University of Tabriz

About: University of Tabriz is a education organization based out in Tabriz, Iran. It is known for research contribution in the topics: Population & Nanocomposite. The organization has 12141 authors who have published 20976 publications receiving 313982 citations.

Heterogeneous photocatalytic degradation of 4-nitrophenol in aqueous suspension by Ln (La3+, Nd3+ or Sm3+) doped ZnO nanoparticles

Abstract: Lanthanide doped ZnO nanoparticles with different Ln (Ln = La, Nd and Sm) contents were synthesized by polymer pyrolysis method and characterized by various techniques such as XRD, UV–vis, SEM, TGA, and TEM. The XRD results revealed that Ln 3+ is uniformly dispersed on ZnO nanoparticles in the form of small Ln 2 O 3 cluster. From SEM and TEM images it was found that the particle size of La-doped ZnO is much smaller as compared to that of pure ZnO. The photocatalytic activity of La-doped ZnO in the degradation of 4-nitrophenol (4-NP) was studied. The effects of the type and amount of loadings on the photocatalytic activity of Ln-doped ZnO were studied and the results were compared with pure ZnO. It was observed that the rate of degradation of 4-NP over Ln-doped ZnO increases with increasing La, Nd and Sm loading up to 4, 4 and 8 wt% and then decreases. It was found that the doping of Ln in ZnO helps to achieve complete mineralization of 4-NP within a short irradiation time. Among the catalysts, the 4 wt% Nd-doped ZnO was the most active and showing high photocatalytic activity for the degradation of 4-NP.

Crack detection in beam-like structures using genetic algorithms

Abstract: A fault diagnosis method based on genetic algorithms (GAs) and a model of damaged (cracked) structure is proposed. For modeling the cracked-beam structure an analytical model of a cracked cantilever beam is utilized and natural frequencies are obtained through numerical methods. Our method utilizes genetic algorithms to monitor the possible changes in the natural frequencies of the structure. The identification of the crack location and depth in the cantilever beam is formulated as an optimization problem, and binary and continuous genetic algorithms (BGA, CGA) are used to find the optimal location and depth by minimizing the cost function which is based on the difference of measured and calculated natural frequencies. Also we present a new cost function based on natural frequencies. The average values of location and depth prediction errors are 1.02% and 1.98%, respectively, using the BGA. These values become 0.73% and 1.11% for the CGA. To validate the proposed method and investigate the modeling and measurement errors some experimental results are also included. The average values of experimental location and depth prediction errors are 10.57% and 11.19%, respectively, for the BGA. These values become 10.21% and 10.39% for the CGA.

Subwavelength atom localization via amplitude and phase control of the absorption spectrum-II

Abstract: We propose a scheme for subwavelength localization of an atom conditioned upon the absorption of a weak probe field at a particular frequency. Manipulating atom-field interaction on a certain transition by applying drive fields on nearby coupled transitions leads to interesting effects in the absorption spectrum of the weak probe field. We exploit this fact and employ a four-level system with three driving fields and a weak probe field, where one of the drive fields is a standing-wave field of a cavity. We show that the position of an atom along this standing wave is determined when probe-field absorption is measured. We find that absorption of the weak probe field at a certain frequency leads to subwavelength localization of the atom in either of the two half-wavelength regions of the cavity field by appropriate choice of the system parameters. We term this result as sub-half-wavelength localization to contrast it with the usual atom localization result of four peaks spread over one wavelength of the standing wave. We observe two localization peaks in either of the two half-wavelength regions along the cavity axis.