Equalization and interference cancellation in linear multiusersystems based on second-order statistics

Potential applications of blind channel identification and equalization in data communication systems have recently been explored. For multiuser systems that are irreducible and column-reduced, second-order statistical methods normally can identify channel dynamics up to a unitary mixing matrix. Additional user separation (equalization) can rely on higher order statistics and other prior information. In this paper, we investigate the equalizability of user signals and the cancellation of unwanted interfering signals based only on second-order output statistics. We show that a user channel can be equalized if it has the longest memory. Furthermore, interfering user signals can be cancelled under a more relaxed multiuser channel condition     

Synergistic Effects of Carbon Fillers of Phenolic Resin Based Composite Bipolar Plates on the Performance of PEM Fuel Cell

The most essential and costly component of polymer electrolyte membrane fuel cells is the bipolar plate. The production of suitable composite bipolar plates for polymer electrolyte membrane fuel cell with good mechanical properties and high electrical conductivity is scientifically and technically very challenging. This paper reports the development of composite bipolar plates using exfoliated graphite, carbon black, and graphite powder in resole‐typed phenol formaldehyde. The exfoliated graphite with maximum exfoliated volume of 570 ± 10 mL g⁻¹ used in this study was prepared by microwave irradiation of chemically intercalated natural flake graphite in a few minutes. The composite plates were prepared by varying exfoliated graphite content from 10 to 35 wt.% in phenolic resin along with fixed weight percentage of carbon black (5 wt.%) and graphite powder (3 wt.%) by compression molding. The composite plates with filler weight percentage of 35/5/3/exfoliated graphite/carbon black/graphite powder offer in‐plane and trough‐plane electrical conductivities of 374.42 and 97.32 S cm⁻¹, bulk density 1.58 g cm⁻³, compressive strength 70.43 MPa, flexural strength 61.82 MPa, storage modulus 10.25 GPa, microhardness 73.23 HV and water absorption 0.22%. Further, I–V characteristics notify that exfoliated graphite/carbon black/graphite powder/resin composite bipolar plates in unit fuel cell shows better cell performance compared exfoliated graphite/resin composite bipolar plates. The composite plates own desired mechanical properties with low bulk density, high electrical conductivity, and good thermal stability as per the U.S. department of energy targets at low filler concentration and can be used as bipolar plates for proton exchange membrane fuel cells.     

Dynamic vulcanization of polyethylene‐based thermoplastic elastomer blends

In this investigation, the effects of blending with ethylene–propylene–diene terpolymer and subsequent dynamic curing with sulfur on the macromolecular structure and properties of pure low‐density polyethylene and high‐density polyethylene were studied. The crosslinking efficiency of polyethylene‐based ethylene–propylene–diene terpolymer blends upon dynamic curing was assessed with torque and gel content measurements. The curing of dispersed ethylene–propylene–diene terpolymer in a polyethylene matrix improved both the mechanical and thermomechanical properties as a result of the formation of a crosslink structure in the rubber phase. In view of the electrical applications of this cured blend material, the volume resistivity was measured. The thermal stability of vulcanized polyethylene/ethylene–propylene–diene terpolymer blends was found to be superior to that of unvulcanized blends. In scanning electron microscopy analysis, good interface bonding between the polyethylene matrix and dispersed ethylene–propylene–diene terpolymer was observed for the cured blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermostable and flame retardant Mesua ferrea L. seed oil based non-halogenated epoxy resin/clay nanocomposites

Bio-based polymer nanocomposites have a unique niche of their own in the domain of green technology. A bio-based sulfone epoxy resin (BPSE) has been synthesized from the monoglyceride of Mesua ferrea L. seed oil, bis(4-hydroxyphenyl) sulfone, bisphenol-A and epichlorohydrin. The formation of resin was confirmed by the determination of viscosity, epoxy equivalent, etc. and the structure was elucidated from FTIR and ¹H NMR spectroscopies. This resin was used as the matrix for the preparation of epoxy/clay nanocomposites by ex situ technique using different doses of organo nano-clay (1, 2.5 and 5%, w/w). XRD, TEM, SEM, FTIR and rheological studies confirmed the formation of nanocomposites with partial exfoliated structure of the nano-clay. The study demonstrated that the tensile strength enhanced from 4 to 11.4 MPa, scratch hardness improved by two-fold, gloss value increased by 20 units, adhesive strength improved by two-fold and thermal stability improved by 19 °C on incorporation of 5 wt% of nano-clay with respect to the pristine polymer. The limiting oxygen index value and UL94 test indicated improvement of flame retardancy of the nanocomposites. The results exhibit the potentiality of these bio-based epoxy/clay nanocomposites for multifaceted advanced applications.     

Shelf-Life Extension of Fresh Ginger (Zingiberofficinale) by Gamma Irradiation

ABSTRACT: Gamma irradiation was found to extend the shelf life of farm fresh ginger. A 5-kGy radiation dose and 10 °C storage temperature were found to keep peeled ginger samples microbe free and acceptable until 70 d of storage, whereas nonirradiated (control) peeled ginger spoiled within 40 d under similar storage conditions. The decrease in 6-gingerol, the compound responsible for the pungency of ginger, was found to be insignificant after irradiation.     

Field instrument for simultaneous large dynamic range measurement of atmospheric hydrogen sulfide, methanethiol, and sulfur dioxide

We describe a membrane-based collection/analysis system that differentially monitors H2S and CH3SH, and to which a conductometric SO2 analyzer using the same collector was coupled. A diffusion scrubber (DS) comprised of a Nafion tube collects H2S selectively while a porous polytetrafluoroethylene (pPTFE) DS collects both H2S and CH3SH. Both gases are measured via their ability to react with fluorescein mercuric acetate (FMA) which results in decreased fluorescence. The limited dynamic range of a negative signal procedure was overcome by using dual DS units comprised of short and long scrubbers, placed serially in the liquid flow line. Different DS designs and membrane materials were investigated. H2S, CH3SH, and SO2 from a biogenic point source were continuously measured, and the H2S/CH3SH data compared well with a standard procedure involving Tedlar bag collection, preconcentration and thermal desorption from a Tenax trap, and measurement by gas chromatography/flame photometric detection. Walkaround portability of the instrument and very large dynamic range measurement of H2S and SO2 were demonstrated around the Mt. Aso volcano.     

Potentiality of Indian pineapple leaf fiber for apparels

The use of textile-grade fiber extracted from the Indian pineapple leaf is an unexplored area. Pineapple leaf fiber (PALF) is fine, soft, and moderately strong and is much acceptable for fashion garment. An attempt has been made to extract and soften Indian PALF from the pineapple leaves by decortication and subsequent water retting. Decorticated cum retted fiber has shown better physicomechanical and surface appearance properties than decorticated fiber. Fine yarn (38 tex) was spun in a suitable spinning system, and the property performance was found to be suitable to make eco-sustainable novelty fabric. Fabric was developed by using cotton as warp yarn and PALF-based yarn as weft in a handloom. The developed fabric shows very good physical and mechanical properties, desired for apparels. This inferred that Indian PALF may be successfully used to make eco-niche apparel quality fabric as well as novelty textiles.     

A simple polyol synthesis of silver metal nanopowder of uniform particles

Silver metal has been synthesized in form of a finely divided loose nanopowder, 10–30 nm particle sizes, using a simple polyol process. In hot water, polymer molecules of polyvinyl alcohol (PVA) induce Ag⁺ → Ag reaction as a weak reducer (suitable to control the final particle size), forming a nanofluid of Ag nanoparticles in situ dispersing in part of PVA molecules. Ag nanoparticles do not aggregate much when casting a viscous Ag–PVA nanofluid (hot) onto a substrate in thin laminates or films. Freestanding Ag–PVA films could be obtained of 1–5 mm thickness after drying at room temperature. Dried sample can be easily peeled from a silicate glass substrate. As small as 5–10 mm Ag–PVA pieces were heated in air in order to recollect Ag nanoparticles by burning off the polymer. At 300–400 °C, Ag–PVA disintegrates and encounters combustion in air, resulting in a pure Ag-powder. As analyzed by X-ray diffraction, a single crystalline phase of an Fm3m cubic crystal structure formed. Lattice parameter a = 0.4071 nm and density ρ = 10.61 g/cm³ compare well the bulk values a = 0.4086 nm and ρ = 10.50 g/cm³.     

Economic and energy efficiency of salvaging biomass from wildfire burnt areas for bioenergy production in northwestern Ontario: A case study

Wildfire burnt forest biomass can be salvaged as feedstock for bioenergy power generating stations. Despite availability of such forest biomass in northwestern Ontario, its procurement has generally been considered uneconomic and no studies have looked into the cost of harvesting, processing, and transporting the burnt material for bioenergy production. In order to meet the demand of biomass for proposed and existing power generating stations using renewable fuels, a standard costing model is used to determine the feasibility of procuring biomass from burnt areas using a full-tree to roadside, roadside grinder to mill system. The case-study was conducted at the Hogarth Plantations near Thunder Bay, Ontario, Canada. The total cost incurred for processing and delivery of biomass from wildfire burnt area with a hauling distance of 7 km and total trip cycle time of 2.55 h was found to be $29.65 gt^?1, with net energy content of 11.4 GJ gt^?1. The total procurement cost depends on the hauling distance and a linear relationship between the two was established. The energy analysis found a net energy output to input ratio of 35:1 for the operation.     

Experimental investigation of dryout phenomena under oscillatory flow conditions

In water-cooled nuclear reactors, the maximum power which can be extracted from the core is limited by critical heat flux (CHF). CHF in the high-quality region is known as dryout. In advanced nuclear reactors, the coolant flow occurs solely by virtue of natural circulation; however, instabilities may occur during off-normal operations. This may lead to premature dryout due to lower coolant flow rates seen by the heater during such oscillations. This paper describes the experimental investigation on the effect of flow oscillations on the CHF with the time period of 120 s, which is observed typically in the large-scale natural circulation system. Based on observations made with respect to temperature transient, the continuous dryout is preceded by the transient dryout for higher flow oscillations. But as flow fluctuation decreases, the transient dryout phenomenon is found to disappear. The applicability of the look-up table to predict CHF under oscillatory flow conditions using suitable correction factors (CFs) for premature dryout has been evaluated. CFs for the CHF under oscillations suggested by previous authors have been compared. The maximum possible degradation in CHF value suggested by previous authors has been found to agree with the present experimental data. Percentage fluctuation in heat transfer coefficient (HTC) at fully developed annular flow conditions has been evaluated, and it is found that fluctuation in HTC is in phase with the fluctuation in flow.