Medium reservation based sensor MAC protocol for low latency and high energy efficiency

In this paper, we present a new MAC protocol satisfying with both high energy efficiency and low transmission latency at the same time over wireless sensor network, named as medium reservation preamble based MAC (MRPM). Unlike other synchronized duty cycle MACs, MRPM does not have separate time frames for SYNC and data traffics. Both traffics are integrated in a short listen period. Also, the channel contention is excluded from listen period and transferred to new period called contention period. The contention period precedes the listen period, and only transmitters wake up in this contention period and contend for medium reservation, whereas non-transmitters bypass it. These approaches enable MRPM to achieve adaptive duty cycle and quite short listen period. Moreover, MRPM uses carrier sensing information for advanced adaptive listening which makes packets to travel multiple hops away in a single sleep/listen cycle. The simulation results verify that MRPM has features of high energy efficiency and low latency.     

A Study on the Electrodeposition Mechanism of Palladium from Ammoniacal Solution Using a Rotating Pt Ring-Cu Disk Electrode

The electrodeposition of palladium in ammonium phosphate solution (pH=10) containing 0.025 M tetramminepalladium(II) ion has been studied at room temperature by means of cyclic voltammetry, potentiostatic current transients and ac impedance measurements on a rotating Pt ring-Cu disk electrode, Cyclic voltammograms and potentiostatic current transients exhibited the characteristic features of the mechanism of progressive nucleation and growth under interfacial electron transfer and diffusion control. The interfacial reaction-controlled growth condition was established on the reverse sweep of the cyclic voltammogram. From the reverse sweep curve of cyclic voltammetry done at various rotation speeds, a Tafel plot of -210 mV per decade and diffusivity of tetramminepalladium(II) ion of 1.4 × 10^?5 cm² s^?1 were obtained. During the electrodeposition of palladium on the Cu-disk electrode, the ring current increased in the anodic direction, indicating the oxidation of reaction intermediates produced on the disk electrode. Complex-plane impedance spectra obtained in the potential range of-0.76 to -0.8 V(SCE) showed a semicircle in the high frequency region and an inductive loop in the low frequency region. Based upon the experimental results, it is suggested that the electrodeposition of palladium from tetrammine palladium(II) ion proceeds partly via two consecutive reactions with the formation of a monovalent reaction intermediate and partly via a direct two electron discharge reaction in which the intermediate acts as a catalyst associated with propagating kink sites.     

Effect of ultrasonic nanocrystal surface modification on the characteristics of AISI 310 stainless steel up to very high cycle fatigue

Effects of ultrasonic nanocrystal surface modification (UNSM) on the very high cycle fatigue response of AISI 310 stainless steel have been investigated. The higher impact force used in UNSM treatment showed a higher fatigue life improvement. The fatigue life improvement was higher in crack initiation from the surface of specimens. The subsurface crack initiation depth in the alloy increased with increase in the fatigue failure cycles. It was concluded that UNSM treatment can increase the life of the alloy significantly up to very high cycle fatigue.     

Enhanced PL and VUV absorption of BaZr(BO3)2:Eu3+ by Al3+ incorporation

Abstract— The photoluminescence (PL) and vacuum‐ultraviolet excitation (VUV) properties of BaZr(BO₃)₂ doped with the Eu³⁺ activator ion were studied as a new red phosphor for PDP applications. The excitation spectrum shows strong absorption in the VUV region with an absorption band edge at 200 nm. The charge‐transfer excitation band of Eu³⁺ was enhanced by co‐doping with an Al³⁺ ion into the BaZr(BO₃)₂ lattices. The PL spectrum shows the strongest emission at 615 nm, corresponding to the electric dipole ⁵D₀ → ⁷F₂ transition of Eu³⁺ in BaZr(BO₃)₂, which results in good red‐color purity.     

Non-thermal inactivation of Lactobacillus plantarum as influenced by pressure and temperature of pressurized carbon dioxide

Summary Non-thermal inactivation of Lactobacillus plantarum cells as influenced by pressure and temperature of pressurized carbon dioxide was investigated to evaluate its potential use for preservation of foods and biological substances. Microbial inactivation by the pressurized CO₂ was dependent principally on the transfer rate of CO₂ into cells and effectiveness could be improved by increasing pressure and temperature. Microbial reduction of more than 6 logs occurred within 30 min under CO₂ pressure of 2000 psi at 30 °C. The results showed that the pressurized CO₂ treatment could be used as a potential non-thermal preservation technology for foods.     

Effects of different substitution concentration and configuration on some properties of magnesium hydrides substituted with titanium; Ab initio study

We investigated hydrogen some properties of magnesium hydrides substituted with titanium by a first principles calculation. In order to evaluate effect of different substitution concentration and configuration on desorption temperature and bulk modulus, we constructed five systems such as Mg₄Ti₂H₁₂, Mg₈Ti₂H₂₀, Mg₁₆Ti₂H₃₆, Mg₁₄Ti₄H₃₆ and Mg₁₂Ti₆H₃₆ by using 1 × 1 × 3, 1 × 1 × 5 and 3 × 3 × 1 super cell of pure magnesium hydride. Among the investigated systems, Mg₁₄Ti₄H₃₆ system showed the best performance as hydrogen storage material in the complex viewpoints of substitution energy, desorption temperature and bulk modulus. In addition to, our results demonstrated that not only substitution concentration but also configuration plays vital effect on material's property of magnesium hydrides. Bader charge analysis explained the reason why desorption temperature is fallen down by substitution with titanium.