Ratcheting Behavior of a Titanium-Stabilized Interstitial Free Steel

Engineering stress-control ratcheting behavior of a titanium-stabilized interstitial free steel has been studied under different combinations of mean stress and stress amplitude at a stress rate of 250 MPa s^?1. Tests have been done up to 29.80 pct true ratcheting strain evolution in the specimens at three maximum stress levels. It is observed that this amount of ratcheting strain is more than the uniform tensile strain at a strain rate of 10^?3 s^?1 and evolves without showing tensile instability of the specimens. In the process of ratcheting strain evolution at constant maximum stresses, the effect of increasing stress amplitude is found to be more than that of increasing the mean stress component. Further, the constant maximum stress ratcheting test results reveal that the number of cycles (N) required for 29.80 pct. true ratcheting strain evolution exponentially increases with increase of stress ratio (R). Post-ratcheting tensile test results showing increase of strength and linear decrease in ductility with increasing R at different constant maximum stresses indicate that stress parameters used during ratcheting tests influence the size of the dislocation cell structure of the steel even with the same amount of ratcheting strain evolution. It is postulated that during ratcheting fatigue, damage becomes greater with the increase of R for any fixed amount of ratcheting strain evolution at constant maximum stress.     

Texture Evolution During Cross Rolling and Annealing of High-Purity Nickel

Evolution of texture during cross rolling and subsequent annealing was studied in high-purity nickel. For this purpose nickel samples were subjected to multipass cross rolling up to 90 pct reduction in thickness followed by annealing at different temperatures ranging between 673 K and 1073 K (400 °C and 800 °C). Cross rolling was carried out by rotating the samples about the normal direction (ND) by 90 deg interchanging the rolling direction and transverse direction (TD) between each consecutive pass. The development of microstructure and texture was characterized using X-ray and electron backscattered diffraction (EBSD) techniques. The deformation texture was characterized by the presence of strong brass ({110}〈112〉) and ND-rotated brass ({011}〈21 $ \overline{13} $ 13〉)) orientations. Upon annealing at 673 K (400 °C), ND||[111] fiber could be observed in the microtexture which originated from the twin formation of the recrystallized TD-rotated cube ({027}〈0 $ \overline{7} $ 2〉) grains. The fiber was weakened after annealing at 1073 K (800 °C) because of the decreased propensity for twin formation, and the microtexture was found to be weak and diffused. EBSD studies on early recrystallization stages indicated the absence of preferential nucleation of cube grains being in agreement with a weak cube texture formation in annealed cross-rolled high-purity nickel.     

Proton microbeam irradiation effects on PtBA polymer

Proton beam lithography has made it possible to make various types of 3D-structures in polymers. Usually PMMA, SU-8, PS polymers have been used as resist materials for lithographic purpose. Microbeam irradiation effects on poly-tert-butyl-acrylate (PtBA) polymer using 20 MeV proton microbeam are reported. Preliminary results on pattern formation on PtBA are carried out as a function of fluence. After writing the pattern, a thin layer of Ge is deposited. Distribution of Ge in pristine and ion beam patterned surface of PtBA polymer is studied using the optical and secondary electron microscopic experimental methods.     

Electro-kinetically enhanced mass transport of charged macro-solutes through a microchannel with porous walls

Electrokinetics of the solute transport across the porous walls of micro channel is important from its practical application but less explored. Transport of the charged macro-solutes across perm-selective walls in a microchannel is investigated. The extended Nernst–Planck equation describes the charged macro-solutes distribution in the mass transfer boundary layer over the porous wall. The transverse electromigration of the charged macro-solute either augments or suppresses the concentration polarization and the permeation rate depending on the wall and solute surface potential (attractive or repelling). The wall potential is screened due to the electrical double layer interaction of the wall and charged solute. It is observed that the charged solute concentration over the channel wall enhances by two times in case of oppositely charged interactions (unlike solute and channel wall) compared to like charges. The findings of this study can facilitate understanding of electrokinetic based drug delivery and separation systems involving charged solutes.     

A novel Block Bi-diagonalization based pre-coding scheme for bit error reduction in mutiple input multiple output-orthogonal frequency division multiplexing

The MIMO-OFDM increases spectral efficiency without the use of channel state information (CSI). However, the bit error rate (BER) in the MIMO-OFDM model increases dramatically due to the increase in nonlinear distortion in the power amplifier (PA). In this research, a novel pre-coder integrated MIMO-OFDM technology is designed for effective BER reduction, and its performance is analyzed. The discrete wavelet-based OFDM system is one of the key ideas to present good orthogonal by emphasizing orthogonal wavelets. It helps to mitigate inter-symbol interference (ISI) and noise within the channel by extending the bandwidth (BW) compared to conventional OFDM systems. But, DWT-OFDM highly suffered due to downsampling, which degrades system efficiency. To overcome this, a redundant discrete wavelet transform (RDWT) is proposed in this article to enhance spectral efficiency. For modulation, 16-bit quadrature amplitude modulation (QAM) is introduced in this work. In addition to this, a block bi-diagonalization (BBD) pre-coder technique is proposed to mitigate unwanted noise and interference in the MIMO-OFDM system. The performance measures such as ergodic sum capacity, BER, throughput, average jitter noise power, mean square error (MSE), and power consumption are analyzed using the MATLAB platform. The proposed method obtains the ergodic sum capacity of 6.25 bps/Hz, a BER of 0.021, a throughput of 95.2%, MSE of −0.47, and a power consumption of 1.15 μW. The simulative results prove the efficacy of the proposed method.     

Annealing-Mediated Microduplex Structure and Texture Evolution in Severely Cold-Rolled Nanolamellar Pearlite: A Perspective on the Effect of Starting Inter-lamellar Spacing

Metallurgical and Materials Transactions A - The effect of inter-lamellar (IL) spacing on the microstructure and texture of severely cold-rolled and annealed pearlite was studied. For this purpose,...     

Cross-modal face recognition with illumination-invariant local discrete cosine transform binary pattern (LDCTBP)

Pattern Analysis and Applications - With the ever-increasing security threats in recent years, biometric authentication has become omnipresent. Among all biometric characteristics, face recognition...     

Emergence of a Non-Van der Waals Magnetic Phase in a Van der Waals Ferromagnet

Manipulation of long-range order in 2D van der Waals (vdW) magnetic materials (e.g., CrI₃, CrSiTe₃ ,etc.), exfoliated in few-atomic layer, can be achieved via application of electric field, mechanical-constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the exposure in the ambient condition and hydrolysis in the presence of water/moisture causes degradation in magnetic nanosheets that, in turn, affects the nanoelectronic /spintronic device performance. Counterintuitively, the current study reveals that exposure to the air at ambient atmosphere results in advent of a stable nonlayered secondary ferromagnetic phase in the form of Cr₂Te₃ (T_C2 ≈160 K) in the parent vdW magnetic semiconductor Cr₂Ge₂Te₆ (T_C1 ≈69 K). The coexistence of the two ferromagnetic phases in the time elapsed bulk crystal is confirmed through systematic investigation of crystal structure along with detailed dc/ac magnetic susceptibility, specific heat, and magneto-transport measurement. To capture the concurrence of the two ferromagnetic phases in a single material, Ginzburg-Landau theory with two independent order parameters (as magnetization) with a coupling term can be introduced. In contrast to the rather common poor environmental stability of the vdW magnets, the results open possibilities of finding air-stable novel materials having multiple magnetic phases.