In this article, we propose a two‐dimensional indoor localization system using fingerprinting of received optical signals emitted from light emitting diodes (LEDs).The transmitters and receiver are designed and constructed to use visible light as the signal for localization. At the transmitter side, the input voltage/current is modulated with continuous waves before being sent to the LEDs, where each transmitter is assigned with a different frequency. At the receiver side, the power spectral density of the received signal is calculated and the location is estimated as one of the fingerprint locations using a novel but yet simple algorithm. Both the simulation and experiment have been conducted to evaluate the accuracy of the system in a controlled environment. We demonstrate that the system has the potential to estimate locations in the level of centimeters. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1218–1227, 2012

The absorption of H atom in H-covered Pd(110) (1×2) missing-row surface is investigated using density functional theory based calculations. For 1.5 monolayer H coverage, interaction among the adsorbed H atoms is found to be negligible and was verified by analyzing the electronic structure of the system and by comparing the calculated binding energies with low H coverage case. Neither the monoatomic absorption of H nor the assistance from the initially adsorbed H atom explains the experimentally observed presence of subsurface H in Pd(110) at high H coverage. Instead, H absorption is realized through the assistance of incoming H atoms from vacuum. The absorption of H in the H-covered surface is non-activated while the dissociation of H2 is the rate-limiting process. Dissociation on ridge site is energetically more preferred than on trough site and the difference in the activation barrier is elucidated by investigating the electronic structures of the system.

No abstract

The role of the presence of Ag atom in Pd 3 Ag(111) surface on the adsorption of N and H atoms and NH species was studied by using first-principles calculations based on density functional theory (DFT). The adsorption energies of N and NH species are weakened by at least 0.50 eV when Ag atom is one of the nearest neighbors, in contrast to the case of H, in which the adsorption energies are weakened by at most 0.15 eV. Local density of states (LDOS) profiles show that for N and NH adsorption near the silver alloy atom, the derived anti-bonding states are shifted below the Fermi level and hence the adsorption energy is weakened on the alloyed surface. In the presence of adsorbed N, the adsorption energies of H on the nearby sites are also reduced. Nonetheless, this reductions in H adsorption energies on the most stable sites are lower in Pd 3 Ag(111) surface. NH formations with H moving across the Pd atom on both surfaces show comparable activation barriers but the barrier is increased by 0.2-0.3 eV when the formation happens across Ag atom.

NO dissociation is an important reaction step in NO reduction reaction, particularly in the three-way catalyst conversion system for automotive gas exhaust purification. In this study, we used first principles...