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Showing 25 results for Naji


Volume 0, Issue 0 (Articles accepted at the time of publication 2024)
Abstract

Teaching is a profession which is intermingled with emotional relationships. Teachers’ relationships with their classes have been shown to positively influence their performance. However, despite the novelty of the concept of teacher-class relationship (TCR) in the field of applied linguistics, examining the relationship between language teachers with the whole class has not received due attention. To shed more light on this novel concept and its antecedents, the present study aimed to investigate the role of psychological well-being, foreign language teaching enjoyment and work engagement in the TCR of language teachers. A sample of 428 English as a foreign language (EFL) teachers participated in the study by completing four online questionnaires, namely the Teacher-Class Relationship Scale, the Psychological Well-being at Work (PWBW) Scale, the Foreign Language Teaching Scale (FLTES), and the Engaged Teacher Scale (ETS). The results of structural equation modeling (SEM) indicated that EFL teachers’ psychological well-being, foreign language teaching enjoyment and work engagement were strong predictors of their TCR. In addition, it was revealed that work engagement was the strongest predictor. The findings were discussed regarding the significance of developing EFL teachers’ TCR. This study suggests that EFL teachers with high level of well-being who enjoy their profession and have dedication to their job are more likely to build strong relationships with their classes. Finally, suggestions for future research were provided. 

 

Volume 1, Issue 4 (Fall 2023)
Abstract

Today, financial development is one of the main drivers of economic growth and development. Since developing countries are focused on the rapid expansion of economic growth, they have taken steps toward the development of financial markets. However, the consequences of financial development on environmental quality are not clear. In addition, since the emission of carbon dioxide caused by production is significantly different from the emission of carbon dioxide caused by consumption in some countries (such as China). Therefore, this article examines the impact of financial development on the consumption-based CO emissions for a panel of 17 developing countries during the period of 1990-2019 with a Panel- Quantile approach. Empirical findings show that the effect of financial development on consumption-based CO emissions is positive and significant in all quantiles. In addition, this study considers gross domestic product, rental rates of natural resources, trade openness, and globalization as control variables. The results of this study provide new evidence for policymakers to maintain environmental quality by focusing on the link between financial development and consumption-based CO emissions.
 

Volume 5, Issue 1 (Winter 2025)
Abstract

Mīr Dāmād’s foundations in sketching the worldview of Yemani Wisdom and formulating the theory of perpetual creation (al-udūth al-darī) is a product of the refining and expanding of the Avicennian worldview. Inspired by certain Quranic verses and traditions, and combining between reason and transmission, Mīr Dāmād aimed at broadening and changing the discussions on perpetuity and eternity, the types of priority and posteriority, and types of creation. He did this without the least disturbing of the rational foundations of Avicennian philosophy, introducing the grounds for the view of real creation and the separable posteriority of the contingent realm. In this research, while explaining Mīr Dāmād’s usage of transmitted arguments and his commitment to the teachings of Avicenna in presenting the theory of perpetual creation, we have shown that Mīr Dāmād changed the structure of Avicennian thought with the great precision that he had. He did this in such a way that avoiding his expansion would close the path to presenting and establishing the theory of perpetual creation. Mīr Dāmād’s attempt to offer a new interpretation of the inception of the world in light of the teachings of religion is considered a great step in the formation of Shiʿi Philosophy.

Volume 5, Issue 4 (winter 2024)
Abstract

The metro not only provides public transportation but also fosters interactions among citizens and contributes to the urban environment. Hence, attention to social interactions and spatial provisions to transform into urban spaces is crucial. The objective of this research is to establish a framework for achieving the quality of life in underground spaces that incorporates a comprehensive expression of placemaking. The research methodology is based on collecting and analyzing textual and documentary data, qualitatively focused on interpretive paradigms. This theoretical article aims to enhance a critical understanding of production and consumption processes within the urban public space. Findings indicate that urban underground spaces, to function as urban areas, need to offer a set of unique qualities aligned with citizens' needs as these spaces extend beyond the defined scope of urban areas. These urban spaces can be examined in the realms of lived space, perceived space, and conceived space by the citizens. In conclusion, in achieving a form of placemaking, the components of daily life, encompassing spatial behaviour, spatial representation, and representational space in alignment with the qualities of underground urban spaces, such as inner space qualities, inter-space qualities and extra-spatial qualities (legibility, inclusiveness, vitality, Accessibility, moderation, providing a variety of services and facilities), significantly shape the landscape of citizens' everyday lives. Identifying these qualities and the interactive dynamics between citizens' daily lives and urban space can lead to the creation of place and the process of placemaking.

Volume 8, Issue 2 (Spring 2020)
Abstract

Aims: The present study aimed to investigate the anatomical properties of wood and xylem functioning of Persian oak affected by crown dieback.
Materials & Methods: Affected Persian oak trees were categorized into four different classes based on the severity of crown dieback (healthy, slight, moderate, and severe trees) with three replicates. The target trees were randomly selected from three forest stands. Branch samples at the age of 4-6 years were randomly taken from the trees’ crowns and the anatomical traits such as tree ring width (TRW), vessel density (VD), average vessel size (AVS), and relative specific conductivity (RSC) were determined. One-way ANOVA and LSD comparison of means were used to analyze the data and their mean comparison.
Findings: The results showed that oak trees are using different hydraulic strategies in different habitat conditions. The effect of severity of canopy dieback on xylem anatomical traits was significant. The narrowest ring width as 257.67, 365.56, and 159.17µm was observed in trees with a severe degree of dieback (with more than 66% canopy dieback). The RSC was decreased in response to reduction in the vessel size (2905.7µm2) and density (26.09mm-2) for declining oak trees from the last site. The AVS was increased in moderate and severe degree of canopy dieback from two sites, resulting in enhanced conducting efficiency. Whoever, their resistance decreases because of the risk of cavitation.
Conclusion: Healthy oak trees showed the highest values of RSC and VD. However, the AVS was not increased. The results suggest that larger and more abundant vessels would allow for more efficient water transport. However, these larger vessels may also promote a greater risk of cavitation during a drought that illustrates the tree's incompatibility with water deficit stress.
 


Volume 8, Issue 3 (fall 2020)
Abstract

George Gordon Lord Byron,a British poet of 19th century, was heavily influenced by Oriental and Persian literature in his works. The poet’s life coincided with beginning of the “Victorian age”, and “romanticism” style emergence and the beginning of the European literature’s impressionability presentation from Iranian literature and Persian language; hence he is known as an outstanding person and European renaissance’s symbol and among the Persian literature’s impressed ones.
In This research attempt to clarify the “Manfred” Play’s contribution among Lord Byron’s works in Persian literature’s impressionability through library and documentary tools and relying on an analytical and comparative method. The result is that the above work is influenced strikingly by the works of Persian literature and language, Oriental myths and culture in “symbols”, “concepts”, “fantasies” and even “lexical” terms, which are collected due to Byron’s studies in his subconscious. Also research data show that the two categories of “Zoroastrianism” and “mysticism”, in effectiveness of Persian literature, had the largest share which are presented under two total categories: character-making level and 
space-making level.

Volume 8, Issue 32 (4-2020)
Abstract

Folk literature, or oral literature, is the forerunner of the written literature. Its orators were pure and reliable people who were not much literature. These folklores stayed with us through their transfer between generations. Part of the folk and oral literature is the "wedding songs" labelled differently in various parts of the country. In Fasa county, this type of literature is known as "Astunk or Wastunak". The present article examines the syntactic structure of this type of oral literature in terms of the type and components of the sentences in popular culture. To this aim, through field study and interview with older and preferably illiterate women, 127 Wastunaks from the folk culture of Fasa were collected and transcribed. They were, then, analyzed syntactically (type and components of the sentence). The data was fed into SPSS 25. The results show that the frequency of the simple sentences is more than the compound ones and in most compound sentences, the subordinates are omitted for the rhythm of the poems. Finally, the three-part and four-part sentences had the highest and lowest frequencies in the Wastunak, respectively.


Habib Sarsangi Aliabad, Abolfazl Naji, Seyed Reza Seyed Mortezaei, Iman Sourinejad, Arash Akbarzadeh,
Volume 10, Issue 3 (9-2021)
Abstract

Biofloc technology has mentioned as a new tool for sustainable aquaculture development and has overcome the problems of water scarcity and discharge of aquaculture effluents to the environment. In this system, nitrogenous wastes (Ammonia and Ammonium) are simultaneously recovered by bacteria and converted into microbial proteins that can be consumed by aquatic animals. The purpose of this study was to investigate the factors affecting the production of biofloc and evaluate it for use in aquaculture. The effect of different temperature levels (24, 28, 32 °C), salinity (0, 4, 8 g/l)  ,and C/N ratio (10:1, 15:1, 20:1) which are the main key factors to the formation and function of biofloc system was evaluated by using a response surface method designing. Moreover, the influence of those factors on total ammonia nitrogen, nitrite, nitrate, floc volume, protein, and lipid content of biofloc was investigated. The results showed that the temperature had a significant effect on floc volume and protein content of biofloc (P < 0.05), but it had no significant effect on other nitrogenous compounds and lipid content (p > 0.05). The protein, lipid and moisture of biofloc particles were decreased by increasing salinity significantly (P < 0.05). Also, TAN and nitrite concentration influenced by C/N ratio inversely. According to the factors Optimization, providing 27 °C and C/N ratio of 18:1 in brackish water and 29 °C and C/N ratio of 14:1 in fresh water resulted in high quality biofloc production and control of nitrogenous wastes in water.

Volume 11, Issue 1 (Winter 2023)
Abstract

Aims: The patient decision-making process can become lengthy and overwhelming. Procrastination in visiting a hospital can have adverse effects on a patient's health. This study aimed to investigate how attitudinal ambivalence affects psychological discomfort and choice deferral in hospital selection. Additionally, the study explores the role of information novelty in reducing choice deferral and accelerating patient decision-making.
Instruments & Methods: This research employed a quantitative approach using a causal study to examine the relationships among variables. The purposive sampling method was used to obtain data based on certain criteria. Data were collected through a questionnaire distributed to patients. The research sample consisted of 385 respondents from private hospitals in Indonesia. Hayes PROCESS Macro software was used to investigate the relationships between variables.
Findings: The attitudinal ambivalence affected psychological discomfort (t=2.737; p=0.0001) and choice deferral (t=4.295; p=0.0001). The psychological discomfort influenced choice deferral (t=3.109; p=0.0001). The psychological discomfort had a mediation role in the effect of attitudinal ambivalence on choice deferral (t=10.678; p=0.0001). Information novelty reduced the effect of attitudinal ambivalence on psychological discomfort (t=2.653; p=0.003) and choice deferral (t=2.243; p=0.013). Finally, Information novelty weakened the effect of psychological discomfort on choice deferral (t=2.876; p=0.011).
Conclusion: Limited information can lead to information asymmetry, which can encourage attitudinal ambivalence and psychological discomfort. Providing comprehensive information to patients through digital media can help reduce anxiety and enhance their treatment experience in the hospital.

Volume 11, Issue 2 (Spring 2023)
Abstract

Aims: Although the Internet has greatly benefited our daily lives, over usage of it can lead to addiction, which can negatively impact our life. This study aimed to assess the impact of digital addiction on emotional status of female high school students.
Instruments & Methods: This descriptive correlational study was conducted in Baghdad Governorate from December 1st, 2022 to April 5th, 2023. 360 female high school students were selected using simple random sampling method. Data were collected using a questionnaire whose validity was confirmed by experts, and a pilot study confirmed the reliability of the results. This questionnaire had a total of 25 questions to measure digital addiction and 21 questions to measure mental health. Through the interview, data were gathered, and descriptive and inferential statistical analysis were used to analyze the data.
Findings: The majority of respondents are female pupils in grades 4, with a mean age of 16.55±1.08 years. 49.7% of the high school pupils reported a high degree of addiction, and 50.6% had a moderate level of emotional status. The amount of time spent using devices during the week (β=-0.218; p=0.0001), the amount of time spent using devices on the weekend (β=0.137; p=0.019), and digital addiction (β=0.282; p=0.0001), all predicted emotional status.
Conclusion: Emotional status is predicted by the time of device use during the week, the amount of device use on the weekends, and digital addiction.
 

Volume 11, Issue 3 (Summer 2023)
Abstract

Aims: Climate change is a global challenge that has already had a detrimental impact on the environment and human health, leading to increased magnitude and frequency of extreme weather events such as heat waves, droughts, and flooding. This study aimed to investigate the efficacy of the expanded health belief model related to the perceived benefits of climate change on collegians at the university.
Materials & Methods: This experimental randomized controlled trial was conducted at the College of Education for Pure Sciences in AL-Nasiriyah City, Iraq, from October 4th, 2022 to January 3rd, 2023. All 144 students entered the study by census method and were randomly divided into two study and control groups. A questionnaire consisting of two parts; demographic data and health benefits of adopting the anti-climate change behavior scale. Data was analyzed in SPSS 21 software by Chi-square and independent T-tests.
Findings: The perceived benefit had no significant difference between the control (29.17±8.82) and the study (29.52±8.05) groups in the pre-test (p>0.05). The study group's perceived benefit in post-test I was increased to 52.31±11.31, which was significantly (p<0.05) higher than the control group (29.49±8.07). Also, the study group's perceived benefit in post-test II was 51.89±11.60, which was significantly (p<0.05) higher than the control group (30.14±8.98). There was no statistically significant difference between study groups in the pre-test period (t=0.349; p=0.727). There were statistically significant differences between the study groups at the post-test I (t=8.276; p=0.001) and II periods (t=8.895; p=0.001).
Conclusion: The administered expanded health belief model increases the perceived benefits of enhancing the climate change counteraction in collegians.
 

Volume 13, Issue 5 (12-2013)
Abstract

Water-storage capacity of reservoir reduces mainly due to sediment laden. Turbidity current has an important role on sediment transfer in reservoir. It is necessary to study sediment interaction and flow in order to predict mechanism of turbidity current. In this paper effects of changes in entrance hydraulic condition of turbidity current on head velocity, layer-average thickness, layer-average velocity, body velocity and turbulent structure have investigated experimentally. The front velocity of the head of turbidity current was determined by video recording and body velocity and turbulence parameters measured by Vecterino. When the initial Froude number decreases the maximum velocity increases in body and head. Positive shear Reynolds stress near bed indicates that major contributor in this region is sweep or ejection while major contributor near interface is inward interaction or outward interaction. Entrainment is dominated at interface. The investigation shows that head velocity depends on inlet Froude number and inlet Reynolds number. Variation of head velocity along channel is exponential. The maximum reduction of head velocity takes place at  whereas variation of head velocity at  is negligible. Driving forces at  are inertial force and gravity force. Driving force decreases after hydraulic jump and only gravity force remains as driving force. Therefore head velocity is constant at . Head velocity increases when inlet Reynolds number increases. Body velocity increases when inlet Froude number decreases, as gravity force increases when inlet Froude number decreases. Effects of inlet Froude as number on body velocity is negligible at the end of channel. Negative value of body velocity at the interface of turbidity current and ambient fluid indicates entrainment phenomenon at this region. When inlet Froude number decreases, vertical component of velocity increases too,then maximum velocity approaches to the bed. Elevation of maximum velocity increases along the channel due to sedimentation of particles and decreases of vertical component of velocity. Body velocity decreases along the channel due to decrease of inertial force. Vertical Reynolds stress decreases when inlet Froude number decreases. Because of increase in particle turbulence dissipates and therefore vertical Reynolds stress decreases. Oscillation of vertical Reynolds stress is due to turbulence at this region. The maximum of vertical Reynolds stress tacks place near bed and interface of turbidity current and ambient fluid and minimum of vertical Reynolds stress tacks place near maximum velocity elevation. Shear Reynolds stress have two maximum values. One is near the bed and the other one is near the interface of turbidity current and ambient fluid. Maximum Reynolds shear stress is positive near bed and negative near interface. Minimum of Reynolds shear stress take place near maximum velocity elevation.

Volume 14, Issue 1 (March & April 2023 (Articles in English & French) 2023)
Abstract

This study sought to investigate the probable relationships among English as a Foreign Language (EFL) teachers' active/passive motivation, their sense of efficacy, and burnout. To this end, the Active/Passive Motivation Scale (APMS), Teacher’s Sense of Efficacy Scale (TSES), and Maslach Burnout Inventory (MBI) were administered to 245 Iranian EFL teachers. Next, in order to substantiate the construct validity of the APMS, Confirmatory Factor Analysis (CFA) was conducted. Moreover, correlational analyses and Structural Equation Modeling (SEM) were employed to explore the relationships among the variables. The results indicated significant relationships between active/passive motivation and all subconstructs of TSES, between active motivation and all subconstructs of burnout, and between passive motivation and two burnout subscales, namely emotional exhaustion and personal accomplishment. Additionally, while no significant relationship was found between age and the three constructs, the results demonstrated that teaching experience and teacher’s sense of efficacy were positively correlated. Female teachers were also found to be less likely to feel depersonalized. Moreover, mediated by active motivation, teacher efficacy was a significant negative predictor of teacher burnout. Finally, the implications of the study for administrators and teachers were discussed and suggestions were made for further research.

Volume 15, Issue 2 (5-2024)
Abstract

In this study, 50 Staphylococcus aureus samples from Baghdad Hospital were collected and examined, 17 samples were infected with methicillin-resistant Staphylococcus aureus (MRSA) and 5 samples were infected with vancomycin-resistant Staphylococcus aureus (VRSA). The sensitivity of the isolates against different antimicrobial agents was evaluated using the VITEK2 standard system. According to CLSI, the minimum inhibitory concentration (MIC) values of zinc oxide quantum dots (ZnO-QDs) were also tested by the Muller-Hinton dilution method. In addition, polymerase chain reaction (PCR) was performed to identify vanA and mecA genes. The antibacterial effects of ZnO-QDs on VRSA were higher than MRSA isolates.
 

Volume 16, Issue 4 (winter 2016 2016)
Abstract

The government of Iran has faced with budget deficits during 1979 – 2010, which has been financed mainly through money creation. Theoretically, the impacts of budget deficit and inflationary tax on macroeconomy are very controversial, so that both decrease and increase in consumption, investment, net exports and total expenditure have been supported by empirical researches. Using structural cointegrating vector autoregressive, this paper investigates the impacts of inflationary finance on the demand side of Iran’s economy during mentioned period. Budget deficit is defined as the difference between operating budget deficit (minus net operating balance) and capital balance surplus, or net lending (net acquisition of nonfinancial assets). The results show that both operating budget deficit and net lending have positive impacts on consumption, investment and net imports in the short run. So changes in the demand side have not necessarily same orientation with increase or decrease in budget deficits, but the source of change in budget deficit determines its effects. Reducing budget deficits through positive shock to net lending and a policy of increasing operating budget deficit have similar effects. Furthermore, the results show that the operating budget deficit has no effect on demand components in the long run. The complementarity of inflationary tax and financial repression is confirmed in both short run and long run. In addition, the results indicate that an increase in operating budget deficit and/or net lending induce more inflationary tax and financial repression. Although the budget deficit has no effect on demand side in the long run, but its two outcomes -inflationary tax and financial repression- have opposite effects on the consumption, investment and net imports in both short run and long run.
 

Volume 16, Issue 4 (2-2014)
Abstract

Objective: This study investigated tissue damages induced by chronic subcutaneous administration of nano- and microparticles of manganese dioxide (MnO2) on the liver, kidneys and testes of rats. Methods: Rats (n=210) were divided into three groups: control, MnO2 nanoparticle injected and MnO2 microparticle injected. The experimental groups received subcutaneous injections with either nano- or microparticles of a solution that contained MnO2 (100 μg/kg) once per two weeks for 14 weeks. Once every two weeks, we randomly selected five rats from each group for histological evaluations of the liver, kidneys, and testes. Tissue lesions were initially evaluated by hematoxylin and eosin staining, then kidney and liver tissue sections were stained by the Jones and Masson's trichrome methods, respectively. The changes in diameter of basement membrane and cell numbers of the various parts of the nephrons in different groups were measured by Image Tools version 2 software. Results: The liver tissues of the nano- and microparticle groups exhibited severe damage histopathologically. Cloudy swelling was observed in the cytoplasm of hepatocytes. The liver tissue and its canaliculi structures were severely damaged. Inflammation and ductular reaction signs were seen in liver tissue. Deposition of particles in the basement membrane of the nephrons were observed in the nanoparticle-treated group. There was a significant reduction in glomerular and tubular cells in the nanoparticle-treated group compared to the control and microparticle-treated groups. Some of the structural and functional parameters of the testes in the nanoparticle-treated group had significant pathobiological variations. Conclusion: Administration of MnO2 nanoparticles when compared with the same dose of MnO2 microparticles caused more tissue damage in all examined tissues. Reduction in particle size from micrometer to nanometer appeared to exacerbate the damaging mechanisms of these particles in the examined tissues.

Volume 16, Issue 95 (January 2019)
Abstract

Gums are long chain polysaccharides components with high molecular weight wildly used in the food and many other industries as stabilizer, texture modifier, gelling agent, thickener and emulsifier. The aim of this study was to investigation evaluation of physicochemical and emulsifying properties of protein-free balangu seed (Lallemantia royleana) gum. The results showed, balangu and protein-free balangu were obtained from molecular weight 3120 and 3360 kDa, respectively. Major functional groups were identified from FTIR spectrum of balangu and protein-free balangu, include O-H, C-H, C=O, -COO-, and C-O-C. The results of GC-MS showed that the major monosaccharides specified in Glucose, Galactose, Arabinose, Xylose and Rhamnose. According to the rheological protein-free balangu had the lowest protein content and this led to formation of large oil droplet size and lower emulsion stability. The parameters of Herschel–Bulkley model were showed, the values of coefficients of determinations (R2) were near to 1 and Root Mean Square Error (RMSE) values were lower than 0.4, which indicate the suitability of this model to describe the flow behaviour of samples. Moreover all emulsions represented flow behaviour index values less than 1, which reveals shear thinning behaviour of emulsions, but no significant difference was found between emulsions (p>0.05). On amplitude sweep test, the storage modulus values were greater than loss modulus values in all emulsions, which indicates their elastic behaviour. On frequency sweep test, the storage modulus values were greater than loss modulus values in all emulsions, which confirmed solid like behavior. The indices of power law’s storage modulus balangu and protein-free balangu emulsions had near to zero which reflect high elastic behaviour of emulsion.
 

Volume 17, Issue 5 (12-2017)
Abstract

Full factorial investigation is necessary in the study of the hydraulic phenomena which are function of different variables with different levels. It is logical to use the full factorial method when the number of variables and their levels are low. However, sometimes due to lack of time and shortage of financial restrictions, using the full factorial method is not possible. The Taguchi method, which is used for design of experiments, uses the fractional factorial instead of full factorial. This method not only decrease the number of studies but also guaranties the correlated comparison of all variables. In this paper the Taguchi method is used for finding the optimized hydraulic parameters like length and location of spur dike in different Froude Numbers in 90 degree bend. Furthermore, the comparison between the Taguchi method and full factorial is done for the number of investigations, finding the optimized level for each parameter and the time needed for study. In order to get the results, the parameters of length, location of spur dike in 90 degree bend, and the Froude Number are considered with three different levels. The SSIIM numerical model is applied to simulate the studies designed by Taguchi and full factorial methods. The results show that the Taguchi method, could predict the optimum parameters only with 9 studies whereas with full factorial method 27 studies was necessary. Also, using Taguchi method leads to more than 66% decrease in the total running time. For studies designed by Taguchi method, the optimum value of length of spur dike is the as one designed by Full factorial method. Also, the length of spur dike is the most effective parameter on flow pattern around spur dike and the position of spur dike and Froude Number are next in rank, respectively. These results are the same for two methods used to design of studies. Using 9 studies designed by Taguchi method, investigation of the effect of other parameter such as the angle of the spur dike is possible without changing the number of studies, whereas 81 studies should be done by full factorial method.
Full factorial investigation is necessary in the study of the hydraulic phenomena which are function of different variables with different levels. It is logical to use the full factorial method when the number of variables and their levels are low. However, sometimes due to lack of time and shortage of financial restrictions, using the full factorial method is not possible. The Taguchi method, which is used for design of experiments, uses the fractional factorial instead of full factorial. This method not only decrease the number of studies but also guaranties the correlated comparison of all variables. In this paper the Taguchi method is used for finding the optimized hydraulic parameters like length and location of spur dike in different Froude Numbers in 90 degree bend. Furthermore, the comparison between the Taguchi method and full factorial is done for the number of investigations, finding the optimized level for each parameter and the time needed for study. In order to get the results, the parameters of length, location of spur dike in 90 degree bend, and the Froude Number are considered with three different levels. The SSIIM numerical model is applied to simulate the studies designed by Taguchi and full factorial methods. The results show that the Taguchi method, could predict the optimum parameters only with 9 studies whereas with full factorial method 27 studies was necessary. Also, using Taguchi method leads to more than 66% decrease in the total running time. For studies designed by Taguchi method, the optimum value of length of spur dike is the as one designed by Full factorial method. Also, the length of spur dike is the most effective parameter on flow pattern around spur dike and the position of spur dike and Froude Number are next in rank, respectively. These results are the same for two methods used to design of studies. Using 9 studies designed by Taguchi method, investigation of the effect of other parameter such as the angle of the spur dike is possible without changing the number of studies, whereas 81 studies should be done by full factorial method.

Volume 17, Issue 11 (1-2018)
Abstract

Hybrid joints (Metal–Composite) is being used more and more in aerospace industry due to their low weight and high strength. Dynamic study of this joint, owing to limitation of increase in screw’s preload in composite substructure, has certain importance. Effective factors on nonlinear behavior of the joint are low preload of the screw and high excitation force amplitude on the structure. Layer Element Model has been used to better the description of joint’s behavior in recent years. In this study effects of nonlinear behavior of joint on the structure has been investigated using 2D layer element theory in two divisions: increase of damping and decrease of stiffness which result in nonlinearity. Stiffness characteristics of the joint was modeled with normal stiffness and damping characteristics of the joint with structural damping in shear direction. Nonlinear frequency response function for two preload and two excitation force was extracted and nonlinear finite element model for stiffness and damping of the joint is suggested by High-order polynomial approximation in terms of response amplitude. Effects of increase of excitation force amplitude and decrease of screw’s preload on increase of nonlinearity was extracted by this finite element model. Results indicate that presented nonlinear finite element model corresponds closely to nonlinear vibration tests.

Volume 18, Issue 1 (3-2018)
Abstract

This paper presents an improved approach for handling stress constraints in minimum weight topological design. The Finite Element Method (FEM) and the material model of Solid Isotropic Material with Penalization (SIMP) is used to formulate the topology optimization problem. To evaluate the stress values in elements, the von Mises stresses are calculated at the so called super-convergent Gauss quadrature points. To reduce the time and computational cost, a clustering approach is here adopted and the P-norm integrated stress constraints are used. Doing this, a large number of local constraints are replaced with a few global ones and consequently the stress constraint sensitivities are calculated by using the adjoint method. The employed formulation as well as a complete explanation of the sensitivity analysis is provided. Due to the complexity of the topology optimization problem in the presence of stress constraints, the Method of Moving Asymptotes (MMA) is here employed. To demonstrate the performance and capability of the procedure, a couple of plane stress elasticity problems are taken into consideration. The resulted layouts indicate the superiority of the approach in generating acceptable and practical topological designs.

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