All-optical carry lookahead adder with the help of terahertz optical asymmetric demultiplexer

An all-optical model of carry lookahead adder (CLA) implemented with a semiconductor optical amplifier (SOA)-assisted Sagnac interferometer (TOAD) is presented. The model accounts for the SOA small signal gain, linewidth enhancement factor, the switching pulses energy and width and the Sagnac loop asymmetry. Adder is a very basic component in a central processing unit. The CLA is the highest speed adder nowadays. Theoritical model is presented and verified through numerical simulation. The method promises both higher processing speed and accuracy. The model can be enhanced the functionality in which carry lookahead adder is the basic building block.     

A Class of Well Behaved Charged Analogues of Schwarzchild’s Interior Solution

A class of well behaved charged analogues of Schwarzchild’s interior solution has been obtained using a particular electric intensity. The solutions of this class are utilized to depict a superdense star model with surface density 2×10¹⁴ g cm⁻³. The solution obtained is new and the pressure (p), density (c ² ρ), velocity of sound and (p/(c ² ρ)) are monotonically decreasing towards the pressure free interface. Moreover the adiabatic constant is found to be more than (4/3) which is necessary for stability under radial perturbation. Also the electric intensity increases monotonically towards the surface. The well behaved model has the maximum mass M=1.740793M _Θ , Radius 12.130308 km. The redshift at the center and on the surface is given by z ₀=0.384261 and z _a =0.292489. Out of the models of superdense star obtained couple of models represent Vela Pulsar for (i) α ²=1.03, b=0.33, , Radius=10.8566 km, M=1.18331M _Θ , I=0.642601×10⁴⁵, (ii) α ²=1.1, b=0.3, , Radius=11.197533 km, M=1.311438M _Θ , I=0.774508×10⁴⁵. All the solutions mentioned above are reducible to Schwarzchild interior solution in the absence of charge.     

Structure Analysis of Solid Lipid Nanoparticles for Drug Delivery: A Combined USANS/SANS Study

Suspensions of solid lipid nanoparticles (SLNs) stabilized with emulsifiers have been extensively investigated (since the 1990s) as drug carriers, although details of their ultrastructure are poorly defined. Previously, a novel microwave‐assisted microemulsion‐based technique to prepare SLNs was reported. To understand the detailed internal structure of these SLNs, ultra‐small angle neutron scattering (USANS) and small angle neutron scattering (SANS) experiments are conducted on suspensions of hydrogenated stearic acid SLNs stabilized with hydrogenated Tween 20 surfactant in D₂O. Together, SANS and USANS gives a combined Q range of 0.000047 to 0.6 Å^?1 (corresponding to a size range of ≈1 nm–15 µm). This extended Q range allows a comprehensive understanding of the hierarchical structure of SLNs. The data are consistent with the multi‐length scale structure of SLNs having polydispersed large particles with roughened surfaces at the microscale level. At the nanoscale level, the results are consistent with the SLNs having an ellipsoidal shape intermediate between spheres and rods, with a crossover from mass fractals to surface fractals. The elucidation of this structure is particularly important given that the structure influences the stability and drug release properties of the nanoparticles. These results assist in the development of systems with desired shape and properties.     

Vertical Sediment Concentration Distribution in High-Concentrated Flows: An Analytical Solution Using Homotopy Analysis Method

Transport of suspended sediment in open channel flow has an enormous impact on real life situations, viz. control and management of reservoir sedimentation, geomorphic evolution such as dunes, rivers, and coastlines etc. Transport entails advection and diffusion. Turbulent diffusion is governed by the concept of Fick's law, which is based on the molecular diffusion theory, and the equation that represents the distribution of sediment concentration is the advection-diffusion equation. The study uses the existing governing equation which considers different phases for solid and fluid, and then couples the two phases. To deal with high-concentrated flow, sediment and turbulent diffusion coefficients are taken to be different from each other. The effect of hindered settling on sediment particles is incorporated in the governing equation, which makes the equation highly non-linear. This study derives an explicit closed-form analytical solution to the generalized one-dimensional diffusion equation representing the vertical sediment concentration distribution with an arbitrary turbulent diffusion coefficient profile. The solution is obtained by Homotopy Analysis Method, which does not rely on the small parameters present in the equation. Finally, the solution is validated by comparing it with the implicit solution and the numerical solution. A relevant set of laboratory data is selected to check the applicability of the model, and a close agreement shows the potential of the model in the context of application to high-concentrated sediment-laden open channel flow.     

A controller for 97 MHz super-conducting QWR for NSC LINAC booster

A resonator controller has been implemented to stabilize the amplitude and phase of rf fields in the super-conducting resonators of NSC LINAC. Due to reduced losses these resonators have intrinsic band width of the order of 0.1 Hz at 97 MHz whereas the vibration-induced center frequency changes are of the order of a few tens of hertz. In the control strategy followed, the resonator is made the frequency selective part of an oscillator. The phase lock is achieved by dynamically adding a phase shift in the oscillator. A slow tuner minimizes the slow drifts in the resonator center frequency. In this paper we present the control strategy, implementation details and performance obtained with this controller.     

Shape transitions in even Mo and Sm isotopes: Study in a new microscopic interacting boson model scheme

A simple dynamic procedure, based on the deformed Hartree-Fock solution of a nucleus, is presented to construct the IBM operators in microscopic basis. The parameters of these operators are evaluated by establishing a Marumori mapping from the truncated shell model space onto the boson space. The transitions from spherical to axial-rotor shape observed in the low-lying levels ofeven ^96–108Mo and^146–154Sm isotopes are reproduced qualitatively by applying this procedure with a fixed set of fermion input parameters to each chain. Variation of a few parameters in fermion space leads to quantitative agreement.     

Effect of flaws on the strength of Si3N4

Fracture-mechanics analysis and fractographic studies were performed to assess the effect of surface flaws on the strength of Si₃N₄. The critical surface-flaw size calculated from fracture-mechanics analysis was in agreement with the fractographically observed flaw size. A comparison of the results of fracture-mechanics calculations with fractographic observations indicates that the failure-initiating flaws grow subcritically before failure. The subcritical growth of these flaws and hence the strength is greatly influenced by the microstructure and grain-boundary phases. Paper was presented at the 1986 SEM Fall Conference on Experimental Mechanics held in Keystone, CO on November 2–5.     

Copper(II) selective electrochemical sensor based on Schiff Base complexes

Plasticized membranes using Schiff Base complexes, derived from 2,3-diaminopyridine and o-vanilin have been prepared and explored as Cu2+-selective sensors. Effect of various plasticizers viz., dibutyl phthalate (DBP), dioctylphthalate (DOP), chloronaphthalene (CN), tri-n-butylphosphate (TBP) etc. and anion excluder, sodium tetraphenylborate (NaTPB) was studied in detail and improved performance was observed at several instances. Optimum performance was observed with Schiff Base (B) having a membrane composition of B(1%):PVC(33%):DOP(65%):NaTPB(1%). The sensor works satisfactorily in the concentration range 5.0×10−6 to 1.0×10−1 M (detection limit 0.3 ppm) with a Nernstian slope of 29.6 mV per decade of activity. Wide pH range (1.9-5.2), fast response time (<30 s), high non-aqueous tolerance (up to 20%) and adequate shelf life (>4 months) indicate the vital utility of the proposed sensor. The potentiometric selectivity coefficient values as determined by match potential method (MPM) indicate good response for Cu2+ in presence of interfering ions. The tolerance level of Hg2+, which causes serious interference in the determination of Cu2+ ions (KCu2+Hg2+Pot(MPM): 0.45), was determined as a function of Cu2+ concentration in simulated mixtures. The sensor was also used in the potentiometric titration of Cu2+ with EDTA.     

New paramagnetic Re(II) compounds with nitrile and cyanide ligands prepared by homolytic scission of dirhenium complexes

The preparation and characterization of three new paramagnetic complexes of the 17-electron Re(II) ion are reported. The salts [Re(triphos)(CH(3)CN)(3))][X](2), X = [BF(4)](-) (1), [PF(6)](-) (2), and [Et(4)N][Re(triphos)(CN)(3)] (3) were prepared by homolytic cleavage of the Re-Re bond in [Re(2)(CH(3)CN)(10)][BF(4)](4) or by disruption of the chlorine bridges in [(triphos)Re(mu-Cl)(3)Re(triphos)]Cl (1) (triphos = 1,1,1-tris(diphenylphosphino-methyl)ethane) and characterized by single-crystal X-ray diffraction, infrared and (1)H NMR spectroscopies, cyclic voltammetry, and magnetic susceptibility measurements. Compound 2 undergoes reversible reduction and irreversible oxidation processes while 3 undergoes a reversible reduction, an irreversible oxidation, and a reversible oxidation. The magnetic susceptibility data for 2 and 3 exhibit a strong temperature independent paramagnetic component which is in accord with a highly anisotropic S = (1)/(2) magnetic ground state. The results of this study indicate that dinuclear Re(2)(II,II) starting materials are viable precursors for producing unusual mononuclear Re(II) complexes.     

A volume‐consistent discrete formulation of aggregation population balance equations

In this paper, a new finite volume scheme for the numerical solution of the pure aggregation population balance equation, or Smoluchowski equation, on non‐uniform meshes is derived. The main feature of the new method is its simple mathematical structure and high accuracy with respect to the number density distribution as well as its moments. The new method is compared with the existing schemes given by Filbet and Laurençot (SIAM J. Sci. Comput., 25 (2004), pp. 2004–2028) and Forestier and Mancini (SIAM J. Sci. Comput., 34 (2012), pp. B840–B860) for selected benchmark problems. It is shown that the new scheme preserves all the advantages of a conventional finite volume scheme and predicts higher‐order moments as well as number density distribution with high accuracy. Copyright © 2015 John Wiley & Sons, Ltd.