Interference Nomenclature in Wireless Mesh Networks

The Quality of Service of Multi-Channel Multi-Radio Wireless Mesh Networks is adversely affected by the complex behavior of interference patterns present between the sender and receiver of a link. This behavior is usually captured using wireless channel interference models. The accuracy of the interference model is highly dependent on the interaction of the Carrier Sense Multiple Access with Collision Avoidance Medium Access Control (CSMA/CA MAC) protocol based on the geometric location of the sender and receiver of the link. Therefore, this paper presents a nomenclature of interference modeling schemes available in Wireless Mesh Network (WMN) literature with respect to the geometric location of the sender and receiver of a link. The behavior and limitations of each model are analyzed with the help of empirical examples. The results indicate that Garetto’s model of interfering links is the best choice to model wireless channel interference in WMNs. In addition, this study provides an interference analysis of Garetto’s model for the two link case by computing the conditional packet loss probability of each class of interfering link. The probability analysis concluded that the links with disconnected senders are highly interfering compared to sender connected links. Further, the analysis will assist researchers and engineers in relay node placement, capacity analysis, channel assignment, and topology control schemes in the WMN.     

Study on thermal,spectroscopic and electrochemical behavior of some ferrocene-containing organometallic polyesteramides and their siloxane-based block copolymers

The thermal, spectroscopic and electrochemical behavior of some novel ferrocene-containing polyesteramides and their siloxane-based block copolymers are described in the present study. The thermal properties of the organometallic materials were investigated by thermogravimetric analysis (TGA) and compared with their terephthaloyl- and isophthaloyl-based organic analogues. The energies of activation of pyrolysis for the polymeric materials were calculated using Horowitz and Metzger method. The spectroscopic and electrochemical properties of the organometallic polymeric materials were examined by means of UV-visible (UV) and cyclic voltammetric (CV) studies. The interactions of these materials with ds.DNA (extracted from chicken blood) were also investigated.     

Porous structures fabrication by continuous and pulsed laser metal deposition for biomedical applications; modelling and experimental investigation

The use of porous surface structures is gaining popularity in biomedical implant manufacture due to its ability to promote increased osseointegration and cell proliferation. Laser direct metal deposition (LDMD) is a rapid manufacturing technique capable of producing such a structure. In this work LDMD with a diode laser in continuous mode and with a CO₂ laser in pulsed modes are used to produce multi-layer porous structures. Gas-atomized Ti-6Al-4V and 316L stainless steel powders are used as the deposition material. The porous structures are compared with respect to their internal geometry, pore size, and part density using a range of techniques including micro-tomography. Results show that the two methods produce radically different internal structures, but in both cases a range of part densities can be produced by varying process parameters such as laser power and powder mass flow rate. Prudent selection of these parameters allows the interconnected pores that are considered most suitable for promoting osseointegration to be obtained. Analytical models of the processes are also developed by using Wolfram Mathematica software to solve interacting, transient heat, temperature and mass flow models. Measured and modelled results are compared and show good agreement.     

Prospects,challenges, and latest developments in lithium–air batteries

Metal–air batteries are being envisioned as a clean and high energy fuel for the modern automotive industry. The lithium–air battery has been found most promising among the various practically applicable metal–air systems, that is, Al–air, Li–air, Mg–air, Fe–air, and Zn–air. The theoretical specific energy of the Li–air battery is ~12 kWh/kg, excluding the oxygen mass. This is comparable with the energy density of gasoline, which is ~13 kWh/kg. It has been hypothesized that the Li–air battery could supply an energy ~1.7 kWh/kg after losses from over potentials to run a vehicle ~300 miles on a single charge. During the first decade of this century, a fair amount of research has been conducted on Li–air battery system. Yet, Li–air batteries could not make an industrial breakthrough, and are still in the laboratory phase since their birth. In this article, we technically evaluated the recent developments, and the inferences have been analyzed from the practical/commercial point of view. The study concludes that low discharge rate, lower number of cycles, oxidation of lithium anode, discharge products at the cathode, and side reactions inside the battery are the key limiting factors in the slow progress of Li–air batteries on an industrial scale. The ongoing researches to overcome these hurdles have also been discussed. This analysis will help the reader to understand the current standing of the lithium–air battery technology. Copyright © 2014 John Wiley & Sons, Ltd.     

Design of momentum LMS adaptive strategy for parameter estimation of Hammerstein controlled autoregressive systems

Neural Computing and Applications - In the present work, strength of momentum least mean square (MLMS) algorithm is exploited for nonlinear system identification problems represented with...     

Initial Plasma Formation in the GLAST-II Spherical Tokamak

This paper reports the initial plasma formation in glass spherical tokamak (GLAST-II) with electron cyclotron resonance pre-ionization assisted startup. Initially, a plasma current of 3 kA has been produced for duration of about 0.5 ms after establishing optimum conditions for microwave absorption at 2.45 GHz. Plasma current is then enhanced up to 5 kA by applying a small vertical magnetic field that provides additional plasma heating and shaping. Applied vertical field is optimized experimentally and optimal value is found to be 40 Gauss for this experiment. Plasma current and loop voltage are monitored by using Rogowski coil and toroidal loop of wire. A fast framing camera (5000 fps) is used for temporal investigation of plasma during the discharge scenario. A fast photodiode (BPX-65) and USB4000 spectrometer are used to record the signature of plasma current and the impurity content (O₂, H etc.). Cross-sectional average electron temperature is also estimated from plasma resistivity and found to be 6.1 eV for maximum plasma current of 5 kA.     

Quantum mechanical interpretation and analysis of perovskite material based single layer fuel cells (SLFCs)

Fossil fuels are unable to meet the current energy demands and polluting the environment with the emission of harmful gases. Therefore, clean energy technology is need of the modern era. One of the energy conversion devices is fuel cell which utilized fuel from renewable sources and convert into electricity in an efficient and clean way. However, for commercialization of this technology high operating temperature, degradation of electrodes and manufacture cost is the key challenges in conventional three layer fuel cell. Significant improvements have been made to reduce the cost and operating temperature by selecting suitable materials. Therefore, single layer fuel cell (SLFC) has been got much attention due to simple geometry. The mechanism inside the SLFC is still mystery which has been explained in this paper using quantum mechanical parameters like band gap and effect of particle size on charge transportation.In this research work, nanocomposite materials for single layer fuel cell have been synthesized by chemical routes. The x-ray diffraction shows the cubic perovskite structure with average crystallite size in the range of 23–37 nm. The particle size and surface area is found to be 23 nm and 86.42 m² g^?1, respectively. Raman spectrum of LBSCF-SDC shows a red shift compared to LBSCF and band gap of the composition 3LBSCF-7SDC is found to be 2.51 eV. Moreover, the conductivity of the sample 3LBSCF-7SDC has been found to be 0.02 Scm^?1 at 750 °C. The quantum mechanical effects governing the working of single layer fuel cells are observed by different analyses. Photon confinement and Fano-Interactions phenomena resulted in a red shift using Raman analysis technique. The red shift in Raman spectrum is referred to a photon confined in a single layer fuel cell system. These effects are studied in single layer fuel cell for the first time with no previous analyses done in this newly field.     

Laser Ablation Process Competency to Fabricate Microchannels in Titanium Alloy

Laser ablation is one of the competent machining processes to fabricate microfeatures in variety of engineering materials. This study has been progressed to evaluate the process capability of generating microchannels of various sizes (50 × 50 µm, 100 × 100 µm, 200 × 100 µm, and 1000 × 500 µm) in titanium alloy (Ti6Al4V) using Nd:YAG laser. Channel's top width, bottom width, depth, and taperness are examined as the four process responses against three laser based parameters to the naming of laser intensity, repetition rate, and scan speed. All the geometrical dimensions are measured through photographic snapshots of SEM of each fabricated channel. The results reveal that the selection of channel size is critical to achieve the desired machining geometries. Wider sized channels (such as 200 × 100 and 500 × 1000 µm) are experienced as more flexible to be generated than narrower sized channels (50 × 50 and 100 × 100 µm). The precise parametric combination is the key to realize more tight dimensional enormities with respect to the targeted machining elements. The most appropriate parametric combinations that can generate the respectable results are explored and applied for machining of different channel sizes.