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1 - Effect of collisions, ionisation and non-extensivity on sheath formation in an electronegative warm plasma under electron emission from the wall
Yetendra Jha Mayank Kumar Hitendra K. MalikThe effect of collisions, ionisation and non-extensivity is studied numerically in an electronegative warm plasma associated with electron emission from the wall. Electrostatic potential, space charge density, net negative charge density and emitted electron beam densit أکثرThe effect of collisions, ionisation and non-extensivity is studied numerically in an electronegative warm plasma associated with electron emission from the wall. Electrostatic potential, space charge density, net negative charge density and emitted electron beam density are plotted with the normalised distance to see the effects of aforesaid parameters The negative ion is described with fluid equations to see it’s effect of the mass ratio (negative ion to positive ion) on emitted electron beam density inside the sheath. The three types of electronegative plasma taken are CF_4, O_2 and C_60. The emitted beam electron density is more in number at the wall for higher collisional and ionisation case and less in higher mass ratio. For super-extensive case the emitted beam electrons is lesser than compared to the Boltzmann distributed electrons. The sheath thickness is found to be more in higher mass ratio, emitted beam electrons and super -extensive case while for higher collisional and ionisation case the sheath thickness is less. تفاصيل المقالة -
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2 - Behaviour of sheath in electronegative warm plasma
Rajat Dhawan Hitendra K. MalikAbstractBehaviour of sheath formed on two types of probes, namely cylindrical and spherical probes, has been investigated in terms of its thickness, in front of the conducting probes immersed in an electronegative plasma for different negative to positive ion mass ratio أکثرAbstractBehaviour of sheath formed on two types of probes, namely cylindrical and spherical probes, has been investigated in terms of its thickness, in front of the conducting probes immersed in an electronegative plasma for different negative to positive ion mass ratios, by considering three electronegative gases, i.e. CF4, O2 and C60. Contrary to others’ work, complete fluid equations are written for negative ions also in addition to those of positive ions considering their different masses. Increasing negative to positive ion mass ratio is found to result in an increment of the sheath thickness. The magnitude of the sheath thickness is enhanced with an increment in the positive ions’ temperature, whereas the magnitude of the sheath thickness is reduced with increased negative ions’ temperature and background density of the negative ions. The analysis of the case of a large probe radius, used in the surface-nitriding process, for both the geometries is attended. Additionally, the comparison between the results for electropositive plasma and electronegative plasma and for behaviour of negative ions with their Boltzmann distribution and fluid approach has also been attempted herewith and a noteworthy difference is realized. The case of doubly charged ions is also entertained herewith. تفاصيل المقالة -
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3 - Structural and morphological properties of ITO thin films grown by magnetron sputtering
Z. Ghorannevis E. Akbarnejad M. GhorannevissAbstractPhysical properties of transparent and conducting indium tin oxide (ITO) thin films grown by radiofrequency (RF) magnetron sputtering are studied systematically by changing deposition time. The X-ray diffraction (XRD) data indicate polycrystalline thin films wit أکثرAbstractPhysical properties of transparent and conducting indium tin oxide (ITO) thin films grown by radiofrequency (RF) magnetron sputtering are studied systematically by changing deposition time. The X-ray diffraction (XRD) data indicate polycrystalline thin films with grain orientations predominantly along the (2 2 2) and (4 0 0) directions. From atomic force microscopy (AFM) it is found that by increasing the deposition time, the roughness of the film increases. Scanning electron microscopy (SEM) images show a network of a high-porosity interconnected nanoparticles, which approximately have a pore size ranging between 20 and 30 nm. Optical measurements suggest an average transmission of 80 % for the ITO films. Sheet resistances are investigated using four-point probes, which imply that by increasing the film thickness the resistivities of the films decrease to 2.43 × 10−5 Ω cm. تفاصيل المقالة -
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4 - مطالعه تاثیر روغن زیتون بر نوزایش بافت پوششی در ترمیم زخم تجربی ایجاد شده در پوست موش صحرایی
مرضیه ابوئی مهریزی، اکرم عیدی ، پژمان مرتضوی .روغن زیتون برای اهداف پزشکی مورد استفاده قرار می‌گیرد و اثرات سودمندی بر بیماریهای قلبی ـ عروقی، متابولیک، التهابی و خودایمنی دارد. هدف از این تحقیق بررسی اثر تیمار موضعی روغن زیتون بر ترمیم زخم پوست در موش صحرایی میباشد. بعد از ایجاد یک زخم جلدی تمام ضخامت در پشت 60 س أکثرروغن زیتون برای اهداف پزشکی مورد استفاده قرار می‌گیرد و اثرات سودمندی بر بیماریهای قلبی ـ عروقی، متابولیک، التهابی و خودایمنی دارد. هدف از این تحقیق بررسی اثر تیمار موضعی روغن زیتون بر ترمیم زخم پوست در موش صحرایی میباشد. بعد از ایجاد یک زخم جلدی تمام ضخامت در پشت 60 سر موش صحرایی نر نژاد ویستار به 6 گروه کنترل، شم، درمان با دوزهای 2، 5 و 10% روغن زیتون و استاندارد تقسیم شدند. گروه کنترل هیچ تیماری دریافت نکرد. گروه شم، اوسرین را به عنوان پایه پماد دریافت کرد. گروه درمان، روغن زیتون در دوزهای 2، 5 و 10% محلول در اوسرین دریافت کرد. گروه استاندارد با فنی توئین 1% درمان گردید. میزان بهبودی زخم پوست در روزهای 3، 7، 11، 14، 18، 21 بعد از ایجاد جراحت مورد ارزیابی قرار گرفت و جهت بررسی های هیستولوژی در روزهای 3، 7 ،14 و 21 موش‌ها آسان کشی شدند. از محل ترمیم زخم همراه با اندکی از پوست سالم مجاور، نمونه‌های بافتی تهیه و به روش تری کرم ماسون رنگ آمیزی شد. در اندازه گیری محل زخم کاهش معنی داری در میزان قطر زخم در گروههای درمان و استاندارد در مقایسه با گروه کنترل مشاهده شد. در مطالعات ریزبینی افزایش معنی داری در میزان نوزایش بافت پوششی در روز 14 در گروههای درمان و استاندارد در مقایسه با گروه کنترل مشاهده شد. نتایج نشان داد که روغن زیتون به طور معنی‌داری ترمیم زخم را تسریع می‌کند. اثر روغن زیتون بر ترمیم زخم احتمالا به افزایش نوزایش بافت پوششی مربوط می‌شود. تفاصيل المقالة -
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5 - آسیب شناسی بافتی تأثیر ژل سیکلوسپورین بر پیوند آزاد تمام ضخامت پوست (آلوگرافت) در موش صحرایی
ارغوان مفیدی، علیرضا جهاندیده، سعید حصارکی .امروزه از پیوند پوست به میزان گسترده درترمیم جراحت های پوستی استفاده می‌شود. سیکلوسپورین یکی از پرمصرف ترین و موثرترین داروهای سرکوبگر ایمنی است که در عین حال استفاده سیستمیک از آن دارای عوارض جانبی و سمیبر روی سیستم عصبی، کلیه و کبد میباشد. هدف از این مطالعه ارزیابی أکثرامروزه از پیوند پوست به میزان گسترده درترمیم جراحت های پوستی استفاده می‌شود. سیکلوسپورین یکی از پرمصرف ترین و موثرترین داروهای سرکوبگر ایمنی است که در عین حال استفاده سیستمیک از آن دارای عوارض جانبی و سمیبر روی سیستم عصبی، کلیه و کبد میباشد. هدف از این مطالعه ارزیابی تاثیرژل 5/0% سیکلوسپورین در رد پیوند آزاد تمام ضخامت پوست در موش صحرایی است. در این مطالعه تجربی از45 موش صحرایی نر بالغ نژاد ویستار به عنوان گیرنده‌ی پیوند و 15 موش نر بالغ اسپراگودالی(SD) به عنوان دهنده‌ی پیوند با محدوده سنی 14 تا 15 هفته و محدوده وزنی 200 ± 10گرم استفاده شد. پس از بیهوشی عمومی، برش تمام ضخامت، پوست دایره‌ای شکل به قطر 5/1 سانتی‌متر شامل لایه‌های اپیدرم و درم از موش‌های دهنده اسپراگودالی به محل وسط کتف گیرنده‌ی ویستار پیوند زده شد. پس از پیوند، موش‌ها به طور تصادفی به 3 گروه 15تایی (شاهد، کنترل مثبت و تیمار با ژل 5/0% سیکلوسپورین تقسیم شده سپس هر کدام خود به 5 گروه 3تایی (گروههای نمونه‌برداری در روزهای 3 ، 7 و 15) تقسیم شدند. در گروه شاهد هیچ درمانی صورت نگرفت. گروه کنترل، سیکلوسپورین داخل صفاقی با دوز mg/kg/day10 دریافت کرد و در گروه تحت درمان روزانه به محل پیوند ژل 5/0% سیکلوسپورین مالیده شد. سپس در روزهای 3 ،7 و 15 پس از پیوند از محل کاشت (پیوند) نمونه‌برداری انجام شد و آسیب‌شناسی بافتی انجام گرفت. داده‌ها با استفاده از آزمون‌های آماری کروسکال والیس (kruskalwallis)و نرم‌افزار SPSS مورد واکاوی آماری قرار گرفت. در مشاهدات ریزبینی استفاده از ژل سیکلوسپورین موجب کاهش معنی دار 05/0p< میزان واسکولیت، فولیکولایتیس، التهاب درم و دژنره شدن اپیدرم در روزهای سوم و هفتم بعد از پیوند در مقایسه با گروه کنترل شد در حالیکه مانع از رد پیوند در روز پانزدهم پس از پیوند نگردید. به‌نظر می‌رسد استفاده از ژل سیکلوسپورین اثرات قابل قبولی بر روند پذیرش بافت پیوندی پوست دارد اگرچه استفاده از آن به تنهایی مانع از رد پیوند نمی‌شود. برای پذیرش موثرتر پیوند پوست میتوان از ژل سیکلوسپورین به همراه سایر داروهای ایمنوسا پرسی و به صورت ترکیبی استفاده کرد. تفاصيل المقالة -
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6 - اثر ضخامت و تعداد مانع‌های نفوذپذیر بر کنترل و تله‌اندازی جریان غلیظ
علیرضا جهانگیر کاظم اسماعیلی محمود فغفور مغربیشناخت و بررسی جریان سیلابی رودخانه‌ها که در بیشتر موردها از نوع جریان غلیظ است، می‌تواند به کاهش اثرهای نامطلوب رسوب‌گذاری کمک کند. برای این منظور، ایجاد مانع‌ها در بستر جریان موثر خواهد بود. در این مقاله به‌صورت آزمایشگاهی، اثر ضخامت (بعد) و لایه‌ی دوم موانع نفوذپذیر أکثرشناخت و بررسی جریان سیلابی رودخانه‌ها که در بیشتر موردها از نوع جریان غلیظ است، می‌تواند به کاهش اثرهای نامطلوب رسوب‌گذاری کمک کند. برای این منظور، ایجاد مانع‌ها در بستر جریان موثر خواهد بود. در این مقاله به‌صورت آزمایشگاهی، اثر ضخامت (بعد) و لایه‌ی دوم موانع نفوذپذیر بر کنترل و تله‌اندازی جریان غلیظ مورد ارزیابی قرار گرفته است. برای این منظور، از دو گونه مانع‌های شیاری و حفره‌ای دارای شیارها و قطر حفره‌هایی برابر با 3 میلیمتر و ساخته‌شده از صفحات پلاکسی گلاس بهره‌جویی شده است. جریان غلیظ با اضافه کردن یک پلیمر نامحلول و معلق از جنس پلی استایرن انبساطی با میانگین قطر 15/1 میلیمتر و چگالی 135/1 گرم در لیتر ایجاد شد. در انجام آزمایش‌ها از دو غلظت متفاوت (10 و 20 درصد)، پنج تخلخل گوناگون، چهار زاویه‌ی مختلف، چهار ضخامت متفاوت و با دو لایه مانع بهره‌جویی شد. نتیجه‌ها نشان دادند روند عبور جریان غلیظ دارای تخلخل 10 درصد از مانع شیاری با افزایش ضخامت بیشتر می‌شود. لایه‌ی دوم مانع‌ها باعث افزایش روند عبور مواد از هر دو مانع‌های شیاری و حفره‌ای شده است. میزان این افزایش در نوع شیاری برابر 96/1 و نوع حفره‌ای برابر 34/2 ثبت شد. بررسی‌ها نشان دادند که فاصله‌ی بهینه مانع دوم از اول معادل 25/2 متر میباشد. بر مبنای نتیجه‌ها، در شرایط مشابه، همواره موانع حفره‌ای عملکرد بهتری از موانع شیاری دارند. تفاصيل المقالة -
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7 - Stagnation-point flow of a viscous fluid towards a stretching surface with variable thickness and thermal radiation
B. C. Prasanna ‎Kumara ‎‎G. K‎. ‎ ‎Ramesh‎ A. J. Chamkha‎ B. J. ‎Gireesha‎‎‎In the present analysis‎, ‎we study the boundary layer flow of an incompressible viscous fluid near the two-dimensional stagnation-point flow over a stretching surface‎. ‎The effects of variable thickness and radiation are also taken into account an أکثر‎In the present analysis‎, ‎we study the boundary layer flow of an incompressible viscous fluid near the two-dimensional stagnation-point flow over a stretching surface‎. ‎The effects of variable thickness and radiation are also taken into account and assumed that the sheet is non-flat‎. ‎Using suitable transformations‎, ‎the governing partial differential equations are first converted to ordinary one and then solved numerically by fourth and fifth order Runge-Kutta-Fehlberg method with shooting technique‎. ‎The influence of the various interesting parameters on the flow and heat transfer is analyzed and discussed through graphs in detail‎. ‎Comparison of the present results with known numerical results is shown and a good agreement is observed‎. ‎It is found that boundary layer is formed when $\lambda > 1 $‎. ‎On the other hand‎, ‎an inverted boundary layer is formed when $\lambda < 1 $‎.‎ تفاصيل المقالة -
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8 - بررسی واکشیدگی ضخامت کامپوزیت ساخته شده از آرد چوب راش- پلی پروپیلن
شکوه اعتدالی شهنی بهبود محبی مهدی تجویدیبا توجه به محدودیت منابع جنگلی، کمبود چوب در کشور و به تبع آن حجم بالای واردات چوب، الوار، انواع صفحات فشرده و حتی فراورده‌های چوبی که در سال های اخیر نیز شدت یافته است، چند سازه های چوب-پلاستیک در بسیاری از موارد می‌توانند جایگزین مناسبی برای چوب باشند؛ باتوجه به مسایل أکثربا توجه به محدودیت منابع جنگلی، کمبود چوب در کشور و به تبع آن حجم بالای واردات چوب، الوار، انواع صفحات فشرده و حتی فراورده‌های چوبی که در سال های اخیر نیز شدت یافته است، چند سازه های چوب-پلاستیک در بسیاری از موارد می‌توانند جایگزین مناسبی برای چوب باشند؛ باتوجه به مسایل زیست محیطی، بازیافت دورریزهای مواد مختلف به طور روز افزونی در سطح جهان رو به گسترش است. این الیاف به راحتی به چرخه طبیعت باز می‌گردند و از قیمت بسیار پایین‌تری نیز برخوردار هستند. این بررسی به منظور نشان دادن کاهش میزان تغییرات واکشیدگی ضخامت و افزایش ثبات ابعادی کامپوزیت چوب پلاستیک در درصدهای مختلف پلاستیک و آرد چوب در دو روش ساخت اکستروژن و پرس گرم انجام شده است. در این تحقیق تخته های چوب پلاستیک با دانسیته اسمی g/cm3 1 و ابعاد اسمی 1×35 ×35 سانتی متر از آرد چوب راش (ضایعات کارگاه چوب بری) و پلی پروپیلن با نسبت 40، 50 و 60 درصد الیاف ساخته شدند. برای نشان دادن میزان تغییرات واکشیدگی ضخامت و افزایش ثبات ابعادی کامپوزیت چوب پلاستیک، از درصدهای مختلف پلاستیک و آرد چوب ساخته شده با دو روش اکستروژن و پرس گرم استفاده شد. نتایج نشان دادند که میزان واکشیدگی ضخامت حداکثر نمونه چوب پلاستیک با افزایش درصد الیاف از 40 به 60 درصد افزایش می یابد. علاوه بر این، با افزایش درصد الیاف تخته های چوب پلاستیک، در زمان کوتاه تری به اشباع می رسند. هم چنین نمونه‌های ساخته شده با روش پرس گرم از واکشیدگی بیشتری برخوردار بودند. تفاصيل المقالة -
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9 - Preparation and Characterization of Aluminum Nitride Thin Films with the Potential Application in Electro-Acoustic Devices
Fatemeh HajakbariIn this work, aluminum nitride (AlN) thin films with different thicknesses were deposited on quartz and silicon substrates using single ion beam sputtering technique. The physical and chemical properties of prepared films were investigated by different characterization أکثرIn this work, aluminum nitride (AlN) thin films with different thicknesses were deposited on quartz and silicon substrates using single ion beam sputtering technique. The physical and chemical properties of prepared films were investigated by different characterization technique. X-ray diffraction (XRD) spectra revealed that all of the deposited films have an amorphous structure. The Al-N bond information of deposited films on silicon substrates was identified by Fourier transform infrared (FTIR) spectroscopy. FTIR results confirmed the formation of AlN films in prepared samples. Atomic force microscopy (AFM) revealed that the surface of films was smooth with low values of roughness. The low values of roughness can be caused the low acoustic loss in AlN films, which is interesting for applications in electro-acoustic devices. تفاصيل المقالة -
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10 - The Effect of Electroplating Time on Microstructural Properties and Hardness of Silver Coating on C10100 Alloy
A. Taherkhani Y. Shajari K. Mirzavand A. Mellatkhah Z. S. SeyedraoufiIn the present study, the effect of electroplating time on the intensity of flow and the constant potential difference on the thickness of the coating, surface smoothness, microstructure of the interface between substrate and coating and hardness of coating were investi أکثرIn the present study, the effect of electroplating time on the intensity of flow and the constant potential difference on the thickness of the coating, surface smoothness, microstructure of the interface between substrate and coating and hardness of coating were investigated. Microstructural studies by optical microscopy (OM) showed that increasing the electroplating time leads to increase the coating thickness. Investigations showed that increasing the plating time due to growth leads to increase the surface roughness of coating. In the middle part of the coating, by increasing the time of plating, the thickness of eutectic Ag-Cu film increased. The results of microhardness of coatings showed that the maximum hardness was achieved at the highest planting time i.e 8 minutes. The microhardness remained at a constant range for about half a minute to two minutes, but increasing the time to 4 and 8 minutes leads to increase toughness of 107 and 131 Hv. تفاصيل المقالة -
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11 - Environmental Optimization of Building Insulation Thickness in Warm-Dry Regions
E. Anbarzadeh S. M. Ghafoori YazdiIn this study, the environmental effect ( ) of rock wool as a mineral insulation material and expanded polystyrene as a polymer insulation material for a residential building is studied. Initially, the intended building is simulated in Design Builder for warm-dry climat أکثرIn this study, the environmental effect ( ) of rock wool as a mineral insulation material and expanded polystyrene as a polymer insulation material for a residential building is studied. Initially, the intended building is simulated in Design Builder for warm-dry climate regions like Yazd and Isfahan cities and then the effect of different thicknesses of these two insulation materials inside the external wall of the building is studied towards optimizing the thickness value environmentally. Despite the emissions generated by cooling and heating systems while consuming energy throughout the year, embodied values in the manufacturing process until installation are also considered. Eventually, using the Energy Plus simulation engine inside Design Builder and MATLAB software, the environmental optimum insulation thickness regarding emission and embodied values of for a lifetime of ten years in warm-dry regions of Iran such as Yazd and Isfahan cities are calculated. These values for expanded polystyrene are found to be 20 cm for Isfahan and 19 cm for Yazd and values for rock wool are 11 cm for Isfahan and 10 cm for Yazd. Thus, a mineral insulation material such as rock wool has a smaller environmental optimum insulation thickness than a polymer insulation material such as expanded polystyrene. تفاصيل المقالة -
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12 - Environmental Optimization of Building Insulation Thickness for Cold Climates using Neural Network Method
E Anbarzadeh T ShahmohammadiIn this research the environmental effects (CO2) of rock wool as a mineral insulation and expanded polystyrene as a polymeric insulation for building insulation is studied. First the intended building is simulated by Design Builder software for cold climates like Tabriz أکثرIn this research the environmental effects (CO2) of rock wool as a mineral insulation and expanded polystyrene as a polymeric insulation for building insulation is studied. First the intended building is simulated by Design Builder software for cold climates like Tabriz city in Iran, and then the thickness effect of these two insulations is studied at the building’s exterior wall by using Energy Plus simulation engine in Design Builder software in order to find the optimized thickness in terms of environmental effect (CO2). Except considering the gas emission amount of building’s heating and cooling systems in a year, the amount of CO2 gas consumption in production process to installation of various thicknesses has been also taken into account. Finally by using Single Layer Perceptron Artificial Neural Network method, the environmental optimized thickness of insulation in terms of gas emission while consuming energy in building and its production during the manufacturing of insulation over ten years span in cold areas of Iran like Tabriz, is 12.5 centimeters for expanded polystyrene and 8.8 centimeters for rock wool. It is concluded that from gas emission perspective in cold climates, the mineral insulation such as rock wool is has lower optimized thickness comparing to polymeric insulation like expanded polystyrene. تفاصيل المقالة -
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13 - Thermo-Elastic and Time-Dependent Creep Evolution Behaviour of Ferritic Steel Rotating Disks using Theta Projection Concept
H. Daghigh V. DaghighIn this article, thermo-elastic and creep evolution behaviour of ferritic steel rotating disks with variable thickness are investigated. Four thickness profiles of uniform, convex, concave and linear are considered for the disk geometry. The material creep constitutive أکثرIn this article, thermo-elastic and creep evolution behaviour of ferritic steel rotating disks with variable thickness are investigated. Four thickness profiles of uniform, convex, concave and linear are considered for the disk geometry. The material creep constitutive model is defined by the Θ projection concept, based on the experimental results existing in the literature. Loading applied is due to the inertial body force caused by the rotation and a constant temperature field throughout the disk. To achieve history of stresses and displacements, a numerical procedure using finite difference and Prandtl-Reuss relations is used. Stress and deformation histories are calculated using successive elastic solution method. In order to verify the solution approach, both composite and aluminum rotating disks were taken into account and the thermo-elastic and time-dependent creep behaviours for composite as well as the former for aluminum were obtained. Results from the current study were found to be in very good agreement with those available from literature in the area. It was shown that convex thickness profile disks display the least creep displacement, creep effective and circumferential stresses. Additionally, constant and concave thickness profiles were positively correlated with time while for linear and convex ones, it was found to have an inverse trend. تفاصيل المقالة -
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14 - Microstructure and Mechanical Properties of AZ91 Magnesium Cup Processed by a Combined Backward Extrusion and Constrained Ironing Method
M. Khodsetan Ghader Faraji V. Tavakkoli K. AbriniaA combined metal forming process consisted of backward extrusion (BE) and constrained ironing (CI) is used to produce thin walled ultrafine grained (UFG) magnesium cups. In this new method, the initial thick-walled cup is formed from the bulk material using the BE proce أکثرA combined metal forming process consisted of backward extrusion (BE) and constrained ironing (CI) is used to produce thin walled ultrafine grained (UFG) magnesium cups. In this new method, the initial thick-walled cup is formed from the bulk material using the BE process and then the CI process is used to produce a UFG thin-walled cups. The advantage of the CI process is applying compressive stresses that are suitable to form hard to deform materials like magnesium alloys without fracture while achieving higher thickness reduction ratio (TRR). The results showed that after this new combined method, the tensile strength raised to 233 MPa, from the initial values of 123 MPa. Simultaneous improvement in strength and ductility attributes to very high hydrostatic compressive stresses and also breakage of Mg17Al12 precipitates in to smaller parts that facilitate the movement of dislocation. Also, the hardness increased to about 233 MPa from the initial values of 58 HV. Significant grain refinement was also taken place and the grain size in the BE+CI sample reduced to ~1 μm from the initial value of ~150 μm due to imposing high value of strain. This combined method is very promising for processing of UFG thin-walled cup-shaped samples from hard to deform materials. SEM images illustrated the brittle fracture at unprocessed and BE samples with existence of wide crack and shallow-elongated dimples but BE+CI sample revealed brittle fracture with fewer cracks due to hydrostatic pressure. تفاصيل المقالة -
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15 - Fabrication of a Complicated Specimen with Two Point Incremental Forming Process
Mehdi Safari Jalal JoudakiManufacturing of complicated industrial components is one of the main challenges for mechanical engineers in sheet metal forming processes. Incremental sheet metal forming (ISMF) is used widely for forming complicated shapes by a single rotating tool. This paper examine أکثرManufacturing of complicated industrial components is one of the main challenges for mechanical engineers in sheet metal forming processes. Incremental sheet metal forming (ISMF) is used widely for forming complicated shapes by a single rotating tool. This paper examines the experimental investigation of two-point incremental forming of a complicated specimen made of AA3105 aluminum alloy. The part shape consists of positive and negative cavities and the shape complexity limits the manufacturing process to two-point incremental forming process (TPIF). In addition, the effects of selected process parameters such as forming depth in each increment of process, tool rotational speed and various forming patterns on thickness distribution and thinning percentage of specimen are investigated. The forming pattern includes the sequence of forming the cavities (Internal/External pattern and External/Internal pattern). The main finding of the study can be expressed that the thinning ratio of manufactured specimen is increased with an increase in the forming depth in each increment of TPIF. Also, the higher rotational speed leads to a reduction in the thinning of the fabricated specimen. The results prove that the use of Internal/External forming pattern leads to reduction in the thinning of the manufactured specimen. تفاصيل المقالة -
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16 - Influences of Blank Holder Force in The Multi-Step Deep Drawing Process of Aluminum Sheets
Sajad Bakhtiari Seyed Jalal Hashemi Amir Hossein RoohiIn recent decades, the use of aluminium alloys is developed in the automotive industry with regard to the need for lightweight and anti-corrosion components, one of which is AA7075 Al alloy. In this study, the multi-step deep drawing process of AA7075 aluminium sheets u أکثرIn recent decades, the use of aluminium alloys is developed in the automotive industry with regard to the need for lightweight and anti-corrosion components, one of which is AA7075 Al alloy. In this study, the multi-step deep drawing process of AA7075 aluminium sheets under various blank holder forces is investigated through a numerical simulation and is then validated with experimental results. Simulations were conducted by ABAQUS finite element software, and the influences of the blank holder force on the wrinkling height, rupture occurrence and thickness distribution of the sheet were studied. The optimum amount of blank holder force at each drawing step is determined so that the height of wrinkling, and the thinning percentage do not exceed the permissible value. Based on the results, the blank holder force magnitude should be considered descending during the four successive steps to achieve more uniform thickness distribution, and also the wrinkling height could be reduced by increasing the blank holder force in the analysed force range. The optimum amount of blank holder force in the four drawing steps was 28000, 2500, 1500 and 600 N, respectively. In general, the minimum thickness was created in the corner of the punch. The results also showed that an excessive increase in the blank holder force in order to eliminate the wrinkling caused the thinning percentage to increase. Finally, a good accordance between the experimental and numerical results was observed. تفاصيل المقالة -
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17 - Comparative Study of LS-SVM, RVM and ELM for Modelling of Electro-Discharge Coating Process
Morteza Taheri Nader Mollayi Seyyed Amin Seyyedbarzani Abolfazl Foorginejad Vahide BabaiyanThe Electro-discharge coating process is an efficient method for improvement of the surface quality of the parts used in molds. In this process, Material Transfer Rate (MTR), an average Layer Thickness (LT) are important factors, and tuning the input process parameters أکثرThe Electro-discharge coating process is an efficient method for improvement of the surface quality of the parts used in molds. In this process, Material Transfer Rate (MTR), an average Layer Thickness (LT) are important factors, and tuning the input process parameters to obtain the desired value of them is a crucial issue. Due to the wide range of the input parameters and nonlinearity of this system, the establishment of a mathematical model is a complicated mathematical problem. Although many efforts have been made to model this process, research is still ongoing to improve the modeling of this process. To this end, in the present study, three powerful machine learning algorithms, namely, Relevance Vector Machine (RVM), Extreme Learning Machine (ELM) and the Least Squares Support Vector Machine (LS-SVM) that have not been used to model this process, have been used. The values R2 above 0.99 for the training data and above 0.97 for the test data show the high accuracy and generalization capability degree related to the LS-SVM models, which can be applied for the input parameters tuning in order to attain a preferred value of the outputs. تفاصيل المقالة -
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18 - Numerical Analysis of the Effect of External Circumferential Cracks in Transition Thickness Zone of Pressurized Pipes Using XFEM – Elastic-Plastic Behavior
H Salmi Kh EL Had H EL Bhilat A HachimThe elastic-plastic behavior of the material is considered to analyze the effect of an external circumferential crack on a pipe with thickness transitionand double slopes. Using the extended finite element method (XFEM), the J-integral of 3D cracks were investigated and أکثرThe elastic-plastic behavior of the material is considered to analyze the effect of an external circumferential crack on a pipe with thickness transitionand double slopes. Using the extended finite element method (XFEM), the J-integral of 3D cracks were investigated and compared between straight pipes and pipes with thickness transition and different slopes. Considering internal pressure, this work highlighted the investigation of a 3D crack problem ina thickness transition pipe with a double slope,In the extended finite element method (XFEM), the level sets and the enrichment zone were defined. A crack is easily modeled by enrichment functions. The comparison between the values of the J-integral showed that the pipe containing thickness transition with double slopes is more sensitive to the considered cracks, more precisely, the parameters of the first thickness transition have more influence on the variation of J-integral than the parameters of the second thickness transition. The decreasing of the angle of the slopes and the increase of the ratio of the thicknesses is one effective method of reducing the J-integral. تفاصيل المقالة -
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19 - Tangential Displacement and Shear Stress Distribution in Non-Uniform Rotating Disk under Angular Acceleration by Semi-Exact Methods
S JafariIn this paper semi-exact methods are introduced for estimating the distribution of tangential displacement and shear stress in non-uniform rotating disks. At high variable angular velocities, the effect of shear stress on Von Mises stress is important and must be consid أکثرIn this paper semi-exact methods are introduced for estimating the distribution of tangential displacement and shear stress in non-uniform rotating disks. At high variable angular velocities, the effect of shear stress on Von Mises stress is important and must be considered in calculations. Therefore, He’s homotopy perturbation method (HPM) and Adomian’s decomposition method (ADM) is implemented for solving equilibrium equation of rotating disk in tangential direction under variable mechanical loading. The results obtained by these methods are then verified by the exact solution and finite difference method. The comparison among HPM and ADM results shows that although the numerical results are the same approximately but HPM is much easier, straighter and efficient than ADM. Numerical calculations for different ranges of thickness parameters, boundary conditions and angular accelerations are carried out. It is shown that with considering disk profile variable, level of displacement and stress in tangential direction are not always reduced and type of changing the thickness along the radius of disk and boundary condition are an important factor in this case. Finally, the optimum disk profile is selected based on the tangential displacement-shear stress distribution. The presented algorithm is useful for the analysis of rotating disk with any arbitrary function form of thickness and density that it is impossible to find exact solutions. تفاصيل المقالة -
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20 - Nonlinear Investigation of Magnetic Influence on Dynamic Behaviour of Non-Homogeneous Varying Thickness Circular Plates Resting on Elastic Foundations
S.A Salawu G.M Sobamowo O.M SadiqIn this work, a nonlinear investigation of non-homogeneous varying thickness circular plates resting on elastic foundations under the influence of the magnetic fieldis investigated. The non-homogeneity of the circular plates’ material is presumed to occur due to l أکثرIn this work, a nonlinear investigation of non-homogeneous varying thickness circular plates resting on elastic foundations under the influence of the magnetic fieldis investigated. The non-homogeneity of the circular plates’ material is presumed to occur due to linear and parabolic changes in Young’s modulus likewise the density along the radial direction in a unique manner. The geometric Von Kármán equations are used in modelling the governing differential equations. The transverse deflection is approximated using an assumed single term mode shape while the central deflection in form of Duffing’s equation is obtained using the Galerkin method. Subsequently, the semi-analytical solutions are provided using the Optimal Homotopy Asymptotic Method (OHAM), the analytical solutions are used for parametric investigation. The results in this work are in good harmony with past results in the literature. From the results, it is realized that the nonlinear frequency of the circular plate increases with an increase in the linear elastic foundation. Also, the results showed that clamped edge and simply supported edge condition produced the same hardening nonlinearity. However, varying taper and non-homogeneity lower the nonlinear frequency ratio. Also, maximum deflection occurs when excitation force is zero, and attenuation of deflection is observed due to the presence of a magnetic field, varying thickness, homogeneity, and elastic foundation. It is anticipated that the discoveries from this research will boost the design of structures subjected to vibration. تفاصيل المقالة -
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21 - Elastic Buckling of Moderately Thick Homogeneous Circular Plates of Variable Thickness
S.K Jalali M.H NaeiIn this study, the buckling response of homogeneous circular plates with variable thickness subjected to radial compression based on the first-order shear deformation plate theory in conjunction with von-Karman nonlinear strain-displacement relations is investigated. Fu أکثرIn this study, the buckling response of homogeneous circular plates with variable thickness subjected to radial compression based on the first-order shear deformation plate theory in conjunction with von-Karman nonlinear strain-displacement relations is investigated. Furthermore, optimal thickness distribution over the plate with respect to buckling is presented. In order to determine the distribution of the prebuckling load along the radius, the membrane equation is solved using the shooting method. Subsequently, employing the pseudospectral method that makes use of Chebyshev polynomials, the stability equations are solved. The influence of the boundary conditions, the thickness variation profile and aspect ratio on the buckling behavior is examined. The comparison shows that the results derived, using the current method, compare very well with those available in the literature. تفاصيل المقالة -
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22 - Stress Analysis of Rotating Thick Truncated Conical Shells with Variable Thickness under Mechanical and Thermal Loads
M Jabbari M Zamani Nejad M GhannadIn this paper, thermo-elastic analysis of a rotating thick truncated conical shell subjected to the temperature gradient, internal pressure and external pressure is presented. Given the existence of shear stress in the conical shell due to thickness change along the axi أکثرIn this paper, thermo-elastic analysis of a rotating thick truncated conical shell subjected to the temperature gradient, internal pressure and external pressure is presented. Given the existence of shear stress in the conical shell due to thickness change along the axial direction, the governing equations are obtained based on first-order shear deformation theory (FSDT). These equations are solved by using multi-layer method (MLM). The model has been verified with the results of finite element method (FEM). Finally, some numerical results are presented to study the effects of thermal and mechanical loading, geometry parameters of truncated conical shell. تفاصيل المقالة -
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23 - Thermal Stability of Thin Rectangular Plates with Variable Thickness Made of Functionally Graded Materials
M PouladvandIn this research, thermal buckling of thin rectangular plate made of Functionally Graded Materials (FGMs) with linear varying thickness is considered. Material properties are assumed to be graded in the thickness direction according to a simple power law distribution in أکثرIn this research, thermal buckling of thin rectangular plate made of Functionally Graded Materials (FGMs) with linear varying thickness is considered. Material properties are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The supporting condition of all edges of such a plate is simply supported. The equilibrium and stability equations of a FGM rectangular plate (FGRP) under thermal loads derived based on classical plate theory (CPT) via variational formulation, and are used to determine the pre-buckling forces and the governing differential equation of the plate. The buckling analysis of a functionally graded plate is conducted using; the uniform temperature rise, having temperature gradient through-the-thickness, and linear temperature variation in the thickness and closed-form solutions are obtained. The buckling load is defined in a weighted residual approach. In a special case the obtained results are compared by the results of functionally graded plates with uniform thickness. The influences of the plate thickness variation and the edge ratio on the critical loads are investigated. Finally, different plots indicating the variation of buckling load vs. different gradient exponent k, different geometries and loading conditions were obtained. تفاصيل المقالة -
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24 - Free Vibration of Thick Isotropic Plates Using Trigonometric Shear Deformation Theory
Y.M Ghugal A.S SayyadIn this paper a variationally consistent trigonometric shear deformation theory is presented for the free vibration of thick isotropic square and rectangular plate. In this displacement based theory, the in-plane displacement field uses sinusoidal function in terms of t أکثرIn this paper a variationally consistent trigonometric shear deformation theory is presented for the free vibration of thick isotropic square and rectangular plate. In this displacement based theory, the in-plane displacement field uses sinusoidal function in terms of thickness coordinate to include the shear deformation effect. The cosine function in terms of thickness coordinate is used in transverse displacement to include the effect of transverse normal strain. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. Results of frequency of bending mode, thickness-shear mode and thickness-stretch mode are obtained from free vibration of simply supported isotropic square and rectangular plates and compared with those of other refined theories and frequencies from exact theory. Present theory yields exact dynamic shear correction factor π2/12 from thickness shear motion of the plate. تفاصيل المقالة -
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25 - A Power Series Solution for Free Vibration of Variable Thickness Mindlin Circular Plates with Two-Directional Material Heterogeneity and Elastic Foundations
M.M Alipour M ShariyatIn the present paper, a semi-analytical solution is presented for free vibration analysis of circular plates with complex combinations of the geometric parameters, edge-conditions, material heterogeneity, and elastic foundation coefficients. The presented solution cover أکثرIn the present paper, a semi-analytical solution is presented for free vibration analysis of circular plates with complex combinations of the geometric parameters, edge-conditions, material heterogeneity, and elastic foundation coefficients. The presented solution covers many engineering applications. The plate is assumed to have a variable thickness and made of a heterogeneous material whose properties vary in both radial and transverse directions. While the edge is simply-supported, clamped, or free; the bottom surface of the plate is resting on a two-parameter (Winkler-Pasternak) elastic foundation. A comprehensive sensitivity analysis including evaluating effects of various parameters is carries out. Mindlin theory is employed for derivation of the governing equations whereas the differential transform method is used to solve the resulted equations. In this regard, both the in-plane and rotary inertia are considered. Results show that degradations caused by a group of the factors (e.g., the geometric parameters) in the global behavior of the structure may be compensated by another group of factors of different nature (e.g, the material heterogeneity parameters). Moreover, employing the elastic foundation leads to higher natural frequencies and postponing the resonances. تفاصيل المقالة -
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26 - Evaluation of Buckling and Post Buckling of Variable Thickness Shell Subjected to External Hydrostatic Pressure
A.R Ghasemi M.H HajmohammadBuckling and post buckling of cylindrical shells under hydrostatic pressure is regarded as important issue in structure of submarines. These cylindrical shells have variable thickness due to construction process which effected by pressure of buckling and its destruction أکثرBuckling and post buckling of cylindrical shells under hydrostatic pressure is regarded as important issue in structure of submarines. These cylindrical shells have variable thickness due to construction process which effected by pressure of buckling and its destruction. In this paper, effects of changing thickness on buckling and destruction pressure under external hydrostatic pressure of a shell are studied. Results of buckling pressure of cylindrical shell have been obtained with theoretical relations and finite element method. Then, using machining process a sample of cylindrical shell with variable thickness has been produced. Buckling pressure and post buckling of the constructed sample have been obtained with the reservoir under closed-ended hydrostatic pressure. Changes of the test sample size have been considered with closed-ended testing apparatuses which are used for new evaluation of buckling. In this research, results of the pressure have been obtained in terms of the volume change. At the end, results of the finite element method have been compared with results of the analytical solutions and experimental data. Results show that the shell with variable thickness has buckling pressure close to shell bucking pressure with mean thickness. تفاصيل المقالة -
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27 - Free Vibration Analysis of Non-Uniform Circular Nanoplate
M Zarei M Ghalami-Choobar G.H Rahimi G.R FaghaniIn this paper, axisymmetric free vibration analysis of a circular Nano-plate having variable thickness was studied. The variation in thickness of plate was considered as a linearly in radial direction. Nonlocal elasticity theory was utilized to take into account size-de أکثرIn this paper, axisymmetric free vibration analysis of a circular Nano-plate having variable thickness was studied. The variation in thickness of plate was considered as a linearly in radial direction. Nonlocal elasticity theory was utilized to take into account size-dependent effects. Ritz functions was utilized to obtain the frequency equations for simply supported and clamped boundary. To verify accuracy of Ritz method, differential transform method (DTM) also used to drive the size dependent natural frequencies of circular nano-plates. The validity of solutions was performed by comparing present results with those of the literature for both classical plate and nano plate. Effect of nonlocal parameter, mode number and taper parameter on the natural frequency are investigated. Results showed that taper parameter has significant effect on the non-dimensional frequency and its effects on the clamped boundary condition is more than simply support. تفاصيل المقالة -
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28 - Elastic Analysis of Functionally Graded Variable Thickness Rotating Disk by Element Based Material Grading
A.K Thawait L Sondhi Sh Sanyal Sh BhowmickThe present study deals with the elastic analysis of concave thickness rotating disks made of functionally graded materials (FGMs).The analysis is carried out using element based gradation of material properties in radial direction over the discretized domain. The resul أکثرThe present study deals with the elastic analysis of concave thickness rotating disks made of functionally graded materials (FGMs).The analysis is carried out using element based gradation of material properties in radial direction over the discretized domain. The resulting deformation and stresses are evaluated for free-free boundary condition and the effect of grading index on the deformation and stresses is investigated and presented. The results obtained show that there is a significant reduction of stresses in FGM disks as compared to homogeneous disks and the disks modeled by power law FGM have better strength. تفاصيل المقالة -
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29 - Evaluation of the Paleocene-Eocene deposits, Jahrum Formation, base on 2-D seismic data, Central Persian Gulf
Naser Abdi Hossain Rahimpour-Bonab Sayyed Reza Moussavi-Harami Iraj Abdollahi Fard Davood Jahani Ali ChehraziThe Persian Gulf is part of an asymmetric foreland basin related to the Zagros Orogen. It has been episodically flooded for much of its history which are reflected in sedimentary successions. The evaluation of this succession from depositional trend view, in central Per أکثرThe Persian Gulf is part of an asymmetric foreland basin related to the Zagros Orogen. It has been episodically flooded for much of its history which are reflected in sedimentary successions. The evaluation of this succession from depositional trend view, in central Persian Gulf during Paleocene-Eocene, is the aim of this article. The sedimentary rocks physical characteristics effects on seismic data, gives an appearance to the data, which can be a key factor for their evaluation. The reflectors geometry and terminations have been used for their interpretation. The current study the uses seismic data beside drilling wells data, including cutting description and logs. The study result shows progradation toward northeast, the direction in which the accommodation space is increasing. The sedimentary environments changes to lagoon, platform and basin which affect the deposits. These environments demonstrate suitable condition for carbonates and evaporites precipitation, in Jahrum Formation, which are approved by cutting ription. The sediments extension and its trend show high thickness of Paleocene-Eocene deposits in north west of the study area, where the basin is deeper. In some intervals the thickness of sediments is decreased in deep basin, due to sediment starvation. تفاصيل المقالة -
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30 - ارزیابی تجربی اثر زاویه انحراف لوله بر ضخامت کمینه و بیشینه فیلم مایع در جریان دوفازی
آرش غفوری اشکان غفوری عباس کوثری نیا علیرضا دنه دزفولیدر این پژوهش، تأثیر زاویه انحراف محدود جریان دوفازی در یک لوله عمودی بر تشکیل ضخامت فیلم مایع با استفاده از تکنیک ثبت و پردازش تصاویر مورد بررسی قرار گرفته است. برای ایجاد الگوی جریان حلقوی، از جریان ناهمسوی آب و هوا در سه لوله شفاف با قطرهای بین 25 تا 75 میلیمتر استفاد أکثردر این پژوهش، تأثیر زاویه انحراف محدود جریان دوفازی در یک لوله عمودی بر تشکیل ضخامت فیلم مایع با استفاده از تکنیک ثبت و پردازش تصاویر مورد بررسی قرار گرفته است. برای ایجاد الگوی جریان حلقوی، از جریان ناهمسوی آب و هوا در سه لوله شفاف با قطرهای بین 25 تا 75 میلیمتر استفاده گردید. پس از تجزیه و تحلیل نتایج الگوی جریان حلقوی برای محدوده‌های مختلف سرعت ظاهری و عدد رینولدز جریان گاز و مایع، به همراه اقطار مختلف لوله، ضخامت بیشینه و کمینه فیلم مایع و نسبت آنها ارزیابی و ارائه شد. همچنین، مقادیر ضخامت معادل فیلم مایع در لوله‌های زاویه‌دار به صورت بی‌بُعد نسبت به ضخامت یکنواخت فیلم مایع در حالت عمودی کامل ارائه شد. نتایج پژوهش حاضر نشان می‌دهد که با تغییر زاویه انحراف از 90 به 85 درجه، نسبت ضخامت فیلم بیشینه به ضخامت فیلم کمینه افزایش می‌یابد و همچنین ضخامت معادل فیلم مایع با کاهش روبرو بوده که این نتایج با تحقیقات قبلی نیز تطابق قابل قبولی دارد. همچنین آنالیز عدم قطعیت نشان می‌دهد که عدم قطعیت در ارزیابی تجربی ضخامت فیلم مایع حداکثر 4.9 درصد میباشد که در محدوده قابل قبول قرار دارد. تفاصيل المقالة -
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31 - ارائه فرمول جهت محاسبه تعداد سیکل شکست بر حسب ضخامت روکش گالوانیزه گرم در پدیده خستگی
کاظم رضاکاشی زاده علیرضا ارغواندر این مقاله هدف پیش بینی تعداد سیکل شکست در قطعات آبکاری شده با روکش گالوانیزه گرم با ضخامت های مختلف نازک ابعادی در مقیاس میکرون است. به این منظور قطعات فولادی از جنس Ck45 با استفاده از فرآیند آبکاری با ضخامت های 13، 19 میکرون و با شرایط عملیات آبدهی یکسان روکش گالوان أکثردر این مقاله هدف پیش بینی تعداد سیکل شکست در قطعات آبکاری شده با روکش گالوانیزه گرم با ضخامت های مختلف نازک ابعادی در مقیاس میکرون است. به این منظور قطعات فولادی از جنس Ck45 با استفاده از فرآیند آبکاری با ضخامت های 13، 19 میکرون و با شرایط عملیات آبدهی یکسان روکش گالوانیزه بر روی آن ها قرار گرفته است. با انجام آزمایشات بسیار زیاد منحنی S–N هر نمونه بصورت تجربی بدست آمده است. با استفاده از نتایج بدست آمده ضرایب ثابت خستگی آماری برای قطعات بدست آمده است. با استفاده از دو روش میان یابی لاگرانژی و نویل، ضریب K بر حسب ضخامت روکش گالوانیزه بدست آمده است و در نهایت به ارائه رابطه ای پرداخته شده که با دانستن ضخامت روکش گالوانیزه در هر تنش دلخواه می توان تعداد سیکل های لازم تا شکست را تحت پدیده خستگی بدست آورد. نتایج بدست آمده تطابق بسیار خوبی با نتایج آزمایشگاهی دارند و برای نشان دادن میزان دقت روش نتایج حاصل از دو روش مورد مقایسه قرار گرفته‌اند. تفاصيل المقالة -
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32 - Design of Optimum Active Layer Thickness in Double Heterostructure Broad Area Ga As/Al_x Ga_(1-x) As Laser Diodes
nasser moslehi milani mohammad salmani yengejeh Majid shabzendehIn this work, we calculate optimum thickness of bulk active layer for Ga As/〖Al〗_x 〖Ga〗_(1-x) As laser diodes. We have done these calculations for fundamental oscillation mode of laser with different aluminium contents (fractional percents) in confinement layers. Our ca أکثرIn this work, we calculate optimum thickness of bulk active layer for Ga As/〖Al〗_x 〖Ga〗_(1-x) As laser diodes. We have done these calculations for fundamental oscillation mode of laser with different aluminium contents (fractional percents) in confinement layers. Our calculations were based on the analytical solution of Maxwell equations. The results indicate that the optimum thickness for fundamental mode is dependent on difference of refractive indices of active and confinement layers. The results reveal that the best active layer thicknesses for fundamental mode of laser are d_0=0.63,0.44,0.36 and 0.32 μm for x=0.1,0.2,0.3 and 0.4 aluminium percents in separate confinement heterostructure (SCH) layers respectively. تفاصيل المقالة -
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33 - Nanoporous anodized aluminum thickness optimization through pulse current mode
Iman Mohammadi Abdollah Afshar Shahab AhmadiThe purpose of this study was to optimize the thickness of anodizing Aluminum coatings processed under pulse current mode through the Design of Experiments (DOE) method. Thickness measurement, polarization and electrochemical impedance spectroscopy were employed to take أکثرThe purpose of this study was to optimize the thickness of anodizing Aluminum coatings processed under pulse current mode through the Design of Experiments (DOE) method. Thickness measurement, polarization and electrochemical impedance spectroscopy were employed to take Thickness and corrosion behaviors of the anodized coatings into consideration. Also, Field-emission scanning electron microscopy (FE-SEM) was utilized to characterize the surface morphology of the coatings. It was found that the thickness of anodized coatings strongly depends on various parameters among which, time, temperature and pulse current parameters such as current density limit, frequency and duty cycle were considered in the present study. Analysis of variance (ANOVA) was used for estimating the coating thickness. Experimental results showed the maximum value for coating thickness was 62 µm being attained at the maximum and minimum current density of 6.28 and 1.55 A/dm2, a frequency of 150.5 Hz, time of 51 min, duty cycle of 81.5% and the bath temperature of 13.5 oC. Also, FE-SEM observation of the surface of anodized coatings showed that this optimum condition leads to a lower porosity amount. Polarization measurements showed that this lower porosity amount caused an increase in corrosion resistance of anodized coatings. تفاصيل المقالة -
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34 - Numerical and Experimental Investigation of Thickness Variation in the Spinning Process of Al-1060 Alloy
Mohammad Honarpisheh Shayan Namazikhah Iman AlinaghianMetal spinning as a kind of manufacturing process has capability to shape hollow components. In present work shear spinning process is used to formplates into conical shapes. Moreover, the aim of this research is to demonstrate the impact of the process parameters (i.e. أکثرMetal spinning as a kind of manufacturing process has capability to shape hollow components. In present work shear spinning process is used to formplates into conical shapes. Moreover, the aim of this research is to demonstrate the impact of the process parameters (i.e. feeding rate and spindle speed) on wall thickness. This approachwas done by experimental and finite elements method. The results illustrated that wall thickness decreases while feeding rate increases in spinning process. The experimental results confirm the Finite element analysis (FEA) results during thickness evaluations so this shows that FEA results are reliable for this specific case. The results of analysis reveals that the best condition for spinning is for feeding rate of 40 mm/min and spindle speed of 50 rpm in which highest thickness of 1mm is obtained. In consequence, the findings also illustrated that by decreasing the feeding rate and spindle speed, higher thickeners can be observed during shear spinning process. تفاصيل المقالة -
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35 - Using Artificial Neural Networks to Predict Rolling Force and Real Exit Thickness of Steel Strips
Mohammad Heydari Vini1There is a complicated relation between cold flat rolling parameters such as effective input parameters of cold rolling, output cold rolling force and exit thickness of strips. In many mathematical models, the effect of some cold rolling parameters has been ignored and أکثرThere is a complicated relation between cold flat rolling parameters such as effective input parameters of cold rolling, output cold rolling force and exit thickness of strips. In many mathematical models, the effect of some cold rolling parameters has been ignored and the outputs have not a desirable accuracy. In the other hand, there is a special relation among input thickness of strips, the width of the strips, cold rolling speed, mandrill tensions, required exit thickness of strips with rolling force and the real exit thickness of the rolled strip. First of all in this study, the effective parameters of cold rolling process modeled using an artificial neural network according to the optimum network achieved by using a written program in MATLAB. It has been shown that the prediction of rolling stand parameters with different properties and new dimensions attained from prior rolled strips by an artificial neural network is applicable. تفاصيل المقالة -
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36 - مطالعه حالتهای تغییر شکل خطوط لوله مدفون تحت جابجایی ماندگار زمین در محل گسل فعال
محسن عقابی مهدی خوش وطنرفتار لوله های مدفون تحت جابجایی گسل موضوعی پیچیده است. در زلزله های گذشته جابجایی 1/2 و 3 و 4 متر گسل گزارش شده است. مرور تحقیقات نشان می دهد، شناخت حالت های خرابی لوله تحت جابجایی های بزرگ گسل، یک چالش است. در این مقاله، تاثیر پارامتر ضخامت لوله، بر رفتار لوله در تقاط أکثررفتار لوله های مدفون تحت جابجایی گسل موضوعی پیچیده است. در زلزله های گذشته جابجایی 1/2 و 3 و 4 متر گسل گزارش شده است. مرور تحقیقات نشان می دهد، شناخت حالت های خرابی لوله تحت جابجایی های بزرگ گسل، یک چالش است. در این مقاله، تاثیر پارامتر ضخامت لوله، بر رفتار لوله در تقاطع لوله و گسل بررسی شده است. رفتار لوله با تمرکز بر جابجایی های بزرگتر از 1 متر گسل، مورد بررسی قرار گرفته است. با تحلیل دینامیکی و در نظر گرفتن اندرکنش خاک و لوله با نرم افزار المان محدود ABAQUS شبیه سازی انجام شده است. ابعاد مدل خاک و لوله و خصوصیات مصالح در تمامی نمونه های تحلیل، ثابت بوده و مقدار جابجایی گسل (2/0 تا 3 متر) و ضخامت لوله (از 2/8 تا 20 میلیمتر) پارامترهای متغیر مقاله حاضر است. برای دو متغیر مقدار جابجایی گسل و ضخامت لوله تحلیل انجام گرفته است. مقدار حداکثر کرنش محوری و حالت های تغییر شکل لوله تحت جابجایی گسل مورد بحث قرار گرفته است. همچنین، اثر ضخامت لوله و مقدار جابجایی گسل بر مقدار کرنش جداره لوله در تحلیل عددی در نتایج آورده شده است. در جابجایی کمتر از 1 متر، تغییر شکل لوله شبیه به حرف S بوده و کمانش موضعی در لوله رخ می دهد. در جابجایی از 5/1 متر و بیشتر تغییر شکل لوله شبیه حرف Z است و چروکیدگی در لوله رخ می دهد. در جابجایی بیشتر از 5/1 متر، تغییر شکل لوله بصورت اعوجاج و چروکیدگی است. در جابجایی بیشتر از 1 متر با افزایش ضخامت لوله، کرنش کاهش می یابد. تغییر ضخامت لوله، می تواند حالت خرابی لوله را تغییر دهد. تفاصيل المقالة -
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37 - بررسی عملکرد لرزه‌ای دیوارهای برشی فولادی مرکب با تاکید بر تاثیر ضخامت ورق فولادی و پوشش بتنی
مرتضی رستاخیز احمد ملکیدیوار برشی فولادی مرکب به عنوان سیستم مقاوم جانبی است که برای سازه های جدید و هم بعنوان سیستم تقویت کننده برای ساختما های موجود مناسب است. دیوارهای برشی مرکب در مقایسه با دیوارهای برشی بتنی مسلح، یک دیوار مرکب طراحی شده برای همان نیروی برشی، با وجود سختی و مقاومت برشی ب أکثردیوار برشی فولادی مرکب به عنوان سیستم مقاوم جانبی است که برای سازه های جدید و هم بعنوان سیستم تقویت کننده برای ساختما های موجود مناسب است. دیوارهای برشی مرکب در مقایسه با دیوارهای برشی بتنی مسلح، یک دیوار مرکب طراحی شده برای همان نیروی برشی، با وجود سختی و مقاومت برشی بیشتر،دارای ضخامت و وزن کمتری می باشد مقاله ی حاضر به بررسی امکان بهبود پارامترهای لرزه ای دیوارهای برشی مرکب می پردازد. میزان افزایش در ظرفیت باربری، شکل پذیری و میزان استهلاک انرژی از پارامترهایی هستند که مورد بررسی قرار گرفته اند. تحلیل عددی با استفاده از نرم افزارهای اجزای محدود برای بررسی پارامترهای مذکور مورد استفاده قرار گرفته است. بررسی مقایسه ای نتایج آزمایشگاهی با نتایج مدلسازی ها نشان می دهد که نرم افزارهای اجزای محدود توانایی مدلسازی مناسب را داشته باشد. نتایج حاصل از مطالعات عددی نشان داد که افزایش ضخامت ورق فولادی سختی اولیه نمونه ها را افزایش داده است و به ترتیب ضخامت 8.4 و 131 میلی متر برای ورق فولادی و پوشش بتنی بعنوان مناسب ترین ابعاد هندسی برای دیوار برشی مرکب با ابعاد 2.5*3 متر می باشد 35 mm . تفاصيل المقالة -
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38 - Genetic Evaluation of some Carcass Characteristics Assessed by <i>in vivo</i> Real Time Ultrasonography in Baluchi Sheep
ع. محمدی س. حسنی س. زره داران م. باقری ع. میرشاهیIn order to evaluate carcass characteristics of a nucleus flock of Baluchi sheep, in vivo ultrasound technique was used to measure backfat thickness (UBFT) and longissimus dorsi muscle area (ULMA) and also to estimate genetic parameters for these ultrasonic traits and l أکثرIn order to evaluate carcass characteristics of a nucleus flock of Baluchi sheep, in vivo ultrasound technique was used to measure backfat thickness (UBFT) and longissimus dorsi muscle area (ULMA) and also to estimate genetic parameters for these ultrasonic traits and live weights in different ages. The data were collected from 576 animals during 2011. (Co)variance components were estimated by univariate and bivariate animal models using restricted maximum likelihood and Asreml software. Females had higher UBFT and ULMA than males. Estimates of direct heritabilities were 0.32, 0.23, 0.27, 0.02, 0.12, 0.22 and 0.18 for UBFT, ULMA, birth weight (BW0), weaning weight (BW3), 6 month weight (BW6), 9 month weight (BW9) and yearling weight (BW12), respectively. There were positive and high genetic (0.68±0.15) and phenotypic (0.62±0.03) correlations between UBFT and ULMA. The genetic correlations among ultrasonic and pre 6 month weights were positive and low except for BW0 and ULMA (0.39±0.28). Contrarily, moderate to high positive genetic correlations between ultrasonic traits and weaning and post-weaning weights were found (0.33 to 0.61). Phenotypic correlations between ultrasonic and growth traits were positive and ranged from 0.09 to 0.37. High positive genetic correlation between UBFT and ULMA suggests that selection for larger muscle mass result in higher fat carcasses. تفاصيل المقالة -
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39 - Effect of Different Levels of Sunflower Meal and Niacin on Performance, Biochemical Parameters, Antioxidant Status, and Egg Yolk Cholesterol of Laying Hens
پ. باغبان-کنعانی ح. جانمحمدی ع.ر. استادرحیمیThis study was conducted to evaluate the effect of different levels of sunflower meal (SFM) and niacin on laying hens performances, biochemical parameters, antioxidant status, and egg yolk cholesterol concentration. A total of 960, White Leghorn (Hy-Line W-36) commercia أکثرThis study was conducted to evaluate the effect of different levels of sunflower meal (SFM) and niacin on laying hens performances, biochemical parameters, antioxidant status, and egg yolk cholesterol concentration. A total of 960, White Leghorn (Hy-Line W-36) commercial layers were randomly assigned to 12 groupsof 8 replicates with 10 hens each. Hens were allocated to diets 1 through 12 in a 3 × 4 factorial design and the dietary treatments included 3 levels of SFM (0, 10 and 15%) and 4 levels of niacin (0, 175, 225 and 275 mg/kg) fed to the birds for 10 weeks. Feed consumption was not affected (P>0.05) by niacin, SFM and SFM × niacin interaction. Dietary supplementation of 15% of SFM significantly (P<0.05) reduced egg weight, egg production and consequently egg mass. However, dietary addition of 275 mg of niacin/kg of diet increased (P<0.05) egg production and egg mass. Egg weight was not affected (P>0.05) by dietary addition of niacin. Feed conversion ratio was affected (P<0.05) by dietary addition of SFM and was not affected (P>0.05) by dietary incorporation of niacin and the SFM × niacin interaction. In fact, dietary supplementation of 15% of SFM significantly increased (P<0.05) FCR from 2.12 to 2.14. With the exception of shell thickness, all other parameters were not affected (P>0.05) by dietary addition of niacin. Dietary supplementation of 15% of SFM reduced (P<0.05) egg shell thickness from 0.29 to 0.28. However, only egg shell strength was affected (P<0.05) by dietary incorporation 275 mg of niacin/ kg of diet. Egg yolk cholesterol content was affected (P<0.05) by dietary addition of SFM and niacin. Our data also showed that serum concentration of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and triglycerides (TG) levels were not affected (P>0.05) by dietary incorporation of SFM, niacin, and their interaction. By contrast serum concentration of total cholesterol (TC) were affected (P<0.05) by dietary addition of SFM, niacin and their interaction. There were no effects (P>0.05) of the experimental diets on total antioxidant capacity (T-AOC), total superoxide dismutase (TSOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) serum concentration. تفاصيل المقالة -
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40 - بررسی وتحلیل حساسیت شاخصهای موثر بر فشار دینامیکی لوله های GRP در طرحهای ابرسانی ( مطالعه موردی طرح آبرسانی شهرستان سنقر کرمانشاه)
محمدامین گندمی سارا امیرزاده روزبه آقامجیدی نورالدین بازگیرجریانهای ناماندگار در لوله‌ها به شکل‌های گوناگون ممکن است رخ دهد که یکی از اشکال آن، جریان ناماندگار میرا میباشد که ضربه قوچ نامیده می‌شود. این جریان ها به صورت امواج فشاری بوده و اگر به گونه‌ای مهار نشوند، می‌توانند موجب به وجود آمدن خسارت‌های جبران‌ناپذیری در خط لول أکثرجریانهای ناماندگار در لوله‌ها به شکل‌های گوناگون ممکن است رخ دهد که یکی از اشکال آن، جریان ناماندگار میرا میباشد که ضربه قوچ نامیده می‌شود. این جریان ها به صورت امواج فشاری بوده و اگر به گونه‌ای مهار نشوند، می‌توانند موجب به وجود آمدن خسارت‌های جبران‌ناپذیری در خط لوله گردد . در تحقیق حاضر به معرفی پدیده قوچ پرداخته و تاثیرات پارامترهای مختلف ، ضخامت و قطر لوله ، سرعت های مختلف جریان بر بارهای دینامیکی وارده در اثر وقوع ضربه قوچ را مورد بررسی قرار گرفت و در نهایت مشاهده شد که در شرایط یکسان، تأثیر جنس لوله در کاهش حداکثر ضربه، 25 درصد موثر است. افزایش حداکثر ضربه در اثر افزایش ضخامت لوله به اندازه بسیار کم، در حدود 1 درصد می شود. دو برابر نمودن ممان اینرسی باعث کاهش حداکثر فشار ناشی از ضربه در حدود 42 درصد می شود که این بررسی با استفاده از نرم افزار Water Hammer بررسی گردیده است. تفاصيل المقالة -
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41 - Effect of the Physical Properties of Composite Packaging Materials on Keeping Quality of Smoked Catfish
Olayemi, Foline Folorunsho Raji, Abdulganiy Olayinka Bamishaiye, Eunice IyaboSix different composite packaging materials were tested with the trades’ practice of polythene bags in storing smoked catfish for a period of six months. The thickness of the packaging materials ranges from 0.23 to 046 mm with water and oil absorption rates of the أکثرSix different composite packaging materials were tested with the trades’ practice of polythene bags in storing smoked catfish for a period of six months. The thickness of the packaging materials ranges from 0.23 to 046 mm with water and oil absorption rates of the packaging materials varies from 0.23 to 10.00 and 0.28 to 10.857 glcm2/mm respectively. The impact resistance weight also varies from 25 to 50 gm. It was observed that the physical properties of the packaging materials are related to the keeping quality of the stored catfish. The two packaging with better engineering properties offered better barrier functionality that gave better keeping quality for the catfish. [O, Foline Folorunsho et al. Effect of the Physical Properties of Composite Packaging Materials on Keeping Quality of Smoked Catfish. International Journal of Agricultural Science, Research and Technology, 2011; 1(3):127-131]. تفاصيل المقالة -
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42 - Culculation of uncommon water volume in aquifer of Shiramin plain and the ways of decreases
Fatemeh Jafarzadeh Aziz Alinejad Morteza Allaf-NajibShiramin plain, which is located in the East Azarbaijan with an area of about 50 Km2, is important in terms of agriculture activity. The main source of water supply for agriculture of the area is groundwater resources. This research studies the Shiramin plain groundwate أکثرShiramin plain, which is located in the East Azarbaijan with an area of about 50 Km2, is important in terms of agriculture activity. The main source of water supply for agriculture of the area is groundwater resources. This research studies the Shiramin plain groundwater salinity and offers a solution for the decrease of salinity. Based on analyzed water samples which were compared with the old ones, the areas of high electric conductivity, thickness of saturated layers and uncommen waters have been determined. تفاصيل المقالة -
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43 - The role of geological factors on the destruction of Bam city due to the recent earthquake
Mohammad Ghafoori Gholamreza Lashkaripour Hossein Sadeghi Naser Hafezi-Moghaddas Ali HussainiOn Friday, December 26, 2003 at 1:55:56 GMT (5:25:56 local time), a powerful earthquake of moment magnitude (Mw) about 6.5 struck the ancient city of Bam and neighboring villages in the southeastern region of Iran. The highest death has been reported for this earthquake أکثرOn Friday, December 26, 2003 at 1:55:56 GMT (5:25:56 local time), a powerful earthquake of moment magnitude (Mw) about 6.5 struck the ancient city of Bam and neighboring villages in the southeastern region of Iran. The highest death has been reported for this earthquake among all earthquakes in the world in the year 2003. About 70% of buildings in the city were damaged by the earth quake and more than 26000 people were killed. The main reason for such major damage may be weak adobe and brick structures. However, the damage was unexpectedly great for this magnitude. The city is located over low strength of fine grained soils such as silt with low cohesiveness and therefore, this is one of the main reasons for such large-scale destruction by the earthquake. This paper deals with the high damages in the city based on geology, tectonics and directivity of earthquake waves and also geotechnical parameters. تفاصيل المقالة -
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44 - Car paint thickness control using artificial neural network and regression method
J Jassbi M Alborzi F GhoreshiStruggling in world's competitive markets, industries are attempting to upgrade their technologies aiming at improving the quality and minimizing the waste and cutting the price. Industry tries to develop their technology in order to improve quality via proactive qualit أکثرStruggling in world's competitive markets, industries are attempting to upgrade their technologies aiming at improving the quality and minimizing the waste and cutting the price. Industry tries to develop their technology in order to improve quality via proactive quality control. This paper studies the possible paint quality in order to reduce the defects through neural network techniques in auto industry production lines. The inputs as effective factor in paint spray process identified for each thin layer on a plate. In the paint shop, defects generate that correlate with film thickness in paint process. In this work, a sheet of metal in demonstrated 50*20 using as a sample when Saipa Company, Iranian Auto Market Leader, is considered as a case study. In the present paper two models of NN is presented. The first model shows prediction of film thickness by10 input for bell, air layers and 12 inputs variables for dry film thickness or final paint thickness and 6 output points for three layers and second model is predicting of paint appearing uniformity by average and standard deviation of film thickness. Finally the application of Neural Network and statistical method (Regression) in predicting paint thickness and the comparison of the results are presented. تفاصيل المقالة -
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45 - Numerical Investigation of the Effect of Concrete Injection on the Concrete Joints of the Arched Dam, Under the Applied Stresses
Mohammadhossein Mansourghanaei Alireza MardookhpourNumerical Investigation of the Effect of Concrete Injection on the Concrete Joints of the Arched Dam, Under the Applied StressesAbstract Investigating the safety of dams is of great importance given their critical role in the industry and economy of countries and the ca أکثرNumerical Investigation of the Effect of Concrete Injection on the Concrete Joints of the Arched Dam, Under the Applied StressesAbstract Investigating the safety of dams is of great importance given their critical role in the industry and economy of countries and the catastrophic consequences of their failure. Hence, the present paper examines the impact of incomplete contraction joint injection in the Karun 4 double-curvature arch dam as a case study. In this article, the Abaqus 6.12 finite element software was used to model and analyze 3 numerical models of the Karun 4 dam. These models consist of a linear, integrated, and homogeneous model and two nonlinear models considering the nonlinear behavior resulting from two different types of common contraction joints in the dam's body. The results indicated that a lack of injection led to a significant increase in the maximum principal stresses (MPa) at the upstream section of the dam, such that a large part of this section, which originally worked under compression, is now under tension. The tensile stresses at the upstream abutment and the downstream crest also increased. Moreover, a lack of injection considerably increased the vertical compressive stresses between the contact surfaces (µ). These stresses were increased almost twofold near the injection stop level such that the stresses between monolith zero and one increased from a maximum of 5.13 under complete injection to 11.3. According to the results, with an increase in the joint thickness under the absence of joint injection, considerable amounts (of stress) are added to the maximum principal stresses, minimum principal stresses, dam displacement, and the vertical compressive force between the contact surfaces. تفاصيل المقالة -
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46 - تأثیر نوع پایه، الگوی رشد میوه‌ها و تراکم سلولی پوست در بروز عارضه ترکیدگی قبل از برداشت مرکبات
مهرناز علیخانی بابک باباخانی بهروز گلعین محمود اسدی پروانه راهداریعارضه ترکیدگی قبل از برداشت میوه، هر ساله موجب کاهش شدید عملکرد و افزایش پوسیدگی‌های قارچی در میوه مرکبات می‌شود. در این پژوهش نقش پایه و عوامل فیزیکی مربوط به میوه‌های مرکبات در شدت ترک‌خوردگی آنها بررسی شد. به‌این منظور، پژوهشی در سال 96-1395 در قالب آماری بلوک‌های کا أکثرعارضه ترکیدگی قبل از برداشت میوه، هر ساله موجب کاهش شدید عملکرد و افزایش پوسیدگی‌های قارچی در میوه مرکبات می‌شود. در این پژوهش نقش پایه و عوامل فیزیکی مربوط به میوه‌های مرکبات در شدت ترک‌خوردگی آنها بررسی شد. به‌این منظور، پژوهشی در سال 96-1395 در قالب آماری بلوک‌های کامل تصادفی به صورت فاکتوریل با سه تکرار روی درختان 15 ساله سه رقم نارنگی پیج، کارا و کادوکس (کلمانتین کادوکس) پیوندی روی چهار پایه نارنج، ترویر سیترنج، سیتروملو و کلئوپاتراماندارین در شرایط بدون آبیاری در شهرستان تنکابن (باغ خصوصی) انجام شد. نتایج این پژوهش نشان داد که هر دو عامل پایه و رقم در بروز ترکیدگی قبل از برداشت نقش بارزی داشته‌اند. مشخص شد که ارقام پیوند شده روی پایه‌های نارنج و سیتروملو به‌ترتیب بیشترین و کمترین درصد ترکیدگی را داشته و ترویر سیترنج و کلئوپاتراماندارین هر دو در سطح مشابه و در بین این دو حد بودند. همچنین، الگوی رشد میوه، میزان ضخامت پوست و تراکم سلولی در ناحیه گل‌گاه ارقام مختلف سبب شد تا ارقام نارنگی پیج و کادوکس به‌ترتیب بیشترین و کمترین شدت ترکیدگی را داشته باشند. نتایج این بررسی همچنین نشان داد که در میوه‌های ترک‌خورده هر رقم، تراکم سلولی پوست در ناحیه گل‌گاه میوه کمتر از میوه‌های ترک‌نخورده است. تفاصيل المقالة -
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47 - بررسی تاثیر عملیات حرارتی پس از جوشکاری بر خواص خوردگی فصل مشترک اتصال انفجاری ورق های Cu/SS 304
علی ابراهیمی اکبرآبادی عباس سعادت محمدرضا خانزاده حمید بختیاریدر تحقیق حاضر به بررسی تاثیر عملیات حرارتی بر رفتار خوردگی و تغییرات ریز ساختاری ورق‌های دو لایه فولاد زنگ نزن 304- مس پس از فرآیند جوشکاری انفجاری پرداخته شده است. جوشکاری انفجاری به صورت موازی با بار انفجاری 46 و 63 میلی متر و فاصله توقف 3-2 میلی متر انجام شده است. پس أکثردر تحقیق حاضر به بررسی تاثیر عملیات حرارتی بر رفتار خوردگی و تغییرات ریز ساختاری ورق‌های دو لایه فولاد زنگ نزن 304- مس پس از فرآیند جوشکاری انفجاری پرداخته شده است. جوشکاری انفجاری به صورت موازی با بار انفجاری 46 و 63 میلی متر و فاصله توقف 3-2 میلی متر انجام شده است. پس از اعمال جوش انفجاری، فرایند عملیات حرارتی در دمای 350 و 450 درجه سانتیگراد و برای مدت زمان‌های نگهداری 8 و 16 ساعت انجام شد. از نتایج آزمون امپدانس الکتروشیمیایی می توان دریافت که عدد n در نمونه عملیات حرارتی شده در دمای 350 درجه سانتیگراد و زمان 8 ساعت کمتر از نمونه عملیات حرارتی شده در دمای 450 درجه سانتیگراد و زمان 8 ساعت است و در نتیجه جریان خوردگی در نمونه عملیات حرارتی شده در دمای 350 درجه سانتیگراد و زمان 8 ساعت بیشتر است که باعث کاهش مقاومت انتقال بار می‌شود. با مقایسه نمونه‌های عملیات حرارتی شده در دمای 350 درجه سانتیگراد و زمان 8 ساعت و عملیات حرارتی شده در دمای 450 درجه سانتیگراد و زمان 8 ساعت با دمای آنیل متغیر، زمان آنیل ثابت است و نمونه عملیات حرارتی شده در دمای 450 درجه سانتیگراد و زمان 8 ساعت با بیشتر بودن دمای آنیل دارای عدد n (80/0) بیشتر و پس از آن نمونه عملیات حرارتی شده در دمای 350 درجه سانتیگراد و زمان 8 ساعت (66/0n=) است و علت آن افزایش دمای آنیل و کاهش انرژی ذخیره شده در فصل مشترک است. تفاصيل المقالة -
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48 - Numerical study on the effect of hammering pressure on thickness reduction in hot tube metal gas forming process
علی طالبی انارکی محسن لوح موسویNowadays, light weight and high strength metals are being used in various industries such as automotive and aerospace. Using aluminum-magnesium alloys is an efficient way to reduce the weight of a specific part. These alloys have poor formability in room temperature thu أکثرNowadays, light weight and high strength metals are being used in various industries such as automotive and aerospace. Using aluminum-magnesium alloys is an efficient way to reduce the weight of a specific part. These alloys have poor formability in room temperature thus they should be formed at elevated temperature. Warm hydroforming and hot metal gas forming are conventional methods to form aforementioned alloys. It is proven that using hammering pressure is an efficient way in order to optimize hydroforming process that it improves formability and thickness distribution. In this paper, the effect of hammering pressure on hot free bulging of an Al6063 tube is investigated numerically and the results are compared with the results of constant pressure path. Results show that reduction of thickness is greater for peak constant pressure while using hammering pressure, due to gradual thickness reduction, could improve formability and thickness distribution. Results also show that axial feeding, increase the effect of formability caused by hammering pressure. تفاصيل المقالة -
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49 - The effect of the anodization voltage changes on the electric resistance of porous anodic alumina barrier layer and its thickness used in strain sensing devices
Abolfazl Salehi Amnieh KhuzaniTo investigate the influence of aluminum anodization voltage on the barrier layer thickness of porous anodic alumina (PAA) and its electric resistance used in different technologies such as strain-sensing technology, samples in different voltages and variety condition o أکثرTo investigate the influence of aluminum anodization voltage on the barrier layer thickness of porous anodic alumina (PAA) and its electric resistance used in different technologies such as strain-sensing technology, samples in different voltages and variety condition of mild and hard anodization were fabricated. In different researches, different anodic alumina thicknesses have been tested and their effect on protection against humidity is studied by monitoring sensor resistance. Measurement of electrical resistant of barrier layer during the voltage changing shows that there is a transition region in which electric resistance of samples is located between hard and mild anodized region. The SEM investigation reveals that the barrier layer thickness is linearly proportional to the anodization voltage. But the barrier layer resistance in hard anodization is lower than that one in mild anodization. The observed paradox can be related to higher ionic mobility of ions in barrier layer which is formed in hard anodization. تفاصيل المقالة -
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50 - The effect of explosive welding variables on corrosion behavior of 304 stainless steel–copper joint in 3.5% NaCl solution concentration environment
MohammadReza Khanzadeh Reza Peykari Hamid BakhtiariIn this study, the corrosion behavior and microstructural variations of two-layer sheets consisting of 304 stainless steel copper have been investigated after the explosive welding process. Explosive welding is carried out by variable explosive charges and changing the أکثرIn this study, the corrosion behavior and microstructural variations of two-layer sheets consisting of 304 stainless steel copper have been investigated after the explosive welding process. Explosive welding is carried out by variable explosive charges and changing the distance between the sheets. To investigate the corrosion behavior of the welding zone, dynamic potential polarization and electrochemical impedance imaging were used. Besides, to perform microstructural analysis, metallographic tests using an optical microscope and scanning electron microscope (SEM) were employed. In addition, micro-hardness is considered to investigate the effect of shock waves caused by the explosion. The results showed that the sample with an explosive thickness of 79 mm has the highest interface hardness (HV 549) due to the high thickness of the explosive layer and standoff distance (3 mm). Also, the polarization test results indicated that the lowest corrosion rate corresponds to the sample with an explosive charge thickness of 79 mm and a standoff distance of 2 mm, and the highest corrosion rate was related to the sample with a 46-mm explosive charge thickness and standoff distance of 3 mm. Based on the results obtained from the electrochemical impedance spectroscopy, It can be concluded that by increasing the amount of copper in the locally frozen melt of the samples, the intensity of corrosion caused by the galvanic cell increases. تفاصيل المقالة -
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51 - Stress analysis of non-linearly variable thickness rotating disk in gas turbine engine using hyper-geometric method
Behrooz Shahriari Nedasadat SeddighiIn this paper, the numerical and exact analytical calculation of elastic strains and stresses in gas turbine engine rotating disk with variable thickness, subjected to temperature gradient are presented. Galerkin method is applied to solve any kind of profiles with arbi أکثرIn this paper, the numerical and exact analytical calculation of elastic strains and stresses in gas turbine engine rotating disk with variable thickness, subjected to temperature gradient are presented. Galerkin method is applied to solve any kind of profiles with arbitrary thickness, temperature and density functions while the other numerical and analytical methods used in previous works, are applied to profiles with certain thickness functions. Therefore, a comprehensive approach that takes all the circumstances into account was used in an attempt to fill this gap. To verify the numerical method, a few examples of rotating disks with non-linear variable thicknesses were solved using the analytical method as a reference method and their results were compared with numerical solution. A good agreement between numerical and analytical solutions was observed. In the analytical part, a new method to convert equilibrium equation of rotating disks to hyper-geometric differential equation was provided and then it was solved. Using hyper-geometric method is the main novelty of this research. The distributions of radial displacement and stresses were obtained and an appropriate comparisons and discussions were made at the same environmental conditions. تفاصيل المقالة -
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52 - Investigation on Buckling of Orthotropic Circular and Annular Plates of Continuously Variable Thickness by Optimized Ritz Method
فاطمه فرهت نیا آرش گل شاهThis paper investigates symmetrical buckling of orthotropic circular and annular plates of continuous variable thickness. Uniform compression loading is applied at the plate outer boundary. Thickness varies linearly along radial direction. Inner edge is free, while oute أکثرThis paper investigates symmetrical buckling of orthotropic circular and annular plates of continuous variable thickness. Uniform compression loading is applied at the plate outer boundary. Thickness varies linearly along radial direction. Inner edge is free, while outer edge has different boundary conditions: clamped, simply and elastically restraint against rotation. The optimized RayLeigh-Ritz method is applied for buckling analysis. In this method, a polynomial function that is based on static deformation of orthotropic circular plates in bending is used. Also, byemploying an exponential parameter in deformation function, eigenvalue is minimized in respect to that parameter. The advantage of this procedure is simplicity in comparison with other methods, while whole algorithm for solution can be coded for computer programming. The effect of variation of radius, thickness, different boundary conditions, ratio of radial Young Modulus to circumferential one, ratio of outer radius to inner one in annular plates on critical buckling coefficient are investigated. The obtained results show that in plate with identical thickness, increasing of outer radius decreases the critical buckling coefficient. In addition increasing of thickness of the plates results in increase of critical buckling coefficient. تفاصيل المقالة -
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53 - بررسی اثرات هیستوپاتولوژیک عصاره هیدروالکلی سرشاخه گلدار گل راعی ( )Hypericumperforatumبر روند التیام زخم جلدی تمام ضخامت تجربی درموش
مرتضی اصغریه اهری محمدرضا فرهپورالتیام زخم به عنوان یکی ازاصلیترین مباحث جراحی،همواره ذهن محققان را به خود معطوف داشته است . یکی از روشهای مختلفی که در راستای اثرگذاریبر سرعت التیام وکیفیت بافت التیامی نهایی میتوان از آن بهره برد، استفاده از مواد بیولوژیک، چه با منشاء گیاهی و چه با منشاء حیوانی، میباش أکثرالتیام زخم به عنوان یکی ازاصلیترین مباحث جراحی،همواره ذهن محققان را به خود معطوف داشته است . یکی از روشهای مختلفی که در راستای اثرگذاریبر سرعت التیام وکیفیت بافت التیامی نهایی میتوان از آن بهره برد، استفاده از مواد بیولوژیک، چه با منشاء گیاهی و چه با منشاء حیوانی، میباشد. تحقیقاتاخیر در مورد استفاده از عصاره گیاه هیپریکوم پرفوراتوم (گیاه گل راعی،) حاکی از وجود آثار شفا بخش آن در روند التیام زخم و درمان بیماریهای پوستمیباشد . در این مطالعه که برروی 36موش صحرایی (رت) نژاد ویستار با میانگین وزنی 200±10گرم و از جنس نر انجام گرفت، ابتدا اقدام به ایجاددو زخمهای دایره وار استانداردی به قطر 7میلیمتر روی پوست پهلوهای راست وچپ حیوان مورد مطالعه شد و سپس هر 12موش به طور تصادفی دریک گروه مطالعاتی قرار داده شدند ؛ بدین ترتیب که یک گروه به عنوان شاهد و دو گروه دیگر به عنوان گروههای درمانی تلقی گشتند ؛ وجهت بررسی اثرعصاره گیاه گل راعی بر روند التیام زخم در گروههای درمان از پماد حاوی %1و %2عصاره مزبور و در گروه شاهد از پماد فاقد عصاره (دارونما) استفادهگردید و این شیوه درمانی تا پایان هفته سوم پس از ایجاد زخم ادامه یافت . درطول اجرای طرح، در پایان روزهای سوم، هفتم، چهاردهم و بیست ویکم اززخمهای گروههای مختلف، به منظور بررسیهای هیستو پاتولوژیک میزان خونریزی، نفوذ سلولهای نوتروفیل و لنفوسیت، نو عروق زایی و تشکیل بافتپوششی،توسطپانچمخصوصبیوپسی،جهت بررسی نمونهای اخذگردید. لازم به ذکر است جهت جلوگیری از ایجاد اختلال در نتایج حاصل، هرحیوان که موردنمونه برداری قرار میگرفت از دور مطالعه خارج میگشت. نتایج بدست آمده از ارزیابی کیفی التیام در گروههای کنترل و آزمایش، نشان دهنده اختلاف بسیارچشمگیر بین دو گروه بوده به نحوی که نشان دهنده اثرات مثبت عصاره هیدروالکلی سرشاخه گلدار گیاه گل راعی بر روند التیام زخمها میباشد در مجموعاز لحاظ تاثیر گذاری، پماد 2درصد عصاره هیدروالکلی سرشاخه گلدار گل راعی نسبت به گروه پماد 1درصد عملکرد بهتری را نشان میداد تفاصيل المقالة -
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54 - Effects of Slaughter Weight on Growth Performance, Carcass Characteristics, and Fatty Acid Composition of Afshari Male Lambs
N. Papi M. ZahedifarThis study aimed to investigate the difference in growth performance and carcass characteristics of lambs slaughtered at 56, 84, 112, and 140 days of age. Thirty-two male fat-tailed Afshari lambs, with an initial body live weight of 30.2 ± 3.6 (SD) kg and an average age أکثرThis study aimed to investigate the difference in growth performance and carcass characteristics of lambs slaughtered at 56, 84, 112, and 140 days of age. Thirty-two male fat-tailed Afshari lambs, with an initial body live weight of 30.2 ± 3.6 (SD) kg and an average age of 90 ± 15 (SD) days, were used in this study. The lambs were equally and randomly distributed in 4 groups. The experiment was conducted in four peri-ods, including 56, 84, 112, and 140 days, and the nutrient requirements of lambs in each period were deter-mined using NRC 2007. At the end of each period, four lambs were randomly chosen and slaughtered, and longissimus thoracic muscle (LT) sampled. The results showed that by increasing the weight of slaughter, dry matter intake (DMI), feed conversion ratio (FCR) (i.e., kg DM/kg gain), and empty body weight in-creased, but empty digestive tract decreased linearly. The side carcass cuts (neck, shoulder, brisket-flank, rack-loin, and leg) were unaffected by slaughter weight. By increasing the slaughter weight, backfat thick-ness, LT area increased, and the percentage of dressing, tail fat, and internal fat also increased linearly. As the slaughter weight increased, the ratio of total unsaturated fatty acids to saturated fatty acids (UFA/SFA) decreased in LT fat, but that ratio increased in LT muscle linearly. تفاصيل المقالة
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