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Open access

A. Maleki and A. Ahmadi

Abstract

This paper presented a three dimensional analysis for the buckling behavior of an imperfect orthotropic thick cylindrical shells under pure axial or external pressure loading. Critical loads are computed for different imperfection parameter. Both ends of the shell have simply supported conditions. Governing differential equations are driven based on the second Piola–Kirchhoff stress tensor and are reduced to a homogenous linear system of equations using differential quadrature method. Buckling loads reduction factor is computed for different imperfection parameters and geometrical properties of orthotropic shells. The sensitivity is established through tables of buckling load reduction factors versus imperfection amplitude. It is shown that imperfections have higher effects on the buckling load of thin shells than thick ones. Results show that the presented method is very accurate and can capture the various geometrical imperfections observed during the manufacturing process or transportation.

Open access

M. Pahlevani, A. Ahmadi and S. Razavi

Assessment of Safflower for Susceptibility to Pythium Ultimum, the Causal agent of Damping-Off

Genetic resistance against Pythium species would be an efficient control of this major seed and seedling fungal pathogen in safflower (Carthamus tinctorius), but so far no source has been identified. Therefore, identifying and then incorporating genetic resistance into the cultivars would be an ideal method of control for this disease. So in this study the resistance to seed rot and damping-off caused by Pythium ultimum among seventeen genotypes of safflower collected from all major production regions of the crop in Iran and some other countries was investigated. Pythium ultimum, previously identified as the most prevalent Pythium isolates on safflower, were used to infest the sterilized soil, which was seeded with safflower genotypes in greenhouse conditions. The experiment was conducted as a split plot design in which sterile and Pythium-infested soils were considered as main plots, and seventeen genotypes of safflower were sub plots. In sterile media, percent of seedling emergence (SES) and in Pythium-infested media, percent of seedling emergence (SEI), percent of diseased seedlings (DSI), percent of uninfected seedlings (USI) and percent of non-emerged seeds (NSI) were recorded. Symptoms showed that in safflower, damping-off occurred in both forms of pre and post emergence. Genotypic variation was existed for level of susceptibility to P. ultimum. Significant differences in SES and SEI were detected among safflower genotypes (P < 0.01), and a significant correlation between SES and seed weight (P < 0.05); SES with SEI (P < 0.05) were detected. Result showed that between evaluated genotypes there wasn't any genotype with complete resistance (100%) to P. ultimum, so the susceptibilities were assayed. Based on the assessed variables, genotypes LRV-55-295, Aceteria, PI-250537 and IL-111 appear to be highly susceptible to the Pythium infection, whereas 34040, Arak281, and Isfahan were the least susceptible to the disease. Further research will be conducted to determine whether the resistance detected in these genotypes is heritable.

Open access

R. Ahmadi, A. Kalbasi-Ashtari and S. Gharibzahedi

Physical properties of psyllium seed

Physical properties ie dimensions, volume, surface area, sphericity, true density, porosity, angle of repose, terminal velocity, static and dynamic friction coefficients on plywood, stainless steel, glass and galvanized iron sheet, force required for initiating seed rupture in horizontal and vertical orientations of psyllium seed at a moisture content of 7.2% (w.b.)were determined.

Open access

A. Khatiby, F. Vazin, M. Hassanzadeh and A. Ahmadi Shadmehri

Abstract

Drought is an important factor that could restrict plants growth and productivity through several biological and physiological processes. Salicylic acid (SA) has a key role in many physiological processes of plants and stimulate specific responses against various stresses biotic and abiotic, in some of plants. In order to evaluate the effect of foliar application by salicylic acid (SA) under drought stress on some morphological characteristics sesame, a split-plot experiment with a completely random design with three replications was performed. There were three levels of irrigation: control (normal irrigations), water stress at flowering stage and water stress at seed production stage, as main plot and sub plot consisting of four levels of the foliar application of salicylic acid: 0 (control), 1, 1.5 and 2.25 mM. Results indicated that the effects of water stress on traits, such as plant height, height of first capsule from soil surface, number of branches, number of capsules per plant showed significant difference at a level of 1%, while on the number of seeds per capsule, seed weight, leaf area index, biological yield, grain yield sesame, without significant difference indicated. Foliar application with salicylic acid was not so significant (P< 0.05) at different concentrations on measured traits, as well as interactive effects between drought stress and different amounts of salicylic acid, without significant difference observed.

Open access

G. Kavei, K. Ahmadi, A. Shadmehr and A. Kavei

Abstract

(Bi2Te3)x(Sb2Te3)1−x solid solutions with x = 0:2, 0.25 and 0.3 − p type thermoelectric compounds with an excess of Tellurium dopant up to 4 wt% were crystallized. By increasing the Bi2Te3 content in the Bi-Sb-Te system, the hole concentration decreased and in consequence caused an optimum Seebeck coefficient and a decrease in electrical conductivity and thermal conductivity, thus resulting in an increase in the figure of merit at x = 0:25. The results showed that optimum thermoelectric properties can be achieved for a mixture of x = 0:25 with 3 wt% Te added. Structural characterizations of this compound in the absence and presence of the dopant were carried out by means of X-Ray diffraction measurement, scanning electron microscopy, electron backscattering diffraction and atomic force microscopy. Detailed analyses confirm that the improvements in thermoelectric parameters due to the intrinsic structure and minimum defects during crystallization of the compounds result from the excess of Te.

Open access

H Bahadoran, MR Naghii, M Mofid, MH Asadi, K Ahmadi and A Sarveazad

Abstract

Objectives. Kidney stone disease is a common form of renal disease. Antioxidants, such as vitamin E (Vit E) and boron, are substances that reduce the damage caused by oxidation.

Methods. Adult male rats were divided into 5 groups (n=6). In group 1, rats received standard food and water for 28 days (control group); in group 2, standard rodent food and water with 0.75% ethylene glycol/d (dissolved in drinking water) (EG Group); in group 3, similar to group 2, with 3 mg of boron/d (dissolved in water) (EG+B Group); in group 4, similar to group 2, with 200 IU of vitamin E injected intraperitoneally on the first day and the 14th day, (EG+Vit E Group); in group 5, mix of groups 3 and 4, respectively (EG+B+Vit E Group).

Results. Kidney sections showed that crystals in the EG group increased significantly in comparison with the control group. Crystal calcium deposition score in groups of EG+B (160), EG+Vit E, and EG+B+Vit E showed a significant decrease compared to EG group. Measurement of the renal tubules area and renal tubular epithelial histological score showed the highest significant dilation in the EG group. Tubular dilation in the EG+B+Vit E group decreased compared to the EG+B and EG+Vit E groups.

Conclusions. Efficient effect of boron and Vit E supplements, separately and in combination, has a complimentary effect in protection against the formation of kidney stones, probably by decreasing oxidative stress.

Open access

Fatemeh Rahimi-Ajdadi, Ezzatollah Askari Asli-Ardeh and Adel Ahmadi-Ara

Abstract

Various conditions of a parboiling process affect the qualitative parameters of paddy milling. In this study, the effects of drying temperature (45 and 60 °C), moisture content (8, 10 and 12% w.b.), steaming time (10, 20 and 30 min) and paddy varieties (Hashemi and Alikazemi) were investigated on head rice yield (HRY). The samples were husked using a rubber roller husker and whitened by a laboratory abrasive whitener. Results showed that the main effects of all parameters were significant on HRY (P <0.01). The utilization of higher temperature (60 °C), in comparison with non-parboiled rice, without reducing the milling quality was found as one of the advantages of parboiling. Among all experiments, the highest HRY (68.647%) was achieved in the combination of Alikazemi/45 °C/10 min/8%. In the majority of cases, the combinations including Alikazemi variety had higher HRY than Hashemi. For Hashemi variety, the highest HRY (67.297%) was achieved in combination 45 °C/10 min/8%. In terms of HRY, parboiling causes an increase of 25.8% and 43.3% respectively for Hashemi and Alikazemi. Therefore, it is highly recommended in processing of Alikazemi variety.

Open access

S. A. Hosseini, A. Akbarpour, H. Ahmadi and B. Aminnejad

Abstract

Underground spaces having features such as stability, resistance, and being undetected can play a key role in reducing vulnerability by relocating infrastructures and manpower. In recent years, the competitive business environment and limited resources have mostly focused on the importance of project management in order to achieve its objectives. In this research, in order to find the best balance among cost, time, and quality related to construction projects using reinforced concrete in underground structures, a multi-objective mathematical model is proposed. Several executive approaches have been considered for project activities and these approaches are analyzed via several factors. It is assumed that cost, time, and quality of activities in every defined approach can vary between compact and normal values, and the goal is to find the best execution for activities, achieving minimum cost and the maximum quality for the project. To solve the proposed multi-objective model, the genetic algorithm NSGA-II is used.