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.

Evaluation of the photocatalytic antimicrobial effects of a TiO2 nanocomposite food packaging film by in vitro and in vivo tests

Abstract: The ability to inactivate Pseudomonas spp. and Rhodotorula mucilaginosa by a photocatalyst thin film, obtained via a combination of anatase and rutile titanium dioxide incorporation into a low density polyethylene (LDPE) polymeric matrix by a melt blending method, was addressed in this study. The number of surviving cell of the Pseudomonas spp. was decreased by 4 log CFU/ml and 1.35 log CFU/ml after 3 h of UVA illumination on TiO2 nanocomposite thin film and LDPE thin film, respectively. The number of cells of R. mucilaginosa decreased by 2 log CFU/ml and 0.64 log CFU/ml on TiO2 nanocomposite thin film and LDPE thin film, respectively. In an in vivo test carried out on fresh pears packaged in TiO2 nanocomposite film and stored under illumination by a fluorescent light lamp at 5 °C for 17 days, the number of mesophilic bacteria and yeast cells decreased significantly compared to samples stored in LDPE film. The greatest effects were recorded by combining UVA illumination and active film. It was also proven that the photocatalyst thin film prepared by extrusion could be effectively used in fruit packaging applications.

Precipitation Forecasting Using Wavelet-Genetic Programming and Wavelet-Neuro-Fuzzy Conjunction Models

Abstract: Forecasting precipitation as a major component of the hydrological cycle is of primary importance in water resources engineering, planning and management as well as in scheduling irrigation practices. In the present study the abilities of hybrid wavelet-genetic programming [i.e. wavelet-gene-expression programming, WGEP] and wavelet-neuro-fuzzy (WNF) models for daily precipitation forecasting are investigated. In the first step, the single genetic programming (GEP) and neuro-fuzzy (NF) models are applied to forecast daily precipitation amounts based on previously recorded values, but the results are very weak. In the next step the hybrid WGEP and WNF models are used by introducing the wavelet coefficients as GEP and NF inputs, but no satisfactory results are produced, even though the accuracies increased to a great extent. In the third step, the new WGEP and WNF models are built; by merging the best single and hybrid models’ inputs and introducing them as the models inputs. The results show the new hybrid WGEP models are effective in forecasting daily precipitation, while the new WNF models are unable to learn the non linear process of precipitation very well.

A Single-Phase Transformerless Inverter With Charge Pump Circuit Concept for Grid-Tied PV Applications

Abstract: This paper proposes a new single-phase transformerless photovoltaic (PV) inverter for grid-tied PV systems. The topology is derived from the concept of a charge pump circuit in order to eliminate the leakage current. It is composed of four power switches, two diodes, two capacitors, and an LCL output filter. The neutral of the grid is directly connected to the negative polarity of the PV panel that creates a constant common mode voltage and zero leakage current. The charge pump circuit generates the negative output voltage of the proposed inverter during the negative cycle. A proportional resonant control strategy is used to control the injected current. The main benefits of the proposed inverter are: 1) the neutral of the grid is directly connected to the negative terminal of the PV panel, so the leakage current is eliminated; 2) its compact size; 3) low cost; 4) the used dc voltage of the proposed inverter is the same as the full-bridge inverter (unlike neutral point clamped (NPC), active NPC, and half-bridge inverters); 5) flexible grounding configuration; 6) capability of reactive power flow; and 7) high efficiency. A complete description of the operating principle and analysis of the proposed inverter are presented. Experimental results are presented to confirm both the theoretical analysis and the concept of the proposed inverter. The obtained results clearly validate the performance of the proposed inverter and its practical application in grid-tied PV systems.