Nonwoven viscose fabric-polyvinyl alcohol based flexible composite

Development of ecofriendly packaging materials is still a challenging area. Researchers are continuously working to improve the mechanical and barrier properties of the different polymers which are used in the packaging industry. Selection of reinforcement and matrix for any composite are based upon end use applications. The novelty of the work is development of fully biodegradable, flexible, lightweight biocomposite by reinforcing needle punched flexible nonwoven viscose fabric to the PVA solution. The effect of PVA concentration and areal density of viscose fabric on the properties of prepared composite is examined. The composite thus prepared is assessed in terms of mechanical, thermal, breathability, and UV blocking properties. The nonwoven viscose-PVA composite shows excellent improvement in tensile strength of 100% to 300% with respect to PVA film of equivalent concentration for two different areal densities of viscose fabric. The composite also exhibits improved thermal stability and UV blocking property with respect to parent components. However, a reduction in flexibility (with respect to PVA film) as well as breathability (with respect to viscose fabric) of the composite is observed. Based upon the improved performance of the viscose-PVA composite in terms of mechanical properties, UV and water vapor permeability, it seems that the composite has a strong potential for application in the packaging sector as a flexible as well as biodegradable composite.     

Efficient disparity estimation from stereo images using hybrid-guided image filter

Stereo vision process involves capturing the pictures from a camera of the same scene from at least two different locations and calculating the three-dimensional information. Conventionally, these two versions of snapshots are called left and right views which yield the depth information of an object upon relative comparison of its location in two views. Although the stereo image and its applications are becoming increasingly prevalent, there has been very limited research on disparity estimation from stereo images. Most of the existing techniques suffer from the gradient reversal artefacts issue. Therefore, to handle this issue, we have proposed a hybrid-guided image filter for improving the disparity estimation from stereo images. The hybrid filter utilizes the features of guided image filter and Bayesian non-local means with edge aware constraint. Maximum likelihood and local area homogeneity analysis are used to generate the guidance image for the proposed filter. To enhance the quality of disparity estimation from stereo images, segmentation is also done using the modified mean shift technique. Experimental results show that the proposed technique can efficiently estimate the depth maps over the available techniques. One-way ANOVA analysis on experimental results validates that the hybrid filter-based stereo matching outperforms consistently over the state-of-art approaches.     

Properties of Ferroelectric Liquid Crystal/Multiwall Carbon Nanotube Doped Composite

Carbon nanotubes-ferroelectric liquid crystal composites have been prepared and studied. Doping of carbon nanotubes into ferroelectric liquid crystal in varying concentration has been investigated in thin cells in the frequency range of 50 Hz–1 MHz. Decrease in the dielectric permittivity and dielectric strength is found with the doping of carbon nanotubes, however ～32% increase in the relaxation frequency has been observed in higher concentration carbon nanotubes doped ferroelectric liquid crystal composite than pure ferroelectric liquid crystal sample. A decrease in conductivity has also been noticed after doping.     

Characterization of flexural and compressive behavior in polylactic acid composites for low-cost transtibial prosthetic applications: Influence of reinforcements

Loss of a lower limb leads to immobility, necessitating the use of prosthetic foot and socket as substitutes for lost limbs. However, the production of these prosthetic devices poses challenges due to the wide array of printing settings, materials, and post-processing techniques involved. The objectives of this study were to examine the compression and flexural behavior of polylactic acid reinforced with carbon fiber fabricated via fused filament fabrication (FFF) and to investigate the effects of process constraints, namely nozzle hole diameter (0.20, 0.40, and 0.60 mm) and internal filling pattern (rectilinear, honeycomb, and triangle). The study employed compression and flexural tests, along with the analysis of failure morphology, on build samples. The resulting data were analyzed using Taguchi ANOVA and response surface methodology (RSM) to determine how compression and flexural behavior vary with the specified process constraints. The research findings demonstrate that the prosthetic socket and foot prosthesis created using FFF exhibit superior flexural and compressive behavior and strength, respectively. These results signify the potential for cost reduction in the production of prosthetic devices. The significance of these results lies in the improvement of prosthetic device production, enabling enhanced mobility and independence for amputees.     

MGR Hash Functions

Abstract

GOST-R 34.11-94 is a Russian standard cryptographic hash function that was introduced in 1994 by the Russian Federal Agency for the purposes of information processing, information security, and digital signature. Mendel et al. (2008 Mendel, F., N. Pramstaller, C. Rechberger, M. Kontak, and J. Szmidt. 2008. Cryptanalysis of the GOST hash function, Advances in Cryptology – CRYPTO 2008, vol. 5157, 162–178. [Google Scholar]) and Courtois and Mourouzis (2011 Courtois, N., and T. Mourouzis. 2011. Black-box collision attacks on the compression function of the GOST hash function. SECRYPT. Proceedings of the International Conference on Security and Cryptography, 325–332, IEEE. [Google Scholar]) found attacks on the compression function of the GOST-R structure that were basically weaknesses of the GOST-R block cipher (GOST 28147–89, 1989 GOST 28147-89. 1989. Systems of the information treatment, cryptographic security, algorithms of the cryptographic transformation (in Russian). [Google Scholar]). Hence in 2012, it was updated to GOST-R 34.11-2012, which replaced the older one for all its applications from January 2013. GOST-R 34.11-2012 is based on a modified Merkle-Damgård construction. Here we present a modified version of GOST-R 34.11-2012 (Modified GOST-R (MGR) hash). The design of the MGR hash is based on wide-pipe construction, which is also a modified Merkle-Damgård construction. MGR is much more secure as well as three times faster than GOST-R 34.11-2012. Advanced Encryption Standard (AES)-like block ciphers have been used in designing the compression function of MGR because AES is one of the most efficient and secure block ciphers and has been evaluated for more than 14?years. A detailed statistical analysis with a few other attacks on MGR is incorporated into this paper.     

Lead‐Free Double Perovskite Cs2SnX6: Facile Solution Synthesis and Excellent Stability

Long‐term instability and possible lead contamination are the two main issues limiting the widespread application of organic–inorganic lead halide perovskites. Here a facile and efficient solution‐phase method is demonstrated to synthesize lead‐free Cs₂SnX₆ (X = Br, I) with a well‐defined crystal structure, long‐term stability, and high yield. Based on the systematic experimental data and first‐principle simulation results, Cs₂SnX₆ displays excellent stability against moisture, light, and high temperature, which can be ascribed to the unique vacancy‐ordered defect‐variant structure, stable chemical compositions with Sn⁴⁺, as well as the lower formation enthalpy for Cs₂SnX₆. Additionally, photodetectors based on Cs₂SnI₆ are also fabricated, which show excellent performance and stability. This study provides very useful insights into the development of lead‐free double perovskites with high stability.     

Spectrum sensing based on two state discrete time Markov chain in additive Laplacian noise

Wireless Networks - In this paper, spectrum sensing for primary user (PU) is considered in additive Laplacian noise. Further, we consider dynamic behaviour of PU, where the transitions of PU in...     

Rietveld refinement,Raman, optical,dielectric, Mössbauer and magnetic characterization of superparamagnetic fcc-CaFe2O4 nanoparticles

This article describes synthesis of superparamagnetic fcc-CaFe₂O₄ nanoparticles by a metal nitrate-citrate monohydrate sol–gel route and characterization using X-ray diffractometry, Raman spectroscopic, UV–Vis–NIR optical absorption spectroscopic, Mössbauer spectroscopy, dielectric and SQUID magnetometry measurements. Rietveld refinement of the X-ray diffraction pattern and observation of active A_1?g, T_2?g & E_g modes in the Raman spectrum confirmed formation of single phase CaFe₂O₄ nanoparticles in the spinel ferrite type fcc structure without impurity. Mössbauer and Rietveld data analysis revealed that nanocrystalline CaFe₂O₄ is dominantly an inverse ferrite in which 85% Ca atoms preferentially occupy the octahedral site in the fcc symmetry and the Fe ions are in high spin Fe⁺³ state. Nanocrystalline CaFe₂O₄ significantly absorbs optical light below 500?nm and the direct band gap energy is estimated to ~1.83?eV, which is higher than 1.26?eV reported for orthorhombic CaFe₂O₄. Temperature and field dependent magnetic studies showed that fcc-CaFe₂O₄ nanoparticles exhibit superparamagnetism at room temperature with high saturation magnetization of 1.07μ_B. The blocking temperature is ~53?K at 1000?Oe and ~72?K at 500?Oe clearly shows lowering of blocking temperature at higher magnetic field. Interestingly below the blocking temperature at 20?K, CaFe₂O₄ nanoparticles behave as non collinear soft-ferrimagnetic material with a saturation magnetization of 1.16 μ_B, coercivity of 150?Oe and remanence of 4.45?emu/g. The magnetic momenta of Fe⁺³ ions residing at the octahedral sub-lattice are canted at ~25?°.     

Stress Alleviation and Crop Improvement Using Silicon Nanoparticles in Agriculture: a Review

Silicon - Silicon (Si) is not considered as essential element for plant growth and development but it provides benefits to the plants in several ways. Due to distinguishing physiological features,...     

Dielectric and polarization switching studies in nickel nanoparticles dispersed ferroelectric liquid crystal mixtures

ABSTRACT

We have investigated the effect of nickel nanoparticles (NiNPs) in a pure ferroelectric liquid crystal (FLC) mixture. Dielectric spectroscopy was done in the frequency range of 20 Hz–10 MHz. Switching time, spontaneous polarisation, rotational viscosity has been measured using field reversal technique in SmC^* phase. The spontaneous polarisation increases for NiNPs-FLC sample which may be due to the induced dipole moments around FLC molecules. Response time decreases with temperature and NiNPs dispersion. The relaxation frequency and dielectric strength of observed mode in SmC^* phase is also discussed in pure FLC and NiNPs-FLC samples. The relaxation frequency in NiNPs-FLC sample decreases than pure FLC sample and found ～120 Hz.