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Showing 73 results for Saadat


Volume 22, Issue 2 (6-2022)
Abstract

Fragility curves are powerful tools to assess and control of possible damages to the existing structures and estimate the exceedance probability from the seismic behavior of the structures under the influence of different earthquake levels. these curves present the probability of damage as a function of the ground motion characteristics. The main goal of the current study is to examine the existing methods and the presentation of a suitable method for the production of analytical seismic fragility curves and the proposal of appropriate relationships for the exceedance probability from different performance levels. For this purpose, three high-rise building frames with 20, 25, and 30 stories with a slimming ratio greater than π, according to the standard 2800 and the sixth issues and tenth issues of the national building regulations of Iran, were designed. Then, by using Perform 3D program, their analytical model was defined and validated. To evaluate the seismic response demand of frames, incremental nonlinear dynamic analysis (IDA) was performed. For IDA analysis, the 22 recommended records in the FEMAP695 guideline and two earthquakes in Iran were used. Spectral acceleration of the first mode of the structure with damping of 5 Percentage (Sa (T1.5%)) was used to introduce the intensity of the earthquake (IM) and the inter story drift ratio was used to introduce the engineering demand parameter (EDP) Or damage measure (DM). To find the appropriate function of the exceedance probability from limit states and use them in the production of fragility curves, the results of IDA analysis and nineteen different probability functions using the suitable program were used. in order that the used distribution describes the sample data in the best manner, the goodness of fit tests was used. the results obtained from the goodness of fit tests show that The probability distribution rank used by researchers (log normal) versus other probability distribution functions varies in ranking the best fitted probability distribution. and selecting the appropriate probability distribution is effective in the conclusions and determining the probability exceedance of the structure from the desired limit states. Therefore, in order to reduce the uncertainty related to the mathematical model (epistemic uncertainty) in the template of a comprehensive view and according to accuracy and the required seismic target, a suitable method for developing fragility curves for types of steel structural systems with different heights with the name of intelligent seismic fragility curve (ISFC) is introduced and presented. Such that if only one distribution is desired to compare several options, including deciding how to reinforce or comparing the seismic performance of several structures to plot the fragility curve, it is recommended: to use the probability distribution "Generalized Extreme Value", due to having more parameters and the ability to fit better than the distribution "log normal", but for more sensitive structures, such as nuclear power plants and hospitals that are of great importance and require high precision or in order to achieve the most accurate fitted possible to decide on about  the vulnerability estimation of any structural system, It is then recommended: to estimate the exceedance probability from performance levels at the structure, before fragility analysis, by probabilistic evaluation and using the goodness of fit tests on suitable probability functions, At First, a best fitted probability distribution should be selected at all performance levels and then the vulnerability of structures is estimated by fragility curves.

Volume 22, Issue 5 (7-2020)
Abstract

This research studied changes in antioxidant enzymes activity, Total Soluble Proteins (TSPs), Malondialdehyde (MDA), and proline content in the leaves of three olive (Olea europaea L.) cultivars (Amphisis, Gorgan, and Manzanilla) at five different dates, and investigated their relationship with cold tolerance. The results revealed that cold-acclimation dramatically increased cold tolerance. Furthermore, antioxidant enzymes activity, MDA, TSP, and proline content increased throughout the acclimation stage, whereas they declined in the de-acclimation stage. The ascorbate peroxidase, catalase, peroxidase, and superoxide dismutase activities in the leaves tissues correlated with the alterations in cold tolerance. Higher TSP, greater antioxidant enzyme activities, and more proline content together with lower MDA content in Amphisis cultivar led to relative improvement in cold tolerance capacity of this cultivar. Our results showed antioxidant enzymes activities, TSP and proline content could be useful indices to screen cold tolerance in olive cultivars.

Volume 23, Issue 2 (3-2021)
Abstract

The Severe strain of Beet Curly Top Virus (BCTV-Svr) and Beet Curly Top Iran Virus (BCTIV) are considered as the main causal agents of sugar beet curly top disease in Iran and mixed infections of BCTV-Svr and BCTIV usually occur in nature. As the use of resistant cultivars is the safer and stable tool for management of the disease, the objective of current work was to identify sugar beet genotypes resistant to both agents. To this end, the reaction of thirty-eight sugar beet genotypes to infection by each of BCTV-Svr and BCTIV was separately evaluated using their infectious clones under the greenhouse condition. Incubation period, recovery, and disease severity index were considered for selection of resistant genotypes. As a result, ten and seven sugar beet genotypes resistant to, respectively, BCTV-Svr and BCTIV were selected. To evaluate the resistant genotypes, the experiments were repeated under greenhouse condition. In the field experiment with natural infection of viruses, the resistant genotypes were assessed and six sugar beet genotypes (S1 91019, S1 91022, S1 91023, S1 91028, S1 91029, and S1-91041) resistant to BCTV-Svr and BCTIV were identified; which could be used in future breeding programs.

Volume 23, Issue 10 (October 2023)
Abstract

Endmilling is a type of machining tool for chipping the surfaces of parts, which has received attention due to its wide application in industries such as molding. Therefore, today, the need of the industry to find the optimal parameters of the process is felt so that the quality of the desired surface can be achieved. In general, the selection of effective parameters in any milling process significantly affects the surface quality of a finished part. In this research, using E-fast statistical sensitivity analysis method, the simultaneous influence of input parameters including spindle speed, depth of cut, and feed rate on the output parameter of surface roughness for the samples has been investigated quantitatively. Machining experiments have been carried out under different cutting parameters as defined in steady state conditions for the milling tool. surface roughness and vibration rate of machining with non-linear quadratic forms; It has been modeled based on the cutoff parameters and its interactions through several regression analysis methods. The results of this research showed that the spindle speed time parameter is known as the most influential parameter on the surface roughness with 67% influence. It was also observed that the feed rate parameter with 30% effect of cutting depth with 3% are known as the second and third influencing parameters on surface roughness.

Volume 24, Issue 4 (7-2022)
Abstract

Silver Nanoparticles (AgNPs) are widely used in medical and pharmaceutical applications due to their antimicrobial properties. In this study, Ag-NPs were synthesized using Viola tricolor aqueous extract as a reducing and capping agent. The presence of synthesized Ag-NPs was first confirmed with UV-Visible, SEM, TEM, XRD, and FTIR analyses, and then their antimicrobial characteristics were studied based on the Minimum Inhibitory Concentration (MIC). The SEM analysis showed that the synthesized AgNPs were spherical in shape. The particle size histogram revealed that the average particle size of the AgNPs was 49.45 nm. Findings from the FTIR and UV-Vis spectra showed the successful formation of Ag-NPs because the functional groups involved in the synthesis process and adsorption peaks were well developed. Furthermore, the Ag-NPs had a peak absorption at 420 nm in the spectrometry. MIC results showed the strong antimicrobial effects of the synthesized Ag-NPs. Results of the Minimum Bactericidal Concentration (MBC) revealed the dose-dependent cytotoxicity of the Ag-NPs. Nanoparticles could exert the inhibitory effect of DDPH free radicals in a dose-dependent manner. Methyl tetrazolium (MTT) results showed that silver nanoparticles had a dose-dependent cytotoxic effect and significantly reduced cell survival. The IC50 values for Ag-NPs and the extract were 11.83 and 204.4 μg mL-1, respectively. This study showed a higher cytotoxic effect of the green synthesized nanoparticles on hepatocellular carcinoma cells than the extract. Consequently, the biosynthesis of Ag-NPs using aqueous extract of V. tricolor is clean, inexpensive, and has antibacterial, anticancer and antioxidant activities. Hence, it can be used as a drug candidate.

Volume 24, Issue 5 (May 2024)
Abstract

Superhydrophobic surfaces have gained significant attention as a promising approach for drag reduction of submerged objects. Accurate evaluation and prediction of drag reduction induced by these surfaces require expensive experimental measurements, numerical simulations, or the development of reliable models and correlations. In this paper, a model is proposed for calculating the skin friction coefficient and drag reduction of superhydrophobic flat surfaces. Utilizing previous data on the skin friction coefficient of flat surfaces under no-slip boundary conditions, a model is developed to estimate the skin friction reduction and skin friction coefficient of these surfaces after applying superhydrophobic coatings. The validity of the model is verified by comparing its results with those of computational fluid dynamics (CFD) simulations of flow over a flat plate at different velocities. The results of the model and simulations indicate that for inlet velocities of 1, 5, and 25 m/s and a slip length of 50 μm, drag reductions of 15%, 41%, and 77%, respectively, are expected. Additionally, the skin friction reduction increases with increasing flow Reynolds number. The developed model is validated for flat surfaces and its ability to accurately estimate the skin friction coefficient and drag force of these surfaces is thoroughly examined. However, further investigations are required to assess the model's validity for curved surfaces and variable slip lengths.

Volume 24, Issue 6 (June 2024)
Abstract

Gears are a very important part of mechanical equipment in industry. Due to the fact that in mechanical processes, the teeth are subjected to long-term load, the surface of their teeth is usually rusty, worn out and even broken. Timely fault detection cannot only increase the life cycle of the gears, however it can even prevent property losses and losses due to breakdowns. Therefore, it is necessary to monitor and diagnose the health of the gears to ensure the normal operation of the invaluable machines in industry. In this research, fault detection in polymer gears using audio signal is considered as a non-contact inspection method. Sound signals were recorded from 50 pairs of gears in normal condition, worn teeth and broken teeth at two speeds of 66 and 99 rpm. In the following, using wavelet packet transformation (WPT), the sound signal is analyzed in the time-frequency domain and 12 statistical features are extracted from the 16 coefficients of the fourth level of WPT. In order to study the performance of the fault detection algorithm, four classifications of linear discriminant analysis, K-nearest neighbor, decision tree and support vector machine have been used. The values of accuracy, true positive rate, true negative rate, positive predictive value, negative predictive value, geometric-mean, F1 score, and Matthews correlation coefficient have shown that by using WPT, a significant distinction can be found between normal and faulty gears. Therefore, the proposed method is a suitable approach for timely error detection of polymer gears used in mechanical equipment.

Volume 25, Issue 1 (4-2019)
Abstract

Academic engagement is crucial for the accomplishment of education and success in it, yet, with respect to existing challenges in the course of education, some students encounter with problems in this area. The main purpose of the present research is to promote academic engagement by using the stress inoculation training for students where academic stress and academic exhaustion play intermediary roles. For this purpose, we used a pretest-posttest design with a control group. 40 students were selected through a convenience sampling and randomly assigned to control and experimental groups. The experimental group was trained for 8 sessions of 120 minutes each. The groups were evaluated at three stages: pre-test, post-test, and follow-up. For data analysis, structural equation models with partial least squares approach were used in the form of the MIMIC model. The results showed that the stress inoculation training can firstly reduce academic exhaustion and academic stress significantly and in the second step can increase academic engagement indirectly and promote it. The follow-up model also confirmed these effects. In sum, the conceptual model of research explained 70% of academic engagement variance in the post-test phase as well as 38% in the follow-up phase which indicate the importance and effectiveness of Mindfulness Program.
 

Volume 26, Issue 6 (11-2024)
Abstract

Developing high-yielding varieties of sunflower as oilseed staple crops requires knowledge of physiological and molecular mechanisms involved in yield formation. Source strength, sink demand, and their interactions play crucial roles in the yield formation of sunflowers. The persistence of assimilate flux to the developing grains mainly determines sink demand. There was no information on the molecular mechanism for assimilate flux to the sink organ of sunflowers. To shed light on molecular events engaging in assimilate flux to sink organs, two experiments were carried out on five sunflower inbred lines differing in their grain yields. Source-related parameters (such as leaf biomass, area, and number) and sink-associated attributes (such as floret number at the first anthesis and capitulum biomass and diameter, in addition to changes in biomass of capitulum and stem, at the first anthesis with those at physiological maturity) were evaluated across all the inbred lines. The Invertase gene expression level was measured on the receptacle base of three inbred lines, showing discrepancies in the source, sink, and grain yield performances. While no significant correlation was found between source strength and sink demand with grain yield, the results showed that higher grain yield was likely attributed to the persistence of assimilate flux to the capitulum base during grain filling. This phenomenon is discussed to be due to higher Invertase activity in the receptacle base.

Volume 26, Issue 6 (11-2024)
Abstract

High-density Single Nucleotide Polymorphisms (SNPs) panels are expensive, especially in developing countries. However, methods have been developed to detect critical SNPs from these panels and design low-density chips for genomic evaluation at lower cost. This study aimed to determine the efficiency of Random Forest (RF) and Gradient Boosting Machine (GBM) algorithms, and Linear Model (LM) in identification of SNPs subsets to predict Genomic Estimated Breeding Values (GEBVs) for Body Weights at 6 (BW6) and 9 (BW9) weeks in broiler chickens and compare the predicted GEBVs with those obtained by the 60K SNP panel. The data were collected on 312 F2 chickens that genotyped with 60K Illumina SNP BeadChip. After applying quality control, the remaining 45,512 SNPs were ranked based on p-values, mean square error percentage, and relative influence, obtained by LM, RF and GBM methods, respectively. Then, subsets of top 400, 1,000, 3,000 and 5,000 SNPs, selected by each method, were employed to construct genomic relationship matrices for the prediction of GEBVs with genomic best linear unbiased prediction model. Results indicated that predicted accuracies by RF and GBM were generally higher than LM. A Subset of 1,000 SNPs selected by RF and GBM algorithms compared to the total SNPs increased accuracy from 0.38 to 0.64 and 0.66 for BW6, and from 0.42 to 0.60 and 0.66 for BW9, respectively. The findings of the present study provide that machine learning methods, especially GBM, can perform better than LM in selecting important SNPs and increasing the accuracy of genomic prediction in broiler chickens.


Volume 27, Issue 3 (6-2020)
Abstract


Defensive fortifications in different regions of Iran have been an effective factor in the survival ‎of residential centers and commercial routes. An investigation on defensive structures will ‎provide useful information on this kind of architecture. The study of remains of castles in the ‎Rey region has provided an important context for archaeological research. In the present ‎study, the Seljuk fortifications (Rashkān fortress, Gabri and Kāsni Castles) are introduced and ‎recognized as inner city castles. It aims at identifying and studying the Seljuk fortifications of ‎Rey, identifying the function of inner city fortifications, and comparing them with other samples ‎in neighboring regions in terms of characteristics. The data were gathered through field and ‎documentary studies while an analytical-historical method was applied in the course of the ‎research. Important questions intended to be addressed were: 1. what has been the role of ‎Seljuk fortifications of Rey in security provision of the region? 2. In which categories can the ‎Seljuk fortifications of Rey be classified in terms of structural characteristics and architectural ‎classification? Among the Seljuk fortifications of Rey, Kohandez (e.g. Rashkān Fortress) had ‎functioned as the political headquarters, and in other inner city castles, larger circular towers ‎have been usually located in four angles and interspersed with subsidiary towers. These types of ‎defensive architecture indicate the progress in the urban construction and security provision. ‎

Volume 28, Issue 4 (9-2021)
Abstract

Tis was one of the most important commercial ports of Iran in the early and middle centuries of the Islamic era. It played an important role in maritime or caravan export and import. Not only is this port less mentioned in historical sources, but also little research has been done on it. One of the archaeological findings of this region is various ceramics from Islamic periods, which are distributed on different parts of the site. Except for brief references in a few sources, there has been no independent research on ceramics of Islamic periods of Tis. Accordingly, the main purpose of this study is to know the economic and social life of Tis port in the Islamic era through study, analysis, and chronology of pottery. The method of this research is descriptive-analytical. The information is collected through field and library studies. According to research, the ceramics of the Islamic periods of Tis, probably belong to the 7-17th centuries, but most of them date back to the 9th-12th centuries. During this period, various types of glazed and unglazed ceramics were used in this area, some of which, such as unglazed red ware and Celadon, were probably imported from near and far areas such as India, China, and others like a group of Sgraffito were domestically produced.  

Volume 28, Issue 4 (1-2025)
Abstract

The present research, using the qualitative method and analytical-descriptive method, aims to performance a comparative study and explain the foundations and examples of the civil responsibility of electricity supply institutions. The findings of this research show that the civil liability of the mentioned institutions in Iran and America in the stages of production and transmission is considered as "Sovereign Acts" and in the stage of distribution among subscribers and consumers is considered as "Employee Acts"; In addition, the civil liability of the electricity supplier entities is "Contractual and Non-Contractual" in nature, and both Iranian and American legal systems consider the civil liability of the electricity supplier entity in the production phase, which is a liability based on the contract; with the difference that the basis of responsibility is different in these two legal systems; As in Iranian law, this responsibility is based on "Fault" and claimable damages resulting from the violation of contractual obligations are subject to the specification of the parties, custom or law; But in American law, the basis for establishing the contractual liability of the aforementioned entities is "Pure Liability" or liability without fault, and the liability of these entities is established solely based on the breach of obligation; Therefore, in this legal system, as soon as a breach of contractual obligations is established, regardless of the reason for the breach or fault, the obligee is responsible for compensation. In the stage of electricity distribution, in Iran's legal system, it is possible to point out the responsibility resulting from the lack of care and maintenance of the facilities and equipment for the transmission and distribution of electricity to the subscribers, as well as the responsibility resulting from negligence and failure to take preventive measures, which is the factor of "Fault" Civil liability plays a fundamental and key role for the aforementioned supplier institutions; But in the American legal system, one can find very limited cases in which civil liability can be proposed for the mentioned institutions at this stage, and basically it is very difficult to establish civil liability at this stage, and this is due to the mechanisms that exist in this country in In order to comply with electricity transmission and distribution standards, division of responsibility and the involvement of consumers and subscribers in possible damages are applied.
 

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