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Simultaneous effects of thickness and texture on the anisotropy of mechanical properties and fracture behaviors of commercially pure titanium thin sheets were studied. The activation of different deformation systems, due to the split distribution of basal texture, led to mechanical properties anisotropy. The crack initiation and propagation energies, when the loading direction was parallel to the initial rolling direction, decreased with increasing thickness ranges from 0.25 to 1 mm. The changes of size, shape and distribution of dimples with increasing thickness confirmed the restriction of deformation systems and the development of triaxial stress state and plane-strain condition at the... 

Effects of microstructure and texture, before and after phase transformation, on the anisotropy of the mechanical properties and fracture behaviors of commercially pure titanium were studied. Before phase transformation, due to the split distribution of basal texture the activation of different deformation systems led to mechanical properties anisotropy. Although the fracture mechanism in both specimens was voids nucleation, growth and coalescence, the shape, size and distribution of dimples were affected by active deformation systems. However, after phase transformation, basal plains in most grains were aligned with the transverse direction. This texture component led to the activation and... 

Simultaneous effects of notch and texture on strengthening mechanisms of rolled thin sheets of commercially pure titanium were investigated. The presence of notch led to the restriction of deformation systems and different fracture behaviors compared to un-notched specimens. The loss of material's ability to accommodate plastic deformation at the notch tip with increase in rolling reductions changed the notch strengthening phenomenon to the notch weakening one. At medium levels of deformation, due to the simultaneous development of a triaxial stress state and strong basal texture at the notch tip, a new strengthening mechanism which is called "notch-texture strengthening mechanism" led to a... 

In the present work tensile and tear properties of commercially pure titanium with different rolling reductions and specimens directions were investigated. The experimental results showed that in low levels of deformation the microstructure refining and mechanical twins have fewer significant effects on the anisotropic behavior of both tear and tensile properties and the crystallographic texture controls the mechanical properties anisotropy. The increase in rolling reduction up to 50% led to the formation of strong-basal texture and resulted in the activation of almost same deformation systems and isotropic mechanical response. However, at high levels of deformation, due to the split... 

-In this paper, a new optimized structure for two-speed, capacitor-run, single-phase axial flux induction motor (AFIM) for direct-drive operation is presented. Although, there are many advantages for direct-drive systems, their axial forces between the stator and rotor increases with reduction in air-gap length and is of serious concern. An increase in the air-gap length will result in the deterioration of performance characteristics of the motor. In this paper, a new construction technique is proposed to fabricate an AFIM with adjustable air-gap length. After presenting a comprehensive design algorithm, all geometrical dimensions and electrical equivalent circuit parameters are analytically... 

Surfaces of cast 1100 aluminum were treated by multi-pass friction stir processing (MP-FSP), which is a solid-state microstructural modification technique using frictional heat and stirring action. An improvement in the mechanical properties was accomplished due to the microstructural modification and reduction of porosities. The yield strengths of the MP-FSPed specimens were significantly increased to about 1.4 times versus that of the base metal. The elongation of MP-FSP sample is about 30% higher than that of the base metal. Also the ultimate tensile strength and hardness of MP-FSPed specimens are improved. Moreover the effect of tool rotation rate and tool travel speed on the mechanical... 

Recently, V. Sorokine et al. (see IEEE Trans. Commun., vol.48, no.10, p.1660-8, 2000; vol.48, no.11, p.1818-28, 2000) have introduced a class of low-density parity-check (LDPC) codes which, when applied on an IS-95 CDMA system, show, at BER=10-3, a five-fold and two-fold increase in capacity compared to the traditional uncoded scheme and to state-of-the-art low-rate orthogonal convolutional codes, respectively. However, these codes suffer from an error-floor at lower BERs which are needed for high-quality services, such as data. To enhance the capacity of CDMA systems, not only for moderate BER values but also for lower BER values, we modify the construction of these codes slightly, to... 

In this work, a novel method is proposed to study the BIBO stability of a fractional delay system. The characteristic equation of a fractional delay system with some transcendental terms has infinitely many roots. Applying D-subdivision method and the Rekasius substitution divide one-dimensional parametric space of the time delay to infinite intervals with finite unstable roots. The number of unstable roots in each interval is calculated with the definition of root tendency on the boundary of each interval. Two illustrative examples are presented to confirm the proposed method results  

Several unicast and multicast routing protocols have been presented for MPSoCs. Multicast protocols in NoCs are used for cache coherency in distributed shared memory systems, replication, barrier synchronization, or clock synchronization. Unicast routing algorithms are not suitable for multicast, as they increase traffic, congestion and deadlock probability. Famous multicast schemes such as tree-based and path-based schemes have been proposed originally for multicomputers and recently adapted to NoCs. In this paper, we propose a switch tree-based multicast scheme, called STBA. This method supports tree construction with a minimum number of routers. Our evaluation results reveal that, for... 

Resolver is an electromagnetic position sensor typically used in the closed-loop control of permanent magnet synchronous motors (PMSMs). In terms of structure and principle of operation, resolvers are very similar to electrical machines. In this regard, different numerical and analytical models have been developed for the performance prediction of a resolver, with a compromise between computational burden and accuracy. Therefore, a fast and accurate hybrid model of the resolver is presented in this article, which can be used for resolvers with different structures. Additionally, this model can easily be implemented in software such as MATLAB/SIMULINK. The performance of different variable... 

This article focused on the longitudinal end effect (LEE) in linear variable reluctance (VR) resolvers. The LEE can significantly decrease the accuracy of the linear sensor. Therefore, a novel method based on a magnetic equivalent circuit (MEC) model is proposed for accurate modeling of this phenomenon and used in an optimization routine to suppress that. The LEE is modeled by adding three extra permeances into the conventional MEC model without increasing the complexity and simulation time. Besides, the method of calculating these permeances is described. After that, some techniques are presented to decrease the computational burden of the MEC model. Then, the model is used to compensate... 

This paper has been prepared, based on reports regarding extraordinary induced ac voltage on buried gas pipelines in residential and industrial areas of the capital city of Tehran, especially in densely populated central areas. Also, some reports are considered on the existence of ac induced voltage in buried gas pipelines under the overhead transmission lines, for example, one case located 80 Km to the west of Tehran, in an agricultural region of the town of Abyek. In this paper, the results of an extensive theoretical, experimental and practical investigation and implementation of methods carried out during the last two years are introduced. Furthermore, this paper includes evaluation of... 

Achieving dense off-chip interconnection with satisfactory electrical performance is emerging as a major challenge in advanced system engineering. Graphene nanoribbons (GNRs) have been recently proposed as one of the potential candidate materials for both transistors and interconnect. In addition, development is still underway for alternative materials and processes for high aspect ratio (AR) contacts. Studding the effect of varying aspect ratio on relative stability of graphene nanoribbon interconnects is an important viewpoint in performance evaluation of system. In this paper, Nyquist stability analysis based on transmission line modeling (TLM) for GNR interconnects is investigated. In... 

The remarkable properties of graphene nanoribbons (GNRs) make them attractive for nano-scale devices applications, especially for transistor and interconnect. Furthermore, for reduction interconnects signal delay, low dielectric constant materials are being introduced to replace conventional dielectrics in next generation IC technologies. With these regards, studding the effect of varying dielectric constant (e{open}r) on relative stability of graphene nanoribbons interconnect is an important viewpoint in performance evaluation of system. In this paper, Nyquist stability analysis based on transmission line modeling (TLM) for graphene nanoribbon interconnects is investigated. In this... 

In this work, studies of underground gas storage (UGS) were performed on a partially depleted, naturally fractured gas reservoir through compositional simulation. Reservoir dynamic model was calibrated by history matching of about 20 years of researvoir production. Effects of fracture parameters, i.e. fracture shape factor, fracture permeability and porosity were studied. Results showed that distribution of fracture density affects flow and production of water, but not that of gas, through porous medium. However, due to high mobility of gas, the gas production and reservoir average pressure are insensitive to fracture shape factor. Also, it was found that uniform fracture permeability... 

Linear position sensors are essential parts of linear motion control systems. Among different linear sensors, linear resolvers are an appropriate choice for harsh environments. Design optimization of linear resolvers needs an accurate, but computationally fast model for their performance prediction. Slotting effect of the cores and end effect are two important phenomena that must be accurately involved in the model to ensure its reliable results. Therefore, in this paper a semi-analytical model based on subdomain modeling technique is proposed for linear resolvers. Then, according to the developed model, the induced voltages in the signal windings of the resolver are calculated and... 

Linear resolvers are position sensors that are being used in a wide range of applications for linear motion systems. The electromagnetic design of a linear resolver, similar to any other electromagnetic device, demands an accurate, functional, and fast tool. While the finite element method (FEM) is considered the most accurate tool for electromagnetic analysis, it is not a good candidate for an optimization-based design which is an iterative process. In this article, first off, an analytical tool based on the subdomain model is briefly presented. This model is very accurate and much faster than FEM. However, it has high computational time for iterative design and optimization processes.... 

Multi-speed resolvers are used in the applications that need higher accuracy. However, they suffer from losing absolute position information. To overcome this challenge and improve the reliability of detecting position, using multi-turn resolvers is recommended. The conventional configuration of multi-turn resolver is using two individual resolvers on one shaft and into a common frame. Using such configuration needs special care on setting the distance between two resolvers. In this paper a new structure based on dual side configuration is proposed. The performance of the double sided resolver is analyzed and optimized using an analytical model based on magnetic equivalent circuit (MEC).... 

In this letter, we examine the positioning in wireless networks in the presence of IRSs. We show that IRSs can be used to localize the user when there are not enough transmitters (Base Station). To this end, we consider a network of one transmitter, few IRSs, and one receiver, whose location should be determined. Our results indicate that we can achieve the accuracy required in the localization by controlling the number of elements of IRSs and properly selecting the location of IRSs for a given region. © 2012 IEEE