khalil rahimi

Swimming pool water is quickly contaminated by swimmers which can cause the transmission and prevalence of various types of microbial infection through contact with the human body or accidently ingestion. Proper and regular chlorination of water in swimming pools, along with health monitoring by health care providers, and regular measurement of remaining chlorine along with controlling pH values, can be a useful tool to ensure the lack of risk to aforementioned diseases.
Material and In a cross-sectional study, during the four seasons of the year, 44 active swimming pools in Tabriz from 57 existing swimming pools were examined and the remaining chlorine, water temperature, ambient temperature and pH were measured. In addition to extraction of descriptive parameters, the obtained data were under the analysis of variance to compare the mean of the data.
In the studied pools, the minimum residual chlorine content was measured at zero and the maximum value of 5 mg/L was measured. The pH of the pools was in most cases near neutral and more alkaline (>7). In the main pools, there was no significant difference between the mean of measured parameters with regard to different seasons (P> 0.05). Correlation analysis indicated a significant inverse relationship between residual chlorine and water temperature in these pools (R = -0.694, p Based on the results of this study, it was revealed that the limits and recommended standards for residual chlorine, pH, pool temperature and ambient temperature in the pool environment are not observed in four types of main, Jacuzzi, chiller, and children pools examined in Tabriz. Particularly, in the case of Jacuzzi and chiller pools, the present situation was more unfavorable in terms of residual chlorine and water pH compared to other types, which requires serious attention.

This paper presents a new soft switched topology for losses reduction in a three-phase four-wire shunt active power filter (SAPF). The soft-switching technique not only offers a reduction in switching loss and thermal requirement, but also allows the possibility of high frequency and snubberless operation. Improved circuit performance and efficiency as well as reduction of EMI emission can be achieved. The resonant dc link inverter with low voltage stress is used for power converter of a three-phase four-wire shunt active power filter. It is assumed that the active power filter is connected to a load that can be unbalanced and may also draw harmonic currents. The p-q theory is used for controlling the SAPF. The proposed topology and operation principle of the control method is discussed in detail, finally the feasibility of such a scheme is demonstrated through simulation studies.