List of Articles های تجربی

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  1 - Analysis on Modeling and Simulation Methods of Fire Spread in the Forests
  Saeedeh Eskandari
  Nowadays, the phenomenon of forest fires as a natural disaster threatens a large part of the world'sforests. Due to the devastating effects of fire on forest, Research conducted by using new methods topredict the spread of fire, is very valuable.This study has been done More

  Nowadays, the phenomenon of forest fires as a natural disaster threatens a large part of the world'sforests. Due to the devastating effects of fire on forest, Research conducted by using new methods topredict the spread of fire, is very valuable.This study has been done to investigate the differentmethods of fire spread modeling and fire simulation in the forests of the world and Iran. Computerprograms are based on mathematical models in order to simulate fire behavior. These models aredivided to four categories of theoretical models, physical systems, experimental models and semiexperimentalmodels. Theoretical models have the ability for universalization to the differentecosystems, but their validation is difficult. Physical model (surface, crown, ground, spot) have beendeveloped regarding to the type of forest fires, but these models often don’t have the enough accurateand their validation is difficult. The experimental models are very practical due to the ease of use, butthey are applicable just for ecosystems which they have the similar conditions with that used informulation and test of model. The semi-experimental models are taken into consideration because ofeasier validation, simplicity and compatibility with the raster data, but lack of ability for crown andspot fires, difficult programming and necessity of availability of the required data for all effectiveparameters are deficiencies of these models. The theoretical models, physical models of surface fire,semi-experimental models of Rothermel, FARSITE and cellular automata can be the best models forfire spread of Iranian forests regarding to conditions of these forests Manuscript profile
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  2 - A Review of Weed Interference Models
  rahman khakzad Mostafa Oviesi Reza Deihimfard
  Weeds represent a continuous problem in agricultural production due to their dynamic and resilient nature. Mathematical models offer a significant tool for understanding and predicting the crop yield losses incurred due to weed-crop interference. Weed-crop competition m More

  Weeds represent a continuous problem in agricultural production due to their dynamic and resilient nature. Mathematical models offer a significant tool for understanding and predicting the crop yield losses incurred due to weed-crop interference. Weed-crop competition models help to inform weed management decisions, both on a short-term basis to tackle the present weed population and in the long term to plan sustainable weed management strategies. Most competition studies are based on empirical models. Empirical functions are the most commonly used models, which provide information for weed threshold values. The limitations of such models are that they are based on statistical functions and usually do not consider biological insights for crop-weed interference. Crop-weed competition is a complex phenomenon, and to understand this, a detailed mechanistic model offers better insights than an empirical model. Mechanistic or explanatory models take into account all underlying processes or mechanisms and their dependence on each other with respect to time and external drivers. Competition models can be integrated within the framework of a decision support system (DSS). In this review, we present empirical and mechanistic models that are currently in use for studying crop-weed interference. Manuscript profile
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  3 - مقایسه روش‌های تجربی محاسبه تبخیر- تعرق پتانسیل در اقلیم نیمه مرطوب معتدل سرد (مطالعه موردی: شهرهای بروجن، شهرکرد، کوهرنگ و لردگان)
  کبری خیری شلمزاری امیر سلطان محمدی
  روش پیشنهاد شده برای محاسبه تبخیر تعرق پتانسیل روش فائو پنمن- مانتیث است اما روش های دیگری نیز وجود دارند که نیاز به داده های هواشناسی کمتر اما برآورد نزدیک به روش فائو پنمن مانتیث در شرایط اقلیمی مختلف را دارند. بررسی عملکرد این روش ها لازمه انتخاب آن ها به عنوان روش ج More

  روش پیشنهاد شده برای محاسبه تبخیر تعرق پتانسیل روش فائو پنمن- مانتیث است اما روش های دیگری نیز وجود دارند که نیاز به داده های هواشناسی کمتر اما برآورد نزدیک به روش فائو پنمن مانتیث در شرایط اقلیمی مختلف را دارند. بررسی عملکرد این روش ها لازمه انتخاب آن ها به عنوان روش جایگزین با توجه به داده های موجود می باشد. در این تحقیق مقادیر روزانه تبخیر تعرق پتانسیل در دوره زمانی 21 ساله (2015-1994 میلادی) با استفاده از روش های تجربی کوپایس، تورگ، هارگریوز، هارگریوز سامانی، ریتچی، ایرمک و سه شکل معادله والیانتز برای چهار ایستگاه بروجن، شهرکرد، کوهرنگ و لردگان محاسبه و با مقادیر محاسبه شده با روش فائو پنمن مانتیث مقایسه شد. برای مقایسه نتایج از ریشه میانگین مربعات خطا، خطای قدر مطلق و ضریب تبیین استفاده شد. نتایج نشان داد که معادله های ایرمک و والیانتز (RS, T,RH,U) بهتر از دیگر معادله‌های تجربی در هر چهار ایستگاه تبخیر- تعرق پتانسیل را برآورد کرد و معادله هارگریوز با 25/95 درصد خطای نسبی نسبت به معادله  فائو پنمن- مانتیث تخمین بسیار ضعیفی از تبخیر- تعرق پتانسیل را نشان داد. هچنین مقایسه مجموع تخمین‌های  حاصله از معادلات تجربی مشخص کرد که روش‌ های ایرمک و والیانتز (Rs,T, RH,U) به ترتیب برای همه ایستگاه ‌ها کارآمد ترین روش بودند. Manuscript profile
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  4 - بررسی و مقایسه‌ آماری مدل‌های تجربی آبشویی نمک‌های محلول از نیمرخ خاک‌های شور و سدیمی (مطالعه موردی: استان خوزستان)
  زهرا عبداله پور ابراهیم پذیرا
  در مناطق خشک‌، همچون بیشتر نواحی ایران که دارای بارندگی کم و تبخیر زیاد می‌باشند، تجمع نمک‌ها در سطح و نیمرخ خاک امری اجتناب‌نا‌پذیرخواهد بود‌. در خاک‌های شور و سدیمی به علت افزایش غلظت نمک‌های محلول در فاز محلول خاک، جذب آب به وسیله گیاه دچار اختلال شده که در نهایت باع More

  در مناطق خشک‌، همچون بیشتر نواحی ایران که دارای بارندگی کم و تبخیر زیاد می‌باشند، تجمع نمک‌ها در سطح و نیمرخ خاک امری اجتناب‌نا‌پذیرخواهد بود‌. در خاک‌های شور و سدیمی به علت افزایش غلظت نمک‌های محلول در فاز محلول خاک، جذب آب به وسیله گیاه دچار اختلال شده که در نهایت باعث توقف و اثرات نا مطلوب در رشد و نمو آن می‌گردد. نخستین گام برای بهسازی این خاک‌ها‌، کاهش شوری خاک تا حد بهینه از راه آبشویی نمک‌ها و جلوگیری از ماندابی‌شدن زمین‌ها می‌باشد. در طرح‌های مطالعاتی، بررسی امکانات اصلاح فیزیکی و شیمیایی خاک‌های شور یا شور و سدیمی و تعیین میزان آب لازم برای آبشویی نمک‌های محلول از نیمرخ خاک‌ها از طریق آزمون‌های میدانی توصیه گردیده است‌. هر چند می‌توان با تقریب و دقت قابل قبولی با استفاده از مدل‌های شبیه‌سازی رایانه‌ای نسبت به تعیین مقدار آب آبشویی و زمان لازم برای آبشویی اقدام کرد. برخی پژوهشگران به دلیل مشکلاتی که تغییرات مکانی ویژگی‌های خاک در مزرعه ایجاد می‌کنند،‌ استفاده از مدل‌های تجربی را پیشنهاد داده‌اند. هدف از این تحقیق، ارزیابی و مقایسه آماری مدل‎های تجربی حاصله برای آبشویی نمک‎های محلول از نیمرخ خاک‎ها و معرفی مناسب‎ترین مدل تجربی برای استان خوزستان با مساحتی حدود ۶۴۰۵۷ کیلومترمربع می‌باشد. نتایج بدست آمده از این تحقیق نشان داد که مناسب‌ترین مدل برای محدوده مورد مطالعه مدل  توانی و منطقه‌ای پذیرا و کشاورز (1378) بوده است. Manuscript profile
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  5 - Investigating the possibility of occurrence of geological hazards in the existing formations at the Hamrov tunnel
  Vahid Hosseinitoudeshki
  Knowledge of geological hazards plays an important role in the selection and installation of timely support system for underground structures.  The Hamrov tunnel with an approximate length of 1294 meters in the main way of Sanandaj- Marivan is under construction. B More

  Knowledge of geological hazards plays an important role in the selection and installation of timely support system for underground structures.  The Hamrov tunnel with an approximate length of 1294 meters in the main way of Sanandaj- Marivan is under construction. Based on the geo-mechanical conditions of rock masses in the tunnel, it is necessary to investigate the possible geological hazards such as squeezing. In this study, using geological surveys and drilling of boreholes, the way of the tunnel been divided into different units and then the severity of squeezing in each section have been investigated. By comparing the different methods of squeezing evaluation, it was found that the empirical Hoek-Marinos method evaluate the minimum of squeezing and the Jethwa method evaluate the maximum of squeezing for the rock masses of the tunnel. The utmost squeezing potential is related to section of the tunnel where there is the alternation of sandy shale and limestone with shale. According to the survey, the Hamrov tunnel is divided into three sections: A (km 5293 to 5543) with squeezing extreme serious to serious, B (km 5543 to 5973) with squeezing severe to very low, and C (5973 to 6133 km) almost without risk of squeezing.   Manuscript profile
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  6 - Numerical and Statistical Evaluation of Squeezing Potential of West Kermanshah Tunnel Convey
  Vahed Ghiasi ALI Godarihemat
  In this paper, based on the results of experimental and analytical methods, crushed zone and gurpy rocks masses were identified as the squeezing sections. Then crushed zone and gurpy sections creep parameters at the Bruger model were obtained in the laboratory. Then cru More

  In this paper, based on the results of experimental and analytical methods, crushed zone and gurpy rocks masses were identified as the squeezing sections. Then crushed zone and gurpy sections creep parameters at the Bruger model were obtained in the laboratory. Then crushed zone and gurpy sections modelling using the software Flac2D with burgers model for 30 days (long-term) were performed. Our numerical modelling results show the large displacements due to very low quality of the rock mass and high overburden in this sections of the tunnel. The results of the numerical modelling in the short-term, that TBM shield would be stuck in this section of tunnel. Also modeling this section in the long-term showed that stability and not seen failure of the segmental support system. But effect squeezing in two sections is not critical. Among the important phenomena that makes problem for tunneling, support and tunnel usage is squeezing which is a type of problems that takes place in weak rocks. Squeezing of the rock is time dependent large convergence, which occurs around the tunnel, and is essentially associated with creep caused by exceeding limiting shear strength. Squeezing is one of the important phenomena in the tunneling industry so drilling in the squeezing cases can be causing serious problems. Predicting the amount of displacement, radial strain, shear strain and plastic zone increment as functions of the squeezing degree resonator factors is one of the basic needs in drilling and tunnel maintenance. Squeezing is behavior that related with weak rock mass deformation and strength properties. This phenomenon is associated with large deformations and time dependent convergence during tunnel excavation. It takes place when a particular combination of induced stresses and material properties pushes some zones around the tunnel beyond the limiting shear stress at which creep starts. Deformation may terminate during construction or continue over a long period of time. West Kermanshah tunnel conveyance (WKTC), with about 8550 meters long and 6.884 m in diameter in the west of Iran is located in Kermanshah province. Mainly parts of the tunnel pass through weak rock make is including types of argillaceous, sandstone and shale, with high 570 meters overburden and will be probably under squeezing condition. Duets in this project the effect of experimental methods, analytical and semi-analytical are evaluated. Then critical section of the squeezing potential presented and finally numerical modelling of this phenomenon is done. Manuscript profile
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  7 - Evaluation of empirical desalinization models in saline soils and determining an appropriate model for north-Ahwaz area, Iran
  Marouf Siosemarde fereydon kaveh ebrahim pazira hosein sedgi seead jamil ghaderi
  Soil salinization and sodification caused by salt accumulation are the common phenomena that manifest in irrigated agriculture in arid and semiarid regions, and reclamation of salt-affected soils has become an important tool for improving crop production. The irrigated More

  Soil salinization and sodification caused by salt accumulation are the common phenomena that manifest in irrigated agriculture in arid and semiarid regions, and reclamation of salt-affected soils has become an important tool for improving crop production. The irrigated agriculture is suffering severe secondary salinization. A large quantity of irrigated land has been abandoned due to salt accumulation which is threatening local environment and socio-economy. The aims of this research was evaluation of empirical desalinization models of saline soils, and determining the appropriate model for soil reclamation at these sites. For this purpose, two experimental areas (Sl, S2) of north-Ahwaz at Khuzestan province, Iran were selected and four treatments with three replications by series of double rings were applied. The treatments were included 25, 50, 75 and 100 cm water application. It was concluded that 87.12 and 84.54% of initial salinity in pilots S1 and S2 was removed by 100 cm water leaching at one meter layer of soil, respectively. In this study, 18 empirical models were compared by using initial and final values of electrical conductivity (EC) relation to net leaching water depth to soil depth. The results showed that cubic and exponential models were the best models with high correlation and accuracy in pilots S1 and S2, respectively. Manuscript profile