Collaborative linear dynamical system identification by scarce relevant/irrelevant observations

Multidimensional Systems and Signal Processing - In the current paper, linear dynamical system identification by relevant and irrelevant multi-sensor observations is presented. In common system...     

Cryptanalysis and improvement of a robust smart card secured authentication scheme on SIP using elliptic curve cryptography

The session initiation protocol (SIP) has been receiving a lot of attention to provide security in the Voice over IP (VoIP) in Internet and mobility management. Recently, Yeh et al. proposed a smart card-based authentication scheme for SIP using elliptic curve cryptography (ECC). They claimed that their scheme is secure against known security attacks. However, in this paper, we indicate that Yeh et al.’s scheme is vulnerable to off-line password guessing attack, user impersonation attack and server impersonation attack, in the case that the smart card is stolen and the information stored in the smart card is disclosed. As a remedy, we also propose an improved smart card-based authentication scheme which not only conquers the security weaknesses of the related schemes but also provides a reduction in computational cost. The proposed scheme also provides the user anonymity and untraceability, and allows a user to change his/her password without informing the remote server. To show the security of our protocol, we prove its security the random oracle model.     

Extended adsorption transport models for permeation of copper ions through nanocomposite chitosan/polyvinyl alcohol thin affinity membranes

Transport of copper ions through nanocomposite chitosan/polyvinyl alcohol thin adsorptive membranes has been mathematical y investigated in the current study. Unsteady-state diffusive transport model was coupled with the Freundlich isotherm to predict the concentration of the ions in dialysis permeation operation. Pristine model was not successful in predicting the experimental data based upon its low coefficients of determination (0.1﹤R2﹤0.65). Well-behaved polynomial and exponential functions were used to describe time-dependency of the inlet-concentration in the first extension of the model with a little improvement in the model adjustment (0.4﹤R2﹤0.69). Similar time-dependent functions were employed for tracking the ion diffusivity and then applied in combination with the optimized functions of inlet-concentration in the second extension of the model. A sensible enhancement was obtained in the adjustment of the second extended models as a result of this combination (0.73﹤R2﹤0.93). APRE, AAPRE, RSME, RMSE, STD and R-square statistical analyses were per-formed to verify the agreement of the models with the experimental results. Concentration distribution versus time and location (inside the membrane) was obtained as 3D plots with the help of the optimized models. Modeling results emphasized on the transiency of diffusivity and feed-side concentration in dialysis permeation through chitosan membranes.     

Development and application of vanadium oxide/polyaniline composite as a novel cathode catalyst in microbial fuel cell

Polyaniline (Pani), vanadium oxide (V₂O₅), and Pani/V₂O₅ nanocomposite were fabricated and applied as a cathode catalyst in Microbial Fuel Cell (MFC) as an alternative to Pt (Platinum), which is a commonly used expensive cathode catalyst. The cathode catalysts were characterized using Cyclic Voltammetry and Linear Sweep Voltammetry to determine their oxygen reduction activity; furthermore, their structures were observed by X‐ray Diffraction, X‐ray Photoelectron Spectroscopy, Brunauer–Emmett–Teller, and Field‐Emission Scanning Electron Microscopy. The results showed that Pani/V₂O₅ produced a power density of 79.26 mW/m², which is higher than V₂O₅ by 65.31 mW/m² and Pani by 42.4 mW/m². Furthermore, the Coulombic Efficiency of the system using Pani/V₂O₅ (16%) was higher than V₂O₅ and Pani by 9.2 and 5.5%, respectively. Pani–V₂O₅ also produced approximately 10% more power than Pt, the best and most common cathode catalyst. It declares that Pani–V₂O₅ can be a suitable alternative for application in a MFC system. Copyright © 2013 John Wiley & Sons, Ltd.     

Long‐term impacts from damming and water level manipulation on flow and salinity regimes in Lake Urmia,Iran

Lake Urmia in the north‐west of Iran is very large, very shallow and several times more saline than ocean water. The salinity of this terminal lake is of great ecological consequence for the existence and growth of Artemia Urmiana, a unique zooplankton endemic to the lake. It is a main food source for large bird populations. During the past decades, Lake Urmia has been strained by a number of anthropogenic and natural causes. They include extensive damming on the contributory rivers, building a dike‐type causeway and climate change. This paper deals with the long‐term impacts of damming, fresh water overexploitation and water level manipulation on flow and salinity conditions in Lake Urmia. For this purpose, the flow and salinity regimes were numerically simulated for the next four decades. The validity of the pseudo‐three‐dimensional hydrodynamic and advection‐dispersion models was assessed through sensitivity analysis of the models and comparing the simulated results against field measurements. The model predicted that because of damming on the rivers, the mean water level in the lake will possibly experience a drop of 2.2–2.8 m over next 40 years. The results indicated that, over decadal time periods, the lake most probably will be split into two interconnected smaller lakes. The northern lake was foreseen to become extremely saline, which will seriously threaten the Artemia's survival in this area. Over the long‐term periods, the southern lake seemed not to deviate much from its existing conditions. It however appeared to become more responsive to seasonal climatic changes and to the rivers inflow, as compared with its current conditions. Effects from climate changes were not considered in the current study.     

Grafting of ion-imprinted polymers on the surface of silica gel particles through covalently surface-bound initiators: a selective sorbent for uranyl ion

A new ion imprinted polymer coated silica gel sorbent has been prepared using the radical "grafting from" polymerization method through surface-bound azo initiators for selective uranyl uptake. The introduction of azo initiator onto the silica surface was achieved by the reaction of surface amino groups with 4,4'-azobis(4-cyanopentanoic acid chloride). The grafting step was then carried out in a stirred solution of initiator-modified silica particles in the presence of uranyl ion and functional and cross-linking monomers. The prepared sorbent was characterized using FT-IR spectroscopy, scanning electron microscopy (SEM), elemental analysis (EA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and BET adsorption isotherm analysis. The influence of the uranyl concentration, pH, and flow rate of solution on the grafted polymer affinity has been investigated. Maximum uptake of uranyl ion was observed at a pH 3.0. The rebinding behavior of the sorbent has been successfully described by the Langmuir-Freundlich isotherm. The dynamic column capacity of sorbent and enrichment factor for uranyl ion were 52.9 +/- 3.4 micromol g(-1) and 52, respectively. It was found that imprinting results in increased affinity of the sorbent toward uranyl ion over strong competitor metal ions such as Fe(III) and Th(IV). The sorbent was repeatedly used and regenerated for 3 months without any significant decrease in polymer binding affinities. Finally the sorbent was applied to the preconcentration and determination of uranyl ion in real water samples.     

Highly selective and sensitive voltammetric sensor based on modified multiwall carbon nanotube paste electrode for simultaneous determination of ascorbic acid,acetaminophen and tryptophan

A carbon-paste electrode modified with multiwall carbon nanotubes (MWCNTs) was used for the sensitive and selective voltammetric determination of ascorbic acid (AA) in the presence of 3,4-dihydroxycinnamic acid (3,4-DHCA) as mediator. The mediated oxidation of AA at the modified electrode was investigated by cyclic voltammetry (CV), chronoamperommetry and electrochemical impedance spectroscopy (EIS). Also, the values of catalytic rate constant (k), and diffusion coefficient (D) for AA were calculated. Using square wave voltammetry (SWV), a highly selective and simultaneous determination of AA, acetaminophen (AC) and tryptophan (Trp) has been explored at the modified electrode. The modified electrode displayed strong function for resolving the overlapping voltammetric responses of AA, AC and Trp into three well-defined voltammetric peaks. In the mixture containing AA, AC and Trp, the three compounds can well separate from each other with potential differences of 200, 330 and 530 mV between AA and AC, AC and Trp and AA and Trp, respectively, which was large enough to determine AA, AC and Trp individually and simultaneously.     

Influence of the Polyvinyl Pyrrolidone Concentration on Particle Size and Dispersion of ZnS Nanoparticles Synthesized by Microwave Irradiation

Zinc sulfide semiconductor nanoparticles were synthesized in an aqueous solution of polyvinyl pyrrolidone via a simple microwave irradiation method. The effect of the polymer concentration and the type of sulfur source on the particle size and dispersion of the final ZnS nanoparticle product was carefully examined. Microwave heating generally occurs by two main mechanisms: dipolar polarization of water and ionic conduction of precursors. The introduction of the polymer affects the heating rate by restriction of the rotational motion of dipole molecules and immobilization of ions. Consequently, our results show that the presence of the polymer strongly affects the nucleation and growth rates of the ZnS nanoparticles and therefore determines the average particle size and the dispersion. Moreover, we found that PVP adsorbed on the surface of the ZnS nanoparticles by interaction of the C–N and C=O with the nanoparticle’s surface, thereby affording protection from agglomeration by steric hindrance. Generally, with increasing PVP concentration, mono-dispersed colloidal solutions were obtained and at the optimal PVP concentration (5%), sufficiently small size and narrow size distributions were obtained from both sodium sulfide and thioacetamide sulfur sources. Finally, the sulfur source directly influences the reaction mechanism and the final particle morphology, as well as the average size.