Optimal Adaptive Modulation and Coding with Switching Costs

We present an optimal adaptive modulation and coding policy that minimizes the transmission latency and modulation/coding switching cost across a finite-state Markovian fading channel. We formulate the optimal tradeoff between transmission latency and modulation/coding switching cost as a discounted infinite horizon Markov Decision Problem (MDP). By exploiting special structures of the formulated MDP and under certain sufficient conditions, we show that optimal modulation and coding selection policies are monotone in the state variables. These monotone optimal policies are computationally inexpensive to implement and are scalable in terms of channel and switching cost parameters. Numerical results confirm the monotonicity and threshold-based structure of the optimal Modulation and Coding Scheme (MCS) selection policies under the proposed sufficient conditions.     

Microscopic and Spectroscopic Evaluation of Inactivation of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> by Pulsed UV Light and Infrared Heating

Pulsed UV light and infrared heat-treated Staphylococcus aureus cells were analyzed using transmission electron microscopy to identify the cell damage due to the treatment process. A 5-s treatment with pulsed UV light resulted in complete inactivation of S. aureus even after enrichment. The temperature increase during the pulsed UV light treatment was insignificant, which suggested a nonthermal treatment. S. aureus was also infrared heat treated using an infrared heating system with six infrared lamps. Five milliliters of S. aureus cells in phosphate buffer was treated at 700°C lamp temperature for 20 min. The microscopic observation clearly indicated that there was cell wall damage, cytoplasmic membrane shrinkage, cellular content leakage, and mesosome disintegration after both pulsed UV light and infrared treatments. Fourier transform infrared microspectrometry was successfully used to classify the pulsed UV light and infrared heat-treated S. aureus by discriminant analysis.     

Predicting trends in structural and physical properties of a model polymer with embedded natural fibers: Viability of molecular dynamics studies for a bottom up design

The effects of relatively high- and low-shear processing on the macroscopic and microscopic porosities of a standard packaging polymer—linear low density polyethylene (LLDPE) and its composites with pine flour are studied. The macroscopic porosities, represented by deviations of observed density from the theoretical density, primarily drive the trends in mechanical and solvent uptake properties. The microscopic porosities of the system, however, are independent of the processing method and pine flour concentration. Furthermore, by using molecular dynamics (MD), molecules of LLDPE and pine flour were constructed. The material properties of the molecules, specifically microporosity and elastic moduli, were compared to experiment. A semiempirical modeling approach was used to fit the simulated data to the experimental composite moduli. The model of Halpin and Tsai was found to be the most efficacious for this system, and the benefits of the combined MD-semiempirical modeling for bottom up design are discussed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48189.     

Evolution and Impact of Wi-Fi Technology and Applications: A Historical Perspective

International Journal of Wireless Information Networks - The IEEE 802.11 standard for wireless local area networking (WLAN), commercially known as Wi-Fi, has become a necessity in our day-to-day...     

Physical layer impairment-aware shared path protection in wavelength-routed optical networks

The Journal of Supercomputing - In this paper, physical layer impairment (PLI)-aware shared path protection (SPP) scheme for single-link failures in transparent optical WDM mesh networks is...     

Binary Cellulose Nanocrystal Blends for Bioinspired Damage Tolerant Photonic Films

Most attempts to emulate the mechanical properties of strong and tough natural composites using helicoidal films of wood‐derived cellulose nanocrystals (w‐CNCs) fall short in mechanical performance due to the limited shear transfer ability between the w‐CNCs. This shortcoming is ascribed to the small w‐CNC‐w‐CNC overlap lengths that lower the shear transfer efficiency. Herein, we present a simple strategy to fabricate superior helicoidal CNC films with mechanical properties that rival those of the best natural materials and are some of the best reported for photonic CNC materials thus far. Assembling the short w‐CNCs with a minority fraction of high aspect ratio CNCs derived from tunicates (t‐CNCs), we report remarkable simultaneous enhancement of all in‐plane mechanical properties and out‐of‐plane flexibility. The important role of t‐CNCs is revealed by coarse grained molecular dynamics simulations where the property enhancement are due to increased interaction lengths and the activation of additional toughening mechanisms. At t‐CNC contents greater than 5% by mass the mixed films also display UV reflecting behaviour. These damage tolerant optically active materials hold great promise for application as protective coatings. More broadly, we expect the strategy of using length‐bidispersity to be adaptable to mechanically enhancing other matrix‐free nanoparticle ensembles.     

Computational fluid dynamics analysis of MQL spray parameters and its influence on superalloy grinding

The application of emulsion for combined heat extraction and lubrication requires continuous monitoring of the quality of emulsion to sustain a desired grinding environment; this is applicable to other grinding fluids as well. To sustain a controlled grinding environment, it is necessary to adopt an effectively lubricated wheel–work interface. The present work aims to develop a numerical model to replicate the mist formation in minimum quantity lubrication (MQL) grinding using a fluent-based computational fluid dynamics (CFD) flow solver. The MQL parameters considered for this study are air pressure and the mass flow rate. Simulation of the atomization under turbulent conditions was done in a discrete phase model (DPM) owing to the fact that oil mass flow rates are very low and oil acts as a discrete medium in air. Jet velocity and droplet diameters were also obtained under different input conditions to find the optimum value of air pressure and mass flow rate of oil to achieve the desired results (lower cutting force and surface roughness) in MQL grinding of superalloy (Inconel 751). It is seen that medium size (around 16.3 µm) of droplet plays a significant role in improved performance by the way of reduction in cutting force and surface roughness.     

High-yield production of graphene by liquid-phase exfoliation of graphite

Fully exploiting the properties of graphene will require a method for the mass production of this remarkable material. Two main routes are possible: large-scale growth or large-scale exfoliation. Here, we demonstrate graphene dispersions with concentrations up to approximately 0.01 mg ml(-1), produced by dispersion and exfoliation of graphite in organic solvents such as N-methyl-pyrrolidone. This is possible because the energy required to exfoliate graphene is balanced by the solvent-graphene interaction for solvents whose surface energies match that of graphene. We confirm the presence of individual graphene sheets by Raman spectroscopy, transmission electron microscopy and electron diffraction. Our method results in a monolayer yield of approximately 1 wt%, which could potentially be improved to 7-12 wt% with further processing. The absence of defects or oxides is confirmed by X-ray photoelectron, infrared and Raman spectroscopies. We are able to produce semi-transparent conducting films and conducting composites. Solution processing of graphene opens up a range of potential large-area applications, from device and sensor fabrication to liquid-phase chemistry.     

Chemical etiology of nucleic acid structure: comparing pentopyranosyl-(2'-->4') oligonucleotides with RNA

All four members of the family of pentopyranosyl-(2'-->4') oligonucleotide systems that contain beta-ribo-, beta-xylo-, alpha-lyxo-, or alpha-arabinopyranosyl units as repeating sugar building blocks are found to be much stronger Watson-Crick base-pairing systems than RNA. The alpha-arabinopyranosyl system is the strongest of all and in fact belongs to the strongest oligonucleotide base-pairing systems known. Whatever the chemical determinants by which nature selected RNA as a genetic system, maximization of base-pairing strengths within the domain of pentose-derived oligonucleotide systems was not the critical selection criterion.     

Mechanical and Swelling Properties of Copolyurethanes based on Hydroxy-Terminated Polybutadiene and its hydrogenated analog

Copolyurethane networks based on Hydroxy-Terminated Polybutadiene (HTPB) and Hydrogenated HTPB (HHTPB) have been synthesized using toluene diisocyanate as curing agent. Addition of HHTPB results in enhancement of properties, such as tensile strength and modulus, at nearly the same elongation values. It is possible to generate urethane networks with similar modulus and tensile strength with widely varying elongation values and vice versa by jointly altering the comonomer ratio, and the r (NCO/OH equivalent ratio) value. Dynamic mechanical studies have been made to determine the storage and loss moduli, and their variations with temperature. Solid propellant formulations processed with the copolyurethanes have been characterized for their mechanical strengths and burn rates.