done on the important matching parameters such as like wire diameter and helix to the ground plane gap. It is intended that these parameters control the matching without detrimentally affecting the radiation pattern. Using transmission line theory, a simple broadband technique is proposed, which is applicable for perfect matching of antennas with similar design parameters. We provide design curves to help to choose the proper dimensions of the matching section based on the antenna’s unmatched input impedance. Finally, using the proposed technique, a 4-turn axial mode helix is designed at 2.5 GHz center frequency and the measurement results of the manufactured antenna will be included. This parametric study gives a good insight into the input impedance characteristics of axial mode helical antennas and the proposed impedance matching approach provides a simple, useful method for matching these types of antennas.

Keywords: antenna, helix, helical, axial mode, wireless power transfer, impedance matching

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Authors: Sayyed Yaghoub Zolfegharifar, Khairul Anuar Kassim, Hossein Khoramrooz, Khodayar Farhadiasl, Sadegh Jahan

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Iran is one of the world's seismically active countries so that it experiences many small to medium earthquakes annually and a large earthquake every ten years. Due to seism tectonic conditions and special geographical and climatic position, Iran has the potential to create numerous severe earthquakes. Therefore, seismicity studies and seismic zonation of seismic zones of the country are necessary. In this article, the effect of local site conditions on the characteristics of seismic design in Rahmormoz will be examined. After analyzing the seismic hazard for Rahmormoz through deterministic and statistical methods and preparing the necessary geotechnical models based on available data, the ground response will be analyzed for different parts of the city based on four inputs and acceleration level estimated for bedrock through the equivalent linear method and by means of Deep Soil program. Finally, through the analysis of the obtained results, the seismic profiles of the ground surface for different parts of the city will be presented.

Keywords: seismic microzonation, ground response, resonance spectrum, period, site conditions

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