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Showing 31 results for erfani


Volume 6, Issue 4 (Fall 2018)
Abstract

Aims: One of the most commonly used applications in forestry is the identification of single trees and tree species compassions using object-based image analysis (OBIA) and classification of satellite or aerial images. The aims of this study were the valuation of OBIA and decision tree (DT) classification methods in estimating the quantitative characteristics of single oak trees on WorldView-2 and unmanned aerial vehicle (UAV) images.
Materials & Methods: In this experimental study Haft-Barm forest, Shiraz, Iran, was considered as the study area in order to examine the potential of Worldview-2 satellite imagery. The estimation of forest parameters was evaluated by focusing on single tree extraction using OBIA and DT methods of classification with a complex matrix evaluation and area under operating characteristic curve (AUC) method with the help of the 4th UAV phantom bird image in two distinct regions. Data were analyzed by paired t-test, multivariate regression analysis, using SPSS 25, Excel 2016, eCognation v. 8.7, ENVI, 5, PCI Geomatica 16, and Google Earth 7.3 Software.
Findings: The base object classification had the highest and best accuracy in estimating single-tree parameters. Basic object classification method was a very useful method for identifying Oak tree Zagros Mountains forest. With using WV-2 data, the parameters of single trees in the forest can extract.
Conclusion: The accuracy of OBIA is 83%. While UAV has the potential to provide flexible and feasible solutions for forest mapping, some issues related to image quality still need to be addressed in order to improve the classification performance.


Volume 8, Issue 1 (Winter 2020)
Abstract

Aims: Medusahead (Taeniatherum caput-medusae (L.) Nevski) and barbed goatgrass (Aegilops triuncialis L.) are two annual species that drastically affect rangelands worldwide. In the present study, the current distribution range of these species was investigated using ecological niche modelling (ENM), and then their distribution was predicted in 2040 and 2070.
Materials & Methods: In this study, using 19 bioclimatic variables and the recorded presence locations, the current distribution of T. caput-medusae and A. triuncialis was predicted using MaxEnt. Moreover, changes in the distribution ranges of these species in the future (2040 and 2070) were estimated.
Findings: According to the results, the mean temperature of the coldest quarter and Isothermality had the greatest effect on the distribution of A. triuncialis in the present and future. For T. caput-medusae distribution in the present, 2040, and 2070 the mean temperature of the coldest quarter had the highest effect on determining the potential distribution range of this plant. Accordingly, climate change will not affect the distribution range of barbed goatgrass, however, it may facilitate the expansion of medusahead to the upper elevations.
Conclusion: In the present, comparing the two, barbed goatgrass had a higher probability to invade rangelands of Iran. Climate change might facilitate the invasion of medusahead to upper elevations. Grazing exclusion is advised to control the range expansion of these two species where they are present.



Volume 10, Issue 3 (Summer 2024)
Abstract

Background: In this comprehensive study, the prevalence of sepsis, a potentially life-threatening condition, was investigated among 477 patients displaying sepsis symptoms.
Materials & Methods: A detailed questionnaire was used to capture the patients' demographic information and clinical treatment outcomes.The E-test method was employed to determine the susceptibility of Gram-positive bacteria to vancomycin and Gram-negative bacteria to cefepime, ceftriaxone, and imipenem.
Findings: Among the participants, 40 patients (8.6%) were diagnosed with septicemia, a condition whose prevalence significantly increased with age (p= .001). Out of 40 patients with positive blood cultures, 14 (35%) were infected by Gram-positive bacteria, while 26 (65%) were infected by Gram-negative bacteria. Acinetobacter lwoffii and Staphylococcus epidermidis were identified as the most common causes of sepsis among Gram-negative (30.7%) and Gram-positive (57.1%) bacteria, respectively Gram-negative bacteria exhibited the highest resistance to ceftriaxone (38.4%) and the highest susceptibility to imipenem (84.6%) in both laboratory and clinical settings. Gram-positive bacteria demonstrated the high susceptibility to vancomycin (78.5%), with only four patients exhibiting resistance to vancomycin in both laboratory and clinical settings. Encouragingly, there was a 77.5% concordance between laboratory and clinical antibiotic susceptibility testing results.
Conclusion: Based on these findings, vancomycin and imipenem are recommended as the preferred antibiotics for Gram-positive and Gram-negative bacteria, respectively. Given the high concordance (77.5%) between laboratory and clinical results, it is suggested to perform antibiogram test using E-test method on blood culture isolates in septicemia cases to guide appropriate antibiotic treatment.


Volume 11, Issue 1 (Vol. 11, No. 1 (Tome 55), (Articles in Persian) 2020)
Abstract

The present study investigates the Graded Salient Hypothesis and its effect on irony in order to investigate what is an important factor in accessing to the meaning of irony. The purpose of this study was to measure RT (reading time) and to identify and explain the relationship between the three variables, context (literal, figurative), familiarity (familiar, less familiar and unfamiliar) and reading speed (slow, simultaneous, and Fast). The questions that this research sought to answer were:
1. Do unfamiliar ironies and two next expressions in the figurative and literal context are read with equal speed?
2. Do less familiar ironies and two next expressions in the figurative and literal context are read with equal speed?
3. Do familiar ironies and two next expressions in the figurative and literal context are read with equal speed?
The research material consisted of 46 ironies in the Persian language. Ironies were the result of a conversation between a 30-year-old woman and a 28-year-old man. These samples were the result of an 8-hour recording of non-consecutive conversations that were given to two experts to confirm the validity of ironies, and the examples in this study are the confirmed ironies. Then, for every irony, there was an affective context in the figurative meaning and an affective context in the literal meaning of that irony. A pre-test (pre-test 1) was conducted to determine the extent to which individuals were familiar with these ironies. The level of familiarity was determined on a seven-level axis, ranging from 1 (lowest familiarity) to 7 (highest familiarity). The subjects in this pre-test were 20 undergraduate students, this test was considered as their classroom work and for which they were given a score. In pre-test 2, to ensure that the literal and figurative contexts made for less familiar, familiar and unfamiliar ironies were equally strong, seven axial axes were drawn for each of the contexts. On one side, there was the literal meaning of the irony and on the other side, the figurative meaning of the same irony was mentioned. The axis was divided into seven sections and participants were asked to indicate which meaning of every irony was closest to it and how close it was. Two booklets were produced so that each booklet represented only one type of context. One booklet contained various examples of less familiar, unfamiliar and familiar ironies in the literal context, and another booklet contained various examples of less familiar, unfamiliar and familiar ironies in the figurative context. The participants in this pre-test were two groups of 23 people (each consisting of 11 men and 12 women, aged 18 to 27 years) and this pre-test was as a classroom task for them to perform and to obtain score. Each booklet was assigned to one group and each group did not have access to the other group's booklet, and every participant only had access to one context type for every irony. Also, those who were selected for the pre-tests were not included in the main test. A software was used to perform a self-paced moving window test that was able to measure the reading time of expressions. Participants were confronted with high-speed Windows 7 computers (with three-core CPUs and 2 GB of main memory), and the software was run in front of them. The main test was conducted in two stages, with a time interval of two months. In the first stage, the participants were presented with irony in the figurative context and their reading speed was measured. In the second stage, the same subjects were presented with the same ironies in the literal context and their reading speed was measured. The two-month interval between the two tests was because reading one phrase in a particular context not to provide the key for that phrase in the other context. On the other hand, the same participant had to participate again in the second stage. Because his reading speed in the figurative context was to be compared with the reading speed of the same person in the literal context so that individual differences in reading speed did not interfere with the results. The results showed that the ironies did not fully support the Graded Salience Hypothesis, and the results were in contrast to this hypothesis, in that the context often outweighed the salient meaning and influenced perception. Therefore, context and salience effects were not parallel to each other. Also, based on the results of the research, it seems that the salient meaning in both the less familiar and familiar ironies was the figurative meaning and the salient meaning in the unfamiliar ironies was both literal and figurative meaning.
 

Volume 12, Issue 4 (Fall 2024)
Abstract

Aims: The absorption of atmospheric Carbon dioxide for Carbon sequestration plays a vital role in regulating the climate. This study aimed to economically evaluate Carbon absorption and Oxygen supply  in Kerman Province using ecosystem service modeling.
Materials & Methods: Terrestrial Carbon storage was assessed using InVEST software, considering aboveground biomass, belowground biomass, soil, and litter/ dead organic matter. Oxygen supply in the ecosystem was also calculated based on Carbon relationships. The economic valuation of Carbon and Oxygen supply was determined using the social cost of Carbon dioxide and replacement cost, respectively.
Findings: In 2021, Kerman Province was estimated to sequester 6,896,182.89 t.y-1 of Carbon and produce 18,481,770.36 t.y-1 of Oxygen. The economic value of Carbon sequestration and Oxygen supply in the Province was calculated at 354,325,877 and 1,686,461,545 $.y-1, totaling $2,040,787,422 in 2021.
Conclusion: The economic valuation of Carbon sequestration and the Oxygen supply spatially demonstrate the multiple roles of vegetation cover in the economy, which help maintain and restore it. Economic valuation maps of studied ecosystem services have comprehensive  land management and planning applications. Furthermore, they underscore the importance of incentives for long-term Carbon storage to encourage sustainable practices. 


Volume 13, Issue 3 (10-2024)
Abstract

To study the effect of baits type and three lights, green, blue, and white, on the fishing efficiency of Largehead hairtail (Trichiurus lepturus) handline fishing 11,951 samples were done from February to May 2022 in the northern coast of the Oman Sea, Remin Fishing Port. The results showed that only the season and bait had a significant effect on the weight and number of caught T. lepturus caught (P<0.05), while the type of lamp and its interactions did not have a significant effect (P>0.05). The highest CPUE was observed in the months of February and March, using Rastrelliger kanagurta as bait, green LED lamp, at a water depth of 60-110 meters, and a hook depth of 20-30 meters. The use of R.kanagurta bait compared to Sardinella gibbosa has led to a significant increase in the catch of T. lepturus (both in terms of relative frequency and weight), which is recommended to improve the efficiency of hook fishing for fishermen. Due to catch per unite effort and for efficiency of catch rate of T. lepturus in the area, it seems suitable bait, green light and suitable depth of the hook must be used.
 


Volume 14, Issue 64 (6-2016)
Abstract

Along with the increase in pizza cheese production and consumption, identifying the trends of altering the functional properties of this product in order to control its quality is becoming very important. In this study, the changes in Functional properties of processed pizza cheese and low moisture mozzarella cheese samples collected from local manufactures in Khorasan province, Iran were analyzed. Three samples of commercial processed pizza cheeses and one commercial low moisture Mozzarella cheese as well as a sample of processed pizza cheese prepared according to the formulation previously optimized in our laboratory, were collected and stored at 4 ° C in vacuum packages until the day of experiment. Functional properties of all samples such as stretch length, max load, oiling off and meltability were measured and analyzed in days 0, 14 and 28 after production. In general, Statistical analysis showed that storage time had a significant (p≤ 0.05) effect on all measured properties, so that the stretch properties of  low moisture mozzarella cheese and all samples of processed pizza cheese were decreased significantly (p≤ 0.05) during the storage period, whereas meltability and oiling off, follow a significant increase in trend. None of the properties evaluated were out of their standard and acceptance levels at the end of the shelf life, Therefore, it is concluded that the storage of pizza cheese in the fridge instead of freezer up to one month after production is suggested to be an alternative to protect the product from the damage caused by freezing and defrosting while maintaining the quality of the product at the end of the shelf life. The efficacy of TPA and image processing techniques in the measurement of functional properties (stretchability, oiling off and meltability) of pizza cheese samples was also confirmed in this study.

Volume 14, Issue 64 (6-2016)
Abstract

The postharvest life of bottom mushroom is limited due to bacterial attack and enzymatic browning. This study was carried out in order to increasing the storability of mushroom, by antibacterial and anti-browning components. For that, the mushrooms were treated by oxalic and citric acids at concentration of 1.5 and 2.5 mM, hydrogen peroxide at concentration of 1 and 2.5%, ascorbic acid at concentration of 1.5 mM and calcium chloride at concentration of 1% as dipping for 2 min, and then treated mushrooms were packed in cellophane and stored at 4°C. Weight loss, marketability, electro leakage (EL) and bacterial colony forming unit (CFU) were measured after 8 and 16 days. According to the results, calcium chloride, ascorbic acid and hydrogen peroxide controlled browning as compared to control. However, oxalic and citric acids, despite reducing microbial load, did not show any positive effects. Calcium chloride by reducing weight loss, reducing EL and reducing bacterial load, ascorbic acid by reducing EL and reducing bacterial load and peroxide hydrogen by reducing bacterial load tended to increase postharvest life of bottom mushroom.

Volume 15, Issue 2 (4-2015)
Abstract

In this study, the water entry problem of a spherical - nose projectile is investigated numerically and experimentally. For the numerical simulations, a three dimensional model of the projectile with six – degree – of – freedom rigid body motion is considered. A Coupled Eulerian - Lagrangian (CEL) method is employed for modeling fluid - structure interactions. Through Eulerian - Lagrangian contact, Eulerian material can interact with Lagrangian elements. Also, an equation of state model describes the hydrodynamic behavior of the material. The numerical results are well compared with the available experimental results of a falling sphere in the literature and also the experiments of the current study. The experiments are performed for a spherical-nose projectile in a water tank equipped with a launching system and a high speed camera. The simulation results such as air cavity shape and the projectile trajectory are compared with the presented experiment data. The good agreement observed between the numerical results and those of the experiments, revealed the accuracy and capability of the proposed numerical algorithm. Also it has been shown that the pinch – off time is a weak function of impact velocity, however, increasing velocity leads to a linear increase in depth of pinch - off.

Volume 15, Issue 3 (9-2015)
Abstract

Web openings may be provided in structural floor beams for different purposes. The corner radii of web openings can have a significant effect on stress and strain concentrations around the opening. AISC's design guide for steel and composite beams with web openings states that web openings are not recommended for members subjected to significant high cycle-low stress or low cycle-high stress fatigue loading even if a rational corner radii is provided for web openings. This is because, at the time the specification was written, there were only limited references available to the committee which indicates the need for further studies in this field. In this paper, effect of opening corner radii on cyclic behavior of steel moment connections with Reduced Web Beam Section (RWBS) is investigated using finite element analysis. For this purpose, a T-shaped moment connection (without web opening) which has been tested under cyclic loading by another author is used as the reference model. To see effect of opening corner radii, the reference model is considered with square and rectangular web openings of different corner radii. Fracture initiation in models is simulated using Cyclic Void Growth Model (CVGM) which is based on micro-void growth and coalescence. According to this model, fracture under cyclic loading is predicted to occur when the void size exceeds the critical value. Based on the results, for both square and rectangular openings the maximum equivalent plastic strain and fracture index at the opening corners will decrease as the opening corner radii increase. For openings with small corner radii the fracture index at corners will be very high. This is in accordance with recommendation of ASCE 23-97 which indicates that these configurations should not be used in real practice. However, it should be noticed that in the case of rectangular opening the damage index at the corners may be greater than unity even if ASCE 23-97 limitations are met. This means that if it is intended to achieve high rotation capacity at RWBS connections, ASCE 23-97 requirement about minimum corner radii may be non-conservative. As another result, as the opening corner radii increase local buckling around the web opening occurs at higher rotations. In addition to the local effects, the choice of opening corner radii can also affect the global behavior of RWBS connections. In the case of rectangular perforation, as the opening corner radii increase the load carrying and rotation capacity of connection increase too. This is because in these models, the weakening area prevents welds from failure and fracture occurs in the opening corners. As a result, as the opening corner radii increase the fracture index at opening corners decreases and hence the connection can undergo higher rotation capacities. This is not true for square perforation where fracture occurs at connection welds and the connection rotation capacity makes no change as the opening corner radii increase. As a general recommendation it can be said that web openings with the largest corner radii (elongated circular holes) is the best case for perforated steel connections.
Alireza erfani, Neda Samiei, Farzaneh Sadeghi,
Volume 16, Issue 1 (Spring 2016 2016)
Abstract

The short–term inflation dynamics and its cyclical interactions with real economic variables are basic issues in the context of monetary policies analysis. This study investigates and estimates the hybrid new Keynesian Phillips curve for Economy of Iran during 1971-2008. On this curve, the effective variables on current inflation would be future inflation, lagged inflation and GDP gap. This paper makes use of three Kalman, Hodrick- Prescott and band-pass filters to estimate GDP gap. There is a structural break in 1979 due to victory of the Islamic Revolution in Iran. Findings indicate that GDP gap has a significant positive impact on current inflation, which means the effectiveness of real variables, besides monetary policies, on inflation in the long-run. Our findings are consistent with other Phillips curve models, which confirm the effective role of output gap on current inflation. In addition, the coefficients of the expected inflation and lagged inflation variables are statistically significant, which indicate that firms look forward and backward in setting prices, but coefficient of expected inflation variable is higher than that of lagged inflation, means that firms pay more attention to the expected inflation in setting current prices. The evaluation tests indicate the accuracy and reliability of models.  

Volume 16, Issue 3 (10-2016)
Abstract

The column members of moment frames are subjected to high axial forces as well as inelastic rotations during a seismic event. Estimating the boundaries of these simultaneous structural demands on the columns of special moment frames are one the aims of this research. These demands were evaluated in this research by performing a vast number of non-linear time history analyses on some archetype frames. Totally, eight archetype buildings were designed under two levels of spectral accelerations represent the Maximum Credible Earthquake (MCE) and the Design Earthquake (DE). Both geometric and material nonlinearities were taken into account. Far-field earthquake record set proposed by FEMA P696 was utilized in this study to conduct the required time history analyses. This set includes 44 individual seismic records with different magnitudes and other specifications. Each sample SMF was excited by each of the individual records with two different intensity levels referring to DE and MCE respectively. After performing numerous time history analyses, the boundaries and the characteristics of the axial force and the story drift ratio demands on columns were fairly stablished for the seismic events with MCE and DE intensity levels. It was proved that they might experience the axial force around 0.3 of their yielding capacity as well as the drift ratios up to 0.06. Moreover, based on the results of these analyses, a representative loading protocol was also developed for the column members of special moment frames because the effect of simultaneous change of the axial force demand on columns along with the change of plastic rotation in these members was neglected in all of introduced loading framework for these members. On the other hand, the utilized loading frameworks in different research studies were introduced quite arbitrarily and with no root in the real seismic demands of these structural members. Hence, a statistical approach implemented to extract the loading cycles based on the results of the mentioned non-linear time histories. This loading protocol includes cycles of varied axial force ratios as well as simultaneous cycles of lateral loading. Providing such a loading regime can pave the way to investigate the behavior of the columns of moment frames using more sophisticated numerical models that cannot be ordinarily employed to perform time history analyses under seismic records due to excessive computational costs. The overall response of steel columns may be dominantly affected by the local effects like as local bucking at large deflections. Hence, the response of some archetype individual columns was fairly investigated under the proposed loading protocol by utilizing continuum finite element simulations which are expected to be able to capture deliberately these kinds of local effects. The investigation not only revealed more on the details of the behavior of these members, but also proved the versatility of the proposed loading protocol in comparison to the previous loading procedures implemented on columns. In order to do so, the numerical models of the archetype columns were also loaded under the proposed lateral loading protocol besides constant levels of axial loading and the results of both cases were compared. It was shown that implementing a constant axial load besides the cyclic lateral cyclic loading may not be an appropriate loading framework and the results would not represent the seismic demands in these members accurately.

Volume 16, Issue 91 (September 2019)
Abstract


Nowadays, cinnamon essential oil has been considered as an antioxidant and antimicrobial activity for addition to food and biological systems. Directly use of these essential oil for food storage has some limitations due to low solubility in water, high vapor pressure and physical and chemical instability. One of the ways to reduce these limitations is the microencapsulation of essential oils in lipid carriers, including microcapsules. Therefore, the aim of this work was to study the encapsulation of cinnamon essential oil in microcapsules stabilized with sodium caseinate and β-cyclodextrin and also the antimicrobial and antioxidant properties. In this study, in order to encapsulation, different formulations of nano emulsions containing cinnamon essential oil were prepared by ultrasound method and the effect of different polymers on droplet size, encapsulation efficiency, antioxidant properties and turbidity of nano emulsion were investigated. The results showed that the interaction of nano emulsions and encapsulated samples was effective on particle size (p <0.05). The diameters of sodium caseinate with β -cyclodextrin particles size ranged from 234 to 237 nm. Also, the diameter of the β -cyclodextrin particles in the range of 713-717 nm, and the diameter of the essential oil particles size in the range of 84-85 nm. Zeta potential was negative for sodium caseinate with β -cyclodextrin and essential oil. That showed the system had a significant negative charge. The effect of different polymers and essential oil on the encapsulation efficiency and antioxidant properties was significantly different. (P <0.05). The encapsulation efficiency of all formulations was above 70%. SEM-scanning showed homogeneous and spherical shapes with pores. FT-IR analysis confirmed the effect of van der waals forces in the formation of microcapsules.
 

Volume 17, Issue 1 (4-2014)
Abstract

Objective: In recent decades, the anticancer effect of curcumin has been proven by several studies. Curcumin affects multiple cell signaling pathways and prevents cell proliferation, invasion, metastasis and angiogenesis. However, the aqueous solubility of curcumin and its bioavailability are very low which restricts its anticancer properties. In this research, we have synthesized a monomethoxy poly (ethylene glycol)-Oleate (mPEG-OA) di-block copolymer and used a surface PEGylated poly (amidoamine) (PAMAM) dendrimer to improve bioavailability of curcumin in cancer cells. Methods: Thecritical micelle concentration (CMC) of mPEG-OA, drug loading efficiencies, and cytotoxicity in the human glioblastoma cell line (U87MG) of all the prepared nanodevices were thoroughly investigated. Results: Atomic force microscopy (AFM) and dynamic light scattering (DLS) studies have shown that mPEG-OA have two common nanostructures, micelles and polymerosomes. mPEG-OA micelles had a very low CMC (0.03 g/l). The IC50 of free curcumin (0.01 methanol solution) was 48 μM, curcumin-loaded mPEG-OA was 24 μM , and curcumin-loaded PAMAM dendrimer was 13 μM. Moreover, the PEGylated PAMAM was non-cytotoxic. Conclusion: The results indicated that by using these nanocarriers, the bioavailability of curcumin significantly increased compared to free curcumin. Overall, this research revealed that these curcumin nanocarriers could be considered as appropriate drug delivery systems for curcumin delivery in cancer cells.

Volume 17, Issue 3 (9-2017)
Abstract

Strengthening of existing structures is one of the most important issues in the field of structural engineering. Due to avoiding any interruption of service on a structure and economic issues, strengthening process usually occurs when a member is under service loads. On the other hand in the loaded steel columns, it is really difficult to weld plates after unloading the column from existing loads, Therefore one of the important issues being neglected in the redesign process of strengthened columns is the significant axial load existing in the column, caused by service loads before strengthening them. This paper aims at numerically investigating the behavior and ultimate load bearing capacity of in-service strengthened steel box columns with continuous welded plates. Effects of different parameters on the capacity of preloaded strengthened columns are presented and discussed. Included in the result are the effects of initial imperfection; magnitude of preload before strengthening; slenderness ratio of the strengthened column and ratio between cross sectional area of reinforcing plate and unstrengthened column. To investigate the effect of these parameters, each un-retrofitted specimen is exposed to the preloading levels of 0.0, 0.2, 0.4 and 0.6 of the load carrying capacity of unstrengthened column. Then results of this preliminary analysis are defined as a predefined field for the column of same retrofitted model and ultimate bearing capacity of the strengthened model is calculated using a modified Riks analysis method. The critical load carrying capacity of models without pre-existing axial load was set to the theoretical value presented in ANSI/AISC 360-10 and suitable imperfection for each model was calculated. This is because the main objective of this study is the variation of results with respect to the existing design curves. Based on the results of numerical analysis, application of preload to unstrengthened column magnifies the initial geometric imperfection of the column and consequently decreases the ultimate bearing capacity of strengthened column. Also as the magnitude of axial load existing prior to addition of reinforcing plates increases, the ultimate bearing capacity of the strengthened column decreases with respect to the calculated theoretical value. The maximum amount of this reduction for the preload ratios of 0.2, 0.4 and 0.6, is respectively up to 2%, 5% and 9.5% of the load-bearing capacity of strengthened column. As another result, slenderness ratio is one of the main parameters that affect the bearing capacity of specimens with a specified preload level. This means that at a constant preload level the maximum reduction in bearing capacity occurs for models with median slenderness ratio. Also models with cross sectional ratio of reinforcing plates ranging from 0.4 to 1.0 were studied and it was shown that inside this range the cross sectional ratio of reinforcing plates parameter does not have remarkable effect on the ultimate bearing capacity of column. At the end, an empirical relation is proposed to calculate reduction of ultimate bearing capacity for columns with different slenderness ratios and preload level. Results of this study may be utilized to increase the accuracy of redesigning process during in-service strengthening of steel box columns.

Volume 18, Issue 2 (4-2018)
Abstract

In this paper, the three dimensional ventilated cavitating flow in the steady condition around a projectile model is simulated using CFD method combined with a sst k-ω turbulence model and volume-of-fluid technique, With the aid of CFD software ANSYS CFX. The numerical model is validated using comparisons between numerical predictions and existing experimental data and fairly good agreement is revealed. The numerical results show that with increasing the ventilation gas rate at constant Froude number, the cavity length gradually increases to a critical value and then remains fixed upon further increase in gas ventilation rate. Also, it has been observed that rear portion of larger cavity moves upwards due to gravitational effect. With increasing the ventilation gas rate, the gas leakage mechanism at rear portion of ventilated supercavity changes from the re-entrant jet closure mode to twin vortex closure mode. The variation of ventilation gas rate versus cavity length is a function of Froude number and the critical ventilation gas rate increases linearly with Froude number.
Dr Alireza erfani, Dr Hossein Tavakolian, Azadeh Talebbeydokhti,
Volume 18, Issue 4 (winter 2018 2018)
Abstract

Today, achieving financial stability alongside stabilizing inflation and output is of particular importance among monetary policymakers and regulatory authorities. In this study, a Dynamic Stochastic General Equilibrium Model was used for the period 1990: 1 to 2014: 4 in the economy of Iran, in which a measure of financial shock was also introduced. In this model, the financial shock is modeled as a reduction in external financing premium of the firm. Comparison of the performance of policy rules showed that following an expansionary financial shock, macro-prudential policy regime, in which instruments of monetary policy and macro-prudential policy deal with excessive growth of credit, leads to a significant reduction in the external financing premium of the firm.  This in turn leads to less volatility in economic variables, such as inflation and output. This would improve the welfare in the Economy of Iran.

Volume 19, Issue 2 (7-2019)
Abstract

The purpose of this study is to develop the previous proposed analytical model by the first and second authors for short links, so it can be used for all kinds of links including short, intermediate, and long links. Eccentrically braced frames (EBF) offer high lateral stiffness because of their braced configuration while also providing high ductility and energy dissipation. They are widely used as a lateral-force resisting system for multi-story buildings located in seismic areas. The key components of the EBF system include columns, collector beams, braces and active links. The active links are designed to provide ductility and energy dissipation through yielding under design basis earthquakes, while all other structural members are designed to be stronger than the links and stay in elastic range. The link is defined by a horizontal eccentricity between the intersection points of the two brace centerlines with the beam centerline. Sufficient analytical model which can accurately predict the inelastic performance of the links is needed to perform reliable nonlinear analyses of EBFs. Analytical models that are used to study the inelastic seismic response of the EBFs usually reflect the anticipated behavior of the different frame elements. Links are modeled as inelastic elements with concentrated end flexural and shear hinges. Beams outside of the link, braces, and columns are typically modeled as elastic beam-column elements, because no inelastic behavior is anticipated in design. Ricles and Popov proposed an analytical model for short links. Ramadan and Ghobarah replaced the sub-hinges with translational and rotational springs and proposed a new model. Both models had incorrect shear stiffness so that the shear stiffness of model was half the link shear stiffness. Richards and Uang corrected the shear stiffness of the model proposed by Ramadan and Ghobarah, and proposed a new analytical model for short links. Koboevic et al. proposed an analytical model based on the results of experimental test performed by Okazaki and Engelhardt, regardless of the fact that the actual measured dimensions of sections were different from the standard dimensions of sections. To account for this issue, despite of what is said in their paper, the strain-hardening ratio was set to 0.0045. For this reason, the shear stiffness of their proposed model was incorrect and the predicted shear forces are 15 to 24 percent more than the experimental shear forces. Ashtari and Erfani showed that available analytical models do not predict very well the maximum shear forces and deformations too, and proposed an analytical model which can accurately predict both maximum and intermediary values of shear force and deformation of short links. To the authors’ knowledge, currently there are only suitable analytical models for short links. In this study an analytical model which can accurately predict both maximum and intermediary values of forces and deformations for short, intermediate, and long links, is proposed. The parameters of model are established based on test results from several experiments on links and EBFs. Comparison of available test results with the hysteresis curves obtained using the proposed analytical model established the accuracy of the model. The proposed model is recommended to be used to perform inelastic analyses of EBFs.

Volume 19, Issue 127 (September 2022)
Abstract

In order to evaluate the quality and quantity of some important commercial Iranian pomegranate cultivars, in the climatic conditions of Yazd, the fruits of 12 cultivars including: Ardestani Mahvalat, Bejestani, Shishekap Ferdows, Naderi Badroud, Qajaq Qom, Gel Tafti, Shirin Shahvar, Robab Neyriz, Malase Yazdi, Malase Saveh, Malase Yousefkhani and Khazar Bardaskan were harvested at commercial maturity stage and were evaluated for important quantitative and qualitative traits. The results showed, there were significant differences among the cultivars in terms of fruit weight, skin and aril color properties (CIE L *, a *, b * and Hugh angle), soluble solids content, titratable acidity, antioxidant activity and anthocyanin content. Meanwhile, the highest fruit weight was measured in Shirin Shahvar cultivar, this cultivar also had the lowest titratable acidity and the highest taste index among the cultivars, and also this cultivar showed a bright color, however, the brightest color among the cultivars was observed in Naderi Badroud. Based on the skin and aril color properties, anthocyanin content and fruit taste, Malase Yazdi was the best among the cultivars. However, cultivars such as Shishekap Ferdows, also showed good quality characteristics. Also the correlations between traits was investigated and significant relationships were observed between color properties and amount of anthocyanin or between antioxidant capacity and amount of phenol or amount of anthocyanin. 

Volume 19, Issue 132 ( February 2023)
Abstract

In this study, biodegradable film was prepared from polyvinyl alcohol. Silver chloride nanoparticles and spirulina algae powder were used to modify the physicochemical structure and create antioxidant activity in the film. The surface morphology of the film was investigated. Polyvinyl alcohol film and its composites were used for packaging virgin olive oil. D-optimal design was used to investigate the effect of packaging type and storage time on the chemical, color and sensory characteristics of the oil. Chemical characteristics (acidity, peroxide value, refractive index and total phenol), sensory and color characteristics were investigated. The response surface method was used to investigate the effect of independent variables on the oil as well as the created mathematical models. The obtained results showed that in polyvinyl alcohol film modified with silver chloride particles and polyvinyl alcohol modified with silver chloride and spirulina particles, the presence of these particles on the surface of the film was completely evident. The results of the chemical, sensory and color analysis of the oil showed that the chemical, sensory and color quality of the oil decreased with the increase in the storage time of the oil in all packages. Peroxide value as the most important indicator of the quality of oils in normal packaging increased from 1 to 7 (mEq O2/Kg oil) during 30 days of storage, while in oil packaged with polyvinyl alcohol modified with silver chloride and spirulina algae, this increase was from 1 to 2 (mEq O2/Kg oil). In general, oils packaged with polyvinyl alcohol modified with silver chloride and spirulina algae showed the least quality changes compared to normal packaging, which indicates the ability of these films to control the quality and increase the shelf life of virgin olive oil.


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