Analytical Performance Evaluation of a STBC Coded OFDM FSO Communication System over Turbulent Atmospheric Channel

Journal of Communications Technology and Electronics - An analytical approach is presented for an optical IM/DD system with STBC coded OFDM RF subcarrier modulation over a free space optical...     

Retorting of oil shale from new brunswick,canada

Two oil shale samples from the Albert formation in the Moncton Sub-basin, New Brunswick have been retorted in direct and indirect modes in a pilot scale moving bed retort. The maximum oil recoveries were 81% and 89% of the Fischer assay for direct and indirect mode retorting, respectively. Shale grade, bed height, retort temperature profile, recycle gas and its distribution, and air feed rate affected the oil recovery. The spent shale retained approximately 30% of the energy content of the fresh shale.     

Improved quality a-SiC:H films prepared by photo chemical vapour decomposition of silane and acetylene

Hydrogenated amorphous and microcrystalline silicon carbon alloy films have been grown by photo-CVD using C₂H₂ as a source gas of carbon. The hydrogenated amorphous silicon carbon (a-SiC:H) film with a band gap of ~2.0 eV prepared at a very low hydrogen (LD) concentration exhibits better photo-electronic properties compared to that at high hydrogen dilution (HD) having a similar optical gap. Notwithstanding a high deposition rate, the high photosensitivity ( 10⁶), the low density of the defect states ( 6 × 10¹⁶cm⁻³) and the Urbach energy parameter (72 meV) for the a-SiC:H film prepared at low hydrogen dilution and pressure are impressive. On the other hand, low pressure along with high hydrogen dilution have been found to be conducive to microcrystalline silicon carbon alloy (μc-Si:H) formation. Interestingly, crystallites are of silicon while carbon remains in the amorphous and grain boundary regions.     

Dielectric properties of vacuum-deposited Yb2O3 films

The dielectric properties, i.e. the frequency (100 Hz–20 kHz) and temperature (0–125°C) dependence of the capacitance and loss factor tan δ, of vacuum-deposited Yb₂O₃ film capacitors with oxide thickness of 400–2000 Å were studied. The temperature coefficient of capacitance, the percentage variation ΔC/C(%) in capacitance at room temperature normalized at 1 kHz etc. were also investigated.     

Cooperative content delivery exploiting multiple wireless interfaces: methods,new technological developments,open research issues and a case study

In this tutorial paper, we discuss and compare cooperative content delivery (CCD) techniques that exploit multiple wireless interfaces available on mobile devices to efficiently satisfy the already massive and rapidly growing user demand for content. The discussed CCD techniques include simultaneous use of wireless interfaces, opportunistic use of wireless interfaces, and aggregate use of wireless interfaces. We provide a taxonomy of different ways in which multiple wireless interfaces are exploited for CCD, and also discuss the real measurement studies that evaluate the content delivery performance of different wireless interfaces in terms of energy consumption and throughput. We describe several challenges related to the design of CCD methods using multiple interfaces, and also explain how new technological developments can help in accelerating the performance of such CCD methods. The new technological developments discussed in this paper include wireless interface aggregation, network caching, and the use of crowdsourcing. We provide a case study for selection of devices in a group for CCD using multiple interfaces. We consider this case study based on the observation that in general different CCD users can have different link qualities in terms of transmit/receive performance, and selection of users with good link qualities for CCD can accelerate the content delivery performance of wireless networks. Finally, we discuss some open research issues relating to CCD using multiple interfaces.     

Computational analysis of temperature rises in microstructures of HMX-Estane PBXs

The thermomechanical response of HMX/Estane, a polymer-bonded explosive (PBX) is analyzed for initial temperatures between 210 and 300 K. The main objective of this analysis is to gain a better understanding of the concepts that lead to deformation and heating of energetic composites as they undergo mechanical and thermal processes subsequent to impact. A recently developed cohesive finite element method (CFEM) framework is used to study the microstructure-level response of PBX. The CFEM framework allows the contributions of individual constituents, fracture and frictional contact along failed crack surfaces to heating to be tracked and analyzed. Digitized micrographs of actual PBX materials are used. The issues studied include large deformation, thermomechanical coupling, failure in the forms of microcracks in both bulk constituents and along grain/matrix interfaces, and frictional heating. The focus is on the correlation between grain-level failure mechanisms and overall temperature rise in the PBX. The results are used to establish microstructure-response relations that can be used in the design of energetic composites.     

Use of essential oils and phytochemicals against the mycotoxins producing fungi for shelf-life enhancement and food preservation

Mycotoxin-producing fungi are a significant source of crop and food contamination, posing a significant threat to global food safety and security. Essential oils, plant extracts and phytochemicals have emerged as green preservatives to extend the shelf-life of foods due to their unique antimicrobial properties. Unlike conventional synthetic preservatives, they are a sustainable and safe way to preserve food with no or little harmful effects on the environment. Use of nanoformulations containing essential oils and phytochemicals offer enormous potential as a mitigation strategy to lower mycotoxin contamination incidences in food and crop with enhanced release behaviour to efficiently transport them to the target location for a rapid reaction without much impact from environmental variables. Hence, this review overviews various essential oils and phytochemicals utilized through nanoformulations to control the mycotoxigenic fungi, probable mechanism of actions involved as well as emerging mycotoxins and associated safety concerns to ensure food sustainability.     

Behaviour of mortar infilled steel frames under lateral load

An analytical method taking into account the axial deformations of the members of the frame and the slip at the interface has been summarised for linear elastic behaviour of a homogeneous and isotropic infill. The theoretical and experimental results have been compared.