Esfe, M.H.,
Esmaily, R.,
Khabaz, M.K.,
Alizadeh, A.,
Pirmoradian, M.,
Rahmanian, A.,
Toghraie, D. Publication Date: 2023
Tribology International (0301679X)178
In this study, a unique incorporated version is presented to enhance the dynamic viscosity of MWCNT- Al2O3 (40:60)/Oil 5W50 hybrid nanofluid (HNF) the usage of the 3 maximum vast and vital powerful parameters corresponding to temperatures, solid volume fractions (SVFs) and shear rates (SRs). An empirical relationship between energy consumption and these characteristics is presented. Thus, ANNs are used to develop a high-level data analysis model to predict the dynamic viscosity of MWCNT-Al2O3 (40:60)/Oil 5W50 HNF. A sensitivity analysis is employed to assess the importance of various parameters of MWCNT- Al2O3 (40:60)/Oil 5W50 HNF dynamic viscosity and the position of temperature, SVF and SR in simulation. It is found that the highest dynamic viscosity values are observed at temperatures below 5 °C. In addition, the dynamic viscosity is reduced by SR changes from 0 rpm to 800 rpm. Statistical analysis shows that the model performance is nearly equal, ranging between 0.98, 0.978, and 0.925, and that the errors are less than 2.6 % for the training, testing, and validation phases, respectively. Overall, it could be determined that the ANN simulation can generate the connection between the measured dynamic viscosity and anticipated dynamic viscosity of HNF. © 2022 Elsevier Ltd
Publication Date: 2018
Journal of the History of Philosophy (00225053)28(21)
At the beginning of the establishment of the Islamic government, the Messenger of God (SAWS) started to take purposeful measures in order to strengthen his newborn governance. One of his outstanding measures was to codify a general treaty among all the people of Medina including the Jews, which allowed for peaceful coexistence in the town. Among the Jewish tribes inhabiting Medina, Banu Qaynaqa' signed the treaty with the Messenger of God. However, for some reasons to be discussed in the article, later on they took the pathway of hostility and enmity to Islam and the Prophet. Having become unable to oppose the Prophet and Muslims, eventually they surrendered and were banished from Medina in accordance with the divine decision. The opposition between Banu Qaynaqa' and the Messenger of God is among the cases addressed by Quran. The present article aims to answer the question what is the Quran's attitudinal and authorship approach to the opposition. In view of the philosophy of the revelation of Quran, i.e. the guidance of the humankind, it seems that the Qur'anic historical working-through of historical events including Ghazwa Banu Qaynaqa' is unique from both attitudinal and authorship perspectives and directed at the objective of guidance, which distinguishes Quran from historical sources. © 2018 Johns Hopkins University Press. All rights reserved.
Publication Date: 2021
Thin-Walled Structures (02638231)169
In this study, using modified strain gradient theory (MSGT) and the first-order shear deformation assumption (FSDA) framework, wave propagation through air-filled double-walled functionally graded (FG) cylindrical microshells subjected to linear and non-linear thermal loadings are investigated. MSGT has the advantage of having up to three scale parameters and can successfully reproduce size effects. The power-law model is used to express the distribution of material characteristics over the thickness of each shell due to characteristics varying by temperature, and the application of Hamilton's principle results in deducing vibroacoustic equations in coupled relations. The size-dependent coupled vibroacoustic governing equations are solved using an analytical approach in conjunction with a double Fourier series, with the final result providing the appropriate Sound Transmission Loss (STL) equation. The developed solution's accuracy and precision are examined by comparing it to data available from previous studies. Parameter studies reveal the impacts of temperature distribution, functionally graded index, incident angles, acoustic cavity depth, and length scale parameter on STL through double-walled FG cylindrical microshells. © 2021
Gao, X.,
Abbas, W.N.,
Al-zahy, Y.M.A.,
Al-bahrani, M.,
Kumar, N.,
Hanoon, Z.A.,
Salahshour, S.,
Pirmoradian, M. Publication Date: 2024
Physica A: Statistical Mechanics and its Applications (03784371)653
Most studies considered metal matrix nanocomposites (NCs) because of their excellent mechanical and electrical properties. In recent years, external electric fields (EEFs) in the aforementioned NCs were identified as a crucial role in modulating mechanical behavior. The EEF may affect strength, hardness, ductility, and fracture toughness. The explanation for these changes is the interaction of EEF with the nanoparticles in the metal matrix. In the present study, the effects of various EEF values on the mechanical properties of Al/Cu/Al three-layer NCs (TLNCs) were assessed using the molecular dynamics (MD) modeling method and LAMMPS software. MD findings predicted that the EEF reduced the physical stability and mechanical strength of modeled samples. Physically, this performance resulted from a decrease in attraction force among distinct particles inside the computing box in the presence of EEF. The proposed samples' ultimate tensile strength (UTS) and Young's modulus (YM) decreased to 2.587 GPa and 20.19 GPa, respectively, when the EEF value increased to 0.05 V/Å. Finally, it was determined that EEF is a crucial parameter in the mechanical development of MMNC structures and should be used in mechanical bacterial design in industrial applications. © 2024 Elsevier B.V.
Hussein, S.A.,
Omar, I.,
Saddam, A.B.,
Baghoolizadeh, M.,
Salahshour, S.,
Pirmoradian, M. Publication Date: 2024
International Journal of Thermofluids (26662027)24
While machine learning has become the new way of analyzing data, neutral networks form the basis of this revolutionary technology. In this work, we shall employ the power of neural networks to analyze and demystify the processes in nanofluids. By combining the precision of neural networks with the optimization capabilities of genetic algorithms, we aim to create a more accurate and efficient prediction model for MWCNT-alumina/water-ethylene glycol (80:20) hybrid antifreeze. Our approach entails using an MLP neural network and several training functions (LM, GD, BFGS, BN) with an adjustable number of neurons. The inputs of the network are φ (solid volume fraction or ϕ), temperature (T), and shear rate (γ), and the output is μnf of MWCNT-alumina/water-ethylene glycol (80:20) hybrid anti-freeze. To improve the accuracy of the final model, we use genetic optimization to make final adjustments to the parameters of the neural network. Utilizing the detailed analysis of the primary characteristics of these algorithms, we conclude that the BFGS function is the best to obtain neural network training. Steady performance achieved by this function—0.99828 of the R-value and RMSE value significantly equal to 0.213—illustrates good stability and accuracy of the suggested model. This work contributes to progressing the existing knowledge about the behavior of nanofluids and can stimulate further improvement in heat transfer and energy utilization. © 2024 The Author(s)
Publication Date: 2018
Iran and the Caucasus (16098498)22(2)pp. 123-138
In the reports of Chinese travellers submitted to the Emperors, they mentioned the places they had visited or heard of. Although some scholars have tried to identify these Chinese names as specific places in the Iranian Plateau and its bordering plains, their locations are still somewhat vague and debatable. This article discusses the place-names mentioned in Chinese sources and attempts to verify that they could have denoted the localities along the ancient Great Khorasan Road and other routes, which were once the main sections of the Silk Road. Among them, the route that Chinese traveller Gan Ying might have passed before he reached the western frontier of the Arsacid Empire will also be discussed in this study. © Koninklijke Brill NV, Leiden, 2018.
Publication Date: 2021
Iran (05786967)
In sociology, social institutions constitute the most essential institutions, exhibiting their functionality in different aspects in the society, as to cope with the evaluation of social disorders’ management at mega-scale. During Safavid era, based on rational reactive sequential pattern, leading to chain reactions, the core of a special trade institution was established in Iran’s traditional society that lasted until the beginning of Qajar era. The inseparable connection of domestic economy with the political structure next to other influencing factors promoted this move. Following the trade recession and gravity in life condition especially among the tradesmen next to the prepared grounds, due to the injustice on local authorities’ part during Shah-Tahmasp Safavi, the social disobedience began and ended for two years (1571–1573 AD). This article is inspired by the historical institutionalism theory and is presented through a descriptive-analytic method. By applying sociological approaches in the historical events attempt is made to search for a proper answer to the question: By applying the institutionalisation theory approach, to what extend have the political, social and economic factors been effective in the formation of the tradesmen rebellion in Tabriz during Shah-Tahmasp Safavi’s era?. © 2021 British Institute of Persian Studies.
Publication Date: 2018
Journal of Mechanics (18118216)34(4)pp. 483-494
This study investigated the effects of considering surface and nonlocal energy parameters on the buckling analysis of double piezoelectric nanoplate (DPNP) embedded in elastic foundations and thermal environments. Both in-phase and out-of-phase modes of buckling and various boundary conditions are studied and compared with each other. The governing equations were derived by drawing on the principle of virtual work and then solved by employing the finite difference method. Finite difference solution was validated using Navier's method and journal references. A parametric study was also launched in order to investigate the effects of the external electric voltage, nonlocal parameters, different boundary conditions, elastic foundations and thermal environments on the surface effect of DPNP buckling. The obtained numerical results showed that the influence of surface stress on in-phase and out-of-phase modes of buckling of the DPNP was enhanced by augmenting the nonlocal parameters and external electric voltage; on the other hand, it was found to be decreased by increasing elastic foundations and temperature changes. In addition, the value of surface stress effects for the in-phase mode was higher than that of the out-of-phase one. Copyright © The Society of Theoretical and Applied Mechanics 2018.
Askarpour, V.,
Khalili, M.,
Mottaghi, N.,
Sangari, E.,
Moghaddas, A. Publication Date: 2021
Iranica Antiqua (00210870)56pp. 261-275
Annual sacrifice of bull is a local ritual performed in one of the villages near Tabriz, known as Esfanjān. The ritual contains some features in terms of its date of exercise, its eminent emphasis on the bull, and the narrative which surrounds it, that absolutely take it apart from the current religious context of the village's inhabitants, Islam. The present paper concerns with resolving this dilemma by looking for its possible pre-Islamic roots, through an in-depth examination of sacrifice within Avestan traditions. Through a consideration of sacrifice and its status within pre-Islamic religious traditions of Iran, and comparing their basic features with findings of ethnographical observations, it is shown that there is a tight match between the observed cult and pre-Islamic doctrines on animal sacrifice. As a relevant theoretical framework, syncretism is adapted here to discuss the hybrid nature of the Esfanjān event, which is composed of both Islamic and non-Islamic features. Although the exact origin of the Esfanjān bull sacrifice remains unknown, something is clear: it is not a passive remnant of something lost forever, but an active product of a creative process, through which some new and hybrid creature comes out of a successful interbreeding of two different belief systems. © 2021 Peeters Publishers. All rights reserved.
Zhang, Q.,
Li, X.,
Ali, A.B.,
Sawaran singh, N.S.,
Yazdekhasti, A.,
Pirmoradian, M.,
Marzouki, R. Publication Date: 2025
Case Studies in Thermal Engineering (2214157X)72
The increase in performance of home heaters, accompanied by energy and environmental crises, becomes noticeable in the construction industry. Hence, this paper has investigated a solution to enhance the system's efficiency. For this purpose, a novel experimental set-up is provided to simulate the heater, exhaust heater, and indoor environment. This setup includes two boxes, a heat source controlled by a Proportional Integral Derivative (PID) controller and an aluminum box with copper tubes. The heat is transferred from the first box as a heater to the aluminum box as a heat exhaust by the air force of the fan to warm the second box. Also, Lauric acid as a phase change material (PCM) and metal foam are used to increase heat absorption and heat transfer inside the heater exhaust regarding the thermal and physical properties of these two materials. Seven temperature sensors are located in different places to evaluate and control the system. Moreover, 6 modes are designed to find the best arrangement of materials for improving the system. The results show that a new arrangement of materials defined as filling the aluminum box with PCM and covering this box with metal foam, acquires remarkable efficiency. According to the achieved data, the mentioned design can decrease the outlet temperature of exhaust up to 2.3 ± 0.1 °C as well as increase the second box temperature in a home environment to 1.6 ± 0.1 °C. Finally, this mode can improve the efficiencies of the system both in outlet temperature and indoor temperature of the second box as much as 4.73 ± 0.1% in the former and 3.72 ± 0.1% in the latter. © 2025 The Authors.
Sawaran singh, N.S.,
Ali, A.B.,
Abed hussein, M.,
Mohammed, J.K.,
Kharraji, O.,
Pirmoradian, M.,
Hashemian, M.,
Salahshour, S. Publication Date: 2025
Case Studies in Chemical and Environmental Engineering (26660164)11
This study aims to explore the dynamic instability of micro and nano-sized Timoshenko beams as they are traversed by sequentially moving nanoparticles. The beams, characterized by a rectangular cross-section and homogeneity, are situated within a Pasternak foundation, which provides a supportive elastic medium. The research investigation determines nanoparticle inertia effects at velocity while establishing motion equations through Hamilton's principle. The model unites nonlinear von Kàrmàn strain-displacement kinematics with strain gradient theory and Gurtin-Murdoch small-scale accounting. The system's behavior gets analyzed through the implementation of Galerkin method which derives time-periodic motion equations. The incremental harmonic balance approach develops stability boundary maps that separate stable and unstable regions through which analysts can examine parameter spaces containing moving particle mass and velocity values. This study evaluates how different parameters like beam diameters together with small-scale characteristics and elastic medium constants and residual stress and axial compressive forces affect the stability diagram. The analysis demonstrates that stability parameters become substantially modified when researchers include length scale characteristics along with surface effects. The outcome reveals that axial compressive forces reduce stability yet environmental effects strengthen the stability of small-scale beams which leads to transition curve movements towards faster moving particles velocities. This study contributes fundamental knowledge about dynamic instability effects in small-scale beams which will help future advances in nanotechnology and materials science. © 2025 The Authors
Publication Date: 2026
Ancient Iranian Studies (28212215)5(14)pp. 115-126
Daštān is a Persian word meaning the menstrual cycle that happens to every girl after puberty. In Zoroastrianism, the menstrual cycle is tied to mythology so that they believed it occurred after the Ahriman’s kiss on the forehead of Jahī (Demoness of lasciviousness). The consequence of this belief about menstruation (Daštān) resulted in strict rules to prevent pollution and impurities of sacred elements. Most rules were written in post-Sasanian texts. The obligations of a woman in time of Daštān were stated in those texts. This research describes and analyzes the issue of Daštān in texts based on literary evidence. It examines whether the strict laws surrounding Daštān originated from religious laws or were rooted in myth, and what attitude towards women they created. Studies show that Daštān was considered filthy. Since the menstrual cycle is a periodical condition, a set of rules were conducted for women to obey in order to prevent the spread of pollution. In spite of negative ideas in some texts including Bundahišn and Zādspram about this issue, there were no negative approaches towards women. © 2026 The Author(s).
Publication Date: 2020
Journal Of The Brazilian Society Of Mechanical Sciences And Engineering (16785878)42(12)
The purpose of this work is to design and fabricate a balanced passive robotic arm with the capability of applying variable mass to the end-effector in order to upper limb rehabilitation. To achieve this purpose, the first step is associated with establishing a robot structural design in the CAD environment. The next step is focused on developing the kinematic model based on the degrees of freedom and joint range of motion of the lower legs. Thereafter, the potential energy functions are determined for the springs and weight of components applied in the mechanism. The genetic algorithm is employed as a proper optimization program to extract the system design parameters, including the spring stiffness coefficients and their placement positions within the system. A prototype is fabricated for a balanced robot, and the end-effector mass variations are utilized to develop an adjustable balance capability. To create balance in the system, several items are designed, consisting of a control panel, two electric motors, and an electronic processor. This situation provides an equivalent force equal to the weight of selected mass from the end-effector to the user’s hand. (It is done by a reverse process.) The actual mass required for robot balance is compared to the mass defined in the simulation environment. The evaluation results indicate that it is possible to create an optimized balance by using the simulation outputs. © 2020, The Brazilian Society of Mechanical Sciences and Engineering.
Publication Date: 2023
Heliyon (24058440)9(9)
This paper examines the design and fabrication of a soft robot that can connect to a virtual reality environment. This study's primary objective is to utilize these technologies concurrently and demonstrate their applicability in various applications, particularly rehabilitation. Therefore, the process of designing and modeling the soft robot is carried out, and an applied model is created using a 3D printer and silicon material, which is then installed on gloves. Using Unity software, a virtual reality environment is created in which programs, commands, and Arduino processors control the movements of the soft robot, allowing the user to move and pick up an object in a real environment while wearing gloves, and to adjust the amount of pressure and angle of its motion based on the size of each virtual object. During the system evaluation phase, a delay in the performance and reaction time of the soft robot installed on the gloves is observed. This delay is reduced by modifying the programming structure, resulting in optimal system functionality. This capability is used to create proper mobility conditions and rehabilitation for the majority of patients with wrist injuries resulting from strokes and accidents, and it may be effective in accelerating patients' recoveries. © 2023 The Authors
Hashemian, M.,
Jasim, D.J.,
Mohammad sajadi s., S.M.,
Khanahmadi, R.,
Pirmoradian, M.,
Salahshour, S. Publication Date: 2024
Heliyon (24058440)10(9)
This research studied the dynamic stability of the Euler-Bernoulli nanobeam considering the nonlocal strain gradient theory (NSGT) and surface effects. The nanobeam rests on the Pasternak foundation and a sequence of inertial nanoparticles passes above the nanobeam continuously at a fixed velocity. Surface effects have been utilized using the Gurtin-Murdoch theory. Final governing equations have been gathered implementing the energy method and Hamilton's principle alongside NSGT. Dynamic instability regions (DIRs) are drawn in the plane of mass-velocity coordinates of nanoparticles based on the incremental harmonic balance method (IHBM). A parametric study shows the effects of NSGT parameters and Pasternak foundation constants on the nanobeam's DIRs. In addition, the results exhibit the importance of 2T-period DIRs in comparison to T-period ones. According to the results, the Winkler spring constant is more effective than the Pasternak shear constant on the DIR movement of nanobeam. So, a 4 times increase of Winkler and Pasternak constants results in 102 % and 10 % of DIR movement towards higher velocity regions, respectively. Furthermore, the effect of increasing nonlocal and material length scale parameters on the DIR movement are in the same order regarding the magnitude but opposite considering the motion direction. Unlike nonlocal parameter, an increase in material length scale parameter shifts the DIR to the more stable region. © 2024 The Authors
Publication Date: 2025
Research On History Of Medicine (2251886X)14(2)pp. 155-164
In Persian medicine, the concepts of patient and disease, medicine, and treatment are based on the Iranian-Islamic worldview. In this kind of philosophy, they believed that in the human body, the three members (the heart, the brain, and the liver) are the chief due to the vital actions they perform for the body, and they are called the board members (Major vital organs or Azayeh Reiseh). The remaining bodily organs operate as subordinates to these principal members. Each of the Physicians examined in this study has different opinions about the priority of the board members. The main purpose of the research is to review and compare the Physicians’ opinions about the priority of the board members, relying on historical sources and citations and using the library method. The findings of this research show that the sages of Eastern Islamic civilization do not agree with the members of the body board. © Journal of Research on History of Medicine.
Carbon nanotubes are widely used in the design of nanosensors and actuators. Any defect in the manufactured nanotube plays an important role in the natural frequencies of these structures. In this paper, the effect of vacancy defects on the vibration of carbon nanotubes is investigated by using an atomistic modeling technique, called the molecular structural mechanics method. Vibration analysis is performed for armchair and zigzag nanotubes with cantilever boundary condition. The shift of the principal frequency of the nanotube with vacancy defect at different locations on the length is plotted. The results indicate that the frequency of the defective nanotube can be larger or smaller or equal to the frequency of perfect one. The results also show that with the reduction in the tube length, the variations of principal frequency are enhanced. However, the frequency variation is insensitive to the nanotube diameter. As the number of vacancy defects increases, shift in the natural frequency also increases as expected. © 2008 IEEE.
Firouzkouhi, M.,
Alimohammadi n., N.,
Kako, M.,
Abdollahimohammad, A.,
Bagheri g., ,
Nouraei, M. Publication Date: 2021
Ethics, Medicine and Public Health (23525533)18
Introduction: The COVID-19 pandemic is a social problem. Nurses face ethical challenges in providing care activities related to COVID-19. Aim: Therefore, this study aimed to explore the ethical challenges of nurses in COVID-19 pandemic. Method: This is an integrative review study conducted from 2007 to 2020. Databases of PubMed, Google Scholar, Scopus, Web of Science were searched. The results of the eligible studies (12 cases) were analyzed. Results: A total of 228 articles satisfied the inclusion criteria, and 12 articles were selected for analysis. The study units showed that the ethical challenges of nurses in caring for patients with COVID-19 consisted of three areas, including nursing; patient and family; and treatment equipment and facilities. Conclusion: Providing care for patients with COVID-19 pandemic has increased nurses’ ethical challenges. Therefore, nurses need to pay more attention to not face psychological problems and premature burnout. © 2021 Elsevier Masson SAS
Pirmoradian, M.,
Naeeni, H.A.,
Firouzbakht, M.,
Toghraie, D.,
Khabaz, M.K.,
Darabi, R. Publication Date: 2020
Computer Methods and Programs in Biomedicine (01692607)187
Background and Objective: The dental implant is one of the long term proper remedies to recover a missed tooth as a different prosthetic rehabilitation way. The finite element (FE) method and photoelasticity test are employed to achieve stress distribution and sensitivity in dental implants in order to obtain optimum length and thread pitch. Methods: The finite element method and experimental test are developed to evaluate stress distribution and sensitivity around dental implants. Three dimensional FE models of implant-abutment, cortical bone and cancellous bone are created by considering a variation of 0.6 to –1 mm on threads pitch while the implant lengths range from 8.5 mm to 13 mm. Then, axial and oblique forces are applied to the models to obtain the resultant stress contours. Results: The results indicate that the resultant von Mises stresses in the implant-abutment, cortical bones, and cancellous bones are different. The optimized setting for length and pitch is suggested according to maximum von Mises stress and sensitivity analysis. Conclusions: It is concluded that the present FE model accurately predicts stress distribution pattern in dental implants. The results indicate that sensitivity of length play a more significant role in comparison with thread pitch. The accuracy of FEM results in comparison with those of the photoelasticity test recommends applying computation methods in medical practice as great potential in terms of future studies. © 2019
Publication Date: 2011
Journal of the Royal Asiatic Society (14740591)21(2)pp. 131-145
The issue of the purchase of land in one country, in this case Iran, by other countries, in this case Britain and Russia, is one of great significance because of light it may throw on the strength or weakness of national sovereignty, and the ways and degree to which it may be undermined.1 It can also show the strategies deployed by the country challenged to protect its territorial integrity, as here in the case of Iran. The intricacies of foreign landownership patterns thus have implications for international relations, on which they can provide telling detail in terms of contemporary power politics. The details of land purchase also demonstrate considerable differences as between the two outside powers involved in terms of their objectives in Iran, and thus challenge a tendency in the literature to see them as similar. At the same time, from this particular study, Qajar Iran, which is so often represented as weak, näýve and ineffectual in the face of the challenge of great power intervention, emerges as having dealt skilfully with this particular form of intrusion with a variety of stratagems that were not without success for much of the nineteenth century. Finally, the whole issue can be demonstrated as having become inextricably entwined with internal policies of reform which sought to strengthen the government of Iran by centralisation and growing taxation on those who were hitherto exempt. This movement, however, which occurs late in the period, that is to say in the early twentieth century, was to stall during its very weak second decade. Despite the significance of the subject of foreign land ownership and tenancies in Iran in the Qajar period, no detailed study of it exists. Issawi notes that there was a considerable amount of land purchase in Astarabad, Gilan and Azerbaijan byRussian subjects,who became settled there during the second half of the nineteenth century.2 In 1864 Eastwick observed that Gilan was the residence of a large number of Russian prot́eǵees.3 They were especially dominant in Rasht, where they held entire villages by right of mortgage. However, as will be shown, the picture was more complex than it appeared, it varied from region to region, and in particular there was a contrast between the north and the British-dominated south. The nature of the claims of foreigners on land also evolved over time, much depending on the impact of the central government and of foreign trade. Within this framework the present study sets out to examine broadly the ways in which land was acquired between the signing of the Treaty of Turkmanchai in 1828 and the breakdown of Iranian government central control by 1911. It will consider not only claims and ownership themselves, but also the ways in which land was acquired and by what rights, including the legal arguments deployed for and against foreign ownership and leaseholds. It is hoped that the article will thereby trace changes in Iran both in terms of foreign relationships and influence, and in internal development. © 2011 The Royal Asiatic Society.
Mottaghi, A.,
Mokhtarian, A.,
Hashemian, M.,
Pirmoradian, M.,
Salahshour, S. Publication Date: 2024
Forces in Mechanics (26663597)17
This research investigates the free vibrational behavior of a functionally graded porous (FGP) nanoplate resting on an elastic Pasternak foundation in a hygrothermal environment. The nanoplate is modeled based on the nonlocal strain gradient theory (NSGT) and considering several plate theories including the CPT (classical plate theory), the FSDT (first-order shear deformation theory), and the TSDT (third-order shear deformation theory). Several patterns are investigated for the dispersion of pores, and the surface effects are incorporated to enhance the precision of the model. The governing equations and boundary conditions are derived via Hamilton's principle and an exact solution is provided via the Navier method. The impacts of several parameters on the natural frequencies are inspected such as length scale and nonlocal parameters, surface effects, porosity parameter, hygrothermal environment, and coefficients of the foundation. The results show that the impact of the porosity parameter on the natural frequencies of nanoplates is significantly dependent on the porosity distribution pattern. It is discovered that by increasing the porosity parameter from 0 to 0.6, the relative changes of natural frequencies vary from a decrease of 30 % to an increase of 6 %. © 2024 The Author(s)
Publication Date: 2025
Persica Antiqua (27832732)5(8)pp. 19-33
The Territorial conquests of the Medes, as Far East as Hyrcania, could be traced from the first half of the seventh century BC onwards. The first Median kings undertook far-flung campaigns to take control of the region and extend their territory. The existence of the fortified settlement in the Gorgān plain could prove the expansion of centralized Median kingdom as far as Hyrcania. The Assyrian sources of the 9th to 7th century BC are also in overall agreement with the results of the archeological studies in the western steppe of Gorgān plain (Hyrcania). As a result, the Median’s dominance over Hyrcania determined the strategies and political guide-lines of the Median kingdom and set the foundations for its transformation from a confed-eration of tribes to a powerful trans-regional state. Accordingly, in the present paper, beside historical and literary sources, archaeological evidences have also been studied in order to determine the Median’s range of territory in the east of their homeland. © 2025 The Author(s).
Publication Date: 2024
Journal of Archaeological Studies (22519297)16(1)pp. 253-275
The bear hunting silver plate housed in the Abkhazia Museum stands out as a distinctive example of artwork from the Sasanian period. Its portrayal of bears being hunted, alongside the utilization of a lasso as the primary hunting instrument, renders it a unique specimen among Sasanian hunting vessels. This study employs an iconographic analysis approach to investigate the scene depicted on the plate, which has been previously attributed by Lukunin to Bahram I, the fourth ruler of the Sasanian dynasty, prior to his ascension to the throne. The objective of this research is to offer a comprehensive analysis of the entire scene depicted on the plate, followed by a detailed examination of each motif in isolation. Finally, an evaluation is provided regarding the realism or symbolism inherent within the scene, drawing upon available information. This study constitutes a descriptive-analytical inquiry into ancient Iranian art, drawing upon data collected from both library sources and online visual repositories. © 2024 University of Tehran. All rights reserved.
Publication Date: 2019
Acta Mechanica Sinica/Lixue Xuebao (16143116)35(1)pp. 242-263
Parametric resonance is one of the most important issues in the study of dynamical behavior of structures. In this paper, dynamic instability of a moderately thick rectangular plate on an elastic foundation is investigated in the case of parametric and external resonances due to periodic passage of moving masses. The governing coupled partial differential equations (PDEs) of the system, with consideration of the first-order shear deformation theory (FSDT) or Mindlin plate theory, are presented and they are reduced to a set of ordinary differential equations (ODEs) with time-dependent coefficients using the Galerkin procedure. All inertial components of the moving masses are adopted in the dynamical formulation. Instability survey is carried out for three different loading trajectories considerably interested in many practical applications of the issue, i.e. rectilinear, diagonal and orbiting trajectories. In order to analyze the resonance conditions, the incremental harmonic balance (IHB) method is introduced to calculate instability boundaries, as well as external resonance curves in parameters plane. A comprehensive study is done to assess effects of thickness ratio and foundation stiffness on the resonance conditions. It is found that an increase in the plate’s thickness ratio leads to a reduction in values of critical parameters. Moreover, it is observed that increasing the foundation stiffness moves the instability regions and resonance curves to higher frequencies of the moving masses and also leads to further stability of the parametrically excited system at lower frequencies. Time response simulations done via Runge–Kutta method confirmed the results predicted by IHB method. © 2018, The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences and Springer-Verlag GmbH Germany, part of Springer Nature.
Publication Date: 2016
Acta Mechanica (16196937)227(4)pp. 1213-1224
The problem of an elastic beam under the periodic loading of successive moving masses is investigated as a pragmatic case for studying dynamic stability of linear time-varying systems. This model serves to highlight the odds of multi-solutions coexistence, a form of hidden instability which reveals dangerous as it may be precipitated by the slightest disturbance or variation in the model. Since no engineering model perfectly represents a physical system, such situations for which Floquet theory naively predicts stability are potentially inevitable. The harmonic balancing method is used in order to thoroughly explore the stability diagrams for detecting these instability gaps. Although this phenomenon has also been described in other physical systems, it has not been addressed for beam–moving mass systems. This result may find particular importance in applications involving self-induced vibrations of elastic structures and hence also appears of practical relevance. © 2016, Springer-Verlag Wien.
Ali, A.B.,
Al-zahiwat, M.M.,
Fadhil, D.A.,
Nemah, A.K.,
Salahshour, S.,
Pirmoradian, M. Publication Date: 2024
International Journal of Thermofluids (26662027)23
Fossil fuels cause global warming and create greenhouse gases that cause irreparable environmental damage. On the other hand, because the combustion reactions are not completely done, dangerous compounds, such as nitrogen or carbon monoxide are produced which are very toxic and dangerous. As a result, innovative methods were implemented in combustion processes. One such method is to use a catalyst during the combustion process. This study used a molecular dynamics method to examine how the concentration of CuO[sbnd]CeO2 catalyst affected air-methane combustion in a helical microchannel. The results show that the maximum (Max) values of density (Dens), velocity (Velo), and temperature (Temp) in the excess oxygen (EO) state were 0.142 atoms per second, 0.35 Å/ps, and 1089 K, respectively, when the atomic ratio of CuO[sbnd]CeO2 increased from 1 % to 4 %. Subsequently, these values exhibited a declining trend. Also, the values of heat flux (HF), thermal conductivity, and combustion efficiency in 4 % catalyst reached the max values of 2038 W/m2, 1.15 W/m·K and 88 %. The results related to the max values of Dens, Velo, and Temp for the oxygen deficiency state had a similar trend and increased to the max values of 0.103 atom/Å3, 0.41 Å/ps, and 1024 K in 4 % catalyst, and then decreased by increasing the catalyst ratio of CuO[sbnd]CeO2 and reaching 10 %. The thermal behavior of nanostructure was more optimal in the deficient oxygen medium. © 2024 The Author(s)