mohammadreza davoodi

High stiffness to weight ratio, ease and speed of handling, as well as having favorable architectural appearance cause that, double layer grids with ball joint system are widely used to cover large spans. A double-layer grid has a complex behavior due to a large number of elements and a particular type of joints; hence, structural identification of this type of structure is an important issue, which refers to the determination of natural frequencies, mode shapes, and damping ratios. These results are necessary to complete the structural health monitoring, finite element model updating and damage detection. Due to the limitations of input-output methods, modal parameters of civil engineering structures such as bridges, dams, tall buildings, and double layer grids are determined mainly by output-only modal identification. In output-only methods, the vibration parameters are determined based on the information acquired only from the structure’s output. In this work, physical model of a ball jointed double-layer grid with dimensions of 2.8 m at 2.8 m, which is supported on four steel pipes in four corners was made in the laboratory. The grid consists of 32 members connected together with 13 balls, each having ten threaded holes at different angles. each member consists of a middle pipe and connecting parts including conical piece, sleeve and high strength bolt at both ends of the pipe. The middle pipe has the nominal length, diameter and thickness of 120 cm, 7.64 cm and 0.35 cm, respectively. The horizontal center to center distance of adjacent balls in each layer of the grid is 1.414 m and the total height of the structure includes the column length (1.3 m) and the distance between the top and bottom layers (1 m), which is equal to 2.3 m in total. The approximate weight of the structure is 3532 N. All the members and the balls used in the grid are identical. After all the members of the grid have been assembled, the bolt at each joint is tightened in a series of steps by twisting the corresponding sleeve. Exciting the grid, its acceleration response was measured. The modal parameters were obtained using four output-only modal identification techniques; namely enhanced frequency decomposition (EFDD), curve-fit frequency domain decomposition (CFDD), data-driven stochastic subspace identification (SSI-DD) and covariance-driven stochastic subspace identification (SSI-Cov). Two types of excitations were used in output-only modal tests, namely direct and indirect excitations. Since the modal parameters obtained via input-output modal analysis have less uncertainty compared to the output-only modal analysis techniques, an input-output modal test was also performed and the results are considered as reference values. It deduced that parameters identified in the direct excitation, were more accurate compared to indirect excitation. The results showed that the natural frequencies and mode shapes of the double-layer grid were estimated with a high accuracy via the four methods. The greatest relative difference between the natural frequencies belonged to the second mode and equaled 2.07%. The dispersion of estimated damping was much higher compared to natural frequencies and mode shapes. The results indicated that identified damping in the direct excitation was lower than indirect one. Among the 4 methods, SSI-Cov had the least error in damping estimation of the double-layer grid. The values of estimated modal damping ratios were relatively low (fraction of 1%). The mean relative error of the identified parameters showed that the time-domain methods estimated the damping ratios with less error; While the frequency-domain methods identified natural frequencies and mode shapes with higher accuracy.

After the victory of the Islamic Revolution in Iran, many politicians and thinkers turned their attention to the importance of education, and led to numerous efforts to transform the educational process. However, most research has focused on the theoretical aspects of education and neglected its practical dimensions. Ayatollah Mahdavi Kani, a revolutionary figure who focused on youth education before and after the revolution, could discuss theoretical issues in education and implement his educational model practically. He applied this model in places like Imam Sadiq University and the Marvi Islamic Seminary (Hawza). Therefore, examining his statements can help provide a new and practical model in education. This study analyzes Ayatollah Mahdavi Kani’s written works and ethical speeches to extract relevant educational insights and redesign a coherent model based on his views. He viewed education as a complex and delicate process requiring the guidance of a capable and compassionate mentor. He would overemphasize the crucial role of the mentor and teacher in the educational journey. In his view, a mentor should go beyond teaching knowledge and act as a moral and behavioral role model for the students. With patience, the mentor should internalize human virtues and Islamic values in individuals. From this perspective, the mentor’s role as a guide and behavioral model is a significant part of the educational process according to Ayatollah Mahdavi Kani. This comprehensive and practical approach to education can lead to an effective and applicable model in Islamic education.Research

This study analyzes Ayatollah Mahdavi Kani’s educational views and extracts his educational model using qualitative thematic analysis. This method is suitable for analyzing qualitative data such as texts, speeches, and documents. The study involves several stages: coding, conceptualization, categorization, and report writing. During the coding stage, we identify key themes and concepts in the text.In the conceptualization stage, codes are grouped into distinct categories based on their similarities and differences. In the categorization stage, we identify relationships between categories. The research findings are presented in a coherent and organized way in the report writing stage. Using qualitative thematic analysis helps us deeply and accurately understand Ayatollah Mahdavi Kani’s views on education and extract his educational model.Various sources, including his published books and recordings of ethical sessions held at Imam Sadiq University, were loaded into the MaxQDA software. In the first stage, text segments containing themes related to education were extracted and coded. Then, the codes were grouped into distinct categories (concepts) based on their common aspects. Finally, related concepts were grouped under broader categories (general classifications). The software was used for data analysis.

Ayatollah Mahdavi Kani defined education as the construction, purification, and actualization of potential talents, which cannot be achieved without asceticism and adherence to gradualism. He believed that education should be centered on “revealed-Islamic” teachings and that it should simultaneously utilize emotional and rational aspects, with a greater emphasis on practical teachings over theoretical ones. In this educational approach, the individual is prioritized, and he must strive to educate himself before attempting to educate others. In the educational process, Ayatollah Mahdavi Kani proposed principles such as being achievable, prioritizing the elimination of vices over acquiring virtues, realism, voluntariness, the inverse relationship between age and educability, and so on. He considered gradualism the most important principle, facilitating the realization of the other principles.Explaining Ayatollah Mahdavi Kani’s educational model, the “channels of education” were also discussed. These channels include the educator, requirements, necessities, facilities, educational methods, and potential obstacles in the way of education. The “destination of education” category comprises three concepts: objectives, audiences, and the outcomes of education, all of which were mentioned in Ayatollah Mahdavi Kani’s statements. Factors involved in education include controllable factors like the living environment and uncontrollable factors such as temporal exigencies and heredity. He believed that intention shapes the human spirit and forms the essence of a person. This essence can also shape intentions; that is, the spiritual aspects of a person remain due to heredity, education, or environmental influence. This comprehensive and holistic view of education emphasizes the individual’s role in self-improvement and the necessity of gradualism in the educational process. This view considers education dynamic and complex, requiring coordination between rational, emotional, and practical aspects.

The designed model from Ayatollah Mahdavi Kani’s perspective defines education as a gradual, achievable, voluntary, and realistic process with a Divine origin and fixed content. This process, centered on “revealed-Islamic” teachings, and considering temporal exigencies, systematically imparts knowledge within the family and society. The starting point of this process is the educator, whose actions, utilizing progressive and obstacle-removing methods and relying on educational principles, expand exponentially and synergistically. In aiming for the perfection of the individual and society, this process actualizes potential talents by focusing on the human emotional and rational aspects. The ultimate result is an efficient, logical, and humble society before the truth.

Arch bridges have been commonly used in high-seismicity regions of the world, as a result of which notable damage has been documented in several arch bridges during past earthquakes. Certain aspects of seismic behavior of arch bridges are different from those in typical slab-on-girder bridges, including the significance of axial loads, sizable differences between in-plane and out-of-plane stiffness, and the use of piers with different heights. However, limited previous studies have addressed the seismic behavior of concrete arch bridges. In the present study, the effects of earthquake incidence angle and asynchronous support excitation on reinforced concrete arch bridges are investigated. Nonlinear 3-D models of four existing reinforced concrete deck-type arch bridges in Iran were developed. The bridges had arch spans of 23, 35, 45 and 50 meters and were subjected to nonlinear time history analyses using seven acceleration records. The incidence angle was changed in 15 degrees increment between 0 and 90 degrees. Moreover, the effect of asynchronous support excitation was investigated by means of introducing a time delay between excitation input for different supports. The relative displacement (drift) of the piers, the curvature ductility demands within the piers, the curvature ductility demand at different locations of the arch, and the displacement of the deck at the abutments (unseating) were used as damage indicators. The results showed that unseating of the bridge deck from abutments and pier drifts were the most and the least sensitive damage parameter to the change in incidence angle, respectively. The axial force at the end points of the arch was found to change significantly during earthquake, with a maximum of 40 percent in case of 90-degree incidence angle. The effect of asynchronous support excitations was relatively small, with a maximum increase of 10 percent in damage indicators and 5 percent in the axial forces and bending moments.

Social entrepreneurship is a concept derived from entrepreneurship; but it has purposes and goals different from entrepreneurship. Social entrepreneurship activity intends to solve a social problem or to encourage social activity to create a sustainable solution. The purpose of this research was to design a digital social entrepreneurship model and test and fit it through structural equation modeling.
The research is a mixed qualitative and quantitative method. It is practical in terms of purpose and exploratory. The qualitative part is based on data-based theory and the quantitative part is based on structural equation modeling. The statistical population was the qualitative part of the research on businesses in the social and digital fields of the country. The data is based on interviews with 11 expert entrepreneurs and activists of these two business areas, through targeted sampling using the snowball method and a quantitative part by distributing researcher-made questionnaires among the entrepreneurs and managers of the above two regions. Has been collected. Validity and reliability were evaluated and confirmed by the Lincoln and Goba method. Qualitative data analysis was done with the help of Maxquda.2020 software and quantitative data analysis was done with SPSS and Smart PLS.3 software.
Based on the results of the qualitative part of the research, the concept of digital social entrepreneurship has formed the central phenomenon of the model. Out of 33 influential components, causal conditions with four components: personality traits, people's role models, neglected needs of society, special advantages of digital approach; Background conditions with the following components: society's acceptance, availability of entrepreneurship platform, knowledge and expertise of entrepreneurship and application of suitable tools of digital approach; Intervening factors in three categories: strengthening, weakening and potential; Strategies under five categories: partnership strategy, program formulation and professional implementation, facilitating conditions and supporting social businesses, long-term gradual growth and modeling; The consequences have been identified with the following components: the excellence of the society, the acquisition of a superior social position, the promotion of public welfare, the acceleration of affairs, the development of businesses, and the satisfaction of satisfied needs, and based on the findings of the quantitative part, the main relationships of the research model and Confirmed.
If social entrepreneurs advance their activities toward solving social problems, with the bias of digitalization and using online services, they will be able to provide faster, more valuable, and wider services, beyond the territory of Providing a place for more needy people.

Characterized by its Shiite background and the interdependence of religion and politics in governance, the Safavid government bear some significant similarities to the Islamic Republic of Iran and played an important role in shaping Iran's political and social history. The aim of the present research is to examine the causes of the decline and fall of the Safavid government and to investigate the strategies that could have served as a solution to this decline for the Safavids To this end, after a historical investigation, Resaale-ye Teb-ol Mamaalek (the Treatise on State Medicine) written by Qutb al-Din Nayrizi has been chosen as the textual reference to analyze and achieve the research goal. This selection is of great importance due to Qutb al-Din Nayrizi's religious status and his contemporaneity with the reign of Shah Sultan Hussein Safavid (during whose period the fall of the Safavids occurred), and it can significantly reflect the political and social conditions of that era and elucidate Nayrizi's prescriptions for strengthening the political and social foundations of Safavid Iran and overcoming the state of weakness.

Due to the text-oriented nature of the current research, the authors will use the thematic analysis, which is more applicable to written sources. Accordingly, the materials related to the topic were extracted, categorized and coded. Relying on the stated methodological steps, in order to discover the existing topics of the text of  Resaale-ye Teb-ol Mamaalek (the Treatise on State Medicine), the extraction and coding process of the topics in each section has been done by the researchers. Therefore, using MaxQDA software, categories related to the factors of decline and the strategies to prevent it were marked with the symbols Fa and So, and the coding process was carried out.

In the end, the extracted themes were categorized under two main headings: causes of decline and strategies for overcoming the crisis. Through this process, the influential factors in each of these two headings were identified from Qutb al-Din Nayrizi's perspective, and the position of various factors in his thought was recognized. According to the author of this treatise, if the scholars, as one of the important social groups, are weak-willed, worldly, hypocritical, followers of the Sultan, and inactive, the groundwork for societal decline is laid. Nayrizi also mentions "environmental factors," including widespread famine and foreign territorial expansionism, and "divine trials and traditions" as causes of societal decline. 

According to the findings, it can be concluded that this religious thinker classified the factors of degeneration into the following five categories: factors related to the  public, factors related to scholars, factors related to governance, environmental factors, and also divine traditions; he also classified the solutions to deal with it under four categories: solutions related to the  public, solutions related to the scholars, solutions related to governance, and finally, transcendental solutions or divine aid.

One of the most important parts of the safety of each rail network is the fleet cruise control system. All break application processes are carried out in today's modern systems with the help of a system called ATP. This system consists of several units. One of the most important parts of this system is vital digital input and output unit for brake control, which is called VDX. We analyze the automatic train protection system of the made by the Bombardier Company, which is used in the Tehran Metros. Since the VDX unit in this system is responsible for controlling the emergency brakes and the right and left train doors, after examining the unit in this system, a design is presented that, while simplicity all safety and reliability    considerations are observed. as well as the proposed design consists of two processors, four brakes, two controllers for the right and left doors, six relays, six drivers, three flow sensors, a pressure pipe for the brake system and a switch for each door. In addition, the proposed design consists of two processors; four break control circuits, two door controllers, six relays, six drivers, three current sensors, a pressure Cylinder pipe for the brake system, and one switch for each door. Initially, the status of the switches on the right and left doors is checked if the doors are closed, the brakes are released, and if the doors are open, the brakes are engaged. The door status is checked once several milliseconds and opening the doors are considered as an error. The designed system has two units, which act as processor and controller, a fault detection unit, brake interface circuits, and right and left door interface circuits. Fault detection and troubleshooting are performed alternatively within milliseconds. This unit monitors the processors based on high/low signals received from controllers of them. This system monitors the drivers, brake interface & relays via some dedicated sensors as well. Current of the switches help monitoring left and right sides door.

Predicting the vibration behavior of microsystems is of great importance. In this study, the vibration behavior of a microsensor modeled as a two-layer microplate is investigated. The effect of size has been investigated through the modified couple stress theory. The first natural frequency is extracted using the penalty approach. Boundary conditions are modeled using linear or torsional springs. Finally, changes in the natural frequency of the microsystem are presented according to different values ​​of the microplate parameters such as the thickness of the silicon layer and material of the second layer. The results show that the natural frequency decreases as the thickness of the second layer increases. In addition, despite the different first natural frequencies for different parameters, the natural frequency diagram shows the same behavior in terms of system parameters under various boundary conditions. Finally, the effect of the thicknesses ratio   and material length scale parameters ratio  on the natural frequency is investigated.   Predicting the vibration behavior of microsystems is of great importance. In this study, the vibration behavior of a microsensor modeled as a two-layer microplate is investigated. The effect of size has been investigated through the modified couple stress theory. The first natural frequency is extracted using the penalty approach. Boundary conditions are modeled using linear or torsional springs. Finally, changes in the natural frequency of the microsystem are presented according to different values ​​of the microplate parameters such as the thickness of the silicon layer and material of the second layer. The results show that the natural frequency decreases as the thickness of the second layer increases. In addition, despite the different first natural frequencies for different parameters, the natural frequency diagram shows the same behavior in terms of system parameters under various boundary conditions. Finally, the effect of the thicknesses ratio   and material length scale parameters ratio  on the natural frequency is investigated.

A significant number of engineering structures around the world are exposed to fire on a daily basis. The most important effect of fire on the structure is elevated temperatures, which may reach more than 1000 degrees Celsius and cause not only thermal stresses and deformations but also diminished mechanical properties of materials comprising the structure. Fire-related collapses have been observed in numerous structural fires. However, many reinforced concrete structures exposed to fire do not demonstrate notable apparent damage and survive despite having experienced elevated temperatures before the fire is put out. Estimating the residual strength of such structures is of critical importance when deciding whether such structures can be safely used after fire. Moreover, in many industrial applications, there is a need to concrete that can withstand repeated long-term cycles of elevated temperatures without diminished mechanical properties. The objective of this paper is to investigate the effects of silica fume and fly ash as two widely used supplementary cementitious materials on the residual strength of concrete exposed to elevated temperatures and evaluate while such materials can be of benefit in improving the strength retention in case of heat exposure. Using 19 mix designs, a series of 570 concrete cylinders was fabricated using different water to cement ratios (0.35, 0.5, and 0.65), silica fume replacement ratios (0, 10, and 15 percent), and fly ash replacement ratios (0, 10, 20, and 30 percent). The specimens were cured in water for 56 days, after which they were placed in a rate-controlled large-scale electrical furnace, and their residual compressive and tensile strengths were measured before heat, and after heat exposure for 2-, 12-, and 24-hour heating cycles with temperatures reaching 200, 400, and 600 degrees Celsius. To eliminate the risk of explosive spalling, all specimens were preheated at a temperature of 100 degrees for 24 hours before the main heating cycle. Results showed that the compressive and tensile strengths did not reduce noticeably after exposure to 200 degrees but demonstrated a significant drop after exposure to 400- and 600-degree cycles. In many cases, the residual compressive and tensile strengths of specimens were found to be smaller than those predicted in previous studies. The square root equation widely used in the literature was found to provide a reasonable lower-bound estimate of the residual splitting tensile strength of concrete from the residual compressive strength; however, a linear trend was identified to provide a more accurate estimate for the results of this study. Moreover, due to less scatter, the splitting tensile strength was found to be a better indicator of heat damage in the structure than the compressive strength. The use of silica fume did not result in a meaningful trend in the residual compressive strength but reduced the residual tensile strength of specimens. Fly ash, on the other hand, could increase the residual compressive strength of the specimens but reduces the residual tensile strength. The results suggest that generally, and with few exceptions, these two supplementary cementitious materials are not recommendable choices for improving the strength retention of concrete in case of heat exposure.

Change in modal strain energy is one of the indicators used to detect damage in structures. However, in structures with high degrees of freedom, such as double-layer grids, this method requires a relatively large number of mode shapes which in practice is difficult to determine. Therefore, it is necessary to reduce the number of required mode shapes. In this study, a damage detection technique based on modal strain energy and Dempster-Shafer evidence theory is presented for locating damage in double layer grids using only a few number of mode shapes. First, by calculating mode shapes of the grid in undamaged and damaged states, the modal strain energy based index for each mode shape is determined. Then, the results obtained from separate mode shapes are combined using Dempster-Shafer theory to achieve better results. In order to investigate the effect of noise on damage detection, 3% random noise is added to mode shapes. To demonstrate the performance of the proposed method, different single and multiple damage cases with different damage intensities are considered. Numerical results show that using 5 mode shapes, the presented technique can detect up to 3 damaged elements with different damage intensities in different parts of the grid with good accuracy (probability of 92.3%). Considering the fact that the classical modal strain energy method fails to distinguish even 1 damaged element in the double layer grid, the result shows significant improvement.

One way to diagnose damage in structures is to use their modal strain energy change index. Since occurrence of damage in parts of a structure, in addition to changing the modal strain energy of the damaged parts, also changes the modal strain energy of the healthy parts, in the vicinity of the main damaged elements, false damaged elements will appear, which makes it difficult to identify the main damaged elements. To solve this problem, in the present work a two-step method has been used to determine the location of the damage on the deck of a concrete bridge. In the first step, by finite element modelling and performing the modal analysis, the initial damage index of different parts of the bridge deck is determined based on modal strain energy changes, using a few vibration mode shapes. In the second step, using weight coefficients, the modified damage index for each element is calculated separately, minimizing the number of false damaged elements. The proposed method for calculating weight coefficients is simple and at the same time accurate. The efficiency of this method was investigated in several damage scenarios with an intensity of only 5% in different parts of the deck of bridge. The results showed that, while the initial damage index could not distinguish even 3 damaged elements in the bridge deck from the healthy elements, the modified damage index was able to identify up to 7 damaged elements in different parts of the bridge deck with good accuracy using only 2 mode shapes.

One of the most effective ways to achieve the desired foreign policy coordinates in the light of Islamic teachings is to refer to a set of views and opinions of influential elites who are familiar with the theoretical frameworks of Islamic politics and have valuable experience in practical politics. In view of this, the present article seeks to answer the question that "politics, while focusing on the field of foreign policy - as one of the most important areas influencing the maximum provision of national interests - from the perspective of Ayatollah Mahdavi Kani. "From the perspective of Ayatollah Mahdavi Kani, the desirable foreigner of the Islamic Republic of Iran is drawn on the basis of what principles."

‌ In order to answer the written question, the method of thematic content analysis and reference to library resources has been used.

After extracting the related concepts, the principles of foreign policy of the Islamic Republic of Iran were categorized from his point of view and it was found that he divided these principles under the three axes of "justice and oppression", "protection of the oppressed" and "priority of legalism and peace". »Explained.

Finally, the fruits of research show that Ayatollah Mahdavi Kani (RA) in the field of politics, especially foreign policy, with a virtuous approach and realism-oriented idealism looks at this field and the above three principles, respectively, the most importance in his political thought. Has had.

This article examines the collection of "The Eighth Day of the Earth" by Shahriar Mandanipour in accordance with Gerard Genet's Narrative Theory. The results of this article show that Mendenipour emphasizes on the intra-event narrator and expresses the time of narration to all four for narrating events based on three components of narrative time, narrative voice and narrative perspective. The type of post-aphid, pro-post, concurrent and intermittent attention has been shown. The author recounts events in all four levels of the Stone, Eighth Day, Sara Thursday, and Zaman stories, in the long run of deleting, summing up, pausing, parodying and staging. Processing has benefited. Some of the stories are written in a timely manner, indicating the author's view of past and future. By analyzing Mendenipour's stories in this collection and comparing them with Gerard's Genetic Theory of Narrative, one can extract the validity of this collection well and make it a powerful text for narrative studies. He knew)

Changes in modal strain energy of elements before and after damage is a robust damage detection index. However, in structures like double layer grids which have large number of elements, this method has some problems. First, In large structures this method needs more mode shapes to detect damage through modal strain energy method which in practice is difficult to determine. Second, this method introduce some healthy elements as damaged element. To overcome these problems, in this paper a two stage damage detection technique based on modal strain energy method is presented for detecting damage in double layer grids. First, the Modal Strain Energy Based Index (MSEBI) for each mode shape is determined. Then a data fusion technique based on Bayesian theory is used to combine MSEBI values obtained from each mode shape to find damaged elements. Then Charged System Search (CSS) optimization method which is a powerful optimization method is employed to optimize an objective function based on natural frequency to determine damage severity of damaged elements. To demonstrate the performance of the proposed method, a large double layer grid with 1536 elements and different single and multiple damage cases is considered. Numerical results show that the proposed method can successfully find damaged elements and their severities using only few first numbers of mode shapes and frequencies.

Output-only structural identification is conducted by output data of the structure. These data usually include structural response together with some noise. Success of output-only methods in determining the vibration parameters of a structure depends on the signal to noise ratio (SNR) of the output data. In this paper, the vibration parameters (Natural frequency and Mode shape) of a contilever beam have been obtained using output data which have different signal to noise ratios. The vibration parameters of the beam were determined using modal analysis of finite element model and considered as reference parameters. Then, appropriate input was applied to the beam and the acceleration signal was obtained. To generate noisy data, noise with different powers compared to signal powers were added to acceleration signal. The modal parameters of the beam were obtained using two output-only methods, Peak Picking (PP) and Stochastic Subspace Identification (SSI). The vibration parameters having signal-to-noise ratios greater than 25 (lower noise level) for all considered modes were identified properly. At a signal-to-noise ratio of 0.25 to 25 (higher noise level), it was not possible to identify the modal parameters of the first mode of the beam, but the parameters of the higher modes were identified with good accuracy.

In large civil engineering structures, the output-only modal identification is the most applicable technique for estimating the modal parameters such as damping. However, due to no measurement and control of excitation force, the identified parameters obtained by output-only technique have more uncertainty than those derived from the input-output technique. Given the different nature and uncertainties of the two modal identification techniques, in the present study, the damping related to the first 12 modes of a double-layer grid developed from the ball joint system were identified via the two techniques and compared with each other. For this purpose, a double-layer grid was constructed by pipes and balls with free-free boundary conditions provided for both input-output and output-only experiments. Exciting the grid, its acceleration response was measured at appropriate degrees of freedom. Then, by using these data and performing modal analysis, involving four different methods of input-output and five different methods of output-only, the natural frequencies and damping ratios of the desired modes were extracted. The results indicated that despite the good agreement between the modal damping of the grid, as identified by different methods of input-output together and by different methods of output-only together, the results of input-output and output-only methods were different with each other. The damping values through the input-output modal identification methods were on average 65% higher than the corresponding values of the output-only modal identification methods.

The present study is an applied and descriptive-analytic research, while investigating a multi-period portfolio, below the optimal calculated responses to the analytical form of Skaf and Boyd (2009) for models with limited transaction costs and the impossibility The sale of borrowings in the Tehran Stock Exchange is reviewed. In this research, the first 30 active companies in the Tehran Stock Exchange, which have the highest ratings in the period between 2011 and 2016, were first selected, and then, using data envelopment analysis, 8 efficient companies were selected among the 30 companies. The research result Show that the optimal answer is of good quality.envelopment analysis, 8 efficient companies were selected among the 30 companies. The research result Show that the optimal answer is of good quality.

The output data from a structure is the building block for output-only modal analysis. The structure response in the output data, however, is usually contaminated with noise. Naturally, the success of output-only methods in determining the modal parameters of a structure depends on noise level. In this paper, the possibility and accuracy of identifying the modal parameters of a simply supported beam in the presence of noise has been discussed. The output-only modal analysis method with frequency domain decomposition was used and output data with various noise levels were considered. Initially, finite element modal analysis was used to determine the modal parameters for the beam which were afterwards enforced as the reference modal parameters. Then, appropriate input was applied to the beam and the acceleration signals of different nodes were produced through finite element transient analysis. In order to simulate noisy data, noises with different power levels were generated and added to the signals. Finally, the modal parameters were obtained by frequency domain decomposition method. The results showed that the modal parameters corresponding to the first vibration mode could only be identified with acceptable validity at low to moderate noise levels, whereas for higher modes, the modal parameters can be correctly obtained even at high noise levels.

examining the functions of the “Majlis” as one of the components of the political system of the Islamic Republic of Iran-in the intellectual system of Imam Khomeini has special role, "What is the position of the supervisory function among the various functions of the Islamic Consultative Assembly?" To answer this question, the content analysis method and library reference to the collection of Imam Khomeini's Speeches (in “Sahifeh-ye Noor” as the official reference of his statements have been used. Therefore, after extracting the concepts related to the subject, the functions of the Islamic Consultative Assembly have been classified and defined in two pivots of regulation and supervision. By this, the importance of each of these functions is determined and the status of parliamentary oversight is Qualified in different ways. Finally, the results of the research show that, against to the common beliefs that see the legislating as the main function of the Islamic Consultative Assembly, and also the function of this institution in different periods reflects a focus on this task, the founder of the Islamic Revolution of Iran has emphasized on the parliamentary oversight of the affairs and see this status as the main function of the Islamic Consultative Assembly

At the present time, it is impossible to imagine manufacturing organizations without running maintenance systems. Maintenance is a system that supports the core processes. Therefore, a maintenance system is essential for manufacturing organizations in order to maintain competitiveness. As yet many studies have been done on maintenance systems but there is almost no study comprehensively examining various aspects of the system. In this study, defining the attributes of maintenance phenomenon, dimensions and components of maintenance system are clarified. By the use of meta-synthesis approach, previous studies are analyzed and maintenance phenomenon is categorized in five dimensions, 31 sub-dimensions, and 98 components. Finally, the effect of the specified components in 209 previous studies has been determined using Shannon entropy method. And, it has been shown that what factors or codes have received the most emphasis in each theme.

Space grids are highly modular structures assembled from components that are almost exclusively factory fabricated. The components therefore, are usually produced with high dimensional accuracy, with a high quality of surface finish and they are generally easily transportable, requiring little further work except assembly on site. Because of their modular nature, space grids may be extended without difficulty and even taken down and reassembled elsewhere. One of the most popular types of connectors that are widely used in the construction of double layer grids is the MERO system. The Mero KK space truss system, the first commercially available, is still considered to be one of the most elegant solutions for the construction of space grid structures. The elegance and simplicity of the Mero system means that it is not only used in buildings but also for shop displays and exhibition stands using lightweight materials. Circular tube members are connected to cast ‘ball’ joints at the nodes by a single concealed bolt for each tube. A double layer grid is combination of prefabricated tetrahedral, octahedral or skeleton pyramids or inverted pyramids having triangular, square or hexagonal basis with top and bottom members normally not lying in the same vertical plane. The connector is an extremely important part of a grid design. The type of connector depends primarily on the connecting technique, whether it is bolting, welding, or applying special mechanical connectors. It is also affected by the shape of the members. This system is multidirectional system allowing up to fourteen tubular members together at various angles. The system consists of tubular elements that are connected together by means of a MERO connector. The ball is located at the intersection of the longitudinal axes of tubular elements. The longitudinal axis of tabular element and all the constituent parts of its end connectors are along together. This axis is referred to as axis of member. The MERO system had only one type of standard joint, a sphere with 18 threaded holes and machined bearing surfaces at angles of 45, 60 and 90° to each other. A model of MERO connector is presented in this paper for double layer grid structure. The internal forces in the members of double layer grid are found using SAP software. These forces are applied as pressures on the MERO connector. The deflection and rotation patterns of the connector are studied under different loading conditions using the ABAQUS software. The forces to be applied on the connector are calculated using of displacementg control.
In order to take into account the connector effects in structural analysis, their behavior under combined load should be predicted. In double-layer grids that are an important family of space structures, the main internal forces are axial forces. In the present study, to determine the force-displacement relationship of MERO jointing system, some tensile, compressive and bending simulation tests were carried out on a connector of this type using 3D finite element method. The obtained force-displacement and moment- rotation relationship were used under different load. The results of the finite element simulation with experimental results have a good match. It was also found that in both compressive and tensile loading, the ball came to the plastic stage. Compressive axial force increases the flexural stiffness of the connection and with increasing compressive force decreases the elastic bending moment.

One of the most common connecting systems that is used for the manufacture of space structure, is MERO connecting system. So a perfect knowledge of the behavior of this connection is the most essential problem for the engineers and designers. The results has shown that different parameters including the degree of tightness of the bolts affect on the static and dynamic characteristics on these kinds of jointings. Distinctly in this research the effect of the bolts tightness degree and the magnitude of the vibration on the dynamic characteristics of the MERO connecting system has been experimentally evaluated. Therefore a member made by this system in the form of a cantilever beam at different degree of bolt tightness and by the free vibration method and by making initial displacement was experimented in order to determine the quantity of dynamic system parameters including the damping ratio, damping coefficient and the natural frequency. The results obtained showed that, the magnitude of bolt tightness is directly proportional to the structure vibration. Also the maximum damping ratio and damping coefficient occurs at 60 Nm bolt tightness, and if the tightness degree is more or less than this quantity, the magnitude of damping ratio and damping coefficient would be less than that. Also the results showed that there is a direct relation between the initial displacement with the damping, it means that by increasing the vibration amplitude the damping will increase and vice versa.

Agreat number of studies on the vibration of plates subjected to moving loads are available which are gained by the moving force and moving mass modelling frameworks. As a result, evaluating the reliability of approximate simulation of a moving oscillator problem through moving force/mass would be of interest in engineering application. Therefore, in this article, transverse vibration of a thin rectangular plate under a traveling mass-spring-damper system is revealed by eigenfunction expansion method. Both moving force and moving mass modelling approaches are compared with the moving oscillator and various plate fixity cases and load trajectories are involved to present benchmark solutions. The spring stiffness range for which the plate response agrees closely with the corresponding moving force/mass analysis is recommended. The results elucidate that the moving mass can be considerably unrealistic in predicting the contact force of an undamped oscillator. Moreover, errors of orbiting force/mass simplification of the orbiting oscillator in predicting the resonant conditions of the plate vibration are not negligible.

Agreat number of studies on the vibration of plates subjected to moving loads are available which are gained by the moving force and moving mass modelling frameworks. As a result, evaluating the reliability of approximate simulation of a moving oscillator problem through moving force/mass would be of interest in engineering application. Therefore, in this article, transverse vibration of a thin rectangular plate under a traveling mass-spring-damper system is revealed by eigenfunction expansion method. Both moving force and moving mass modelling approaches are compared with the moving oscillator and various plate fixity cases and load trajectories are involved to present benchmark solutions. The spring stiffness range for which the plate response agrees closely with the corresponding moving force/mass analysis is recommended. The results elucidate that the moving mass can be considerably unrealistic in predicting the contact force of an undamped oscillator. Moreover, errors of orbiting force/mass simplification of the orbiting oscillator in predicting the resonant conditions of the plate vibration are not negligible.

This paper offers a design procedure for robust stability, robust H-infinity control and robust H2 control via dynamic output feedback for a class of uncertain linear systems. The uncertainties are of norm bounded type. Then in order to support a high-speed energy storage flywheel, these procedures are applied to an active radial magnetic bearing system. The state space matrices of this controller are the solution of some linear matrix inequalities (LMIs).