Novel optimized tree-based stack-type architecture for 2n-bit comparator at nanoscale with energy dissipation analysis

Comparator is an essential building block in many digital circuits such as biometric authentication, data sorting, and exponents comparison in floating-point architectures among others. Quantum-dot Cellular Automata (QCA) is a latest nanotechnology that overcomes the drawbacks of Complementary Metal Oxide Semiconductor (CMOS) technology. In this paper, novel area optimized 2n-bit comparator architecture is proposed. To achieve the objective, 1-bit stack-type and 4-bit tree-based stack-type (TB-ST) comparators are proposed using QCA. Then, two tree-based architectures of 4-bit comparators are arranged in two layers to optimize the number of quantum cells and area of an 8-bit comparator. Thus, this design can be extended to any 2n-bit comparator. Simulation results of 4-bit and 8-bit comparators using QCADesigner 2.0.3 show that there is a significant improvement in the number of quantum cells and area occupancy. The proposed TB-ST 8-bit comparator uses 2.5 clock cycles and 622 quantum cells with area occupancy of 0.49 µm² which is an improvement by 10.5% and 38%, respectively, compared to existing designs. Scaling it to a 32-bit comparator, the proposed architecture requires only 2675 quantum cells in an area of 2.05 µm² with a delay of 3.5 clock cycles, indicating 9.35% and 28.8% improvements, respectively, demonstrating the merit of the proposed architecture. Besides, energy dissipation analysis of the proposed TB-ST 8-bit comparator is simulated on QCADesigner-E tool, indicating average energy dissipation reduction of 17.3% compared to existing works.

     

Extended Kalman filter based speeds estimation of series-connected five-phase two-motor drive system

The multi-phase machines enables independent control of a few number of machines that are connected in series in a particular manner, and the supply is fed from a single voltage source inverter (VSI). The idea was first implemented for a five-phase series-connected two-motor drive system, but is now applicable to any number of phases. The number of series-connected machines is a function of the phase number of VSI. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information of the rotor speed is extracted from measured stator currents and voltages at motor terminals. Open-loop estimators or closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an EKF-based sensorless control of vector controlled series-connected two-motor five-phase drive system with current control in the stationary reference frame. Results, obtained with fixed voltage and fixed frequency supply fed and hysteresis current control, is presented for various operating conditions on the basis of simulation. The purpose of this paper is to report first time, the simulation results on a sensorless control of a five-phase two-motor series-connected drive system using EKF estimator.     

Trusted consensus protocol for blockchain networks based on fuzzy inference system

The Journal of Supercomputing - Blockchain technology with its inherent security features revolutionizes the field of distributed networks and has become one of the significant areas of research....     

Green synthesis of anisotropic gold nanoparticles using hordenine and their antibiofilm efficacy against Pseudomonas aeruginosa

Pseudomonas aeruginosa is a notorious pathogen that causes biofilm aided infections in patients with cystic fibrosis and burn wounds, resulting in significant mortality in immunocompromised individuals. This study reports a novel one‐step biosynthesis of gold nanoparticles using phytocompound, hordenine (HD), as a reducing and capping agent. The synthesis of the anisotropic hordenine‐fabricated gold nanoparticles (HD‐AuNPs) with an average particle size of 136.87 nm was achieved within 12 h of incubation at room temperature. Both HD and HD‐AuNPs exhibited significant antibiofilm activity against P. aeruginosa PAO1, although greater biofilm inhibition was observed for the nanoparticles as compared to hordenine alone. In the microtitre plate assay and tube method, the nanoparticles significantly inhibited the biofilm formation by 73.69 and 78.41%, respectively. The exopolysaccharide production by the test pathogen was arrested by 68.46% on treatment with the nanoparticles. Further, the effect of HD and HD‐AuNPs on the biofilm architecture of P. aeruginosa was revealed by light and confocal laser‐scanning microscopy micrographs. The overall results of this study suggested the synergistic antibiofilm effect of AuNPs and HD for the treatment of chronic bacterial infections caused by biofilms forming pathogens.Inspec keywords: molecular biophysics, biochemistry, gold, nanoparticles, nanofabrication, microorganisms, organic compounds, particle size, nanobiotechnologyOther keywords: green synthesis, anisotropic gold nanoparticles, hordenine, antibiofilm efficacy, Pseudomonas aeruginosa, pathogen, cystic fibrosis, burn wounds, one‐step biosynthesis, phytocompound, reducing agent, capping agent, particle size, microtitre plate assay, tube method, confocal laser‐scanning microscopy micrographs, Au     

Low temperature densification by lithium co-doping and its effect on ionic conductivity of samarium doped ceria electrolyte

Low temperature densification and improving the ionic conductivity of doped ceria electrolyte is important for the realization of efficient intermediate temperature solid oxide fuel cell system. Herein, we report the effect of lithium co-doping (1, 3, 5 and 7?mol%) in 20?mol% samarium doped ceria on the low temperature sinterability and conductivity. The synthesized nanoparticles by citrate-nitrate combustion method showed a decrease in lattice parameter and increase in oxygen vacancy with lithium content after calcination due to the substitution of Li⁺ into CeO₂ lattice. Upon sintering at 900?°C, the density improved and reached a maximum value of 98.6% for 5% Li which exhibited a dense microstructure than at 7% Li. 5%Li co-doping exhibited the best conductivity of 3.65?×?10^?04–1.81?×?10^?3 S?cm^?1 in the operative temperature range of IT-SOFC (550–700?°C).Our results demonstrate the significance of lithium as co-dopant for efficient low temperature sintering as well as improving the electrolyte conductivity.     

Electrical and electrochemical studies of nanocrystalline mesoporous MgFe2O4 as anode material for lithium battery applications

Nanocrystalline mesoporous spinel magnesium ferrite (MgFe₂O₄) particles with high surface area were prepared by urea assisted modified citrate combustion process. The prepared sample was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, field-emission scanning electron microscope (FE-SEM), BET surface area analyzer and impedance spectroscopy techniques. XRD results confirmed the formation of a single phase of nanocrystalline spinel magnesium ferrite sample. FTIR and Raman spectroscopy (FTIR) results confirmed the structural co-ordination of the magnesium ferrite sample. The spherical shape morphology of the prepared magnesium ferrite particles was confirmed from the FE-SEM images. Specific surface area and porosity of the MgFe₂O₄ sample were obtained from N₂ adsorption–desorption isotherms results. The D.C. and A.C. electrical conductivities of the MgFe₂O₄ sample as a function of temperature and frequency were investigated by analyzing the measured impedance data. The activation energy for the migration of the carriers in the MgFe₂O₄ sample was found to be 0.607 eV. The dielectric studies revealed that the dielectric constant of the mesoporous MgFe₂O₄ sample increases with increase in temperature. Further, lithium battery was fabricated using the developed nanocrystalline mesoporous spinel MgFe₂O₄ as anode material and investigated its electrochemical performance. The charge-discharge studies revealed that the fabricated lithium battery using the developed nanocrystalline mesoporous MgFe₂O₄ as anode exhibited high capacity and good cycleability in the voltage range 0.005–3 V. The results show that the developed nanocrystalline mesoporous spinel magnesium ferrite could be a better anode material for lithium battery applications.     

Maleimide–based donor-π-acceptor-π-donor derivative for efficient organic light-emitting diodes

Herein, we report a highly fluorescent material 3,4-bis(4′-(9H-carbazol-9-yl)-[1,1′-biphenyl]-4-yl)-1-hexyl-1H-pyrrole-2,5-dione (Cbz-MI) based on donor-π-acceptor-π-donor (D-π-A-π-D) backbone. We explored maleimide as an acceptor, phenyl as π-conjugated spacer and carbazole as donor. Photophysical properties revealed high photoluminescence quantum yield of 0.84 and 0.72 in solution and doped matrix, respectively. An encouraging external quantum efficiency of 2.5% with emission peak at 550 nm is achieved utilizing Cbz-MI as emitting layer in doped electroluminescent device structure.     

Low-amperage pulsating direct current has a bactericidal effect on marine fish pathogens in circulating seawater

The bactericidal effect of pulsating direct current (PC) generated at a very low amperage (0.01 A) with a frequency of 5 Hz or 14 kHz against two marine fish pathogens, Edwardsiella tarda and Vibrio parahaemolyticus, in circulating seawater at 15 and 25 °C in comparison with the effect of direct current (DC) of the same amperage was investigated. The bactericidal effect was directly correlated with the generation of active chlorine species (ACS) and the treatment duration. PC treatment at 14 kHz resulted in complete bacterial inactivation when the ACS level reached 0.11–0.12 mg/L after 45–60 min of treatment. PC treatment at 5 Hz required generation of only 0.03–0.07 mg/L ACS to achieve complete bacterial inactivation, although a slightly longer treatment duration (60–90 min) was needed. DC treatment resulted in complete disinfection within a shorter time (30 min) due to greater ACS production. The bactericidal effect and ACS generation were weaker at the higher temperature (25 °C) due to more rapid evaporation of Cl₂ gas. The pH of the seawater maintained at ∼8.0. A disinfection study in circulating non-chloride Na₂SO₄ solution at pH 8.0 showed that the electric pulsation did not have notable bactericidal effect up to 14 kHz at 0.2 A.     

Synthesis,spectral, thermal,and chelation potentials of polymeric hydrazone based on 2,4‐dihydroxy benzophenone

A chelating polymer, poly(2,4‐dihydroxy benzophenone hydrazone–formaldehyde) [poly(DHBPH–F)], was synthesized by the polycondensation of 2,4‐dihydroxy benzophenone hydrazone with formaldehyde in the presence of oxalic acid as a catalyst. Poly(DHBPH–F) was characterized by Fourier transform infrared and ¹H‐NMR spectral data. The molecular weight of the polymer was determined by gel permeation chromatography. Polychelates were obtained when the dimethylformamide solution of the polymer containing a few drops of ammonia was treated with an aqueous solution of metal ions. Elemental analysis of the polychelates indicated that the metal–ligand ratio was 1 : 2. The IR spectra of the polymer–metal complexes suggested that the metals were coordinated through the oxygen of the phenolic? OH group and the nitrogen of the azomethine group. The electron paramagnetic resonance and magnetic moment data indicated a square planar configuration for Cu(II) chelate and an octahedral structure for Ni(II) chelate. The thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction data indicated that the incorporation of the metal ions significantly enhanced the degree of crystallinity. The polymerization initiation, electrical conductivity, and catalytic activity of the polychelates are discussed. Heavy‐metal ions [viz., Cu(II) and Ni(II)] were removed with this formaldehyde resin, and the metal‐ion uptake efficiency at different pH's, the nature and concentration of the electrolyte, and the reusability of the resin were also studied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010