Intra-ONU bandwidth scheduling in Ethernet passive optical networks

Quality-of-service (QoS) support in Ethernet passive optical networks (EPON) is a crucial concern. However, most studies have only focused on optical line terminal (OLT) capacity allocation amongst multiple optical network units (ONU), and the further issue of intra-ONU allocation remains open. In this work a novel decentralized intra-ONU solution is presented using virtual-time schedulers. Results confirm good performance for a wide range of input traffic classes and loads.     

Isolation of NADH from Saccharomyces cerevisiae by ether permeabilization and its purification by affinity ultrafiltration

Cells of Saccharomyces cerevisiae were permeabilized by ether for the isolation of coenzyme NADH. A 4-fold increase in the ether fraction to aqueous fraction resulted in the recovery of 80% of total NADH present in the cell. NADH was separated and purified by affinity ultrafiltration using yeast alcohol dehydrogenase as an affinity ligand. The binding characteristics of the enzyme and coenzyme were established at different pH and ionic strengths using gel filtration. The number of moles of NADH bound per mole of alcohol dehydrogenase (r) was found to be 5.7 at pH 8 and ionic strength (I) 0.1 M. The binary complex of NADH and alcohol dehydrogenase was cleaved by lowering the pH to 6.0. The crude cell permeate on purification by ultrafiltration with 2-fold dilution, gave NADH with an absorbance ratio (A260/A340) of 2.3 and overall yield of 68%. Alcohol dehydrogenase was recovered as retentate with 93% recovery and 15% loss in activity.     

Preparation and evaluation of functionalized goethite nanorods coated by molecularly imprinted polymer for selective extraction of bisphenol A in aqueous medium

Molecular imprinting method is widely used to recognize various templates. Recognition of bisphenol A (BPA) as a harmful template is important. Herein a novel BPA molecular imprinted polymer nanoparticles (BMIPN) is reported by core-shell surface molecular imprinting technology. In this process, BPA was imprinted by polymerizing methacrylic acid (MAA) as functional monomer, in presence of ethylene glycol dimethacrylate (EGDMA) as a cross-linker and goethite nanorods (GNR) functionalized with fumaric acid. The formation of different materials in different steps was confirmed by Fourier transform infrared spectroscopy (FT-IR), the size and surface morphological of material was observed by field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). The BMIPN structure was characterized by X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The important effective factors on adsorption process such as pH, contact time, amount of GNR, initial concentration of BPA, release and reusability and selectivity of BMIPN were studied. The excellent selectivity behavior of BMIPN was evaluated in the presence of phenol (Ph), 4, 4′-biphenol (BPh), hydroquinone (HQ) and 2, 2′-Bis(4-hydroxyphenyl)butane (BPB), as interferences. Based on the isotherm and kinetic studies, the experimental data obey Langmuir isotherm and the pseudo-second-order kinetic models. The results showed that BMIPN had excellent properties for adsorbing BPA in a short time even in the presence of analogous.     

Volume changes upon heating of aerosol particles from biomass burning using transmission electron microscopy

The responses of aerosol particles to heating are important for measurements of their chemical, physical, and optical properties, classification, and determination of origin. However, the thermal behavior of organic aerosol particles is largely unknown. We provide a method to analyze such thermal behavior through heating from room temperature to >600°C by using a heating holder within a transmission electron microscope (TEM). Here we describe in-situ shape and size changes and variations in the compositions of individual particles before and after heating. We use ambient samples from wildland and agricultural biomass fires in North America collected during the 2013 Biomass Burning Observation Project (BBOP). The results indicate that individual tar balls (TB; spherical organic material) from biomass burning retained, on average, up to 30% of their volume when heated to 600°C. Chemical analysis reveals that K and Na remain in the residues, whereas S and O were lost. In contrast to bulk sample measurements of carbonaceous particles using thermal/optical carbon analyzers, our single-particle results imply that many individual organic particles consist of multiple types of organic matter having different thermal stabilities. Beyond TBs, our results suggest that because of their thermal stability some organic particles may not be detectable by using aerosol mass spectrometry or thermal/optical carbon analyzers. This result can lead to an underestimate of the abundance of TBs and other organic particles, and therefore biomass burning may have more influence than currently recognized in regional and global climate models.

Copyright © 2018 American Association for Aerosol Research     

Efficient and secure cryptosystem for fingerprint images in wavelet domain

In this paper, a fingerprint image encryption algorithm is proposed in order to enhance the protection of fingerprint-based systems against replay attacks. The proposed algorithm is consisting of permutation and diffusion operations in wavelet domain, whereas, one-level Lifting Wavelet Transform Integer-to-Integer is performed to the original fingerprint image. The approximation and detail sub-bands are then partitioned into blocks and permuted using a permutation key. It is noteworthy that, for each sub-band the Rubik’s cube principle is applied. The encrypted image is constructed by ordering the encrypted sub-bands. Eventually, an experimental tests and security analysis were conducted on three fingerprint images attained through Fingerprint Verification Competition “FVC 2000” database. The obtained results confirm the effectiveness of the proposed encryption algorithm and clearly show the robustness against common attacks, for example differential and statistical attacks. In addition, it reveals the high security level achieved.     

Capacitance modelling of perforated RF MEMS shunt switch

Microsystem Technologies - This paper presents the capacitance modelling of RF MEMS shunt switch by using the parallel plate, fringing field, and parasitic capacitance. The model carried out...     

Investigation on dual‐port printed MIMO antenna with reduced RCS for C‐band radar application

In this communication, two port printed Multi Input Multi Output (MIMO) antenna with reduced radar cross section and low mutual coupling is designed and analyzed. Reduced mutual coupling (less than ?20 dB) is achieved by placing the electromagnetic band gap structure in between the two identical ports. Frequency selective surface has been used to reduce the radar cross section (more than 30 dB reduction) of the proposed antenna design, which makes it suitable for military applications. The proposed radiating design is fabricated and measured for the purpose of validation. It resonates at 6.8 GHz supporting an impedance bandwidth of 1.03 GHz from 6.12 to 7.15 GHz. It promises a gain of 4.75 dB in the working frequency range. This radiator is suitable for military radars works in C‐band.     

Multilevel heterogeneous network model for wireless sensor networks

The lifetime of a network can be increased by increasing the network energy. The network energy can be increased either increasing the number of sensors or increasing the initial energy of some sensors without increasing their numbers. Increasing network energy by deploying extra sensors is about ten times costlier than that using some sensors of high energy. Increasing the initial energy of some sensors leads to heterogeneous nodes in the network. In this paper, we propose a multilevel heterogeneous network model that is characterized by two types of parameters: primary parameter and secondary parameters. The primary parameter decides the level of heterogeneity by assuming the values of secondary parameters. This model can describe a network up to nth level of heterogeneity (n is a finite number). We evaluate the network performance by applying the HEED, a clustering protocol, on this model, naming it as MLHEED (Multi Level HEED) protocol. For n level of heterogeneity, this protocol is denoted by MLHEED-n. The numbers of nodes of each type in any level of heterogeneity are determined by the secondary model parameter. The MLHEED protocol (for all level heterogeneity) considers two variables, i.e., residual energy and node density, for deciding the cluster heads. We also consider fuzzy implementation of the MLHEED in which four variables are used to decide the cluster heads: residual energy, node density, average energy, and distance between base station and the sensor nodes. In this work, we illustrate the network model up to seven levels (\(1\le n\le 7\)). Experimentally, as the level of heterogeneity increases, the rate of energy dissipation decreases and hence the nodes stay alive for longer time. The MLHEED-m, \(m=2,3,4,5,6,7\), increase the network lifetime by \(73.05, 143.40, 213.17, 267.90, 348.60, 419.10\,\%\), respectively, by increasing the network energy as \(40, 57, 68.5, 78, 84, 92.5\,\%\) with respect to the original HEED protocol. In case of fuzzy implementation, the MLHEEDFL-m, \(m=2,3,4,5,6,7,\) increases the network lifetime by \(282.7, 378.5, 435.78, 498.50, 582.63, 629.79\,\%\), respectively, corresponding to the same increase in the network energy as that of the MLHEED (all levels) with respect to the original HEED. The fuzzy implementation of the HEED, MLHEEDFL-1, increases the network lifetime by \(176.6\,\%\) with respect to the original HEED with no increase in the network energy.     

Effect of temperature on electrical behavior of flyash‐filled epoxy gradient composites

Functionally gradient composites of epoxy resin having different weight percentages of flyash were prepared under centrifugal force to obtain gradient in density, hardness, and electrical properties. Effect of temperature and frequency variation on dielectric constant (ε′), tan δ, and ac conductivity was determined by using a 4274 A Multi‐Frequency LCR meter. Electrical measurements were carried out in a temperature range from 40 to 180°C and in a frequency range from 1 to 100 kHz. It was observed that the dielectric constant and tan δ increased with increase in temperature and decreased with increase in frequency. The ac conductivity increases with increase in temperature and frequency. The increased weight percentage of flyash increased the compaction of flyash particle in the flyash‐rich phase of graded composites, which would have increased the dielectric constant (ε′), tan δ, and ac conductivity. Shore D hardness and density of the functionally gradient composites has also been determined and reported. A continuous increase in the hardness from 69 to 76 and density from 1.287 to 1.41 g/cc has been observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1269–1276, 2006