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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Nanostructures
- نوع مقاله: Journal Article
- کلمات کلیدی: Elastic medium,Bulking,Nonlocal elasticity,Nanowire
- چکیده:
- چکیده انگلیسی: Nano structures such as nanowires, nanobeams and nanoplates have been investigated widely for their innovative properties. In this paper the buckling of nanowires surrounded in a Winkler - Pasternak elastic medium has been examined based on the nonlocal Euler-Bernoully model with considering the surface effects. In the following a parametric study that explores the influence of numerous physical and geometrical parameters on the buckling of nanowires is presented. It has been shown that by growing the ratio of surface area to bulk in nano-size structures, the effect of surface energy turn out to be important and should be taken into consideration. Moreover the results point out that surface elasticity and residual surface tension stimulus the buckling behavior of nanowires.
- انتشار مقاله: 19-12-1394
- نویسندگان: O. Rahmani,S. S. Asemani,S. A. Hosseini
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Nanostructures
- نوع مقاله: Journal Article
- کلمات کلیدی: Sol-Gel,nanocatalyst,Polyhydroquinoline,Hantzsch,Sulfated titania
- چکیده:
- چکیده انگلیسی: Sulfated titania nanoparticles (SO42-/TiO2 NPs) were synthesized using titanium tetraisopropoxide (TTIP) by the sol-gel method. The structure and morphology of the prepared nanocatalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) methods as well as Fourier transform infrared (FT-IR) and energy dispersive X-ray (EDX) spectroscopy. The obtained nanoparticles were used as an efficient, reusable and environmentally friendly catalyst for the synthesis of polyhydroquinoline (PHQ) derivatives via a one-pot multicomponent reaction of various aldehydes, ammonium acetate and 1,3-dicarbonyl compounds under reflux conditions. The desired Hantzsch esters were obtained in good to excellent yields and short reaction times. The SO42- /TiO2 NPs could be recycled at least three times without significant loss of their catalytic activity.
- انتشار مقاله: 29-10-1394
- نویسندگان: A. Tadjarodi,A. Azad,M. G. Dekamin,S. Afshar,R. Hejazi,A. Mollahosseini
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Nanostructures
- نوع مقاله: Journal Article
- کلمات کلیدی: Wet impregnation,MWCNTs,TCVD,Bimetallic catalyst,Monometallic catalyst,Nanometric SiC
- چکیده:
- چکیده انگلیسی: Nanometric Carbid Silicon (SiC) supported monometallic and bimetallic catalysts containing Fe, Co, Ni transition metals were prepared by wet impregnation method. Multiwall carbon nanotubes (MWCNTs) were synthesized over the prepared catalysts from catalytic decomposition of acetylene at 850°C by thermal chemical vapor deposition (TCVD) technique. The synthesized nanomaterials (catalysts and CNTs) were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Raman spectroscopy. In this paper, using of nanometric SiC powder as catalyst support was examined and the effect of applied catalyst type on characteristics of grown CNTs was investigated. The results revealed that iron, cobalt and nickel are in oxide, cobalt ferrite (CoFe2O4) and nickel ferrite (NiFe2O4) forms and nanometric SiC powder can be applied as an appropriate catalyst support in CNT growth process. It was observed that the produced CNTs on bimetallic Fe-Co possess smaller average diameter, less amorphous carbon and denser morphology compared to other binary metallic combinations. It was found that the catalytic activity of bimetallic composition decreased in the order of Fe-Co> Fe-Ni> Co-Ni. Furthermore, the monometallic Fe catalyst has the most catalytic activity compared to monometallic Co and Ni catalysts.
- انتشار مقاله: 12-05-1394
- نویسندگان: F. Shahi,M. Akbarzadeh Pasha,A. A. Hosseini,Z. S. Arabshahi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Nanostructures
- نوع مقاله: Journal Article
- کلمات کلیدی: Wet impregnation,CNTs,Bimetallic catalyst,CCVD,Monometallic catalyst,TiO2 substrate
- چکیده:
- چکیده انگلیسی: Monometallic and bimetallic Ni and Co catalytic nanoparticles supported on Titanium dioxide (rutile phase) substrate were prepared by wet impregnation method. These nanoparicles were used as catalysts for synthesis of multiwalled carbon nanotubes (MWCNTs) from acetylene decomposition at 700°C by the catalytic chemical vapor deposition (CCVD) technique. The nanomaterials (catalyst and CNTs) were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman spectroscopy. In this paper, the usage of TiO2 powder as catalyst support was examined and the effect of applied catalyst type on characteristics of grown CNTs was investigated. The results showed that the rutile phase of TiO2 powder can be applied as a suitable catalyst support in CNT growth process. Furthermore, it was observed that the CNTs synthesized on Ni-Co bimetallic catalyst possess smaller average diameters, better quality and less amorphous carbon compared to Ni and Co monometallic catalyst types.
- انتشار مقاله: 28-02-1393
- نویسندگان: A. A. Hosseini,F. Doustan,M. Akbarzadeh Pasha
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Mining and Environment
- نوع مقاله: Journal Article
- کلمات کلیدی: Geostatistics,Geographic Information System,Gas Content,Prediction Map
- چکیده:
- چکیده انگلیسی: Methane gas emission, accumulation, and explosion are the most important risk factors in underground coal mines. Hence, having a knowledge of methane gas emission potential in underground coal mines is of crucial importance in preventing the explosion risk, loss of life, and property, and providing miners' safety. The purpose of this work is to provide the prediction maps for the C1, C2, and B2 coal seams gas contents, and to identify high gas content panels in the Parvadeh No. 1, Tabas coal mine. For this, the data collected from exploratory boreholes is put into geostatistical analysis in ArcGIS in order to estimate the coal seams gas content in unsampled points using the kriging estimation method. Reviewing the gas content maps has revealed that seams of C1, B2, and C2 have gas contents more than 15 cubic meters per ton in about 84%, 55%, and 22% of the understudied area, respectively. The present work highlights the potential and the need for implementation of a methane pre-drainage system, particularly in deeper longwall panels.
- انتشار مقاله: 23-11-1396
- نویسندگان: M. Mohtasham Seyfi,J. Khademi Hamidi,M. Monjezi,A. Hosseini
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Mining and Environment
- نوع مقاله: Journal Article
- کلمات کلیدی: Fuzzy Analytical Hierarchy Process,Steeply Inclined Coal Seams,Extraction Equipment
- چکیده:
- چکیده انگلیسی: The longwall mining method is one of the most applied methods in extracting low-inclined to high-inclined coal seams. Selection of the most suitable extraction equipment is very important in the economical, safety, and productivity aspects of mining operations. There are a lot of parameters affecting the selection of an extraction equipment in mechanized longwall mining in steeply inclined coal seams. The important criteria involved are the geometric properties of coal seam (dip, thickness, and uniformity of coal seam), geological and hydraulic conditions (faults, fractures, joints, and underground water), and geomechanical properties of coal seam and surrounding rocks. Extraction of inclined coal seams with gradients greater than 40 degree is different from low-inclined seams, and requires a special equipment. Therefore, the influence of the above-mentioned parameters must be considered simultaneously in the selection of extraction equipment for steeply inclined seams. This paper presents an application of the Fuzzy Analytical Hierarchy Process (FAHP) method in order to select a suitable extraction equipment in the Hamkar coal mine. In the proposed FAHP model, fifteen main criteria are considered, as follow: dip of coal seam, thickness of coal seam, seam uniformity, expansion of coal seam, faults, fractures and joints, underground waters, hangingwall strength, footwall strength, coal strength, in-situ stress, equipment salvage, dilution, system flexibility, and operational costs. Among the 6 considered longwall extraction equipment system alternatives, the findings show that the most suitable extraction equipment system is shearer on footwall and a support system using hydraulic props and the transport of coal with the force of gravity.
- انتشار مقاله: 30-08-1395
- نویسندگان: A. Hosseini,M. Najafi,Seyed A. Shojaatlhosseini,R. Rafiee
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Computational and Applied Research in Mechanical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Galerkin method,Natural frequency,Microbeam,Perturbation Method,Nonlinear Vibration,Electrostatic actuation
- چکیده:
- چکیده انگلیسی: This article studied static deflection, natural frequency and nonlinear vibration of a clamped-clamped microbeam under discontinues electrostatic actuation. The electrostatic actuation was induced by applying AC-DC voltage between the microbeam and electrode plate. In contrast to previous works, it was assumed that length of the electrode plate was smaller than that of the microbeam. In addition, it was assumed that a layer whose length was equal to that of the electrode plate was deposited on the lower side of the microbeam. Equation of motion was derived using Newton's second law. The static deflection due to the DC electrostatic actuation and the natural frequency about this position were obtained using the Galerkin method. Nonlinear vibration of the system due to the AC electrostatic actuation was obtained using the multiple scale perturbation method. Variations of static deflection, pull-in voltage, natural frequency and frequency response of vibration about the static deflection of microbeam with respect to variations of second layer length, second layer thickness, electrode plate length and value of electrostatic actuation were also studied. It was shown that, depending on the value of these parameters, static deflection and natural frequency of vibration about static deflection increased or decreased. Moreover, it was demonstrated that, depending on the value of these system parameters, nonlinear vibration of the system due to the AC electrostatic actuation might be realized as a softening or hardening behavior.
- انتشار مقاله: 11-04-1392
- نویسندگان: M. Zamanian,S. A. A. Hosseini
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of AI and Data Mining
- نوع مقاله: Journal Article
- کلمات کلیدی: Software defined network,Controller Placement,Iterated Local Search
- چکیده:
- چکیده انگلیسی: Software defined network is a new computer network architecture who separates controller and data layer in network devices such as switches and routers. By the emerge of software defined networks, a class of location problems, called controller placement problem, has attracted much more research attention. The task in the problem is to simultaneously find optimal number and location of controllers satisfying a set of routing and capacity constraints. In this paper, we suggest an effective solution method based on the so-called Iterated Local Search (ILS) strategy. We then, compare our method to an existing standard mathematical programming solver on an extensive set of problem instances. It turns out that our suggested method is computationally much more effective and efficient over middle to large instances of the problem.
- انتشار مقاله: 28-10-1397
- نویسندگان: A. Moradi,A. Abdi Seyedkolaei,Seyed A. Hosseini
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Veterinary Research
- نوع مقاله: Journal Article
- کلمات کلیدی: zinc,Arginine,lysine,ewe milk,lactation stage
- چکیده: روی (Zn) نقش اساسی در سیستم بدن انسان و حیوان دارد. کمبود روی ممکن است موجب اختلالات بسیاری شود، بنابراین ارائه یک میزان کافی از این ریز عنصر در حیوانات و انسان مهم است. یکی از مهمترین منابع روی، شیر است. هدف از این مطالعه برای تعیین این است که آیا روی میتواند از طریق سلولهای اپیتلیال پستان به شیر توسط سیستم نقل و انتقال با پایه اسید آمینهای در میش شیرده عبور کند. این پژوهش تجربی شامل 54 میش شیرده که از سازمان جهاد کشاورزی استان تهران جمعآوری شده، به 9 گروه به شرح زیر تقسیم شدند: گروهی که کلرید روی را به شکل معدنی (1، 2 و 4 میلیگرم بر کیلوگرم) دریافت کردند، و گروههایی که روی آلی با دوزهای مختلف آرژینین و یا لیزین (1، 2 و 4 میلیگرم بر کیلوگرم) به صورت شلاته شده دریافت کردند. نمونههای شیر، 30 دقیقه قبل و 6 ساعت پس از تزریق داخل وریدی محلولهای روی جمعآوری شد. غلظت روی در شیر با استفاده از روش طیف سنجی جذب اتمی شعله اندازهگیری شد. قبل از تزریق روی معدنی و یا آلی در غلظت روی شیر، تفاوت معنیداری بین دو گروه وجود نداشت (P>0.05). تجزیه و تحلیل دادهها نشان داد که تجویز روی معدنی باعث افزایش قابل توجهی از غلظت روی در شیر در صورت وابسته به دوز شد. در حالی که، تزریق آرژینین و یا لیزین با روی در شکل شلاته باعث کاهش قابل توجهی در غلظت روی شیر در مقایسه با فرم غیر آلی روی، به صورت وابسته به دوز شد. با توجه به نتایج به دست آمده، مصرف فرمهای مختلف روی، غلظت روی در شیر را تحت تاثیر قرار میدهد.
- چکیده انگلیسی: Zinc (Zn) plays an essential role in the human and animal body system. Zinc deficiency might cause many disorders, so it is important to provide a sufficient amount of this microelement in both animals and humans. One of the most important sources of Zn is milk. The purpose of this study was to determine whether Zn can pass through the mammary epithelial cell into milk by a cotransport system with amino acid in the lactating ewes. This experimental research included 54 lactating ewes collected from the Agriculture-Jahad Organization of Tehran Province, that were allocated into 9 groups as follows: groups which received inorganic form as Zn chloride (1, 2 and 4 mg/kg), and groups which received organic Zn with different doses of arginine or lysine (1, 2 and 4 mg/kg) in chelate form. Milk samples were taken 30 min before and 6 h after intravenous injection of Zn preparations. Zinc concentration in milk was measured using the flame atomic absorption spectrometric method. There were no significant differences (P>0.05) between groups in Zn concentration of the milk before administration of inorganic or organic Zn. Data analysis showed that administration of inorganic Zn caused a significant increase of Zn concentration in the milk in a dose dependent manner. While administration of arginine or lysine with Zn in chelate form caused a significant decline in Zn concentration of milk compared to
inorganic Zn in a dose dependent manner. According to our results, administration of different forms of Zn influenced the Zn concentration in milk.- انتشار مقاله: 26-06-1394
- نویسندگان: M. Keshvari,H. Khazali,H. Rokni,A. Hosseini
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Veterinary Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Genotype,yoghurt,Lactic acid bacteria,Phenotype
- چکیده: به منظور شناسایی باکتریهای اسید لاکتیک غالب موجود در ماستهای بومی کشور ایران، خصوصیات مورفولوژیک، بیوشیمیایی و مولکولی این جدایهها مورد ارزیابی قرار گرفت. از 60 نمونه ماست مورد ارزیابی، 137 باکتری اسید لاکتیک جداسازی گردید که از میان آن 66 جدایه کوکسی مربوط به خانواده باکتریهای اسید لاکتیک و 71 ایزوله تحت عنوان لاکتوباسیل شناسایی شدند. نتایج آزمونهای بیوشیمیایی در مورد جدایههای کوکسی نشان داد که 76/9% از جدایهها به صورت هموفرمانتیو مزوفیل، 98/10% هتروفرمانتیو مزوفیل، 56/47% هموفرمانتیو ترموفیل و در میان ایزولههای لاکتوباسیلوس 26% به صورت هتروفرمانتیو اختیاری، 56% هموفرمانتیو اجباری و 18% هتروفرمانتیو اجباری میباشند. دادههای مربوط به آزمون مولکولی 9% از جدایههای لاکتوباسیل و 46/38% از جدایههای کوکسی دارای عدم تطابق با آزمون بیوشیمیایی بودند. مطالعه حاضر به عنوان اولین گام در فرآیند تولید باکتریهای آغازگر به منظور تولید محصولاتی با ویژگیهای حسی ماستهای بومی ایران میباشد. بدیهی است در ادامه این مطالعه بررسی خصوصیات تکنولوژیکی ایزولهها به منظور گزینش کارآمدترین جدایهها ضروری میباشد.
- چکیده انگلیسی: Morphological, biochemical and molecular characteristics were studied to identify dominant lactic acid bacteria (LAB), isolated from traditional yoghurts produced by tribes of Iran. From 60 yoghurt samples, a total of 137 LAB isolates were determined, in which 66 and 71 were identified as lactic acid cocci and bacilli, respectively. Biochemical tests showed the occurrence of 9.76% mesophilic homofermentative, 10.98% mesophilic hetrofermentative, 26.83% thermophilic homofermentative and 47.56% mesophilic homofermentative cocci. As for lactic acid bacilli, mesophilic facultative hetrofermentative (26%); thermophilic obligate homofermentative (56%); mesophilic obligate hetrofermentative (18%) were found. Genetically the presence of the following species were verified: E. faecium; E. faecalis; E. durans; L. lactis subsp. lactis; St. thermophilus; Lb. delbruecki subsp. bulgaricus; Lb. brevis; Lb. diolivorans; Lb. helveticus; Lb. jensenii; Lb. plantarum. 9% of the Lactobacillus isolates showed incompatible results between phenotypic and genotypic characteristics. From the cocci isolates, 38.46% showed identical results between phylogenetic characteristics. The current study constitutes the first step in the designing process of LAB starter cultures, to protect the typical organoleptic characteristics of traditional yoghurt. The results could also be used to introduce new starter cultures for commercial use.
- انتشار مقاله: 25-03-1392
- نویسندگان: S. Roushan Zadeh,M. H. Eskandari,S. S. Shekarforoush,A. Hosseini
- مشاهده