Microstructural Evolution During the Hot Deformation of Ti-55Ni (at. pct) Intermetallic Alloy

The hot deformation behavior of Ti-55Ni (at. pct) alloy was studied using compression testing at 1173 K (900 °C) to 1323 K (1050 °C) and at the strain rates of 0.001 to 0.35 s⁻¹. The microstructure evolution was characterized using optical and scanning electron microscopy (SEM). The influences of hot-working parameters on the flow stress and microstructural features of this alloy were then analyzed. The results indicate that, depending on the temperature and strain rate, the dynamic recrystallization (DRX) is the dominate mechanism. Besides, the particle-stimulated nucleation (PSN) mechanism could partially recrystallize the structure. The PSN phenomenon is of significant importance for the Ti-55Ni (at. pct) that suffers from insufficient workability because of its high content of intermetallic phases. It is of interest that the discontinuous yielding phenomenon has been observed when the specimens were deformed at 1173 K (900 °C). Finally, the optimum parameters for hot working of Ti-55Ni (at. pct) alloy are determined as well.     

Magnetic Moment of a Flat Type-II Superconducting Tape Carrying a Current

I have used the critical state model for investigating the magnetic moment of a flat type-II superconducting strip which carries a current such that the magnetic flux density B generated by this current depends solely on the coordinate along the width of the tape. To do so, I have also calculated the magnetic flux distribution in the film. The calculations clearly show that the magnetic moment of the material exposed to this current is increased as the thickness of the sample is decreased; a behavior similar to the thickness dependence of the critical current density.     

An Inverse Problem Method for Overall Heat Transfer Coefficient Estimation in a Partially Filled Rotating Cylinder

The objective of this article is to study the estimation of an overall heat transfer coefficient in a partially filled rotating cylinder. Herein is an inverse analysis for estimating the overall heat transfer coefficient in an arbitrary cross-section of the aforementioned system from the temperatures measured on the shell. The material employs the finite-volume method to solve the direct problem. The hybrid effective algorithm applied here contains the local optimization algorithm to estimate the unknown parameter by minimizing the objective function. The data measured here are simulated by adding random errors to the exact solution. An investigation is made of the impact of the measurement errors on the accuracy of the inverse analysis. Two-optimization algorithms in determining the overall heat transfer coefficient are used. It is determined that the Conjugate Gradient Method is better than the Levenberg-Marquardt Method because the former produces greater accuracy for the same measurement errors. The resulting observation indicates that good agreement exists between the exact value and estimated result for both algorithms.     

An exact solution for buckling of functionally graded circular plates based on higher order shear deformation plate theory under uniform radial compression

In this research, mechanical buckling of circular plates composed of functionally graded materials (FGMs) is considered. Equilibrium and stability equations of a FGM circular plate under uniform radial compression are derived, based on the higher order shear deformation plate theory (HSDT). Assuming that the material properties vary as a power form of the thickness coordinate variable z and using the variational method, the system of fundamental partial differential equations are established. A buckling analysis of a functionally graded circular plate (FGCP) under uniform radial compression is carried out and the results are given in closed-form solutions. The results are compared with the buckling loads of plates obtained for FGCP based on the first order shear deformation plate theory (FSDT) and classical plate theory (CPT) given in the literature. The study concludes that HSDT accurately predicts the behavior of FGCP, whereas the FSDT and CPT overestimates buckling loads.     

The Effect of Nanoparticles on the Mass Transfer in Liquid–Liquid Extraction

This article investigates the effect of nanoparticles on mass transfer in the liquid–liquid extraction for the chemical system of n-butanol–succinic acid–water. For this purpose, nanofluids containing various concentrations of ZnO, carbon nanotubes (CNT), and TiO₂ nanoparticles in water, as base fluid, were prepared. To examine the flow mode effect on mass transfer rate, different fluid modes including dropping and jetting were employed in the process. Results show that mass transfer rate enhancement depends on the kinds and the concentration of nanoparticles and the modes of flow. It was observed that after adding nanoparticles, the mass transfer rate significantly increases up to two-fold for ZnO nanoparticles. Furthermore, the results indicate that under the circumstances in which the mass flow rate is high enough, the effect of nanoparticles on the mass transfer phenomenon is too slight.     

Anisotropy in wrinkle properties of woven fabric

In this paper, the wrinkle resistance of plain fabrics woven with weft yarn in S‐ and Z‐twist directions and at various twist levels in different test directions has been measured and then analysed. Results show that the wrinkle resistance increases as the weft yarn twist increases. The wrinkle properties of the fabric show that the direction of test has an obvious effect on the results and the wrinkle resistance depends on the method of folding such as face‐to‐face and back‐to‐back methods. The experimental results showed that there is anisotropy in wrinkle properties of the fabric made of yarns with different twist directions. When the fabric is folded face‐to‐face and the weft twist direction is S, the wrinkle resistance of fabric in various test directions shows a convex curvature, whereas when the same fabric is folded in a back‐to‐back manner then results show a linear curvature. This means that the wrinkle resistance of a fabric differs in various directions and in the method of folding (back‐to‐back or face‐to‐face) and shows an anisotropic wrinkle resistance nature.     

Investigation of a flame holder geometry effect on flame structure in non-premixed combustion

In this paper the effect of flame holder geometry on flame structure is studied. The obtained numerical results using realizable k-? and β-PDF models show a good agreement with experimental data. The results show that increasing in flame holder length decreases flame length and increases flame temperature. Additionally, it is observed that flame lengths decrease by increasing in flame holder radius and increase for larger radii. Furthermore in various radii, the flame temperature is higher for smaller flame lengths. It was found that behavior of flame structure is mainly affected by the mass flow rate of hot gases that come near the reactant by the recirculation zone.     

Integrating IPsec within OpenFlow Architecture for Secure Group Communication

Network securityprotocolssuch as IPsechave been used for many years to ensure robust end-to-end communication and are impor-tant in the context of SDN.Despite the widespread installation of IPsec to date,per-packet protection offered by the protocol isnot very compatible with OpenFlow and flow-like behavior.OpenFlow architecture cannot aggregate IPsec-ESP flows in transportmode or tunnel mode because layer-3 information is encrypted and therefore unreadable.In this paper,we propose using the Secu-rity Parameter Index(SPI)of IPsec within the OpenFlow architecture to identify and direct IPsec flows.Thisenables IPsec to con-form to the packet-based behavior of OpenFlow architecture.In addition,by distinguishing between IPsec flows,the architectureis particularly suited to secure group communication.     

Assessment of pitting corrosion in bare and passivated (wet scCO2-induced patination and chemical passivation) hot-dip galvanized steel samples with SVET,FTIR, and SEM (EDS)

In this study, the local electrochemical activity of untreated and passivated (natural or chemical passivation) zinc specimens was observed during immersion in a 0.1-M NaCl solution. The localized anodic activity during the exposure, measured with the scanning vibrating electrode technique, was linked to zinc dissolution by the pitting corrosion mechanism. It was correlated to specific corrosion products characterized by Fourier transmission infrared (FTIR) microscopy. FTIR molecule maps were produced from individual pitting corrosion sites (100–200 µm in width). With argon ion beam milling and latest energy-dispersive X-ray spectroscopy (EDS) technology, element maps with a high spatial resolution (≪100 nm) were recorded from abrasion- and beam-sensitive corrosion products, showing a residual layer structure. This study demonstrates the capability of FTIR mapping, cross-section polishing, and state-of-the-art scanning electron microscopy imaging, and EDS element mapping to produce high-resolution elemental, molecular, and visual information about pitting corrosion mechanisms on a hot-dip galvanized steel sample.     

A novel numerical modeling paradigm for bio particle tracing in non-inertial microfluidics devices

Microsystem Technologies - In this work, we report on the design and implementation of a new method for the two dimensional (2D) simulation of rigid spherical particles trajectory which are to be...