ali heidari

Wavelet transforms have been used for 20 years to reduce dynamic analysis costs, with studies suggesting the use of this method for three levels of decomposition. In addition, in these studies, the time step of the solution is assumed to be equal to the time step of the earthquake record and therefore the stability of the numerical method is essential in such cases. Also, in previous studies, the effects of the distance from the fault on the accuracy of the approximate waves have not been evaluated. This paper examines the accuracy of wavelet-based down-sampling methods for 50 far-field, near-field, and pulse-like earthquake records and 24 wavelet functions. Also, two numerical methods, Newmark's average acceleration and the interpolation-based method are studied. The results of this research show that Newmark's average acceleration method is suitable for wavelet-based dynamic analysis. Also, in this study, it is shown that by choosing the appropriate wavelet function, even up to four levels of decomposition may be used with an error of less than 2%. Therefore, with this work, the cost of calculations may be reduced up to 16 times.

This research aims to provide a comprehensive picture of the status of VUCA (Volatility, Uncertainty, Complexity, and Ambiguity) studies in management and its applications. The present research was conducted using the bibliometric method. The required data were extracted from Scopus (1,120 articles) and Web of Science (345 articles) using the keyword VUCA, and after refinement, 1,139 articles were selected for final analysis. The analyses included examining publication trends, identifying leading authors and institutions, keyword co-occurrence analysis, scientific mapping, and citation network analysis. The results showed that scientific publications in the field of VUCA increased from 1 article in 2008 to 244 articles in 2023. Among 3,105 identified keywords, concepts such as leadership and organizational agility (each with 64 citations), innovation (53.5 citations), and digital transformation (46.4 citations) had the most impact. The co-occurrence analysis led to 7 main clusters, with foresight and business development (25% of articles), leadership and strategy (21%), and technology (17%) being the most significant clusters. Success in the VUCA environment requires adopting a comprehensive and multidimensional approach that includes intelligent use of advanced technologies, developing dynamic organizational capabilities, strengthening the culture of creativity and innovation, and nurturing forward-thinking leaders. Companies that can effectively integrate these elements will not only be able to manage VUCA challenges but can also use these conditions for innovation and increasing organizational effectiveness.

One of the effective tools for expressing complex mystical concepts is the use of an interpretable symbolic language; a language that provides the most suitable forms for explaining spiritual experiences and rational concepts. Examining the extent and manner of symbolism in different poetic periods is a helpful endeavor for entering the world of the poet's emotions and thoughts, as well as understanding the social context of their time. Based on this, the present study investigates the mystical poetry of Mulla Parishan Lak. In this article, through a descriptive-analytical method, the symbols and the method of symbolism used by Mulla Parishan are examined. This research can aid in identifying a significant and unexplored aspect of the thoughts, experiences, and other dimensions of this mystical poet. The findings of the study indicate that the types of symbols used in Parishan's poetry are diverse; although he predominantly employs natural symbols. Furthermore, Mulla Parishan's symbolism is intertwined with religious law and is primarily aimed at conveying mystical themes, while also not lacking references to individual and social ethical subjects.

Despite the growing interest in business divestiture, there is a lack of illustrating framework for divestiture research. The purpose of this research is to present a macro picture and provide valuable insight into the position and trend of research in this field to be helpful for future research. In this research, the bibliometric method was used, which identifies the trends and thoughts of thinkers in this field. The most important authors and journals between 1994 and 2023 have been identified. Ms. Feldman is the most active and influential author in this field, and the Journal of Strategic Management has the most published articles with 28 frequencies. The words performance, diversification, governance, and sale assets are the keywords that have been repeated the most. Based on the results of the histogram mapping, three research paths have been identified, in the first area, the effect of strategies such as acquisition and diversification as a stimulus has been examined, the second area deals with the effect of corporate governance, and the third area examines the consequences of divestment.

Background and goal: 

walnut tree (Juglans regia L.) are cultivated in many countries in Asia, Europe and United States. This tree has high resistance with beautiful pattern and are used in furniture industry, building panels, flooring and covering. Iran are ranked third in the world in the production of walnut fruit after China and US. Thus, with considering high production of this tree in Iran and its diverse application in different industries, a comprehensive studding for physical and mechanical properties of this species in different regions of Iran seems necessary.

Walnut tree (Juglands regia L.) from two different regions, one from northeast (Mashhad) and the other from northwest (Mako) of Iran was selected for this study. Three trees from each region were selected randomly and cut with almost with the same diameter for physical and mechanical experiments. Samples also were cut from 2-4 meter from the ground. ISO 3129 and ASTM (D143-14) were used for doing physical and mechanical experiments respectively and at the humidity of 12%. Statistical analysis of data was performed using Graphpad prism version 8 and t-Test was performed for significant difference of data.

The average dry density of both Mashhad and Mako walnut wood was 0.625 and 0.579 g/cm3 respectively. There were a significant difference for both tangential shrinkage with values of 9.77 and 8.78 and volumetric shrinkage with measurement of 16.26 and 15.42 in Mashhad and Mako respectively. However, there was no significant difference for longitudinal and radial shrinkage in both walnut wood of the two regions. Walnut wood cut from Mashhad region showed higher physical and mechanical properties. The results of the mechanical characteristics of walnuts from two regions showed bending strength 100.54 and 87.61N/mm2 and elasticity modulus 10049.59 and 7504.21 N/ mm2for Mashhad and Mako regions respectively which were significant. Results also showed not significant difference for compression parallel to the grain with values of 37.91 and 33.88N/mm2, for shear parallel to the grain with values of 9.15 and 8.95N/mm2, for Tensile strength parallel to the grain with 127.97 and 125.83 N/mm2, for Screw withdrawal strength in tangential values of 4031.01 and 3685.97N and Screw withdrawal strength in radial values of 4218.63 and 3915.03N and impact strength with the values of 27.81 and 25.24KJ/m2 for Mashhad and Mako regions respectively. Results also showed that the density of walnut wood in the two regions of Iran was similar to the those in Italy and eastern Europe but the mechanical properties of walnut tree such as bending strength and elasticity modules measured from Mashhad region was similar to the wone in turkey.

The results showed that the physical and mechanical resistance of walnut wood located in Mashhad is higher than Mako wood, which was attributed to the higher dry density and the difference in weather conditions. Considering the appropriate mechanical resistance of walnut wood from both regions of Iran, this wood can be used in coating and furniture industries, building panels and flooring.

Business exit strategies are fundamental to ensuring a company's long-term viability. Despite their critical role, this area of research has been surprisingly understudied. This knowledge gap can leave companies unprepared to navigate the complexities of exiting a market or business venture. To bridge this critical knowledge gap, our study conducts a systematic literature review, analyzing research findings from the past three decades (1990-2022). By synthesizing key findings, we aim to provide a comprehensive overview of current research trends in business exit strategies. This analysis will not only offer valuable insights into existing knowledge but also identify potential gaps and opportunities for future exploration. By understanding the research landscape, we can pave the way for more informed decision-making and successful business exit strategies.
 

We employed a combined approach of systematic literature review and bibliometrics using R programming to analyze trends in business exit research.
 

A co-occurrence network analysis revealed three main thematic clusters in business exit research i.e., performance, asset sales, and survival. These clusters, representing the most frequently co-occurring keywords within the field, exhibit the highest cumulative growth over the past three decades. This highlights their thematic significance in exit strategy research. For instance, "performance" frequently co-occurs with concepts like acquisition, governance, diversification, and decision-making, suggesting its central role in exit decisions. Similarly, a review of co-citations identified management publications as the most interconnected followed by financial management and economics publications. This suggests a disciplinary gap within the research area. Four key research themes emerged from the analysis were exit drivers, exit decisions, exit modes, and consequences. Additionally, several theoretical perspectives emerged, including agency theory, corporate governance, resource-based view, and dynamic capability theory.
 

The research landscape is dominated by studies on exit drivers and exit consequences, often explained through frameworks such as agency theory, transaction cost economics (TCE), resource-based view (RBV), and evolutionary theory. Financial research focuses on the exit's impact on subsidiary performance and parent company financials, while economics explores industry factors influencing exit decisions. Financial researchers primarily investigate the exit's impact on subsidiary performance and the parent company's post-exit financial health. Agency theory is the dominant theoretical framework in this area. Economists examine how micro and macroeconomic factors (industry concentration, growth, size, profitability), economies of scale, capital intensity, and sunk costs influence barriers to entry and exit, ultimately driving business exits. Based on these findings, future research avenues include investigating the role of diversification as a driver of business exits, exploring how corporate governance structures influence both firm performance and exit decisions, analyzing factors contributing to non-optimal timing of business exits, examining the potential for reusing resources in new ventures to facilitate exits and minimize negative consequences, investigating the role of organizational capabilities in early detection of exit signals, and conducting a comprehensive exploration of both internal and external consequences of business exits, along with effective response strategies.

Effective management of the food supply chain with a waste plan in mind will play a vital role in the company's success and bring numerous competitive advantages to the stakeholders. Perishability of food products affects economic, environmental and social aspects of food supply chains. Perishable goods impose additional costs on the inventory system due to the spoilage of the goods, so it becomes necessary to use a closed-loop supply chain. According to the literature, the consideration of inspection in food supply chain networks has not been investigated. The use of inspection in the production and distribution center can contribute significantly to the three dimensions of sustainability. Examining this issue as a forward and reverse food supply chain is a challenging issue. In this research, a sustainable forward and reverse supply chain network for food is presented, taking into account inspection in the production and distribution center to prevent the transfer of spoiled products to the next layer. To solve the model, the enhanced epsilon constraint method was used, which is able to provide Pareto solutions suitable for all the objectives of the decision makers, and it was investigated to show the efficiency of the model in the real world of TABAROK food products factory.

This research, involved dynamic optimization of process parameters on the porosity and tensile strength of AA1050/SiC aluminum composite wires produced by friction stir extrusion (FSE) was carried out. In this regard, SiC ceramic particles reinforced AA1050 composite samples were produced using the FSE process. Also, response surface methodology (RSM) was used to design of experiment. The rotational speed of the punch, extrusion force, and reinforcement percentage weight were determined as input variables of the process. The porosity and tensile strength of produced composite samples were determined as response variables. Analysis of variance (ANOVA) and regression analysis were used to analyze the obtained data. The results showed that rotational speed, extrusion force with second-order effects, and reinforcement percentage with linear effects were effective on the tensile strength and porosity of composite samples. Also, the optimization of FSE process parameters to reach the minimum percentage of porosity and maximum tensile strength was performed using the desirability method. Finally, the optimization results were evaluated based on the validation test. Also, by achieving the maximum value of the desirability function (0.9852), the optimal conditions of process input variables were a rotational speed of 787 rpm, an extrusion force of 11.7 kN, and a reinforcement percentage of 3.86% to simultaneously achieve the maximum ultimate tensile strength (155.4 MPa) and minimum porosity percentage (0.45%). Also, the values obtained from the optimization were compared with the experimental values and the accuracy of the results in tensile strength and porosity were confirmed with 2.57% and 6.78% errors, respectively.

 Obesity is a major public health problem whose prevalence has constantly increased worldwide. Obesity is a risk factor for several diseases such as type 2 diabetes, fatty liver disease, hyperlipidemia, cardiovascular diseases, and cancer, all of which reduce the quality of life and life expectancy. This study investigated anti-adipogenic effects of Eryngium billardierei (Ery) extract.

 The nontoxic concentration of Ery extract was estimated via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazoliu bromide (MTT) assay. The differentiation of mouse-derived 3T3-L1 preadipocytes into mature adipocytes was induced in the presence or absence of Ery extract. Then, the accumulation of lipid droplets was identified by Oil Red O staining. Triacylglycerol level and glycerol-3phosphate dehydrogenase (GPDH) activity were also measured.

 The MTT assay showed that 3 mg/mL of the Ery extract can be a nontoxic dose for other analyses. Oil Red O staining demonstrated a reduction of lipid droplets in the extract-treated adipocyte 3T3-L1 compared to the non-treated group. A significant decrease of triacylglycerol level in the treated 3T3-L1 adipocyte (0.32±0.03 mgTG/mg protein) compared with the nontreated group (0.78±0.05 mgTG/mg protein) (P<0.01), and a significant decrease of glycerol-3-phosphate dehydrogenase (GPDH) activity in the 3T3-L1adipocyte treated (15.3±2.1 U/ml) compared to the non-treated group (30.2±3.9 U/ml) (P<0.05) confirmed the inhibitory action of Ery extract on adipocyte differentiation.

 Ery extract, as a safe herbal extract, has anti-adipogenic activity and merits more investigation as a candidate for developing an anti-obesity drug or supplement.

One of the most challenging subjects of Masnavi-e Ma'navi is the delay in the writing of the second Book. Most of the researchers, in following Aflaki, considered the death of Hessam al-Din's wife and the lack of motivation of Molavi as the most important factors of the delay. But some researchers doubted this not very reasonable factor and presented valuable opinions. In this article, one of the factors of the delay, which has not been paid attention to, has been addressed in an analytical-descriptive way. After Salah al-Din's death, some of the affairs of Molavi and his disciples were handed over to Hessam al-Din, but due to some reasons, he was not officially chosen as Caliph. Hessam al-Din persistently requested Molavi to officially announce his caliphate. But apparently, Molavi is in no hurry for such an assignment. This suspension caused resentment of Hessam al-Din. In the final verses of the first book, Hessam al-Din's sadness and resentment reaches its peak and Molavi apparently drives him away. This separation and anger lasts for two years until Hessam al-Din officially becomes the Caliph of Molavi and resumes the writing of the second book. Extratextual and intratextual reasons explain and confirm this matter.

Absence as an inherent feature of language has two levels. The first level, the absence in the normal level of language and the second level, the double absence which is related to literature. By using rhetorical techniques and tricks, poets use some themes either to create beauty or because of the moral limitations they place on themselves or the moral and political prohibitions and controls that exist in the society. They take absent. Nizami is one of the poets who skillfully, according to the content of his romantic poems, has used absence from the simplest level to the most forbidden form to represent the physical matter in his poetry. The statistical population of the present research is Khosrow and Shirin Nizami, in which the verses which the physical aspect is absent, They have been collected in a library manner and have been analyzed by analytical-descriptive method and using the content analysis technique, then they have been classified based on the epistemic-behavioral domains used by the poet. In the following, it is clear that the poet has used fifteen cognitive-behavioral domains. The highest frequency of verses has the absence of unquoted matters and taboo matters related to agriculture with 25% and stones and precious stones with 15% of all verses. Among the fields used, the fields of horse riding and spices and food have the lowest frequency of verses with 2% of the total number of second and third level verses.

Sarapanameh (Peikarsarayee) is a type of poetry in which the poet renders the figure of the beloved. The purpose of the poet in this type of poetry is to illustrate the body of the beloved in addition to expressing the romantic feelings. The poet like an expert painter represents her imaginary or real lover through words. This type of poetry is common among Kurdish, Loor and Laki poets, and usually famous poets have written one or more examples of this type of poetry. The rhyme of most of these poems is ten-syllable and they are often written in the standard language of western Iran. But the previous native poets have tried with their local language instead of the standard language of the west of the country. The late Zulfaqar Mohammadi, an unknown but talented elite poet, was one of the poets who wrote this kind of poem. This Sarapanameh is written in a new format and in syllabic rhyme. The variety of pure similes and phonology, composition, and imagery are among the most important literary features of this one. The poet's interest to local and national customs and traditions, and paying attention to the surrounding nature is exceptional in the selection of terms.

Study skills are among the factors affecting students' academic performance, and it is related to their success in future career. This study aimed to investigate the study skills and academic performance of medical students of Urmia University of Medical Sciences and factors affecting them.

In this cross-sectional study, 267 medical students participated who were selected by random cluster sampling. Data were collected using the study skills questionnaire. Based on their average grade point, students were classified into two groups of "good and average" and "poor" academic performances. The mean and standard deviation of study skill scores, also the proportion of the students with good, average, and poor study skills were estimated. The factors affecting students' study skills and academic performance were determined using logistic regression analysis.

In this study, 51% of students had good and average academic performance, and overall study skill score was moderate for 71.5% of students. The highest mean scores were obtained in the dimensions of "information organizing", "time management" and "concentration and memory". The lowest scores were obtained in the dimensions of "motivation and attitude" and "writing". Study skills were related to gender, father's education, grade and age. Academic performance was related to girl gender (OR=2.79, 95%CI: 1.56-4.97), being married (OR=4.69, 95%CI: 1.22-17.98), time management (OR=1.16, 95%CI: 1.05-1.24), and readiness to exam (OR=1.12, 95%CI: 1.01-1.24).

Academic performance and study skills of medical students are moderate. Improving study skills and identifying other factors affecting academic performance should be considered by university officials.

The purpose of this research is to present a complete picture and an integrated framework of the Business Exit process. The process is complex, dynamic and lengthy. Decisions and actions in each step have a multi-faceted interaction with other steps. To achieve this purpose, in this research, 69 works published during the years 1990-2022 were reviewed and evaluated based on a systematic method. Based on the findings of this research, the exit process is divided into 5 steps (entry strategy, exit drivers, decision making, exit method, and consequences) in order to provide a better understanding and an integrated framework of the business exit process. 34 subcategories and 213 components were also identified. Out of these 69 studies (considering two categories for some articles), exit drivers (43), consequences (28), strategy and method of exit (28), decision-making (23), and entry strategy (11), respectively, are the most studies have been assigned to themselves.

One of the most the challenges of the new age that corporate managers face is identifying, determining the degree of importance and categorizing knowledge that recognizes what knowledge is inappropriate for a good organization or knowledge to prevent its unnecessary accumulation. Therefore, considering the necessities mentioned above, the purpose of designing a model is to investigate and analyze the phenomenon of Organizational forgetting in social security organization using the theme- Dematel Combined approach. In this research, in order investigate and analyze the phenomenon of Organizational forgetting in social security organization, theme- Dematel Combined approach was used. The findings were obtained through an interview with 12 experts (who were experienced managersin social security organization with above master's degree, and experience and knowledge in this area) and a theme- Dematel Combined approach. So, firstly, the theory of Organizational forgetting in the social security organization of Iran was developed using the themeanalysis technique, and then Dematel Combined approach was used to examine the relationship between the components of the Organizational forgetting model. This research was expressed using the shape and size as well as the number of output and input arrows of each criterion, taking into account the assumptions of the Effect and Effectiveness of Dimetl, as well as the severity of the impact and the effectiveness of the criteria.

In this study, the molecular dynamics method is used to simulate the SMAT process in the AZ31 workpiece. Molecular dynamics calculations in LAMMPS software have been used to investigate the effect of size, number, and velocity parameters of carbon steel particles on the mechanical and physical properties of the surface including residual stress, hardness, and surface roughness in AZ31 matrix has been investigated at the atomic scale. The simulation results during the SMAT process show that the residual stress in the AZ31 matrix increases with increasing the diameter of carbon steel particles and the particle velocity in the SMAT process has a significant effect on improving the mechanical properties of the simulated magnesium matrix. The highest residual stress and the largest increase in Vickers hardness in the SMAT process were calculated for the largest colliding particle. The maximum surface temperature of AZ31 decreases after SMAT with the increasing size of carbon steel particles. The results show that the roughness parameter increases with increasing colliding particle size.

The use of porous nanobiocomposite scaffolds for maxillofacial fractures and internal surface optimization of artificial grafts utilizing nanotechnology can improve cell adhesion, mechanical properties, and adsorption rate. Porous scaffolds have been the subject of numerous investigations, especially for broken and damaged parts of the facial bone. The goal of this study was to look into the biological, experimental, and numerical study of the mechanical properties of porous scaffolds under static loading conditions.

In this study, a bone scaffold of polycaprolactone- Fluorapatite (PCL / nFA) nanocomposite materials containing (0, 10, 20, 30 %wt.) Fluorapatite nanoparticles was designed and manufactured using a 3D printer with Fused Deposition Modelling (FDM) process. The scaffolds were designed in SolidWorks software with 70% porosity and then transferred to Abaqus software for simulation.

 In addition, following 28 days of immersion in the simulated body fluid, the bioactivity test of pure and composite scaffolds showed that the PCL /20nFA composite sample produced the most apatite on the surface. DAPI staining and fluorescent microscopy observation, confirm cell viability on the 3D printed scaffold.

The Von Mises stress and compressive test simulations revealed that the porous scaffold model may be used for maxillofacial bone replacement and has good mechanical strength and stability.

In the surface mechanical attrition treatment (SMAT) process, the material surface layer is peened with a high-velocity number of carbon steel shot particles. Various parameters such as the distance of the peening gun to the impacted surface can affect the material's surface mechanical properties in the SMAT process. In this paper, the molecular dynamics (MD) approach has been used to study the effect of particle distance from the impacted surface on mechanical and physical behavior of AZ31 after the SMAT process. For this purpose, Universal Force Field (UFF) and Embedded Atom Model (EAM) force field have been utilized for atomic interactions. Based on the molecular simulation results, residual stress, hardness, and temperature of the atomic surface layer have been obtained for various distances. The simulation results demonstrated that reducing the particle distance in the SMAT process increases residual stress and surface layer hardness. Numerically, the maximum residual stress value of 268 MPa has been obtained for a distance of 5 nm in the SMAT molecular simulation results.

The effects of adding different nano-MgO dosages (0, 1, 2, 3, and 4 wt.% with respect to cement) on microstructural, compressive strength, and phase evaluation of concrete were investigated. Two different post-treatment conditions with water and CO2 gas were used to study the processing method on the samples. The specimens were characterized via SEM and XRD analysis. The mechanical properties of the samples were also investigated. The results showed that compressive strength significantly improved after the addition of magnesium oxide nanoparticles. However, this improvement was more remarkable in the case of post-treatment with CO2 compared to the samples fabricated with water. SEM results showed that the samples treated under CO2 gas had irregular and needle-like morphology. The samples prepared by normal processing had CaCO3 and SiO2 phases, whereas the ones fabricated under CO2 gas contained CaCO3, SiO2, and Ca(OH)2. With the addition of nano-MgO, the density of concrete decreases in the samples post-treated with water, whereas it increases for the samples post-treatment with CO2 gas. Adding 4 wt.% nano-MgO to concrete and further post-treatment with CO2 for 45 days could increase the mechanical properties from ~ 23 MPa to ~ 55 MPa.

Various parameters can affect shot peening such as the number of particles and distance between particles and the surface layer. In this computational study, these parameters' effects on the creation of residual stress and mechanical behavior of Ti-6Al-4V alloy were described. For this purpose, Molecular Dynamics (MD) method is applied in two main steps. First, the simulated titanium surface was equilibrated for 1 ns. Next, the shot peening process was done on the equilibrated surface by using the various numbers of particles and distance. MD simulation results indicated, that by increasing the number of particles from 1 to 5, the mechanical behavior of the titanium surface was improved, and residual stress and hardness of the surface increased and reached 452.02 MPa and 494.46 HV in model 1 (Lj potential between particle and titanium surface), respectively. Furthermore, the results indicated that decreasing the distance from 15 Å to 5 Å led to increasing compressive residual stress and hardness of titanium surface mechanical. Numerically, by decreasing the shot peening distance from 15 Å to 5 Å, residual stress and hardness of titanium surface layer increased and reached -419.63 MPa and 510.83 HV in model 1, respectively.

The present study is applied in terms of purpose because it seeks to evaluate the culture of consumption in schools in Parsabad. Due to the use of a researcher-made questionnaire to collect data, the present study is a quantitative one. In terms of data collection, the present study is a descriptive correlational description. The statistical population included all primary school teachers, which according to Chrissy Morgan's table, 291 people were considered as a statistical sample. Simple random sampling method was used for sampling. To collect Moore Dunya data, the research tool is a researcher-made questionnaire or used by domestic and foreign researchers based on Islamic principles. To analyze the research hypotheses, univariate t-test and independent t-test of two populations were used using SPSS software. Findings showed that there is a reduction in energy consumption in schools by using a culture of consumption in a favorable way. There is also a significant difference between the views of male and female teachers about the culture of consumption.

Marginalization is a social phenomenon that along with its spread, we are witnessing an increase in insecurity, delinquency, crime, etc. in society. Marginalization has always been of interest to urban political managers by affecting social security, especially by providing the necessary context for crime. It should be said that if the subject is not important, the society will be in crisis in various economic, social, cultural and political fields. Because the margins always threaten the text. Insecurity in the margins will naturally affect the text as well. An insecure society will not develop at all. Therefore, the prerequisite for development in various fields of human, social, cultural, economic and political, is the same category of social security that needs to be analyzed comprehensively. The present study aimed to investigate the effect of marginalization on citizens' sense of social security by descriptive-analytical method. The results show that marginalized people may threaten the security of citizens due to the young population, poverty, job instability, low education, lack of recreational facilities, poor health, confusion and depression. Marginalization disturbs public order and security due to incoherence and solidarity with the urban community with increasing social harm. Therefore, city managers and those in charge of maintaining public security should reduce security costs and the destructive effects of marginalization by emphasizing issues such as education, propaganda, building trust, social participation and, most importantly, economic and political development.

Since the outbreak of Covid19 virus to date, various methods have been introduced in order to diagnose the virus infection. One of the most reliable tests is assessing frontal Chest X-Ray(CXR) images. As the virus causes inflammation in the infected patient's lung, it is possible to diagnose whether one is infected or not using his/her CXR image. in contrast to other tests which mostly are based on the virus genome, this test is not time-consuming and it is reliable against new strains of the virus. However, this test requires a specialist to assess the CXR images. As the datasets of Covid19 patient CXR images are increasing in number, it is possible to use machine learning techniques in order to assess CXR images automatically and even online. In this study, we used deep learning approaches and we fine-tuned the Alexent in order to automatically classify CXR images and label the whether "Covid" or "Normal". The data we used in this study include about 10,000 chest images, half of which are related to CXR images and the other half are related to patients with Covid19 infection. The model proved to be very reliable with 99.26% accuracy in diagnosis and 95% sensitivity and 99.7% specificity.

The main purpose of this study is to identify and evaluate the impact and role of Islamic councils in the process of political development of the Islamic Republic of Iran with a macro view of performance and obstacles, and factors of failure and to present strategic plans for the future. The research method is descriptive-analytical and seeks to evaluate the impact of Islamic councils on the political development process of the Islamic Republic of Iran. The results showed that increasing public awareness, public trust in social institutions, realizing the rights of the people, and promoting a culture of accountability and a culture of independence could lead to political development, reduce municipal authority, and overcome political issues tastes over other aspects. Specialized and non-specialized affairs have had a negative impact on political development. Political affairs are not separate from the sphere of people's lives, and political development is not only related to governmental affairs, which for ordinary people is an alien and alien concept and only in the hands of the ruler and his representatives, but the purpose of political development is to increase various capacities. Moreover, society is in everything, which obliges the system to respond better to public demands. The role of the Islamic councils of the city in the political development of the country is not very efficient and colorful; the cities do not have a favorable development process, and the councils do not play a significant role in political development. A principled structural reform can pave the way for solving existing problems and political development, and optimal management of cities and regions.

Development of materials for use in medicine and industries is one of the biggest challenges in research in materials science. Today, absorbable, biocompatible and biodegradable polymers have been identified to be used as alternative materials for biomedical applications. Among the biomaterials used in medical fields, polylactic acid (PLA) have been considered widely. This polymer obtained from completely renewable sources and due to their good physicochemical properties in various industries it is highly recommended. The purpose of this study was to introduce PLA mechanical properties using molecular dynamics (MDs) simulation. The special advantage of PLA over other polymers is its biodegradation, which is generally degraded by a single-step process involving a bacterial attack on the polymer itself. It is easily degraded in atmospheres with high humidity and temperatures of 50-70°C. However, at lower temperatures or lower humidity, the stability of PLA products is higher. The MD analysis indicates that the density value corresponds well to the experimental values. Based on the molecular model, the elastic modulus properties of the model were investigated. In this study, the average elastic modulus of the molecular PLA model was calculated to be about 2.2 GPa.