Electrokinetic transport of charged samples through rectangular channels with small zeta potentials

In this article, we analyze the electrokinetic transport of charged samples through rectangular channels having a small zeta potential at their walls. Using the "method of moments" formulation, the diffusion-advection equation has been solved numerically to evaluate the mean velocity and the dispersion of analyte bands in these systems. In addition, a semianalytical theory has been presented for estimating the solutal spreading rate by decoupling the effects of vertical and horizontal velocity gradients in the channel. We demonstrate that this theory can estimate the band broadening of charged samples in rectangular conduits of all aspect ratios within an accuracy of 5% with significantly less computational effort than that required in the numerical simulations. Moreover, our analysis shows that while the side walls in a rectangular conduit modify the solute velocity only to a moderate extent, they can increase the hydrodynamic dispersion of sample slugs by as much as an order of magnitude under strong Debye layer overlap conditions. In the opposite limit of thin Debye layers, however, the increase in dispersion due to the side regions is only by a factor of 2 and remains nearly unaffected by the transverse electromigration of the solute molecules and the aspect ratio of the channel.     

A Study of Densification Management Using Energy Efficient Femto-Cloud Based 5G Mobile Network

Energy efficiency in wireless communication becomes essential. Power optimization of mobile radio systems has gained attention of network operators because energy costs make up a huge part of operational expenditure. In this regard, deployments of low power small cell base stations considerably raise the challenge of energy-efficient cellular networks. Network densification refers to densification over space, for example dense small cell deployment like picocell, femtocell, and frequency utilization of larger segments of radio spectrum in dissimilar bands. In this article we have illustrated the cause factors of densification and described its effects. The deployment layouts of different base stations are studied and compared with conventional macro-femtocell systems from the perspective of area power consumption and signal-to-interference-plus-noise-ratio.     

Probabilistic Assessment of UPV Test Result of a Degasser Unit

The novelty of this paper is to address a fundamental characteristic of ultrasonic pulse velocity (UPV) test result called distribution pattern and development of a methodology to simplify non-normal distribution patterns of UPV into normal distribution domain for easy applicability of quality assurance criteria for practicing engineers. In this paper probabilistic assessment methodology of UPV test results collected from a de-gasser structure of a refinery in India is discussed. Detailed analysis is performed to identify the distribution characteristics of UPV. No conventional distribution type including normal distribution fitted for UPV test results. A further attempt is made to derive simplified normal distributions with two different modes from the empirical cumulative distribution function of in situ test results. This creates scope for application of existing normal distribution based quality assurance criteria to non-normal domain of UPV. Criteria of characteristic strength instead of mean value is proposed as a better parameter for estimation of the quality of the material. Detailed physical interpretation and justification for the methodology is discussed with mathematical reasoning. The method is discussed in reference to existing literature. It is shown that the method is applicable to derive quality assurance criteria where simple assumption of normal distribution is not valid for UPV. Thus the method has the potential to make UPV a more useful test based on statistical reasoning for application on full scale structures.     

Performance improvement of DC-DC converter using L-D-based modified GaN-FET driver

Bootstrap capacitor in FET gate driver plays an important role in the transient performance of the half bridge configured synchronous buck DC-DC converter especially in the top switch. In this paper, a new bootstrap capacitor based GaN-FET driver is proposed. This new GaN-FET driver is tested in a synchronous buck converter for performance verification like immunity, transient response, and voltage ringing. A comparison study with the existing LM5113 (Texas Instrument)–based driver for GaN-FET and IR2110-based Si-MOSFET driver on a DC-DC converter is carried out to show the performance improvement using the proposed GaN-FET driver. The simulation study is performed on spice-based NI-Multisim 14.1. Finally, the designed GaN-FET driver is tested on a 60-W synchronous buck DC-DC converter in open-loop and closed-loop configuration.     

On a cosmological invariant as an observational probe in the early universe

k-essence scalar field models are usually taken to have Lagrangians of the form L = −V (φ)F(X) with F some general function of X = ▿ _μ φ▿ ^μ ϕ. Under certain conditions, this Lagrangian can take the form of that of an oscillator with time-dependent frequency. The Ermakov invariant for a time-dependent oscillator in a cosmological scenario then leads to an invariant quadratic form involving the Hubble parameter and a logarithm of the scale factor. In principle, this invariant can lead to further observational probes for the early Universe. Moreover, if such an invariant can be observationally verified, then the presence of dark energy will also be indirectly confirmed.     

X-ray studies on microstructural characterization of tantalum substituted tungsten mixed molybdenum diselenide; W0·65Mo35−x Ta x Se2 (0≤x≤0·35)

The wide angle X-ray diffraction on W_0·65Mo_5−x Ta _x Se₂ (0≤x≤0·35) compounds have been used for calculation of the crystallite size by method of variance and Fourier technique and for microstructural parameters purposes. The crystallite size showed the decreasing trend with increasing composition up tox=0·15 and after that it increased sharply. On the contrary, mean fractional change in interlayer spacing, fractions of the planes affected by defects, dislocation density, and root mean square strain showed the opposite trend. The crystallite size anisotropy and stacking fault probability showed 1:1 correspondence in their variation with composition. The radial distribution analysis have also been employed to find out the information about the inter atomic distances, coupling constants and mean square displacements for different pairs of atoms. These results have been interpreted in terms of difference in packing of layers in these compounds.     

Co(II) and Mn(II) catalyzed bulk ring-opening polymerization of cyclic esters

Co(II) and Mn(II) salts were assessed to be good catalysts for the bulk ring-opening polymerization of cyclic esters. These polymerizations are reasonably controlled leading to the formation of polymer with good number average molecular weights (M _n) and narrow molecular weight distributions. The polymerizations were studied in the presence and absence of benzyl alcohol and the polymerization tendency was found to increase in the presence of benzyl alcohol. The polymerization proceeds through the activated monomer mechanism, resulting in the formation of polymers containing the initiator as one of the end terminal groups. All the polymerizations show first-order kinetics with respect to monomer concentration. Ease of handling and low cost of Co(II) and Mn(II) salts make the catalytic process economically attractive.     

A Simple Heuristic for Assignment of Cells to Switches in a PCS Network

This work deals with a design problem for a network of Personal Communication Services (PCS). The goal is to assign cells to switches in a PCS Network (PCSN) in an optimum manner so as to minimize the total cost which includes two types of cost, namely handoff cost between two adjacent cells, and cable cost between cells and switches. The design is to be optimized subject to the constraint that the call volume of each switch must not exceed its call handling capacity. In the literature, this problem has been conventionally formulated as an integer programming problem. However, because of the time complexity of the problem, the solution procedures are usually heuristic when the number of cells and switches are more. In this paper, we have proposed an assignment heuristic which is faster and much simpler than the existing algorithms. Despite its simplicity, experimental results show that it performs equally well in terms of solution quality, and, at the same time, it is faster than its predecessors. We present the algorithm as well as comparative results to justify our claim.     

First principle approach towards logic design using hydrogen‐doped single‐strand DNA

Molecular logic gate has been proposed using single‐strand DNA (ssDNA) consisting of basic four nucleobases. In this study, density functional theory and non‐equilibrium Green''s function based first principle approach is applied to investigate the electronic transmission characteristics of ssDNA chain. The heavily hydrogen‐doped‐ssDNA (H‐ssDNA) chain is connected with gold electrode to achieve enhanced quantum‐ballistic transmission along 〈1 1 1〉 direction. Logic gates OR, Ex‐OR, NXOR have been implemented using this analytical model of H‐ssDNA device. Enhanced logic properties have been observed for ssDNA after H adsorption due to improved electronic transmission. Dense electron cloud is considered as logic ‘high’ (1) output in presence of hydrogen molecule and on the contrary sparse cloud indicate logic ‘low’ (0) in the absence of hydrogen molecule. Device current is significantly increased from 0.2 nA to 2.4 µA (approx.) when ssDNA chain is heavily doped with hydrogen molecule. The current–voltage characteristics confirm the formation of various Boolean logic gate operations.Inspec keywords: molecular electronics, Green''s function methods, hydrogen, logic gates, density functional theory, adsorption, DNA, logic design, logic circuitsOther keywords: hydrogen molecule, contrary sparse cloud, current–voltage characteristics, Boolean logic gate operations, first principle approach, logic design, hydrogen‐doped single‐strand DNA, molecular logic gate, density functional theory, electronic transmission characteristics, H, analytical model, NXOR logic gates, Ex‐OR logic gates, OR logic gates, hydrogen‐doped‐ssDNA chain, nonequilibrium Green''s function, nucleobases, dense electron cloud, improved electronic transmission, enhanced logic properties, H‐ssDNA device, enhanced quantum‐ballistic transmission, gold electrode