A Novel Wormy Cellular Structure for High Altitude Platforms Mobile Communications

In this paper, a novel beamforming technique is proposed for the high altitude platforms (HAPs) mobile communications to generate adaptive radio coverage worm-shaped cells to cover the main highways. This technique is based on pattern summation of individual low-sidelobe narrow beams—which constitute the desired cell pattern—weighted by an adaptive amplitude correcting function. The new shaped cell differs from the conventional hexagonal or elliptical cells as it follows the curvatures of the highway for long distances up to 100 km, therefore it has an important role in reducing the frequent handoff and signaling traffic of location updating from moving users over long highways.

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Association between teat skin colonization and intramammary infection with Staphylococcus aureus and Streptococcus agalactiae in herds with automatic milking systems

The objective of this study was to investigate the association between teat skin colonization and intramammary infection (IMI) with Staphylococcus aureus or Streptococcus agalactiae at the quarter level in herds with automatic milking systems. Milk and teat skin samples from 1,142 quarters were collected from 300 cows with somatic cell count >200,000 cells/mL from 8 herds positive for Strep. agalactiae. All milk and teat skin samples were cultured on calf blood agar and selective media. A subset of samples from 287 quarters was further analyzed using a PCR assay (Mastit4 PCR; DNA Diagnostic A/S, Risskov, Denmark). Bacterial culture detected Staph. aureus in 93 (8.1%) of the milk samples and 75 (6.6%) of the teat skin samples. Of these, 15 (1.3%) quarters were positive in both the teat skin and milk samples. Streptococcus agalactiae was cultured in 84 (7.4%) of the milk samples and 4 (0.35%) of the teat skin samples. Of these, 3 (0.26%) quarters were positive in both the teat skin and milk samples. The PCR detected Staph. aureus in 29 (10%) of the milk samples and 45 (16%) of the teat skin samples. Of these, 2 (0.7%) quarters were positive in both the teat skin and milk samples. Streptococcus agalactiae was detected in 40 (14%) of the milk samples and 51 (18%) of the teat skin samples. Of these, 16 (5.6%) quarters were positive in both the teat skin and milk samples. Logistic regression was used to investigate the association between teat skin colonization and IMI at the quarter level. Based on bacterial culture results, teat skin colonization with Staph. aureus resulted in 7.8 (95% confidence interval: 2.9; 20.6) times higher odds of Staph. aureus IMI, whereas herd was observed as a major confounder. However, results from the PCR analyses did not support this association. Streptococcus agalactiae was isolated from the teat skin with both PCR and bacterial culture, but the number of positive teat skin samples detected by culture was too low to proceed with further analysis. Based on the PCR results, Strep. agalactiae on teat skin resulted in 3.8 (1.4; 10.1) times higher odds of Strep. agalactiae IMI. Our results suggest that Staph. aureus and Strep. agalactiae on teat skin may be a risk factor for IMI with the same pathogens. Focus on proper teat skin hygiene is therefore recommended also in AMS.     

Effects of active chitosan-flaxseed mucilage-based films on the preservation of minced trout fillets: A comparison among aerobic,vacuum, and modified atmosphere packaging

The objectives of the current study were to examine physical–mechanical, structural, and morphological characteristics of chitosan-flaxseed mucilage films enriched with Ziziphora clinopodioides essential oil (ZEO; 0%, 0.25%, and 0.5%) and sesame oil (SO; 0% and 0.75%) and to provide useful information for the preservation of minced trout fillet's using antimicrobial films under aerobic, vacuum, and modified atmosphere conditions for 16 days. The films showed thickness, tensile strength, puncture force, puncture deformation, water vapor transmission rate, water vapor permeability, swelling index, and oxygen permeability values ranging 0.082–0.86 mm, 33.34–46.83 MPa, 25.69–53.08 N, 11.45–28.45 mm, 17.48–26.73 g/m² h, 8.57–12.49 × 10⁻⁴ g mm/m² h Pa, 12.45–38.43%, and 3.02–13.32 × 10⁻¹² cm³/m² s Pa, respectively. The following order of effect on the microbial spoilage population of treated samples was found in the applied packaging methods: modified atmosphere packaging > vacuum packaging > aerobic packaging. The final microbial population of treated samples was 0.35–4.91 log CFU/g lower than the controls after 16 days of refrigerated storage. At the end of the storage, the total volatile base nitrogen, peroxide value, and thiobarbituric acid reactive substances of untreated samples were 34.02–48.6 mg of N/100 g, 1.43–2.32 meq of peroxide/1000 g, and 3.33–4.24 mg of malondialdehyde/kg, respectively. The lowest corresponding values were recorded for the treated samples with ZEO 0.5% + SO 0.75% films by 14.26–17.73 mg of N/100 g, 0.48–0.86 meq of peroxide/1000 g, and 1.08–1.48 mg of malondialdehyde/kg, respectively.     

Effects of carbon nanotubes and interphase properties on the interfacial conductivity and electrical conductivity of polymer nanocomposites

L_c is the minimum length of carbon nanotubes (CNTs) required for efficient transfer of filler conductivity to polymer matrix in polymer CNT nanocomposites (PCNTs). In this work, L_c is correlated with the dimensions of the CNTs and the interphase thickness. Subsequently, the interfacial conductivity as well as the effective length and concentration of CNTs are expressed by CNT and interphase properties. Moreover, a simple model for the tunneling conductivity of PCNTs is developed with these effective terms. The impacts of all parameters on L_c, the interfacial conductivity, the fraction of CNTs in the networks and the conductivity of the PCNT are explained and justified. In addition, the predictions of the percolation threshold and conductivity are compared with the experimental results of several samples. The desirable values of interfacial conductivity are achieved by thin, short and super‐conductive CNTs, high waviness and a thick interphase. However, thin and long CNTs, low waviness, a thick interphase, poor tunneling resistivity due to the polymer matrix and a short tunneling distance advantageously affect the conductivity of PCNTs, because they produce large conductive networks. The predictions also show good agreement with the experimental measurements of percolation threshold and conductivity, which confirms the developed equations. © 2020 Society of Chemical Industry     

Electro-osmotic flow of fractional second-grade fluid with fractional Cattaneo heat flux through a vertical microchannel

This study investigates the unsteady electro-osmotic flow (EOF) of a fractional second-grade fluid through a vertical microchannel with convection heat transfer. The fractional Cattaneo heat flux model will be used to modify the heat equation. The solutions for the velocity and the temperature have been derived by employing the Laplace and finite Fourier sine transforms and their numerical inverses. The results show that at the beginning of the time period, the fractional parameter postpones the movement of the fluid. Furthermore, the results show that at the high values of retardation time (non-Newtonian case), the required time for the velocity and the flow rate to reach the steady state increases. Moreover, the heat relaxation time reduces the heat transfer until a critical time, and then the effect reverses.     

Performance Analysis of Novel Multi-band Monopole Antenna for Various Broadband Wireless Applications

Wireless Personal Communications - This study investigates a novel concept of using slot and Coplanar Waveguide fed antenna to obtain multiband operation. The compact antenna includes a star...     

Estimation of average contact number of carbon nanotubes (CNTs) in polymer nanocomposites to optimize the electrical conductivity

The present paper suggests an equation for the average contact number of carbon nanotubes (CNTs) in CNT-reinforced polymer nanocomposites (PCNT) by two developed equations for electrical conductivity. Several novel parameters in PCNT such as CNT size, CNT concentration, network fraction, interphase depth, tunneling effect, and CNT wettability by the polymer medium are considered to define the average contact number (m). “m” is calculated for some samples and the variation of “m” is explored over a range of parameters’ values. The results show that dense interphase, high fraction of networked CNTs, reedy and short CNTs, low CNT surface energy, high polymer surface energy, low tunneling distance, and small contact diameter increase the “m” improving the conductivity. Moreover, tunneling distance and CNT contact diameter have the greatest effects on the “m”. The optimized level for “m” is necessary to control the nanocomposite’s conductivity.