The positioning methods based on received signal strength (RSS) measurements, link the RSS values to position of mobile station(MS) be located. Their accuracy depends suitability propagation models used for actual conditions. In indoor wireless networks, these conditions are very difficult predict due unwieldy and dynamic nature RSS. this paper, we present a novel method which dynamically estimates that best fit environments, by using only measurements obtained in real time. This is...

Bulk hot deformation is a relatively old manufacturing technique widely adopted in different industry fields to form and shape metallic alloys. Martensitic stainless steels (MSS) are class of metals used industries with extreme conditions. Hot forming this highly complex process comprising several coupled thermo-chemo-physical phenomena. The microstructural changes MSS make it challenging develop an overall system governing equations for theoretically analyzing the behavior during process....

The evolution of the microstructure changes during hot deformation high-chromium content stainless steels (martensitic steels) is reviewed. microstructural taking place under high-temperature conditions and associated mechanical behaviors are presented. During continuous dynamic recrystallization (cDRX), new grains nucleate growth in materials with high stacking fault energies (SFE). On other hand, ultrafine could be produced steel material irrespective SFE employing temperatures. gradual...

In this study, dissimilar sheets including AA3003 aluminum and A441 AISI steel were welded via cooling-assisted friction stir welding (FSW). Three different cooling mediums forced CO2, water, air employed, a non-cooled sample was processed to compare the condition with traditional FSW condition. The highest rate belongs CO2 lowest as FSW. best macrograph without any segregation at interface water-cooled poorest joint notable sample. exhibits smallest grain size due suppression of growth...

This paper studies the influence of diverse friction models on numerical analysis an industrial skew rolling mill using FORGE®.The originality present contribution is effect model important parameters, namely, consumed power, plastic deformation and surface temperature.The aim to evaluate which these appropriate for simulating processes.The high values temperature, pressure sliding velocity at contacts make assessment incidence temperature evolution fundamental, given its importance...

In this study, the formability of super Cr13 martensitic stainless steel (MSS) is examined by means hot tensile tests at different temperatures (900 o Ce1100 C) and t strain rates (0.01s À1 -10s ).The potential effect on mechanical properties, microstructure fracture surface MSS were examined.The post-test analysis, which includes hardness measurements, X-ray diffraction (XRD), analysis scanning electron microscope (SEM), Energy-dispersive spectroscopy (EDS), was carried out.Results show...

This research analyzes the impact of various friction conditions at interface tube piercing machine tools and Super Cr13 steel workpiece. For this reason, three-dimensional finite element method (FEM) is employed in simulation process. The are simulated considering Tresca, Viscoplastic, IFUM Neumaier models which have been implemented Rollers-Billet (RF), Plug–Billet (PF), Diescher–Billet (DF) interfaces. After testing their performance, Viscoplastic selected for RF interface, Tresca PF DF...

In this paper the effects of rollers-billet friction coefficient (RFC) and plug-billet (PFC) during skew rolling piercing process are investigated. The has been simulated plastic deformation, temperature evolution, surface twisting pierced tube analysed. Results show that deformation super-martensitic Cr13 stainless steel increases at higher RFC decreases PFC. same trend observed for material strain rate, which with but increasing addition, it found does not affect evolution billet. fact,...

The wall thickness eccentricity is one of the most important weaknesses that appears in seamless tubes production, since this imperfection subsequently transferred downstream through manufacturing stages until final product. For reason, article a finite element model rotary tube piercing (RTP) process developed aimed at analysing imperfection. Experimental data extracted from industrial used for validation model, including operational variables like power consumption and velocity,...

Abstract Skew rolling is a manufacturing process in which two or three rolls are used to reduce the diameter modify shape of cylindrical workpiece, manufacture mechanical components such as shafts, rods balls. Hot conditions overcome limitations related material ductility, residual stress and machine capacity. In this paper, warm skew (WSR) 42CrMo4 modeled by finite element method. The effects forming parameters, namely initial temperature roll rotational velocity, on strain rate, thermal...

Through scanning electron microscopy and local chemical analysis by energy-dispersive X-ray spectroscopy, alkali–silica reaction (ASR) products in two Spanish dam concretes accelerated mortar bar test samples (UNE 146508:1999) were compared. In composition, gels formed the revealed marked differences to concrete. Higher sodium lower calcium potassium contents especially noteworthy samples. Further, very marked, contrary tendencies evolution of composition between concrete those observed....

This paper is aimed at modelling the flow behaviour of P91 steel high temperature and a wide range strain rates for constant also variable strain-rate deformation conditions, such as those in real hot-working processes. For this purpose, an incremental physically-based model proposed behavior. formulation considers effects dynamic recovery (DRV) recrystallization (DRX) on mechanical properties material, using only stress, rate state variables not accumulated strain. Therefore, it reproduces...

In the numerical simulation of hot forming processes, correct description material flow stress is very important for accuracy results. For complex manufacturing such as rotary tube piercing (RTP), constitutive laws based on both power and exponential mathematical expressions are commonly used due to its inherent simplicity, despite limitations that this approach involves, namely, use accumulated strain a state parameter. paper, model P91 steel derived from evolution dislocation density with...

In this article an analysis of the cone-type rotary piercing process seamless tubes by means a finite element model is presented. The originality proposed study utilisation shear strain material for experimental validation model. complex procedure in which subjected to severe plastic deformation and surface twisting that leads deformations. addition, extreme friction conditions high temperatures occur during increase difficulty itself its simulation. Consequently, numerical models cannot be...

During the hot piercing phase of seamless tube production, friction and contact conditions between tools workpiece significantly influence final product quality energy consumption. The effects on production high alloyed steels like Super Cr13 steel are critical. This study analyses effect different at workpiece-tool interface in bars to minimize total consumption such a manufacturing process. For this purpose, three-dimensional finite element method (FEM) is employed simulate analyze variety...