High Gain Modified Dual-Band and Dual-Circularly Polarized Array Antenna

Wireless Personal Communications - A novel design of double-layer dual-band circularly polarized array antennas (DDCPAAs) is presented in this paper. First, a DDCP single antenna is introduced as...     

The correlation among deposition parameters,structure and corrosion behaviour of ZnNi/nano-SiC composite coating deposited by pulsed and pulsed reverse current

The present work shows how the parameters of pulsed current (PC) deposition affect structural and morphological characteristics of electrodeposited ZnNi/nano-SiC composite coating and its corrosion properties. In this regard, ZnNi coatings containing SiC nanoparticles were electrodeposited from chloride bath by PC and pulsed reverse current (PRC) methods, and the effect of duty cycle, frequency and reverse current density were studied. With low and high duty cycles the SiC content of the coating was more than the coating deposited by medium duty cycle. Changing the duty cycle affected the coating composition, structure and morphology. Elevation of the pulse frequency increased SiC content of the coating. Application of PRC produced a coating with a complex and dendritic structure. In most of the electrodeposition conditions, in addition to direct effects of PC on coatings characteristics, it was seen that the more SiC was deposited in the coating the less Ni was deposited, and this also affected the corrosion behaviour. The best corrosion resistance behaviour was shown by coatings with more compact structure and less porosity.     

Determination of phenobarbital in real sample using carbon quantum dots modified with tungsten as a fluorescent nanoprobe

Journal of Materials Science: Materials in Electronics - In this study, a sensitive and selective fluorescence nanoprobe has been designed based on carbon quantum dots modified by tungsten (WCQDs)...     

Trust establishment in cooperative wireless relaying networks

In cooperative wireless networks, relay nodes are employed to improve the performance of the network in terms of throughput and reliability. However, the presence of malicious relay nodes in the network may severely degrade the performance of the system. When a relay node behaves maliciously, there exists a possibility that such a node refuses to cooperate when it is selected for cooperation or deliberately drops the received packets. Trust establishment is a mechanism to detect misbehaving nodes in a network. In this paper, we propose a trust establishment method for cooperative wireless networks by using Bayesian framework. In contrast with the previous schemes proposed in wireless networks, this approach takes the channel state information and the relay selection decisions into account to derive a pure trust value for each relay node. The proposed method can be applied to any cooperative system with a general relay selection policy whose decisions in each cooperative transmission are independent of the previous ones. Moreover, it does not impose additional communication overhead on the system as it uses the available information in relay selection procedure. Copyright © 2012 John Wiley & Sons, Ltd.     

Deposition and characterization of nanocrystalline and amorphous Ni–W coatings with embedded alumina nanoparticles

Nanocrystalline and amorphous Ni–W coatings containing Al₂O₃ nanoparticles were electrodeposited from three different ammoniacal citrate baths by direct current (DC) method. The effects of nanoparticles on compositional, structural and morphological features of Ni–W coatings were investigated. The effects of bath chemical composition and current density on codeposition behavior of nanoparticles were also studied. Guglielmi model for particle deposition was applied to identify the kinetics of particle deposition. The presence of nanoparticles may affect on coating grain size, tungsten content and the rate of metal deposition. In addition, nanoparticles can result in more compact coatings with fewer defects. The extent of these effects depends on bath chemical composition and may be influenced by the synergistic effect of Ni on deposition of W. It was also found that the kinetics of particle deposition and the effect of current density on codeposition behavior of nanoparticles are highly dependent on bath chemical composition.     

Design of Novel Ultra-Wideband Bandpass Filter with High Selectivity and Wide Stop Band and Optimizing it with Neuro-Genetic Method

This paper develops a novel ultra-wideband bandpass filter with high selectivity, deep stop band and compact size. By linking a broadband bandstop filter at two sides with two feed lines via interdigital coupled lines with enhanced coupling degree, an initial ultra-wideband bandpass filter is created. In this filter, all undesired pass bands are rejected by broadband bandstop filter embedded in middle of ultra-wideband filter. Then, stepped impedance open stubs are used for realizing transmission zeros in pass band edges to increase selectivity. Finally, a neuro-genetic method is applied for optimizing of proposed ultra-wideband bandpass filter. For this task, first a nonlinear relation is established between the input (layout parameters) and output (electrical responses) data by using neural network. Then, genetic algorithm is used in conjunction with neural network model for optimizing the ultra-wideband bandpass filter parameters. The designed filter was fabricated and measured that showed good characteristics including deep stop band and very high pass band selectivity.     

The effect of pure iron in a nanocrystalline grain size on the corrosion inhibitor behavior of sodium benzoate in near-neutral aqueous solution

The effect of grain size reduction on the electrochemical and corrosion behavior of iron with different grain sizes (32–750 nm) produced by direct and pulsed current electrodeposition were characterized using Tafel polarization curves and electrochemical impedance spectroscopy. The grain size of deposits was determined by X-ray diffraction analysis and scanning electron microscopy. The tests were carried out in an aqueous electrolyte containing 30 mg L⁻¹ NaCl + 70 mg L⁻¹ Na₂SO₄. Results obtained suggested that the inhibition effect and corrosion protection of sodium benzoate inhibitor in near-neutral aqueous solutions increased as the grain size decreased from microcrystalline to nanocrystalline. The improvement on the inhibition effect is attributed to the increase of the surface energy.     

The effect of molybdate concentration and hydrodynamic effect on mild steel corrosion inhibition in simulated cooling water

The effects of two important factors namely concentration and hydrodynamics on the inhibition efficiency of molybdate were investigated using potentiodynamic polarization and electrochemical impedance spectroscopy tests. Results showed that molybdate was capable of inhibiting the corrosion of mild steel in simulated cooling water. The inhibition efficiency of molybdate was increased with increasing both its concentration and water circulation velocity. These two factors seem to promote the adsorption of molybdate and oxygen ions on the metal surface, leading to the formation of a protective layer with a greater charge transfer resistance and lower permeability. A model is also proposed which facilitates the probable mechanism of inhibition.     

Systematic and deterministic graph minor embedding for Cartesian products of graphs

The limited connectivity of current and next-generation quantum annealers motivates the need for efficient graph minor embedding methods. These methods allow non-native problems to be adapted to the target annealer’s architecture. The overhead of the widely used heuristic techniques is quickly proving to be a significant bottleneck for solving real-world applications. To alleviate this difficulty, we propose a systematic and deterministic embedding method, exploiting the structures of both the specific problem and the quantum annealer. We focus on the specific case of the Cartesian product of two complete graphs, a regular structure that occurs in many problems. We decompose the embedding problem by first embedding one of the factors of the Cartesian product in a repeatable pattern. The resulting simplified problem comprises the placement and connecting together of these copies to reach a valid solution. Aside from the obvious advantage of a systematic and deterministic approach with respect to speed and efficiency, the embeddings produced are easily scaled for larger processors and show desirable properties for the number of qubits used and the chain length distribution. We conclude by briefly addressing the problem of circumventing inoperable qubits by presenting possible extensions of our method.