Stochastic dynamic output feedback stabilization of uncertain stochastic state-delayed systems

This paper addresses the problem of stochastic dynamic output feedback (SDOF) stabilization for a class of stochastic continuous-time state-delayed systems with norm-bounded nonlinear uncertainties. The aim is to design a linear, delayless, and SDOF control for all admissible uncertainties. The designed control ensures stochastically exponentially stability in the mean square, independent of the deterministic time delay. Using the Finsler's lemma, the necessary and sufficient conditions for the existence of such a control are proposed in terms of certain linear matrix inequalities. These results are illustrated with a simple example to demonstrate the applicability of the proposed design approach.     

Feature Extraction Method Based on Social Network Analysis

Due to rapid development of Internet technology and electronic business, fraudulent activities have increased. One of the ways to cope with damages of them is fraud detection. In this field, there is a need for methods accurate and fast. Therefore, a novel and efficient feature extraction method based on social network analysis called FEMBSNA is proposed for fraud detection in banking accounts. In this method, in order to increase accuracy and control runtime in the first step, features based on network level are considered using social network analysis and extracted feature is combined with other features based on user level in the next phase. To evaluate our feature extraction method, we use PCK-means method as a basic method to learn. The results show using the proposed feature extraction as a pre-processing step in fraud detection improves the accuracy remarkably while it controls runtime in comparison with other methods.     

Enhancing the fluidization quality of nanoparticles using external fields

Fluidization quality of beds containing alumina and iron oxide nanoparticles in the Agglomerate Bubbling Fluidization (ABF) was improved by applying a combination of vibration and magnetic field. Pressure fluctuations were measured and analyzed by Fast Fourier Transform (FFT), Recurrence Plot (RP) and Recurrence Quantitative Analysis (RQA). Results of FFT showed that the wall vibration creates a periodic signal at 100?Hz which is not originated from the bed hydrodynamics. RP of pressure fluctuations before and after applying the assisting forces showed that the white areas in the plot decrease in size, which indicates an increase in the contribution of meso-structures such as agglomerates and small bubbles. The transition in the equilibrium bed hydrodynamics, between the condition in which assisting forces are not applied and condition in which they are applied, was tracked. It was shown by the determinism of pressure fluctuations that when the iron oxide nanoparticles exist alongside with alumina nanoparticles, this transition to the new equilibrium condition was reached in a shorter time. Determinism of pressure fluctuation of beds containing iron oxide decreased after applying the assisting forces. This trend confirms that large bubbles start to disappear and become substituted by smaller structures when magnetic field is applied to the bed. Under this condition, the interphase contact efficiency increases and the bed becomes closer to the Agglomerate Particle Fluidization (APF) regime.     

Nigella arvensis leaf extract mediated green synthesis of silver nanoparticles: Their characteristic properties and biological efficacy

In the present study, the potential of aqueous leaf extract of Nigella arevensis for biosynthesis of silver nanoparticles (AgNPs) was evaluated. The formation of AgNPs was confirmed by color changes and UV–visible spectroscopy, which showed absorbance maxima peak at 416?nm. The transmission electron microscope (TEM) image showed the AgNPs to be anisotropic and mostly spherical with sizes in the range of 5–100?nm. Fourier transform infrared (FTIR) analysis indicated that the flavonoids, alkaloids and phenolic groups present in leaf extract were involved in the reduction and capping of phytogenic AgNPs. These nanoparticles showed the cytotoxic effects against H1229 and MCF-7 cancer cell lines with an IC₅₀ value of 10?μg/mL. AgNPs showed insignificant antioxidant properties compared to the crude extract, and it was effective against clinical isolated bacterial strains. Furthermore, the bioderived AgNPs displayed significant catalytic activity against methylene blue. These results confirmed the advantages and applications of these phytogenic AgNPs using the green method in various fields.     

Further criterion for stochastic stability analysis of semi‐Markovian jump linear systems

This article is devoted to provide further criterion for stochastic stability analysis of semi‐Markovian jump linear systems (S‐MJLSs), in which more generic transition rates (TRs) will be studied. As is known, the time‐varying TR is one of the key issues to be considered in the analysis of S‐MJLS. Therefore, this article is to investigate general cases for the TRs that covered almost all types, especially for the type that the jumping information from one mode to another is fully unknown, which is merely investigated before. By virtue of stochastic functional theory, sufficient conditions are developed to check stochastic stability of the underlying systems via linear matrix inequalities formulation combined with a maximum optimization algorithm. Finally, a numerical example is given to verify the validity and effectiveness of the obtained results.     

Robust image watermarking scheme using bit-plane of hadamard coefficients

Multimedia Tools and Applications - Nowadays, due to widespread usage of the Internet, digital contents are distributed quickly and inexpensively throughout the world. Watermarking techniques can...     

A Variable Current-Limit Control Scheme for a Bi-directional Converter used in Ultracapacitor Applications

In ultracapacitor applications, generally, a bi-directional converter is connected to a DC bus and is designed to compensate rapid load variations on the bus. During transient phases, overloaded DC bus can push the converter out of its operating limits. For providing the necessary power, converters should be put in parallel, while each converter is limited into its optimal operating range. In a boost converter, this operating limit can be related to the inductor current and UC voltage. In this study, a variable current-limit is proposed for inductor current which then determines the operating range of the boost converter. This method will provide stability of the converter during overload transients. An experimental setup consisting of a bi-directional converter, a controllable load/source, and an ultracapacitor is presented, to validate the proposed method. Several scenarii are applied to analyze the performance of the system in overloaded phases and theoretical and experimental results are presented.     

The synergistic cooperation between MCM-41 and azithromycin: a pH responsive system for drug adsorption and release

The capability of MCM-41 silica for accepting and delivering poorly soluble azithromycin (AZT) in water is reported as robust drug delivery system. This property has been evidenced by using two MCM-41 samples with different pore sizes as hosts of AZT. The choice of this macrolide antibiotic is due not only to its low bioavailability but also to its molecular size which lies in the range of pore diameter of MCM-41s. The drug was loaded inside the pore voids of the mesoporous when MCM-41 was stirred at AZT solution, based on XRD, Nitrogen adsorption–desorption isotherms, TGA analysis data and FT-IR spectroscopy. The amount of AZT stored inside the pores of MCM-41 s was between 22 and 25 wt%. The loaded drug was released in different rates from the particles by changing the pH (1.7 and 7.4) to give a smart pH-responsive carrier system. The drug release kinetics was fitted to Korsmeyer–Peppas and Higuchi models which indicated that the rate of drug release was controlled by the diffusion of the drug. The result of the present study confirms that the controlled adsorption and liberation of AZT may improve the oral bioavailability of poor water soluble AZT. This study demonstrates the feasibility of designing reliable drug delivery systems by appropriate choice of the matrix and the organic molecule. In general, MCM-41 is a promising matrix for AZT adsorption with different application from drug delivery to wastewater filtration.     

Defocus estimation from stroboscopic cryo-electron microscopy data

Defocus estimation is an important step for improving the resolution of single particle reconstructions. It can be troublesome to estimate the defocus from low-dose cryo-electron microscopy (cryo-EM) data, particularly if there is not sufficient contrast present in the Fourier transform of the micrograph. Most existing approaches estimate the defocus from the presence of Thon rings within the power spectrum, employing image enhancement techniques to highlight these rings. In this paper, an approach to estimating the defocus from a stroboscopic image series is described. The image series is used to obtain two statistical metrics: figure of merit (FOM) and Q-factor. These metrics have been used to estimate the defoci from low-dose stroboscopic cryo-EM data consisting of a variable number of images.     

Characterization of triple electrospun layers of PVDF for direct contact membrane distillation process

Recently, electrospinning technique was applied successfully to fabricate porous hydrophobic membranes for MD applications. In this work, a novel triple layer configuration with diameter gradient for PVDF nanofiber membranes is proposed, with the objective of to minimize mass transfer resistance and heat loss. In outer layers of these membranes, the minimum concentration of PVDF (20 wt%) was used to produce bead-free nanofibers with thinner diameters and middle layers were composed of thicker nanofibers formed at higher polymer concentrations (21.5-26 wt%). Characterization of prepared membranes was conducted by the measurement of porosity, thickness, liquid entry pressure (LEP), scanning electron microscopy (SEM), contact angle, thermal and mechanical properties. Direct contact membrane distillation performance of fabricated membranes was tested using 42 g/L NaCl as feed solution. Water permeate flux of triple layer membranes (27.8-31.5 kg/m² h) was found to be considerably higher than that obtained from single layer membrane (15.4 kg/m² h), indicating the proposed configuration can effectively improve evaporation efficiency.