فهرست مطالب hadi shakeri

There is no acceptable method for investigating the tool wear phenomenon in soft grounds. In this article, first, a new equipment made at Sahand University of Technology is introduced, which is used for simulation of TBM tunneling mechanism. Next, the effect of various soil grading parameters such as D10, D30, and D60 (which indicate the corresponding diameters on the soil grading diagram where 10, 30, and 60% of the grains are smaller than these values, respectively), coefficient of gradation, uniformity coefficient, sorting coefficient and effective size on the cutting tools wear. The initial studies show that in soils with fine grains greater than 10%, by increase in the values of D10, D30, D60, and effective size, the tool wear increases. However, in soils with fine grains less than 10%, by increase in the above-mentioned parameters, the soil abrasiveness reduces. Also in soils with more than 10% fine grains, by increase in the coefficient of gradation value, the soil abrasiveness reduces. But in soils with fine grains less than 10%, by increase in the value of this parameter, the tool wear increases. The results of experiments show that sorting coefficient could be a good criterion for investigating the soil abrasiveness.

Place is the center of geography and identity; it is the manifestation of culture in place. Parliamentary elections, as a political event, play an effective role in representing the voters' spatial identities. The interests of individuals play a decisive role in directing their work. The performance and action of humans are subject to the understanding and perception they have of the surrounding geographical environment, which gives meaning to their interests. The geographical environment is a concept mixed with social, political, economic, and natural factors whose intertwining has played a fundamental role in giving direction and meaning to human character, effort and spatial identity. Elections are the highest level of representation of local identities in heterogeneous constituencies in which local identities are  reflected. Due to its geographical location throughout history, Iran has had a wide variety of local identities, among which the elections of the Islamic Council played a role in revealing this diversity of identity and, accordingly, the diversity of spatial voting patterns. In North Khorasan, it is one of those culturally diverse areas from a linguistic point of view, and the identities arising from this diversity have played an effective role in pushing and pulling the votes of the candidates for the election of the Islamic Council. Identities and cultural contexts have sometimes led to the neglect of worthy candidates and competent representatives at the center of national decision-making.

Esfarayen Constituency includes the cities of Bam, Safi Abad and Markazi, which is the third constituency in the province in terms of population. In terms of language, the residents of this area speak the Kurdish dialect of Kurmanji, Tati, Farsi, and Turkish, and religiously, they follow the Shiite religion. This constituency was a part of the constituencies of Khorasan province until the sixth term of the Islamic Council elections, and from the seventh term, with the separation of Khorasan province, this constituency was assigned to North Khorasan province. Esfarayen Constituency has a representative in the Islamic Council. The current research aims to investigate and analyze the impact of spatial identities arising from linguistic diversity on the orientation of the spatial pattern of voting in the Esfarayen constituency. The methodology governing the text has a descriptive-analytical nature, and the statistics and information needed for the research were collected by the library and field method   (questionnaire) and then analyzed using spss software.

The result of the research showed that the elements of place identity such as the number of co-citizens and co-speakers of the candidate, ethnicity, co-lingualism, ethnic population and co-speakers of the candidate being co-citizens with the election candidate, respectively, had the greatest impact in creating the voter base for the candidate representing the Islamic Council at the constituency level. On the contrary, the parliament candidate's belonging to a particular party, the opinion of religious elders and clan elders, the candidate's experience and education, and the correctness of the candidate were, respectively, less important in getting the votes of the candidates.

The performance of mechanized excavation depends on the soil abrasivity and the resistance of cutting tools against wear. The wear has a negative effect on excavation machine parameters, such as penetration rate, and reduces the machine's efficiency. Worn tools require replacement, which interrupts the project and incurs high maintenance costs. For this reason, many efforts have been made to understand the interaction between soil and cutting tools. Various wear-measuring devices have been designed and built to measure soil abrasivity and cutting tool wear. In this research, to study the mechanism of tunnel excavation in the laboratory, a tunnel boring machine laboratory simulator was designed and built, and the effect of the operating parameters of the excavation machine on the average wear of cutting tools was studied. The features of this machine are its horizontal excavation, the low rotation speed of the cutterhead, continuous contact of the cutters with fresh soil during the test, and continuous injection of materials with a specific injection pressure during the test. Using the granulation of soil prepared from Tabriz metro line 2 in three moisture content of zero, 7, and 13%, the effect of the rotation speed of the cutterhead, rotation time, and penetration rate on the wear of cutting tools was studied. The investigations showed that with the increase in the rotation speed of the cutterhead, the average wear increases. Also, the increasing rotation time has caused more friction between the cutting tools and the cutterhead with the soil, and the wear has increased. The wear decreased with the increase in the penetration rate, despite the increase in the intensity of the conflict between the soil particles and the cutting tools. The results obtained from this research by using a tunnel boring machine laboratory simulator are in good agreement with previous studies.

Hydraulic fracturing is one of the most important stimulation methods for oil and gas reservoirs with low permeability. Various factors, such as in-situ stresses, joints and natural fractures of the formation, fluid rheology, mechanical properties of the formation, injection fluid flow rate and perforation operation, effect on the pressure and hydraulic fracture geometry. Many researchers have studied hydraulic fracturing behavior of rocks since decades ago. The researches have showed that hydraulic fracturing operations increase the production of oil wells by up to 30 percent and increase gas wells by 90 percent. Currently, this operation is performed on about 60% of all drilled wells.

In this research, for the experimental investigation of the hydraulic fracturing, considering the reservoir condition, 39 concrete cubic samples with 100 × 100 × 100 mm dimensions and 60 concrete cylindrical samples with a diameter of 54 mm and a height of 110 mm were constructed and the effect of the sample geometry and in-situ stress field on the fracture geometry, breakdown pressure, the pattern of crack propagation and finally the cross fractures in vertical wellbores were investigated.

In cubic specimens under uniaxial stress, with increasing vertical stress to 8 MPa, first the breakdown pressure has been increased by about 132% and then with increasing vertical stress to 16 MPa, the breakdown pressure has been decreased by about 69%. In cylindrical specimens under uniaxial stress, with increasing vertical stress to 12 MPa, first the breakdown pressure increased by about 113% and then with increasing vertical stress to 16 MPa, the breakdown pressure decreased by about 6%. As the vertical stress increases to a certain limit, the pores and micro-cracks inside the sample close, thus the tensile strength and breakdown pressure increase. In the following, increasing vertical stress causes more small cracks to open and reduces the tensile strength of the rock. In cubic specimens under triaxial stresses, with increasing vertical stress, the breakdown pressure has been increased. Also, in cylindrical specimens under triaxial stresses as the maximum horizontal stress increased, the breakdown pressure increased.

The obtained results demonstrated that increasing the uniaxial stress in the vertical wellbore in both types of studied sample geometry, first the breakdown pressure increases and then from one boundary onwards, with increasing vertical stress, the breakdown pressure decreases. In cubic specimens under triaxial stress, with increasing vertical stress, the breakdown pressure increases. Additionally, in cylindrical specimens under triaxial stresses as the maximum horizontal stress increases, the breakdown pressure increases, so that, in the 8 MPa maximum horizontal stress, the breakdown pressure increases by about 81%../files/site1/files/151/3.pdf

There has been obvious and hidden effort to overcome the space in the context of individual and group scans. Space and space are conceptualized with the social, political, economic and natural processes that their long-term diversity and long-term integration play a fundamental role in the direction and meaning of the efforts and manners of the people living in it. The context has provided them with a sense of belonging and life sustainability. Inside the interior of nature are intrinsically powerful. Elections are firmly established as one of the individual power-building processes or political currents with the elements and processes of the spacecraft. Meanwhile, environmental perception, along with the sense of people's place of belonging, plays a significant role in their voting behavior. The province of Bojnourd in the northern Khorasan province is the domain of various cultures (linguistic and religious). The present paper relies on the hypothesis that identity identities (linguistic and religious) in the form of spatial identities are the most fundamental factor in shaping the model of voting space in this electoral domain. The methodology governing the text is a descriptive- An analysis has been carried out and the statistics and information required for research have been collected by a library method. The result of the research showed that the rise of the element of identity and location of the locals of the province has been selected at least in all courses by at least one candidate for the Kurdish language.

Hydraulic fracturing is one of the most important stimulation methods for oil and gas reservoirs to increase fluid flow from low permeability reservoirs to wellbores. Various factors, such as in-situ stresses, joints and natural fractures of the formation, fluid rheology, mechanical properties of the formation, injection fluid flow rate and perforation operation, effect on the pressure and hydraulic fracture geometry. In this research, for the experimental investigation of the hydraulic fracturing, considering the reservoir condition, a three-axial machine with the ability to apply the main stresses was designed and built. Then, 32 concrete cubic samples with 10 × 10 × 10 cm dimensions were constructed and cured in the laboratory and the effect of the in-situ stress field and stress regime on the geometry and breakdown pressure, the pressure-time diagram, the pattern of crack propagation and finally the cross fractures in both vertical and horizontal wellbores were investigated. The results showed that increasing the maximum horizontal stress in the vertical wellbore leads to increased breakdown pressure and increasing deviatoric stress in the horizontal wellbore reduces the breakdown pressure.

Hydraulic fracturing is one of the most important methods for the propagation of oil and gas reservoirs, which is used to increase the inflow to well bore in low permeability formations. Various parameters such as in-situ stress field, joints and natural fractures of the formation, the fluid rheology, the mechanical properties of the formation, injection fluid flow and perforation affect the hydraulic fracturing pressure. In this research, a triaxial machine was designed and built for experimental investigation of the hydraulic fracturing in conditions close to the field conditions, so that all three of the main stresses in field conditions are applied in laboratory tests. Then, the influence of different perforation parameters such as perforation geometry (including length, diameter and shape), phase of perforation (in both vertical and horizontal wells) and minimum horizontal stress in the presence of perforation, using 38 artificial specimens (plaster + sand) with dimensions of 10×10×10 cm, was considered on the geometry and breakdown pressure, pressure-time diagram, and the development of micro-cracks. The results showed that increasing the perforation diameter, changing the perforation angle to the maximum horizontal stress and increasing the minimum horizontal stress in the case of reverse fault, rises the breakdown pressure. 

Hydraulic fracturing is a stimulation technique used in oil and gas wells to increase the inflow to well bore in low permeability formations. Various parameters such as in-situ stress field, joints and natural fractures of the formation, the fluid rheology, the mechanical properties of the formation, injection fluid flow and perforation affect the hydraulic fracturing pressure. Currently, more than half of the USA oil and gas wells are not able to produce without the use of hydraulic fracturing technology. Many researchers have studied hydraulic fracturing behavior of rocks since decades ago. The researches have showed that hydraulic fracturing operations increase the production of oil wells by up to 30 percent and increase gas wells by 90 percent. 

In this research, a triaxial machine was designed and built for the experimental study of hydraulic fracturing and to apply in-situ stresses with different values. This machine has the ability to apply anisotropic stresses in laboratory scale. Abaqus software was utilized to design the machine in terms of stability against the applied stresses. Then, using physical modeling, 38 samples with dimensions of 10×10×10 cm including plaster and sand were constructed and the influence of different perforation parameters such as perforation geometry (including length, diameter and shape), phase of perforation (in both vertical and horizontal wells) and minimum horizontal stress in the presence of perforation on hydraulic fracturing operations were investigated. Finally, the breakdown pressure, hydraulic fracturing geometry, pressure-time diagram and the development of micro-cracks were studied. 

The results of this study showed that increasing the perforation diameter, changing the perforation angle to the maximum horizontal stress and increasing the minimum horizontal stress in the case of reverse fault, rises the breakdown pressure. Also, the increase of the perforation length and its geometry have not significant effect on the breakdown pressure. Additionally, the change in the perforation angle and the minimum horizontal stress relative to the change in the perforation geometry, including length, diameter, and shape, have more effect on the breakdown pressure and changing the perforation angle relative to changing the in-situ stress in the horizontal well bore is more effective on the breakdown pressure.

Hydraulic fracturing is a reservoir stimulation technique which is used to increase the flow from low permeability formations. In this paper, the mechanism of hydraulic fracturing with a focus on factors affecting hydraulic fracturing pressure has been investigated. The effects of axial and confining stresses are examined via a triaxial cell that has been designed and made in Sahand University of Technology. To this end, thirty one rock samples including reservoir samples (Aghagari sandstone, Asmari limestone and Sarvak limestone) and non-reservoir samples (Varzaghan field sandstone) are used. Water-based mud is used to study the effect of fluid type and viscosity. Xanthan gum, Guar gum, and polymer are added to increase the viscosity of the water. Axial stress applied to the top of cylindrical sample and the confining stress applied radially. The direction of failure by stresses (axial and confining stress) is determined. The results show that the fracture pressure increases by increasing the confining stress; also, fracture pressure goes through a maximum of 10 MPa by raising the axial stress but decrease from 10 Mpa. The initiation and extension of cracks in hydraulic fracturing are influenced by the rock permeability and the fracturing fluid viscosity. The fracture pressure for low viscosity fluid (water) is less than that of high viscosity fluid (xanthan gum).

Objective(s)In recent years highly selective COX-2inhibitors were withdrawn from the market because of an increased risk of cardiovascular complications. In this study we were looking for potent compounds with moderate selectivity for cox-2. So, four analogues of 4, 5-diaryl-2-(2-alkylthio-5-imidazolyl) imidazole derivatives were synthesized and their anti-inflammatory and anti-nociceptive activities were evaluated on male BALB/c mice (25-30 g). Molecular modeling and in vitro COX-1 and COX-2 isozyme inhibition studies were also performed. Materials and Methods2-(2-Alkylthio-5-imidazolyl)-4,5-diphenylimidazole compounds were obtained by the reaction of benzyl with 2-alkylthio-1-benzylimidazole-5-carbaldehyde, in the presence of ammonium acetate. Spectroscopic data and elemental analysis of compounds were obtained and their structures elucidated. Anti-nociception effects were examined using writhing test in mice. The effect of the analogues (7.5, 30, 52.5 and 75 mg/kg) against acute inflammation were studied using xylene-induced ear edema test in mice. Celecoxib (75 mg/kg) was used as positive control.ResultsAll four analogues exhibited anti-nociceptive activity against acetic acid induced writhing, but did not show significant analgesic effect (P< 0.05) compared with celecoxib. It was shown that analogues injected 30 min before xylene application reduced the weight of edematic ears. All analogues were found to have less selectivity for COX-2 in comparison to celecoxib. ConclusionInjected doses of synthesised analogues possesses favorite anti-nociceptive effect and also has anti-inflammatory effects, but comparing with celecoxib this effect is not significantly different. On the other hand selectivity index for analogues is less than celecoxib and so we expect less cardiovascular side effects for these compounds.