B-GWO based multi-UAV deployment and power allocation in NOMA assisted wireless networks

Wireless Networks - Unmanned Aerial Vehicles (UAVs) deployed as flying base stations is a promising technology for enhancing the quality of service (QoS) and quick recovery from unexpected damages...     

Quick high-temperature hydrothermal synthesis of mesoporous materials with 3D cubic structure for the adsorption of lysozyme

Three-dimensional cage-like mesoporous FDU-12 materials with large tuneable pore sizes ranging from 9.9 to 15.6 nm were prepared by varying the synthesis temperature from 100 to 200 °C for the aging time of just 2 h using a tri-block copolymer F-127(EO₁₀₆PO₇₀EO₁₀₆) as the surfactant and 1,3,5-trimethyl benzene as the swelling agent in an acidic condition. The mesoporous structure and textural features of FDU-12-HX (where H denotes the hydrothermal method and X denotes the synthesis temperature) samples were elucidated and probed using x-ray diffraction, N₂ adsorption, ²⁹Si magic angle spinning nuclear magnetic resonance, scanning electron microscopy and transmission electron microscopy. It has been demonstrated that the aging time can be significantly reduced from 72 to 2 h without affecting the structural order of the FDU-12 materials with a simple adjustment of the synthesis temperature from 100 to 200 °C. Among the materials prepared, the samples prepared at 200 °C had the highest pore volume and the largest pore diameter. Lysozyme adsorption experiments were conducted over FDU-12 samples prepared at different temperatures in order to understand their biomolecule adsorption capacity, where the FDU-12-HX samples displayed high adsorption performance of 29 μmol g⁻¹ in spite of shortening the actual synthesis time from 72 to 2 h. Further, the influence of surface area, pore volume and pore diameter on the adsorption capacity of FDU-12-HX samples has been investigated and results are discussed in correlation with the textural parameters of the FDU-12-HX and other mesoporous adsorbents including SBA-15, MCM-41, KIT-5, KIT-6 and CMK-3.     

Analysis of indoor particles and gases and their evolution with natural ventilation

The air composition and reactivity from outdoor and indoor mixing field campaign was conducted to investigate the impacts of natural ventilation (ie, window opening and closing) on indoor air quality. In this study, a thermal desorption aerosol gas chromatograph (TAG) obtained measurements of indoor particle‐ and gas‐phase semi‐ and intermediately volatile organic compounds both inside and outside a single‐family test home. Together with measurements from a suite of instruments, we use TAG data to evaluate changes in indoor particles and gases at three natural ventilation periods. Positive matrix factorization was performed on TAG and adsorbent tube data to explore five distinct chemical and physical processes occurring in the indoor environment. Outdoor‐to‐indoor transport is observed for sulfate, isoprene epoxydiols, polycyclic aromatic hydrocarbons, and heavy alkanes. Dilution of indoor species is observed for volatile, non‐reactive species including methylcyclohexane and decamethylcyclopentasiloxane. Window opening drives enhanced emissions of semi‐ and intermediately volatile species including TXIB, DEET, diethyl phthalate, and carvone from indoor surfaces. Formation via enhanced oxidation was observed for nonanal and 2‐decanone when outdoor oxidants entered the home. Finally, oxidative depletion of gas‐phase terpenes (eg, limonene and α‐pinene) was anticipated but not observed due to limited measurement resolution and dynamically changing conditions.     

Performance analysis of 2 level DWT-SVD based non blind and blind video watermarking using range conversion method

Microsystem Technologies - The recent availability of inexpensive digital recording and storage devices have created an environment to obtain, replicate and distribute digital content without any...     

Optimization of processing parameters of medium density fiberboard using response surface methodology for multiwalled carbon nanotubes as a nanofiller

In the present work, medium density fiberboard (MDF) panels were produced using multiwalled carbon nanotubes (MWCNT) reinforced urea formaldehyde resin. Response surface methodology was employed to optimize the relationship between the three variables, viz. pressing time, percentage of UF resin and percentage of MWCNT, used in the fabrication of MDF, and the influence of variables on the internal bonding (IB) and modulus of rupture (MOR) was studied. The optimum conditions based on the IB strength were determined as 8.18 % of UF resin, pressing time of 232 s, and MWCNT of 3.5 %. Similarly, the optimized conditions for MOR are also reported in this paper.     

Mechanical characterization of a bituminous mix under quasi-static and high-strain rate loading

There are various methods to determine the compressive and tensile strength of asphalt concrete under static loading conditions and most studies on asphalt strength and fracture have been conducted under such loading conditions. However, pavement materials also have to withstand a wide variety of loading and temperature conditions which may vary from quasi-static to high-strain rate impact, and pavement breakdown may occur due to fracture and/or fatigue failure. In the present study, a bituminous mix with 30% RAP has been characterized under quasi-static (10^?3–10^?4 strain/s) and high-strain rate (200–700 strain/s) regimes. The experimental studies have been performed to better understand the compressive, tensile and fracture response of bituminous mixes. Split Hopkinson pressure bar (SHPB) and its modifications were used for high-strain rate characterization of this bituminous mixture. It was observed that the mechanical properties of the hot mix asphalt (HMA) changed significantly under high-strain rate testing. Also, the failure mechanisms observed under the high-strain rate loading were found to be considerably different from those obtained in static testing, where failure of binder was a predominant mechanism. It was observed that high-strain rate loading caused trans-aggregate failures in the specimens; in addition to failure of the binder.     

Modeling the drain current and its equation parameters for lightly doped symmetrical double-gate MOSFETs

A 2D model for the potential distribution in silicon film is derived for a symmetrical double gate MOSFET in weak inversion. This 2D potential distribution model is used to analytically derive an expression for the subthreshold slope and threshold voltage. A drain current model for lightly doped symmetrical DG MOSFETs is then presented by considering weak and strong inversion regions including short channel effects, series source to drain resistance and channel length modulation parameters. These derived models are compared with the simulation results of the SILVACO (Atlas) tool for different channel lengths and silicon film thicknesses. Lastly, the effect of the fixed oxide charge on the drain current model has been studied through simulation. It is observed that the obtained analytical models of symmetrical double gate MOSFETs are in good agreement with the simulated results for a channel length to silicon film thickness ratio greater than or equal to 2.     

Moving ion fronts in mixed ionic‐electronic conducting polymer films

The aim of this paper is to analyze moving front dynamics of ions and holes in a planar, mixed ionic‐electronic conducting polymer film. As cations invade the film, holes evacuate; thus, an ionic current is converted to an electronic signal. Recent experiments show that the location of the advancing ion front increases as the square‐root of time, a scaling typically associated with diffusive transport, which is surprising given the large driving voltages utilized. Ionic and electronic transport is modeled via the drift‐diffusion equations. A similarity transformation reduces the governing partial differential equations to ordinary differential equations that are solved numerically. The similarity transformation elucidates the origin of the square‐root‐of‐time front scaling. The similarity solution is then compared to the numerical solution of the full drift‐diffusion equations, finding excellent agreement. When compared with experimental data, our model captures the front location; however, qualitative differences between the ion profiles are observed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1447–1454, 2015     

Morphology‐dependent electrocatalytic activity of nanostructured Pt/C particles from hybrid aerosol–colloid process

An optimum nanostructure and pore size of catalyst supports is very important in achieving high catalytic performances. In this instance, we evaluated the effects of various carbon nanostructures on the catalytic performances of carbon‐supported platinum (Pt/C) electrocatalysts experimentally and numerically. The Pt/C catalysts were prepared using a hybrid method involving the preparation of dense, hollow, and porous nanostructured carbon particle via aerosol spray pyrolysis followed by microwave‐assisted Pt deposition. Electrochemical characterization of the catalysts showed that the porous Pt/C catalyst gave the best performance; its electrochemical surface area was much higher, more than twice than those of hollow or dense Pt/C. The effects of pore size on electrocatalysis were also studied. The results showed the importance of a balance between mesopores and macropores for effective catalysis with a high charge transfer rate. A fluid flow model showed that good oxygen transport contributed to the catalytic activity. © 2015 American Institute of Chemical Engineers AIChE J, 62: 440–450, 2016