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Articles 1 - 6 of 6
Full-Text Articles in Mechanical Engineering
تعيين عرض تختال در ورودي كوره هاي پيش گرم ناحيه نورد گرم مجتمع فولاد مباركه با استفاده از پردازش ديجيتال تصاوير, Eaman Alibeigi, Rasoul Amirfattahi, Masoud Harooni, Hamid Montazerolghaem
تعيين عرض تختال در ورودي كوره هاي پيش گرم ناحيه نورد گرم مجتمع فولاد مباركه با استفاده از پردازش ديجيتال تصاوير, Eaman Alibeigi, Rasoul Amirfattahi, Masoud Harooni, Hamid Montazerolghaem
Masoud Harooni
هر يك از تختال هاي توليد شده در بخش ريخته گري مداوم ناحيه فولاد سازي، پس از مارك زني و تعيين مشتري به يكي از دو صورت هوايي يا سيالي خنك شده و در زمان مقرر به وسيله غلطك هايي وارد كوره پيش گرم مي شوند. در اين مرحله، 1/6 mm تختال تا حرارت 1100 درجه سانتيگراد گرم شده و عمليات نورد گرم بر روي آن به منظور تهيه ورق فولاد با ضخامت صورت مي گيرد. تعيين دقيق مشخصات ابعادي تختال ها از جمله طول، عرض و ضخامت آنها قبل از ورود به كوره هاي پيش گرم و تطبيق دادن …
Gtaw ايجادشده با روش جوشکاری Tini-Tic و Tini بررسی ريزساختاری پوشش, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Gtaw ايجادشده با روش جوشکاری Tini-Tic و Tini بررسی ريزساختاری پوشش, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Masoud Harooni
هدف از انجام اين پژوهش بهبود سختي سطحي و ريزساختار فولاد ساده کربنی از نوع 52 و مقايسه ريز ساختار اين دو با هم GTAW ايجاد شده به روش جوشکاری TiNi-TiC و TiNi پوششی از بترتيب با نسبت استوکيومتری مساوي و نسبت ۲۰ Ti-Ni-C و Ti-Ni است. بدين منظور مخلوط پودری به طور جداگانه توسط روش فعال سازی مکانيکی فعال شد و سپس بر سطح TiC درصد تقويت کننده به ضخامت ۱ ميليمتر پيش نشانده شده با استفاده از روش جوشکاری قوسی St نمونه های فولادی 52 تنگستن- گاز ذوب و با فلز پايه امتزاج يافته است. جهت بررسي نوع …
Thermal Stability Of Electrodeposited Liga Ni-W Alloys For High Temperature Mems Applications, Haseeb Asma
Thermal Stability Of Electrodeposited Liga Ni-W Alloys For High Temperature Mems Applications, Haseeb Asma
Haseeb ASMA
For thermally stable LIGA materials for high temperature MEMS applications LIGA Ni-W layers and micro testing samples with different compositions (15 and 5 at% W) were electrodeposited. In order to investigate the thermal stability the Ni-W layers were annealed at different temperatures (300-700 degrees C) and for different durations (1, 4, 16 h). Their microstructure and micro-hardness were than analysed after annealing and compared with those of as-deposited states. The observed microstructures show, in comparison to pure LIGA nickel, a small grain growth and a relatively stable structure up to 700 degrees C. The micro-hardness values of the LIGA Ni-W …
The Dependence Of Measured Modulation Error Ratio On Phase Noise, Ron D. Katznelson
The Dependence Of Measured Modulation Error Ratio On Phase Noise, Ron D. Katznelson
Ron D. Katznelson
This paper reviews the algorithms used by Vector Signal Analyzers to measure Modulation Error Ratio (MER) and derives the explicit functional dependence of measured MER on phase noise of digital transmitters. The modulation error model is introduced and the analytical expression for key estimated parameters required to obtain MER measure are derived. The essential elements of algorithms employed by MER measurement instruments to estimate amplitude scale, frequency offset, and initial phase intercept and the resulting MER are identified. The frequency response of the effective phase-noise rejection filtering action associated with a given measurement epoch is derived. It is shown that …
Liga Fabrication Of Nanocrystalline Ni-Walloy Micro Specimens From Ammonia-Citrate Bath, Haseeb Asma
Liga Fabrication Of Nanocrystalline Ni-Walloy Micro Specimens From Ammonia-Citrate Bath, Haseeb Asma
Haseeb ASMA
Ammonia-citrate bath has been investigated for the deposition of nano crystalline Ni - W alloy micro components using the LIGA process. First the bath stability and deposit characteristics were studied. Fabrication of micro specimens were then carried out on silicon substrates covered with novolac as well as thick PMMA resist for LIGA. Effects of different parameters like current density, nickel ion and tungsten ion concentration in the bath, deposition time etc. on the deposit characteristics and current efficiency were studied. The deposited Ni - W samples were characterized by scanning electron microscopy, energy depressive X-ray spectroscopy, light optical microscopy and …
Friction And Wear Characteristics Of Electrodeposited Nanocrystalline Nickel-Tungsten Alloy Films, Haseeb Asma
Friction And Wear Characteristics Of Electrodeposited Nanocrystalline Nickel-Tungsten Alloy Films, Haseeb Asma
Haseeb ASMA
Electrodeposited nanocrystalline nickel-tungsten alloys are being investigated as an attractive alternative to electrodeposited nickel for applications involving fabrication of micro electro mechanical systems (MEMS). Ni-W alloys are also being considered as an environmentally friendly alternative to hard chrome plating in some cases. In applications involving sliding contacts such as in micro-gears in MEMS, mould inserts, etc., tribological properties of Ni-W alloys would be of relevance. In this work, the sliding friction and wear characteristics of Ni-W alloys with different tungsten contents were investigated and compared with that of nickel film deposited from sulphamate bath commonly used in microfabrication. For wear …