فهرست مطالب m. naeimi

Due to the lack of magnets and the suitable final price, synchronous reluctance motors are potential applicants for household electric appliances and so on. But in general, they suffer from high torque ripple. Optimized design of the synchronous reluctance rotor structure is presented for two different types of barrier shape with aiming to reduce the torque ripple along with increasing the average torque.In this paper, the optimization of rotor geometries with a fixed machine size for C-shaped barriers and circular barriers type is investigated. Most of the rotor parameters such as the width of iron parts, and the width of barriers along d and q axis are optimized by a new method using the PSO algorithm. Besides, the angle of end points for each barrier with constant rib and insulation factor are considered in optimization process. Minimizing the torque ripple without losing or even increasing the average torque is the most critical optimization achievement. Two prototypes of the optimized rotor with the C-shaped and circular barriers type have been fabricated and experimentally compared. The results obtained from the 2-D Finite Element Simulation of the recommended machine conform well to the experimental result.

Sugar beet, scientifically known as Beta vulgaris L, is allogamous, diploid, biennial plant of the spinach genus that is cultivated to produce storage roots. The growth period of sugar beet, depending on environmental conditions and genotype, varies from 5 to 9 months and is known as a late maturing plant. Therefore, estimating the yield reduction due to leaf fall plays an important role in farm management. In addition to the effects of stressors, some farmers may use sugar beet leaves to raise livestock during the growing season. In this case, too, the leaves are damaged. In the experiment of complete removal of leaves in three sugar beet cultivars, it was observed that complete removal of leaves in Antek and Vico cultivars led to reduced root yield and subsequently white sugar yield was significantly reduced, but In Sharif cultivar, leaf removal had no significant effect on root yield and sugar yield. They also reported that leaf removal increased the percentage of root sugar in Sharif cultivar. Effect of leaf removal time on quantitative and qualitative characteristics of autumn sugar beet cultivars in Gorgan region.

This experiment was carried out in factorial design during the 2019-2020 crop year in Varsen of Gorgan based on randomized complete block design with three replications. The first factor includes 6 autumn sugar beet cultivars including Monotana, Jerra-kws, Rosagold, Chimneh, Veles and Sharif and the second factor includes three levels, pruning in May (leaf development), pruning in June (reducing leaf development) and no pruning (control). Pruning was done using a sickle and the entire aerial part (petiole and leaves) was cut from a height of 5 cm above the crown. Seed bed preparation operations including plowing, retorting, leveling and farrowing were performed before planting. According to the planting plan, they were planted by hand on top of the ridges on November 2019. At the end of the growing season of each harvested plant, root yield and qualitative traits were calculated. The most common method of measuring sugar percentage by polarimetry method was calculated using saccharimeter, sodium and potassium by flame photometry method, harmful nitrogen by aqueous number method and other qualitative characteristics. The analyzed traits were analyzed using SAS software and the means were compared by LSD method at a statistical level of 5%.

Sugar beet cultivars showed significant differences in sugar content (grade), sodium, potassium, extractable sugar content, sugar and molasses extraction coefficient; However, no significant differences were observed between cultivars in terms of harmful nitrogen, alkalinity and root dry matter. Leaf pruning treatments except sodium and molasses were significant in other studied traits. The interaction between cultivars and pruning has also been significant in potassium and molasses traits. Significant differences were observed between the treatments by applying pruning treatment; So that the highest percentage of sugar (14.7%) was observed in the control treatment and the lowest percentage of sugar was observed in the June treatment (12%). The highest root yield was related to Chamineh cultivar with an average of 98 tons per hectare and the lowest root yield was related to Rosagold cultivar with an average of 80 tons per hectare. Due to the decrease in leaf production at the end of the sugar beet growing season, the amount of damage caused by root yield in leaf removal treatment in the final stages of growth (June pruning) is much less than the effect of leaf removal in the middle stage of growth.

Removal of sugar beet leaves in the final stages of growth had an effect on root quality properties such as sugar content, extractable sugar percentage and sugar extraction coefficient and root yield and reduced the mentioned traits. Root impurities also increased due to defoliation. Most yield losses were obtained when sugar beet leaves were removed or eliminated in the middle stages of growth (May pruning).

The occurrence of wind erosion and the spread of dust particles can be regarded as one of the most important and threatening environmental factors. Climate change and the frequency of droughts have played an important role in exacerbating or weakening these events. The primary objective of the present study was to investigate the trend of changes in four important climatic elements (precipitation, temperature, wind speed and relative humidity) and dust storm index (DSI) in Qazvin city using the Mann-Kendall pre-whitened test and to determine the relationship between them based on the multiple linear regression method. Assessment of the meteorological drought status based on two standardized precipitation index and standardized precipitation, as well as the evapotranspiration index and analysis of their effect on activity level of dust events, was the other objective of this study in the study area. For this purpose, after preparing and processing the climatic data and calculating the dust storm index, the trend of changes and the relationship between climatic parameters and dust events were investigated. The results showed that the changes of trend in the annual precipitation and relative humidity in Qazvin city were increasing, while the trend of annual changes in the wind speed and the mean air temperature was a decreasing one. Investigation of the monthly changes in the dust events also showed that there was a sharp decrease in the occurrence of wind erosion and the spread of domestic dust particles only in July. On a seasonal scale, with the exception of winter that has been reported without trends, in other seasons, the intensity of these events was significantly reduced. The effect of the meteorological drought on wind erosion was estimated to be 11% at the confidence level of 99%. In general, these findings indicate a decreasing trend of land degradation and desertification caused by wind erosion in Qazvin.

The breakfast as the most important meal is ignored more than other meals by children and adolescents. This study was aimed to investigate the effect of education based on knowledge, perception and performance about having Breakfast on primary school student boys.

This quasi-experimental study (controlled type) was conducted in 2013 on 200 primary school student boys in Qom city into both case (n=100) and control(n=100) groups. Random sampling was used. Data were collected using researcher-made questionnaire based on HBM constructs, which its validity and reliability was confirmed. Educational intervention included of three 45-minute sessions of the group discussion, lecture, question and answer, role play and pamphlets delivery. Collected data were analyzed by SPSS software.

Before the intervention, there wasn’t significant differences in terms of knowledge and perceived susceptibility, severity, benefits, barriers, and performance in both case and control groups. While these factors were significantly higher in the intervention group compared to the control group and perceived barriers have fallen after the intervention (p<0.05).

Designing HBM-based educational programs can be effective on student's eating behaviors. Regarding the important role of students as the future generation and also low cost of health education compared to other activities in this area, such programs need to be extend and expand.

In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as additives has been investigated. Nickel and Cobalt were added to Tungsten powder by two distinct Methods mixing elementally and reduction of salt solution. The coated Tungsten powders were compacted under controlled pressures to make porous skeleton with 32-37 vol. % porosity. Infiltration process was carried out at 1100 ̊C under a reducing atmosphere for 1h. The effect of additives on infiltration of Ag and density were evaluated by SEM and Archimedes methods. Properties of the specimens were compared following two distinct processes namely: I) sintering simultaneously with infiltration process and II) sintering prior to infiltration (pre-sintering process). It was found that specimens which were pre-sintered and then infiltrated with molten silver represent higher hardness and finer microstructure than the specimens infiltrated simultaneously with sintering.