A survey of wireless technologies coexistence in WBAN: analysis and open research issues

Wireless Body Area Network (WBAN) is the most convenient, cost-effective, accurate, and non-invasive technology for e-health monitoring. The performance of WBAN may be disturbed when coexisting with other wireless networks. Accordingly, this paper provides a comprehensive study and in-depth analysis of coexistence issues and interference mitigation solutions in WBAN technologies. A thorough survey of state-of-the art research in WBAN coexistence issues is conducted. The survey classified, discussed, and compared the studies according to the parameters used to analyze the coexistence problem. Solutions suggested by the studies are then classified according to the followed techniques and concomitant shortcomings are identified. Moreover, the coexistence problem in WBAN technologies is mathematically analyzed and formulas are derived for the probability of successful channel access for different wireless technologies with the coexistence of an interfering network. Finally, extensive simulations are conducted using OPNET with several real-life scenarios to evaluate the impact of coexistence interference on different WBAN technologies. In particular, three main WBAN wireless technologies are considered: IEEE 802.15.6, IEEE 802.15.4, and low-power WiFi. The mathematical analysis and the simulation results are discussed and the impact of interfering network on the different wireless technologies is compared and analyzed. The results show that an interfering network (e.g., standard WiFi) has an impact on the performance of WBAN and may disrupt its operation. In addition, using low-power WiFi for WBANs is investigated and proved to be a feasible option compared to other wireless technologies.     

Synthesis,Characterization and Effect of a Solvent Mixture on the CMC of a Thio-Based Novel Cationic Surfactant Using a UV–Visible Spectroscopic Technique

A novel thio-based cationic surfactant has been synthesized by a new method. It was characterized by different techniques such as NMR, FTIR and its critical micelle concentration was determined by a UV–Visible spectroscopic technique. It is soluble in polar solvents like ethanol and partially soluble in water due to its thio-based functionality. The detailed study of the compound 4-chloro-N-((dodecanoyl(ethyl)ammonio)carbonothioyl)-N-ethylbenzenaminium bromide (4CDTB) was done using a UV–Visible spectrophotometric technique. The effect of solvent mixtures of different ratios was investigated. On the basis of solvent–solvent interaction the compound showed different results. The critical micelle concentration varied with solvent mixture ratios. The CMC of 4CDTB decreased as the ratio of water increased in the mixture of the ethanol–water system. The decrease in critical micelle concentration with the solvent mixture ratio has been discussed on the basis of solvent properties, structures, and their hydrophilic and hydrophobic interactions.     

High Yield Synthesis,Detailed Spectroscopic Characterization and Electrochemical Fate of Novel Cationic Surfactants

Two new cationic surfactants, N-(dodecanoyl(ethylammonio)carbonothioyl)-N-ethylbenzenaminium bromide and N-(dodecanoyl(ethylammonio)carbonothioyl)-N-ethyl-N-phenylbenzenaminium bromide were synthesized with a high yield by the reaction of appropriate amounts of lauryl chlorides, potassium thiocyanate, amine and alkyl halides. The structures were characterized by ¹H-NMR, ¹³C-NMR, FTIR and UV–Vis spectroscopy. Cyclic, square wave and differential pulse voltammetry were used to investigate the electrochemical fate of both surfactants over a wide pH range.     

An improved genetic algorithm for robust permutation flowshop scheduling

In order to deal with uncertainties, a robust schedule for M-machine permutation flowshop is proposed. The presented robust schedule is aimed to maximize the probability of ensuring that makespan will not exceed the expected completion time. An improved genetic algorithm (GA) with a new generation scheme is developed, which can preserve good characteristics of parents in the new generation. Experiments are performed to get robust schedules for well-known Car and Rec permutation flowshop problems, taken from OR library. The schedules obtained from the improved GA are compared with the schedules formed by well-known heuristic in literature. Computational results show that the permutation flowshop schedules obtained from improved GA are robust to produce an affirmative percentage increase in the probability of getting makespan less than expected completion time.     

Feather Fiber‐Based Thermoplastics: Effects of Different Plasticizers on Material Properties

Poultry feather fiber is transformed into biothermoplastics using a twin screw extruder, and the plasticizing effect of four different plasticizers on the material properties is investigated. Conformational changes, viscoelastic behavior, thermal degradation, and phase transitions are assessed by means of FTIR spectroscopy, DMA, TGA, and DSC, respectively. The mechanical properties of the plasticized resins are assessed by tensile measurements, while optical transmittance is recorded using UV‐Vis spectrophotometry. The water uptake behavior of the fiber keratin and plasticized resins is also investigated.

     

Optimal quantum well width and the effect of quantum well position on the performance of transistor lasers

Transistor laser (TL) model based on InGaP/GaAs/InGaAs/GaAs is analyzed and presented. It is realized that quantum well (QW) with width of 10 nm may be formed for low base threshold current density J th . The emission wavelength is found to be 1.05 μm, and the indium (In) composition is 0.25 for optimal QW width. It is identified that J th decreases with the movement of QW towards the base-emitter (B-E) interface. Small signal optical response is calculated, and the effect of QW position is studied. The bandwidth is enhanced due to the movement of the QW towards the emitter base junction.     

Optimized Mechanical Properties,Corrosion Resistance and Bactericidal Ability of Ti-15Zr-xCu Biomedical Alloys During Aging Treatment

The effects of different aging conditions on the microstructure, strength, corrosion resistance, cytotoxicity and antibacterial ability of Ti-15Zr-xCu (3 ≤ x ≤ 7, wt%) (TZC) alloys were systematically investigated. Microstructural evolution and behavior were analyzed by X-ray diffraction (XRD) patterns and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), while potentiodynamic polarization technique was employed to characterize the corrosion response of the alloys after solution-treatment and aging (STA). High-temperature aging at 660 °C for 4 h (660-4) gave the best combination of properties by enabling significant precipitation of the Cu-rich Ti₂Cu and Zr₂Cu compounds, and mild formation of the Zr₇Cu₁₀ secondary phase. The high kinetics at this condition was beneficial to the complete precipitation and more homogeneous distribution of the intermetallic particles. These led to the inhibition of dislocation movements and allowed for significantly improved mechanical strengths with added ductility, availability of more Cu ions for the desired oligodynamic activity without evoking cytotoxicity, better corrosion resistance and very high antibacterial ability (over 99.5%), thus improving the overall properties of the TZC alloys for biomedical applications.