Microstructure and properties of porous nanocomposite films: effects of composition and process parameters

Porous nanocomposite films based on polypropylene (PP) and titanium dioxide (TiO₂) nanoparticles were prepared by melt extrusion followed by uniaxial stretching. The effects of drawing temperature, extension rate, stretching ratio and composition of the base films on the final properties and microstructure of the stretched films were studied. Water vapor permeability (WVP) results showed a significant decrease in permeability of the films stretched at temperatures higher than 60 °C. Porosity, pore size and water vapor transmission rate in the porous nanocomposite films had a direct relation with nanoparticle content, extension rate and stretching ratio. Study of the morphology of the stretched films, using SEM, revealed that the pores form due to PP/TiO₂ interfacial debonding at low stretching ratios. Higher stretching ratios cause an enlargement of the pores and the formation of a PP fibril structure parallel to the stretching direction. Quantification of dye adsorption revealed that the quantity of adsorbed dye increased with porosity and surface area of the pores. © 2014 Society of Chemical Industry     

Stabilization of Discrete-Time Nonlinear Switching Systems

This paper presents sufficient conditions for the stabilization of saturated switching nonlinear discrete- time systems. The type of nonlinearity is the so-called Lur’e type. Less conservative stability regions are obtained. This fact is shown upon a numerical example.     

Fault‐tolerant saturated control for switching discrete‐time systems with delays

In this paper, fault‐tolerant control problem for discrete‐time switching systems with delay and saturated input is studied. Sufficient conditions of building an observer are obtained by using multiple Lyapunov function. These conditions are worked out using cone complementarity technique, to obtain LMIs with slack variables and multiple weighted residual matrices. The obtained results are applied on a numerical example showing fault detection, localization of fault, and reconfiguration of the control to maintain asymptotic stability even in the presence of a permanent sensor fault and saturation on the control. Copyright © 2014 John Wiley & Sons, Ltd.     

Morphology and antibacterial properties of plasticized chitosan/metallocene polyethylene blends

In this work, plasticized chitosan-based materials were produced through a molten process. A thermo-mechanical treatment was used to achieve chitosan plasticization in the presence of water, acetic acid, and glycerol. Water and glycerol acted as plasticizers, while acetic acid was used as a solvent and plasticizer for chitosan. The influence of acetic acid total content, chitosan/acetic acid solution ratio, and chitosan/glycerol ratio were examined in this study. The various plasticized compounds were blended with a metallocene polyethylene (mPE) and the morphology, rheological, and antibacterial properties of this novel blend system were examined. It was found that an increase in acetic acid content allowed better chitosan dissolution, while a higher glycerol concentration resulted in improved dispersion of the plasticized chitosan phase in the mPE. Following thermo-mechanical treatment, blends presented good antibacterial properties with a reduction of the number of bacteria (non-pathogenic Escherichia coli) by 2 log(CFU/mL) for the chitosan-containing systems with respect to neat mPE. Mechanical properties of the mPE/plasticized chitosan blends were improved by compatibilization with ethylene vinyl acetate, while antibacterial properties were not affected.     

H ∞ Filtering of Two-Dimensional T-S Fuzzy Systems

The H _∞ filtering problem for two-dimensional Takagi–Sugeno fuzzy systems described by the Fornasini–Marchesini (FM) model is studied. Attention is focused on the design of an H _∞ fuzzy filter such that the filter error system is asymptotically stable and preserves a guaranteed H _∞ performance. By using basis-dependent Lyapunov functions and adding slack matrix variables, the coupling between the Lyapunov matrix and the system matrices is eliminated. Then, a linear matrix inequality (LMI)-based approach is developed for designing the H _∞ fuzzy filter. Finally, an illustrative example is provided to show the effectiveness of the proposed approach and less conservatism.     

A Lightweight Approach (BL-DAC) to Secure Storage Sharing in Cloud-IoT Environments

The growing advent of the Internet of Things (IoT) users is driving the adoption of cloud computing technologies. The integration of IoT in the cloud enables storage and computational capabilities for IoT users. However, security has been one of the main concerns of cloud-integrated IoT. Existing work attempts to address the security concerns of cloud-integrated IoT through authentication, access control, and blockchain-based methods. However, existing frameworks are somewhat limited by scalability, privacy, and centralized structures. To mitigate the existing problems, we propose a blockchain-based distributed access control method for secure storage in the IoT cloud (BL-DAC). Initially, the BL-DAC performs decentralized authentication using the Quantum Neural Network Cryptography (QNNC) algorithm. IoT users and edge nodes are authenticated in the blockchain deployed by distributed Trusted Authorities (TAs) using multiple credentials. The user data is classified into sensitive and non-sensitive categories using the Enhanced Seagull Optimization (ESO) algorithm. Also, the authentication to access this data is performed by a decentralized access control method using smart contract policy. Sensitive user data is encrypted using the QNNC algorithm and stored in the private cloud. In contrast, non-sensitive data is stored in the public cloud, and IPFS is used to store data in a decentralized manner with high reliability. In addition, data security is improved by using a hierarchical blockchain which improves scalability by managing the multiple blockchains hierarchically and is lightweight using Proof of Authentication Consensus (PoAH). The BL-DAC is simulated and validated using the Network Simulator-3.26 simulation tool and validated. This work shows better results than the compared ones in terms of validation metrics such as throughput (26%), encryption time (19%), decryption time (16%), response time (15%), block validation time (31%), attack detection rate (16%), access control precision (13%), and scalability (28%).     

ECG signal filtering based on CEEMDAN with hybrid interval thresholding and higher order statistics to select relevant modes

Multimedia Tools and Applications - In this paper, we propose a novel ECG signal enhancement method based on Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) and Higher...     

Ambient‐Dried, 3D‐Printable and Electrically Conducting Cellulose Nanofiber Aerogels by Inclusion of Functional Polymers

This study presents a novel, green, and efficient way of preparing crosslinked aerogels from cellulose nanofibers (CNFs) and alginate using non‐covalent chemistry. This new process can ultimately facilitate the fast, continuous, and large‐scale production of porous, light‐weight materials as it does not require freeze‐drying, supercritical CO₂ drying, or any environmentally harmful crosslinking chemistries. The reported preparation procedure relies solely on the successive freezing, solvent‐exchange, and ambient drying of composite CNF‐alginate gels. The presented findings suggest that a highly‐porous structure can be preserved throughout the process by simply controlling the ionic strength of the gel. Aerogels with tunable densities (23–38 kg m^?3) and compressive moduli (97–275 kPa) can be prepared by using different CNF concentrations. These low‐density networks have a unique combination of formability (using molding or 3D‐printing) and wet‐stability (when ion exchanged to calcium ions). To demonstrate their use in advanced wet applications, the printed aerogels are functionalized with very high loadings of conducting poly(3,4‐ethylenedioxythiophene):tosylate (PEDOT:TOS) polymer by using a novel in situ polymerization approach. In‐depth material characterization reveals that these aerogels have the potential to be used in not only energy storage applications (specific capacitance of 78 F g^?1), but also as mechanical‐strain and humidity sensors.     

Analytical 2D modeling for potential distribution and threshold voltage of the short channel fully depleted cylindrical/surrounding gate MOSFET

A two-dimensional analytical model for fully depleted cylindrical/surrounding gate MOSFET is presented. We used the evanescent mode analysis to solve the 2D Poisson's equation and to deduce analytically the surface potential and threshold voltage expressions of this device. Comparison with the other models reveals a good agreement.