مهندس سعید احمدی

Microperforated panels (MPPs), often considered as potential replacements for fiber absorbers, have a significant limitation in their absorption bandwidth, particularly around the natural frequency. This study aims to address this challenge by focusing on the optimization and modeling of sound absorption in a manufactured MPP.

The study employed Response Surface Methodology (RSM) with a Central Composite Design (CCD) approach using Design Expert software to determine the average normal absorption coefficient within the frequency range of 125 to 2500 Hz. Numerical simulations using the Finite Element Method (FEM) were conducted to validate the RSM findings. An MPP absorber was then designed, manufactured, and evaluated for its normal absorption coefficient using an impedance tube. Additionally, a theoretical Equivalent Circuit Model (ECM) was utilized to predict the normal absorption coefficient for the manufactured MPP.

The optimization process revealed that setting the hole diameter to 0.3 mm, the percentage of perforation to 2.5%, and the air cavity depth behind the panel to 25 mm resulted in maximum absorption within the specified frequency range. Under these optimized conditions, the average absorption coefficient closely aligned with the predictions generated by RSM across numerical, theoretical, and laboratory assessments, demonstrating a 13.8% improvement compared to non-optimized MPPs.

This study demonstrates the effectiveness of using RSM to optimize the parameters affecting MPP performance. The substantial correlation between the FEM numerical model, ECM theory model, and impedance tube results positions these models as both cost-effective and reliable alternatives to conventional laboratory methods. The consistency of these models with the experimental outcomes validates their potential for practical applications.

In recent years, due to the high costs of pavement construction and environmental considerations, various recycled materials have been used in the roller compacted concrete pavements. On the other hand, due to the increase in the price of bitumen in flexible pavements, the use of roller concrete in the construction of pavements seems to be more economical. In this research, the mechanical properties, abrasion resistance and impact resistance of rolled compacted concrete containing recycled asphalt and fly ash have been investigated. A total of 15 mixture design were studied with replacement amounts of 10%, 20% and 30% of fly ash as a substitute for cement and 5%, 10% and 15% of fine-grained recycled asphalt as a substitute for aggregate. In order to determine the optimal amount of fly ash, first, compressive and bending strength tests were performed on 7-day samples containing 10%, 20% and 30% of fly ash, and the optimal percentage was obtained. Therefore, in mixtures 4 to 6, the amount of fly ash to replace cement for all mixtures was considered the optimal value (10%). It should be noted that for more accuracy, the 28-day samples containing different amounts of fly ash were also examined. Results of this research showed that the use of fine-grained recycled materials at the rate of 5%, 10% and 15% along with 10% of fly ash led to an increase in compressive strength by 20%, 12% and 4%, bending strength by an average of 10% and tensile strength on the average is about 40% compared to control sample. However, all samples containing recycled asphalt have shown a significant decrease in abrasion resistance.

Nowadays, concrete roll is used in various fields of civil engineering and architecture. Therefore, improving the mechanical properties of this product is important in order to increase the scope of its using. In this study, the effect of yarn and weave of 3-D spacer fabric was investigated on flexural and tensile strengths of concrete roll. For this purpose, four samples of 3-D spacer fabrics with different yarns and weaves were prepared and the cement was injected into these samples. After hydration of concrete roll, the initial cracking stress, final stress and tensile strength were obtained. The results showed that the number of spacer yarns has a significant effect on the amount of initial cracking stress, and the final stress of flexural strength is also increased almost with increasing the initial cracking stress. The results also showed that the type of yarn used in the 3-D spacer fabric has a significant effect on the tensile strength. The tensile strength of concrete roll is increased with increasing the capillary ability of the samples, due to the better hydration of concrete.

Monitoring the transactions of municipalities is one of the key mechanisms of good urban governance, therefore, in countries that have a long history of "rule of law", there are usually legal and political mechanisms to monitor these institutions on their income, expenditure and transactions. Considering this issue, this article is looking for an answer to the question, what are the most important damages and loopholes in Tehran Municipality transactions? In this regard, we investigated this hypothesis by using a systemic model: lack of rule of law, corruption, lack of transparency in transactions, lack of responsibility and lack of accountability of city managers, lack of proper and continuous interaction of citizens and urban civil and union organizations with municipalities. and councils, lack of formal and informal monitoring of urban management, lack of supervision and control over financial income and expenditure and municipal transactions in the form of a legal and logical framework and the principles of the rule of law and its supervision among the most important damages and loopholes of transactions It is the municipality of Tehran. This article showed with a descriptive-analytical method that the system model, on the one hand, has a high strategic, practical and knowledge-based capacity to realize good governance in municipal affairs. In this regard, the use of systemic theory in this article is an innovative method in the analysis of legal transactions of Tehran municipality from the perspective of good governance.

Disturbing noise can cause physical and mental illnesses among workers; for this reason, it is necessary to restrain it, especially in workplaces. Using sound-absorbing materials with suitable acoustic properties has been a growing trend in mitigating noise. This study aimed to improve the acoustic properties of polyurethane foam (PUF) as a sound absorber.

In the present study, PUF was synthesized with different percentages of clay nanoparticles (0 -1.2 wt.%), and then the Sound Absorption Coefficient (SAC) of the synthesized PUF was measured by the acoustic impedance tube in the frequency range of 63 to 6400 Hz according to the ISIRI 9803 standard without an air gap behind the sample. The morphology of the foam was also investigated by Scanning Electron Microscope (SEM).

The results showed that the addition of clay nanoparticles to PUF improved the sound absorption behavior of the samples, and the best sound absorption behavior was for PUF with 1.2% weight of nanoparticles at low frequencies (500-2600 Hz). This increase in the absorption coefficient can be due to the increase in the number and smaller size of the pores with the increase in the amount of nanoparticles in PUF.

This study illustrates that the incorporation of clay nanoparticles into PUF at varying percentages results in an enhanced absorption coefficient. The presence of clay nanoparticles leads to a reduction in cell size and an increase in the number of pores, consequently enhancing surface friction. The absorption coefficient was observed to increase with the growing concentration of clay nanoparticles in PUF.

The emission of pollutants from power plants fueled by fossil resources has perennially contributed to climate pollution. Carbon dioxide emissions, particularly, have been catalysts for global warming and climate upheavals. Governments worldwide are diligently endeavoring to avert these climate shifts by means of multifaceted strategies and policies. To mitigate environmental degradation, the substitution of fossil fuel facilities with renewable energy sources emerges as a commendable solution. This article focuses on the West Mazandaran gas power plant, boasting a nominal capacity of 50 megawatts and an annual output of 0.1 terawatt hours in Mazandaran Province. Through a rigorous evaluation of three distinctive scenarios spanning two phases, namely 1403 and 1405, this facility is eliminated from the energy production cycle and is instead substituted by renewable sources. The energy systems employed in this study are meticulously modeled and analyzed by the ENERGY PLAN software, while the statistical data utilized in this article are derived from the energy balance sheet of Iran. The first scenario entails the replacement of 40 megawatts of wind power, the second scenario embraces the substitution of 31 megawatts of solar power, and the third scenario revolves around augmenting the operational hours of the Black Forest hydroelectric power plant, thereby facilitating the generation of 0.1 terawatt hours of electricity. The project demonstrates several positive outcomes, including a reduction in carbon dioxide emissions by 60,000 tons, the preservation of the thermal value equivalent to 50 GWh of petroleum products and 130 GWh of natural gas, and a surge in the share of renewable energy production from 12 percent to 14.5 percent. To achieve the noble objective of clean and sustainable energy, meticulous and principled short-term, medium-term, and long-term planning are imperative.

Severe hydraulic gradients in open channels cause severe bed erosion and problems caused by sedimentation. Fabric concrete is a unique product with high execution speed that can replace traditional concrete surfaces. According to the mechanical resistance parameters of this product, in addition to its good durability against corrosive factors, one of the applications of fabric concrete is its use on the surface of canals and water course culverts. In this research, first, the flow of open channels in trapezoidal section is simulated under 9 scenarios, which include 3 common channel geometries in the state of a straight path, a path with bends and deviations, and finally, a channel path with a change in height at the bottom of the channel. In each of the states, 3 different flow regimes have been investigated along with flow turbulence modeling using flow-3d software.Different flow regimes have been investigated along with flow turbulence modeling using flow-3d software. Using ABAQUS software, fabric concrete components and their connection areas have been modeled, and by applying forces equated to the concrete surface and vulnerable connection areas, the amount of created stresses has been checked. The results show that the created stresses are very low compared to the tensile and compressive stress capacity of fabric concrete. In order to validate the hydraulic studies of flow and concrete, the relevant laboratory results have been used.

The concrete canvas product consists of three main parts: the three-dimensional (3D) substrate with the cement mixture, the geo-membrane layer and the desired adhesive to connect the geo-membrane layer to the three-dimensional substrate. The three-dimensional layer is generally made of polyester, polypropylene and other engineered polymer had good mechanical and chemical properties, and has different thicknesses, suitable for various applications. This three-dimensional layer is designed in such a way that it has different textures on both sides so that the cement is poured into the space of the three-dimensional layer on one side and nothing spills out of the other layer. In the next step, this process is completed by connecting the geo-membrane layer to it. In industrial application; the geo-membrane layer formulation (including polymer-based resin, emollient, impact curing, filler, etc.) is designed in such a way that in addition to moisture insulation properties, mechanical strength and good chemical resistance to moisture dilute alkaline and acidic environments. In this way, a desired adhesive with desired formulation (including adhesive base resin, solvent, activator and type of catalytic additive, etc.) was selected for connecting of geo-membrane to 3D substrate. To achieve a suitable product, in addition to the geo-membrane layer, the adhesive selected to connect the geo-membrane layer to the three-dimensional substrate must have the appropriate viscosity to be able to completely cover the three-dimensional substrate and cause the two layers to be fully connected to each other. . If the adhesive used cannot create a suitable coating on the geo-membrane layer, by penetrating the fluid around the adhesive, it will weaken and thus destroy the entire coating layer and thus separate the layered concrete layers. In this way, one of the main disadvantages of concrete canvas produced by conventional methods is the separation/layering of the coating layer from the concrete canvas substrate due to thermal and mechanical stress, which weakens the adhesive connecting the layer to the substrate which creates practical problem for this product. In this work, the polymer casting technology based on polyvinyl chloride paste was used to cover a concrete canvas and the properties of the product were investigated. In this method, the polymer paste is coated on the three-dimensional substrate in one step without using (geo-membrane / adhesive) by Dr. Blade knife in a certain thickness. The results showed that the fabric concrete made based on the PVC paste casting method, has good sealing, mechanical and chemical resistance and has good resistance against layering. The results showed that the fabric concrete product obtained from the polymer casting method based on (resin / polyvinyl chloride paste) in terms of mechanical strength, showed acceptable properties compared to the geo-membrane layer and the overall fabric concrete product and also in terms of chemical properties (resistance to various solvents), it has a much better resistance than the sample made by conventional methods (geo-membrane / adhesive). This product (concrete canvas) has also shown better resistance to water leakage against the sealing of the product, the overall product made by the polymer casting method.

Corruption, especially administrative corruption, has adverse effects on various dimensions of human society's life and is one of the main problems facing the world's political systems. The ratification of the United Nations Convention against Corruption Merida 2003 is an international confirmation of this. In the legal system of Iran, by joining this convention, various measures have been taken in the two dimensions of preventing administrative corruption and dealing with it criminally. In addition, Iran's legal system has also paid attention to international cooperation to fight corruption. According to the results of the research, there are still serious problems in some areas to effectively fight corruption, and the most important problems in this field is the lack of criminalization of administrative corruption. In the private sector, the non-adoption of differential criminal procedure for administrative corruption crimes, the absence of a comprehensive national program for the prevention of administrative corruption, the existence of parallel regulatory institutions and the lack of detailed explanation of their duties, are the lack of serious attention to the internal control system. Therefore, It can be said that Iran's legal system does not have the necessary coherence and coordination in the field of dealing with administrative corruption. Solutions to improve and promote the fight against corruption in two theoretical, research and practical formats should be considered. Solutions such as local and comparative research on the root corruption, including the large size of the

Nowaday, there are wide applications for satellite images in agriculture monitoring and management. According to high spatial, spectral and temporal resolution of Sentinel-2 images, we used them for precise agriculture in Qorveh country. Proposed methd consist of five step: firstly, multi-temporal images are collected based on agriculture calender of crops. Then feature space is generated based on spectral reflectance and vegetation indices which consists of 70 features. According to high dimensionality of feature space, principle component analysis is applied to reduce its dimension. Four power classifiers include support vector machine, k-nearest neighbour, multi-layer perceptron and random forests classify the reduced spectral feature space. On the other hand, spatial information are extracted from multi-temporal multispectral images. For this pupose, strandard deviation (STD) maps are generated for red, NIR and SWIR bands of each epoch. Then, by averaging the STD maps, final STD map is obtained. Edge detection is performed on STD map and it improves by removing small lines, smoothing, thining, etc. Finally, crop mapping is done by fusion of four classification maps and agriculture farm boundaries. The obtained results show that classification accuracy of k-nearest neighbour, support vector machine, multi-layer perceptron and random forest classifiers are 77.78%, 79,16%, 76.41% and 76.89%, respectively. The overall accuracy of the proposed method improve up to 94.72% which proves high potential of the proposed method.

The aim of this research was the study of relationship of virtual education and cognitive creativity with mediator role of academic satisfaction.

This research was one of the descriptive correlation researches. The statistical population of the research included all the second high school students of Firuzabad city in the academic year of 2001-1401, in the number of 4470 people, and using the multi-stage cluster sampling method, 350 students were selected. In order to collect information, the creativity questionnaires of Rawdesp (1999), the e-learning questionnaire of Ozetkin, Zenio and Ezgur (2011) and the academic satisfaction questionnaire of Huebner (2001) were used. The validity and reliability of the tools were calculated using item analysis and Cronbach's alpha coefficient.

The results of this research showed that the level cognitive creativity in secondary school students of FiroozAbad was lower than the average. The virtual education has a significant relationship with cognitive creativity. The virtual education has a significant relationship with academic satisfaction. The academic satisfaction has a significant relationship with cognitive creativity. There was significant relationship between virtual education and cognitive creativity with mediator role of academic satisfaction.

In general, there is a statistically significant relationship between virtual education and cognitive creativity with the mediating role of students' academic satisfaction. Education officials can provide the fields of creativity for students with happy programs that suit their needs and interests.Key words: cognitive creativity, virtual education, academic satisfaction, students.

One of the main challenges of conventional concrete canvas is the separation of the geo-membrane layer from the fabric concrete substrate, which has caused major problems in the discussion of the application of this product. In this work, the method of casting polymer paste based on acrylic resins was used to create a single-layer coating of sealing resin with the high overall mechanical strength of the product, and the properties of the product were investigated. In this method, polymer paste is formed in one step without the use of adhesive and geo-membrane layer on the three-dimensional substrate bed, and the overall productivity of concrete canvas is formed. The results showed that concrete canvas produced based on polymer paste casting method with suitable mechanical strength (30 (kN / mm2)), better sealing (up to 30 days without changing weight against water), non-layering, Suitable chemical resistance against hexane, toluene, benzene and octane and better temperature resistance (from -20 to 100 C) than conventional concrete canvas product.

Sistan and Baluchestan province is located in the southeast of Iran and has a dry and unfavorable climate. The drying up of Lake Hamoon, as well as the 120-day winds, have provided suitable conditions for wind erosion and the occurrence of dust storms, which cause sand dunes to move at high speeds. By locating and constructing windbreaks, the movement of flowing hills can be largely prevented. The purpose of this study is to determine the suitable plant species of the province for the construction of windbreaks and select the optimal sample using the distance-based method. It is important to find the best option for use as a natural windbreak that, in addition to adapting to the climate of the region, has the best response and also does not lead to high costs. In this study, the rate of decrease in wind speed before and after the windbreak and the appropriate distance of its construction from an area were determined by studies. Finally, it was found that Chesh and Kurt, coriander, turmeric, hawthorn and almond trees are suitable for planting in this area. The distance-based method (DBA) defines good values of traits in a process by defining the optimal state. Using this method, it was found that the eye and plum tree is more suitable for constructing windbreaks than other species.

Today, in the research of researchers, the use of waste materials with heat transfer capability in various asphalts, especially warm mix asphalt (due to environmental benefits) has been considered. Obtaining the modulus of elasticity is very important in determining the efficiency of asphalt, which can be achieved by various methods. Also, the sound absorption of this type of asphalt has been studied using ultrasonic waves. In this study, asphalt samples containing fillers of zinc slag, iron slag, converter sludge, copper slag and earth filler reducing electrical resistance each with 35%, 70% and 100% weight replacement of lime filler (normal) in asphalt. Through SCB three-point bending test, the amount of modulus of elasticity was obtained and then on Marshall samples using underwater method and using ultrasonic waves, the amount of longitudinal modulus and the amount of sound absorption of the samples were investigated. The results show the fact that on average, in the mixtures containing BOF, steel slag, GIM and copper slag, it can be said that mixtures containing BOF by 7% and mixtures containing steel slag, GIM and copper slag by 4, respectively. , 20 and 6% have more impedance than the control sample (WMA). Furthermore, the results showed that the longitudinal modulus obtained by ultrasonic wave method for the samples has the same trend of modulus of elasticity by three-point bending method. The results also showed that statistically, although the type of filler is effective on the performance of the longitudinal modulus, but the percentage of conductive filler (replacement of lime filler) is not effective on the performance of asphalt.

The present study was conducted to investigate the relationship between e-learning and communication skills and research skills of high school students in Firoozabad in terms of purpose, application and according to the data collection method was a descriptive correlational study.The statistical population of the present study included all high school students in the city of Firoozabad in the academic year 1399-1400 to 3445 people. In order to select the desired sample, cluster random sampling method was used. In the present study, in order to collect information, three communication skills questionnaires of Queen Dam (CSTR) (2004), the research skills assessment questionnaire of Mokhtari et al. (2014) and the e-learning questionnaire of Watkin et al. (2004) were used. Data were analyzed using Pearson correlation coefficient and regression in SPSS23 software. The results showed that there is a significant relationship between e-learning and communication skills and students 'research skills and also e-learning predicts students' communication skills and research skills.

Human being as a multidimensional creature has been always an important subject in prophet’s divine training. Knowing all dimensions of the man, either its body or soul have a special function and message in the path of sublimation. The phantom is one of the most effective elements among diversities especially the human beings. Ion This article studies the position of phantom in religious training based on Islami mysticism and wisdom. The research method is descriptive analysis with a positive approach to the subject. At first it describes the conceptual and confirmative cognition of the religious training. Then it focuses on the wisdom as a medium and some features such as creativity, mimesis, and epistemic values of conceptual cognition. Finally, we disproved that wisdom is the starting point of religious training.

This research was conducted with the aim of designing a competency-based curriculum in the field of Information Technology Engineering. The research was a case study in terms of qualitative research component design. The potential research participants included 12 faculty members in Fars province universities in the field of information technology and 15 employers who were selected through purposive sampling. The research data were collected using two tools: "Document review" and "Semi-structured interview". The data validation was confirmed by matching method and data analysis method was used to analyze the data. In the following, data coding was performed to identify factors, criteria and model markers. Initial qualitative data were obtained through interviews and qualitative validation measures were used to measure the initial validity of the data. Using the method of analysis of the content, the framework of the model was formed and, based on the results, dimensions and components were embedded in a comprehensive theme. The most important findings of the research were: The proposed framework for teaching IT education can be presented in four general competencies: technical, behavioral, context and perceptual. The results of this study can be considered by planners in the design and development of an IT engineering curriculum.

Punch press is contributed as one of the major industrial machines to produce metal objects, which typically propagates hazardous noise. Acoustic enclosure is the most common method to mitigate noise transmitted from industrial equipment. This study aimed to assess the role of opening dimension and location in a partial acoustic enclosure on occupational noise exposure of punch press’s operator.

A punch press with the capacity of 60 tons in an automotive manufacturing company was considered as a real noise source. Equivalent noise exposure level was measured with reference to ISO 9612 using Cassella Cell-450 sound meter, before and after noise control intervention. Rubber sheet and mineral wool as insulation and absorption acoustical material with the thickness of 2 and 50 mm, respectively, applied to build acoustic enclosure. Rubber sheet sound transmission loss was measured using BSAW SW 477 acoustic impedance tube to predict acoustic performance of enclosure. In addition, Partial acoustic enclosure with the dimensions of 1.4 by 1.2 by 3 meter was constructed and opening areas which was equal to 2, 3, 5 and 7 percentage of total area of enclosure was created in front of punch press operator. Finally, an opening equals to 2 percentage of total area of enclosure was created on the left sidewall of enclosure to assess the location of opening on noise level.

Punch press operator noise exposure level was measured to be 89 and 67 dBA before and after using full acoustic enclosure respectively.  After using partial acoustic enclosure with open area percentage of 2, 3.5 and 7 on the front side of press, operator noise exposure level was measured 78, 79, 78 dBA, respectively which was a little bit more than predicted noise. As the opening position was relocated from the front wall to the sidewall of the enclosure, operator noise exposure was reduced from 78 to 69 dBA respectively. Although, there was not significant differences between mean sound level of the punch press after relocation of opening. 

Utilizing full acoustic enclosure constructed from insulation material recommended in this study, reduced punch press operator noise exposure remarkably. Although, opening area of partial acoustic enclosure was increased to some general extent to feed punch press, there was a slight change in noise exposure of press operator. On the other hand, press operator noise exposure was plummeted with the relocation of opening. Therefore, front opening dimension could be chosen fairly wide to access and feed operation zone of punch press without exposing operator with more noise level. Furthermore, repositioning the opening from the front wall to the side wall of the enclosure and automatically feeding the press through side opening could substantially reduce the operator noise exposure.