amirmohammad hassanzadeh
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بتن به عنوان یکی از پرکاربردترین مصالح ساختمانی، رفتاری شکننده دارد. افزودن الیاف به بتن بر شکل پذیری، مقاومت در برابر ضربه، میزان جذب انرژی، مقاومت پس از ترک خوردگی، مقاومت سایشی و مقاومت کششی بتن اثرگذار بوده و از گسترش ترک جلوگیری می کند. به همین منظور، پژوهشی برای بررسی تاثیر ترکیبات مختلف الیاف پلی پروپیلن، الیاف فولادی سینوسی و نانوسیلیس کلوئیدی بر مقاومت خمشی، مقاومت فشاری، مقاومت کششی و درصد جذب آب بتن انجام شده است. نتایج آزمایش های انجام شده نشان می دهد که با افزودن الیاف فولادی سینوسی، الیاف پلی پروپیلن و نانوسیلیس کلوئیدی به نمونه های بتنی، مقاومت خمشی، مقاومت فشاری و مقاومت کششی افزایش می یابد. بهترین طرح اختلاط مربوط به نمونه ی 7 درصد الیاف فولادی و 3 درصد نانو سیلیس کلوئیدی (S7N3) می باشد، که مقاومت خمشی، مقاومت فشاری و مقاومت کششی این ترکیب به ترتیب 34/54، 62/35 و 31/26 درصد نسبت به نمونه شاهد (OPC) افزایش نشان می دهد. در نمونه حاوی 3 درصد نانوسیلیس (N3) نسبت به نمونه شاهد جذب آب 32 درصد کاهش یافته است.
کلید واژگان: نانوسیلیس کلوئیدی، الیاف فولادی، الیاف پلی پروپیلن، خصوصیات مکانیکی بتن، بتن الیافیConcrete, as one of the most widely used construction materials, has a brittle behavior. Adding fibers to concrete has an effect on formability, impact resistance, energy absorption rate, post-cracking resistance, abrasion resistance and tensile strength of concrete and prevents crack propagation. For this purpose, a research has been conducted to inves-tigate the effect of different combinations of polypropylene fibers, si-nusoidal steel fibers and colloidal nanosilica on the performance of flexural strength, compressive strength, tensile strength and water ab-sorption percentage of concrete. The results of the experiments show that by adding sinusoidal steel fibers and colloidal nanosilica to con-crete samples, bending strength, compressive strength and tensile strength are increased. The best mixing design is related to the sample of 7% of steel fibers and 3% of nano colloidal silica (S7N3), which the bending strength, compressive strength and tensile strength of this combination are 54.34, 35.62 and 26.31% respectively. The control sample (OPC) increases. In the sample containing 3% nanosilica (N3), compared to the control sample, water absorption has decreased by 32%.
Keywords: Colloidal Nanosilica, Steel Fibers, Polypropylene Fibers, Mechanical Prop-Erties Of Concrete, Fiber Concrete -
Today, monitoring groundwater quality and the trend of its changes for drinking, industrial and agricultural uses is very important for the general health of society. Due to changes in groundwater quality that can be due to climatic or human factors, it is necessary to consider and study these resources to maintain their quality. The purpose of this study is to investigate the quality and effective factors in groundwater quality changes in Khorramabad from 2005 to 2018 using the global water quality index (WQI) and coherence and cross wavelet. To achieve this goal, first, the drought assessment of Khorramabad city has been studied according to precipitation data using index (SPI). Then, using the world water quality index (WQI), the groundwater quality of Khorramabad has been studied. The results showed that the quality of groundwater in Khorramabad during the years 2005 to 2018 was in standard condition. Also, the correlation between the chemical parameters of groundwater has been evaluated. The results of coherence and cross wavelet showed that the relative effect of precipitation with a wavelet coherence coefficient of 0.5 has been more compared to other factors in changes groundwater quality Khorramabad city. Therefore, it can be said that the relative impact of climatic factors on changes in groundwater quality in Khorramabad has been more than the other factors. Accordingly, appropriate management strategies for groundwater quality resources and mitigation solutions are imperatively needed to ensure the sustainability of the groundwater resource and the protection of public health in the Khorramabad city.
Keywords: SPI, Water Quality, Khorramabad, WQI, Coherence Wavelet -
Today, Metaheuristic Algorithms are considered as one of the most important and appropriate methods to achieve good solutions and optimization. In this research, a Particle swarm optimization (PSO) algorithm with a nonlinear objective function has been used to solve the problem of optimizing the reservoir water allocation of the Eyvashan earth dam based on the reservoir water balance for irrigation periods (2014-2020). The results show that the highest agricultural demand downstream of the dam in June was 8.96 (MCM). The amount of reservoir release calculated by the model to meet the water requirement downstream of the dam (37.80MCM) is much more optimal than the total amount of downstream needs (41.03MCM). Also, the minimum amount of water shortage due to severe drought while controlling floods is easily possible due to the useful volume of the reservoir and the annual flow of the reservoir. According to the PSO model, in each period of operation of Eyvashan earth dam, about 7.9% can be saved in the reservoir release for the needs of downstream agriculture in the months of high water consumption in summer.
Keywords: PSO algorithm, optimization, Eyvashan earth Dam, Metaheuristic methods
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