Spatial analysis of seasonal precipitation over Iran: Co-variation with climate indices

Temporary changes in precipitation may lead to sustained and severe drought or massive floods in different parts of the world. Knowing the variation in precipitation can effectively help the water resources decision-makers in water resources management. Large-scale circulation drivers have a considerable impact on precipitation in different parts of the world. In this research, the impact of El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North Atlantic Oscillation (NAO) on seasonal precipitation over Iran was investigated. For this purpose, 103 synoptic stations with at least 30 years of data were utilized. The Spearman correlation coefficient between the indices in the previous 12 months with seasonal precipitation was calculated, and the meaningful correlations were extracted. Then, the month in which each of these indices has the highest correlation with seasonal precipitation was determined. Finally, the overall amount of increase or decrease in seasonal precipitation due to each of these indices was calculated. Results indicate the Southern Oscillation Index (SOI), NAO, and PDO have the most impact on seasonal precipitation, respectively. Additionally, these indices have the highest impact on the precipitation in winter, autumn, spring, and summer, respectively. SOI has a diverse impact on winter precipitation compared to the PDO and NAO, while in the other seasons, each index has its special impact on seasonal precipitation. Generally, all indices in different phases may decrease the seasonal precipitation up to 100%. However, the seasonal precipitation may increase more than 100% in different seasons due to the impact of these indices. The results of this study can be used effectively in water resources management and especially in dam operation

Quasirecognition by prime graph of Cn(4)C_{n}(4) , where n≥17 n\geq17 is odd

Let $G$ be a finite group and let $\Gamma(G)$ be the prime graph of $G$. We assume that $n\geq 17$ is an odd number. In this paper, we show that if $\Gamma(G) = \Gamma(C_{n}(4))$, then $G$ has a unique non-abelian composition factor isomorphic to $C_{n}(4)$. As consequences of our result, $C_{n}(4)$ is quasirecognizable by its spectrum and by prime graph

Energy-Exergy Analysis and Optimal Design of a Hydrogen Turbofan Engine

In this study, the effect of inlet air cooling and fuel type on the performance parameters of thrust-specific fuel consumption (TSFC), thermal and exergetic efficiencies, entropy generation rate, and Nitrogen oxide emission intensity index (SNOx) of the GENX 1B70 engine is analyzed in two states of take-off. The results show that with a 20˚C reduction in inlet air temperature on design conditions and JP10 fuel usage, the thermal efficiency and entropy generation rate, thrust and fuel mass flow rate, and TSFC of the engine increase by 1.85, 16.51%, 11.76%, 10.53%, and 2.15% and SNOx & exergetic efficiency decrease by 2.11% and 26.60%, respectively. Also, optimization of the GENX 1B70 engine cycle as hydrogen fuel usage with three separate objective functions: thrust maximization, thermal efficiency maximization, and propulsive efficiency maximization on design point condition was performed based on the Genetic algorithm. Based on the economic approach and exero-environmental, the best cycles from the optimal states were selected using the TOPSIS algorithm. In on design conditions, entropy generation rate, nitrogen oxide production rate, and TSFC for the chosen cycle based on economic approach +18.89%, +10.01%, and -0.21%, respectively, and based on exero-environmental approach -54.03%, -42.02%, and +21.44% change compared to the base engine, respectively

Thermal and vibratory response of sprung square cylinder with four nature-inspired fin-shaped bumps

Nature provides man with various interesting structures, offering him a constant source of manufacturing tools and invention. The main purpose of the present paper is to investigate the effect of shark-inspired fins, which are installed on the top and bottom plates of a sprung cylinder on the vibration response and heat transfer of square cylinder. Two fin sizes, i.e. small and big, are used. Three configurations for the fins on the top and bottom plates of the square cylinder are considered: at the corners of the square cylinder, spaced from the corners, and in the middle of the plates. The results indicate that adding fins increases the amplitude of vortex-induced vibrations and extends the lock-in region which is both intensified as the size of fins increases. In particular, for the cylinder equipped with small fins in configurations 1–3, the maximum VIV amplitude increases by, respectively, 36 %, 57 % and 52 % compared with the plain cylinder. In contrast, shark fins can lower the galloping amplitude by as much as 87 % and shrink the galloping zone such that for big fin size in the second and third configurations, the galloping zone and its corresponding vortex-shedding mode are not observed. Adding fins to the cylinder augments heat transfer. The increase in mean Nusselt number depends on vortex-shedding mode, and the rise in Nusselt number is higher in the 2P + 2S mode

Comparison of thorasis kyphosis and postural stiffness between elderly females and males in Tehran elderly recreation association

Background and Aim: Hyperkyphosis can lead to reduced respiratory capacity, postural disturbance and increased risk of falling. Despite the evidences about the more postural stiffness and kyphosis in elderly compared with young subjects and despite the known role of sex hormones and menopause in lowering the bone density, there is not any study about the effect of sex on the amount of thoracic kyphosis. The objective of this study is measuring and comparing the amount of spinal thoracic kyphosis and postural stiffness between the old females and males.Methods and Materials: In this descriptive-analytical study, in 36 healthy old subjects (21 female and 15 male) the amount of spinal thoracic kyphosis was measured by flexible ruler mounted between the spinous process T12 and C7 during, relaxed and erect postures. The difference of the kyphosis in relaxed and erect posture was used as an index of postural stiffness. The kyphosis and postural stiffness was compared between the females and males.Results: The average amount of kyphosis in relaxed and erect standing didn’t have statistically significant difference between females and males. The subjects in both groups could decrease theirs kyphosis in standing erect position (P=0.0001), but the amount of this decrease (postural stiffness) was not different between the females and males. Conclusion: In old women (which aren’t osteoporotic) hormonal changes due to menopause didn’t induce a statistically significant difference compared to old men in kyphosis and postural stiffness.Postural stiffness was increased by increasing the BMI that could suggest the BMI as an efficient factor in reducing the mobility of the spine

Introducing Copula as a Novel Statistical Method in Psychological Analysis

During the past decades, the relationship between various psychological parameters had been studied in detail. However, the dependency structure of correlated parameters was rarely investigated. Knowing the dependence structure helps in finding the probability matrix of the interaction between the parameters. In this research, a novel approach was introduced in psychological analysis using copula functions. For this purpose, the self-esteem and anxiety of 141 university students in Iran were extracted using the Coopersmith Self-esteem Inventory and the Zang Anxiety Scale. Then the dependence structure of self-esteem and anxiety were established using copula functions. The Frank copula achieved the best fit for the joint variables of self-esteem and anxiety. Finally, the probability matrix of different classes of anxiety, taking into account self-esteem classes, was extracted. The results indicated that poor self-esteem leads to severe or very severe anxiety, with more than 98% probability, while strong self-esteem may lead to normal and mild anxiety, with about 80% probability. It can be concluded that the method was promising, and that copula functions can open a window to the dependence structure analysis of psychological parameters