mohamad reza mohammadi

The US interventions in changing government systems in other countries,include overt and covert attempts with the aim of changing, replacing ormaintaining foreign governments. These attemps included widespreadand various spectrum ranging from measures consisting of supporting agovernment’s opposition groups, economic sanctions, measures within theSecurity Council framework, supporting coups, spionage and finally, directmilitary intervention.

In this paper, a non-isolated high step-up soft-switching converter is proposed. The proposed converter is a boost converter combined with two voltage multiplier cells for boosting output voltage. Also, extend voltage gain of the proposed converter is achieved by using a coupled-inductor. Compare with other similar high step-up topologies with the same number of components, the proposed converter has a higher voltage gain and higher efficiency. An active clamp circuit is used so, the zero-voltage switching (ZVS) is achieved. Also, in the proposed converter, the voltage stresses on the switches are low. As the voltage stress decreases on the switch, Ron</sub> of the MOSFET is deceased and as a result conduction loss of the switch is decreased. So, the efficiency of this converter increased. In this paper, operational principle of the converter is described and the analytical, simulated results and prototype converters are validated using a 20V input and 400V </strong>output converter at 200W load.

The interleaved boost converters are the power circuits that provide high-voltage, high-power with regulated output voltage for renewable energy systems which are generally suffer from low-voltage and unregulated output voltages. The soft switching methods reduce electromagnetic noises and switching losses in these converters. In this paper, a ZVT interleaved boost converter with a simple auxiliary circuit is proposed. The proposed converter has a simple structure with low size and cost. In the proposed converter, soft switching condition is provided without any extra voltage and current stress on the main switches. The auxiliary circuit comprises two diodes and one auxiliary switch. The leakage inductance of the utilized coupled inductors is used as resonant inductor. The auxiliary switches benefit from significantly reduced voltage stress without requiring floating gate driver. The proposed converter can achieve zero voltage switching operation for the main switches and zero current switching for diodes and auxiliary switches, which causes to alleviate the reverse recovery problems of all diodes.

Anthropometric studies in children and adolescents are important to screen changes in growth and puberty. Hence, standard percentiles and cutoffs are set by the World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), and Iranian national criteria. This study aimed to examine and compare the prevalence of weight disorders in children and adolescents in Lorestan province according to different criteria.

Children and adolescents (6–18 years) were randomly selected from the urban and rural areas by the multistage stratified cluster sampling method. All Iranian citizens aged who resided in Lorestan province for at least one year were eligible to participate in this study. After obtaining consent forms, researchers gathered the accurate anthropometrics and body mass index (BMI) measurements.

A total of 866 children and adolescents took part in the study, 447(51.6%) of whom were girls and 419 (48.4%) were boys. The overall prevalence of overweight and obesity was 17% in boys and 12.5% in girls. The prevalence of underweight in girls was 5.8%; while in boys it was 4.5%. The total prevalence rate of underweight according to the national criteria was 5.2%. However, this rate increased to 12% and 12.6% by using WHO and CDC cut-off points, respectively. The highest prevalence of overweight was obtained by CDC (15.8%), followed by WHO (13%); while national cut-off points resulted in 9.7%. Furthermore, 9.2% of the studied population was found to be obese by WHO; while this rate was 4.2%, and 5% by CDC and national cut-off points.

This study indicated the coexisting prevalence of underweight and obesity and high prevalence of overweight among children and adolescents in Lorestan province. Furthermore, using the WHO and CDC criteria leads to overestimating the prevalence of weight disorder compared to the national cut-off points in Iran.