s.e. razavi

In the present investigation, a detailed numerical investigation of the flow and heat transfer characteristics of a channel with an elastic fin (vortex generator) and an elastic wall has been carried out using finite element method. The Fluid-Structure Interaction (FSI) model is used to capture the interaction between the fluid and the solid structure. A sinusoidal time dependent velocity profile has been imposed at the inlet of the channel and the right half of the upper wall of the channel is heated and exposed to constant temperature boundary condition. Due to the sinusoidal velocity profile at the inlet, the elastic fin oscillates periodically and act as a vortex generator, which causes more turbulence in the flow. The obtained results showed that the Nusselt number over the heated wall is affected by the position of the flexible fin, height of flexible fin and elasticity modulus of elastic fin. Moreover, due to the elasticity of the elastic wall and sinusoidal behavior of the inlet velocity, the elastic wall oscillates periodically upward and downward. The Nusselt number values over the heated wall are increased with decrease of the elastic modulus value of the elastic wall. However, the decrease in elastic modulus value of the elastic wall contributes to an increase in the pressure drop inside the channel. It should be added that the interplay between the fluid motion and the deformable structures leads to enhanced turbulence, as the flexible fin and elastic wall introduce additional disturbances and fluctuations into the flow regime. Consequently, this heightened turbulence level has profound implications for heat transfer processes within the system.

Rice is one of the most important grains in the world and large part of its consumption is related to Middle East. Iran ranks 23rd in production, 26th in cultivation, and 13th in rice consumption with nearly 560,000-hectare rice lands and an annual production of nearly 2.5 million tons. In natural and agricultural ecosystems, plants are associated with large populations of microorganisms in the rhizosphere, endosphere (inside the root), leaves (phyllosphere), as well as pollen and seeds. These microorganisms spend all or part of their life cycle inside the healthy tissues of host plant without any obvious sign of disease. The stable coexistence between endophytes and plants is due to production of biological secondary metabolites with a unique structure, which positively affects the survival of plant growth in adverse conditions. Studies have shown that endophytic fungi increase resistance to drought, insects, diseases and host tolerance level, especially in stress conditions. Considering the increase in the risk of dehydration and the lack of sufficient water resources and the development and adoption of aerobic rice cultivation, it is important to identify endophytic fungi that increase tolerance to drought stress and improve the growth factors of the host plant. There are relatively few studies on endophytic fungi that colonize healthy tissues of rice plants under aerobic conditions. Therefore, the aim of this study is to evaluate endophytic fungal collections in different parts of aerobically cultivated rice plants.

In this study, in order to identify endophytic fungi in aerobic cultivation of rice in Golestan province, sampling were carried out from several aerobic rice fields in Golestan province, including Gorgan, Kordkuy, Bandar Gaz, Aliabad and Kalaleh cities during the months of May to September in 2019-2020. Plant tissues were transferred to the laboratory (Department of Plant Protection) in separate paper bags along with specifications. Purification was performed on a 2% water-agar medium using Hyphal tip method. Based on investigations and morphological data, a number of isolates were selected as representatives for molecular identification. Genomic DNA was extracted from mycelia grown in PDB (Potato Dextrose Broth) culture medium according to the CTAB method with a slight modification, and the polymerase chain reaction (PCR) was performed according to Nemati and Abdulhazadeh method. The ITS region (ITS4-5.8S-ITS5) of the selected isolates was amplified during the PCR reaction using ITS5 (5'-GGAAGTAAAAGTCGTAACAAGG-3') and ITS4 (5'- TCCTCCGCTTATTGATATGC-3') primers and The β-tubulin region was amplified by T1 (5'-AACATGCGTGAGATTGTAAGT-3') and β Sandy-R (5'-GCRCGNGGVACRTACTTGTT-3') primers. Purification and sequencing of PCR products was done by Pishgam Biotechnology Company. The sequences of ITS and β-tubulin regions were modified and extracted using Chromas 2.6.6 software. Nucleotide sequences of the selected isolates were compared with the available sequences in the Gene bank by Blast algorithm and the sequences data were submitted in the NCBI database website. Phylogenetic trees were drawn using the Maximum likelihood method and MEGA 6.06 software.

Based on preliminary morphological studies, 20 isolates were selected as representatives of purified isolates and were identified by molecular analysis. In this study, a total of 39 fungal isolates were obtained, that the highest number of the isolates belonged to the pods of rice plants with the frequency of 17 isolates and the lowest number of isolates belonged to the roots of rice plants with 10 isolates. Among the 6 genera identified in this research, the largest number of isolates was belonged to Alternaria and Fusarium genera, with 18 and 6 isolates, respectively, and the highest number of species was belonged to Fusarium genus with 6 species. Fungal species include: F. chlamydosporum, F. proliferatum, F. incarnatum, F. solani, F. fujikuroi, F. verticillioides, S. bactrocephalum, N. sphaerica, N. oryzae, A. alternata, E. nigrum, C. cladosporioides. Among these species, Nigrospora sphaerica, E. nigrum and S. bactrocephalum are reported for the first time in this study as rice plant endophytes in Iran.

Investigation of endophytic fungi in the present study indicates that some of these isolates, including F. chlamydosporum, F. proliferatum, F. fujikuroi are pathogenic fungi. It means that range of the endophytic life and pathogenic life cannot be separated and determined and environmental conditions and nutritional status determine the type of interaction. F. chlamydosporum causes Fusarium root and crown rot, is reported in some sources as an endophytic fungus in various plants.

In this paper, forced, free, and mixed convections in incompressible flow were studied numerically. Nano-sized Al2O3, TiO2, MgO, and ZnO ceramics with water were considered as nano-fluids. Simulations were carried out for cavity flow with different boundary conditions and aspect ratios, as well as flow over stationary and rotating cylinders. The mean Nusselt number ((Nu) ̅) and friction factor for cavity flow and (Nu) ̅ for flow over a cylinder were compared for different nano-fluids. A new code was developed in FORTRAN 95 for numerical simulations. A fifth-order Runge-Kutta method for time discretization and a characteristic-based scheme for convective terms were used in this code. The averaging scheme on the secondary cells is used to obtain viscous fluxes. Primary results are validated with other researcher's outputs. Results showed that MgO-water and ZnO-water had maximum and minimum heat transfer rates, respectively. Moreover, maximum and minimum shear stresses were recorded for the Al2O3-water and TiO2-water, respectively. Using nanofluid increases the heat transfer rate between 15 and 37 percent depending on the Richardson number and selected nano-particles.

Natural gas must be preheated to prevent phase change and gas hydrate in pressure reduction stations. This paper aims to investigate the effect of the fins of gas tubes and their configuration, arrangement, and shape on the heat transfer and thermal efficiency of gas. To conduct a parametric study, two tube cases with fins and without fins, and in the finned case for the fin’s configuration, two longitudinal and circular arrangements, and the formation of the fins, two solid and interrupted forms were analyzed. Also, three types of cross-sections, including rectangular, convergent parabolic, and divergent parabolic, for the shape of the fins have been studied. For this simulation, the three-dimensional, incompressible, and steady flow was considered, and for analysis and discretization of convective heat equations, the characteristic-based method was applied. FORTRAN software was also used to implement and solve the equations. The results show that in solid and interrupted fins and increasing the number of fins in parallel, the dimensionless heat transfer coefficient increases. Also, the dimensional heat transfer coefficient decreases with increasing the ratio of fin height to the tube’s diameter. Also, the most significant heat transfer improvement was related to the divergent parabolic cross-section.

During recent decades, much attention has been paid to solving different kinds of dynamic systems, including pendulums, to observe their chaotic behavior. The governing equations of a double pendulum are investigated numerically in this paper. The pivot of the first pendulum is considered to be moving, following a certain mathematical template. Also, the pendulum, as a dynamic system, shows regular and chaotic behavior, under different conditions of its motion, such as initial angles and velocities (as the initial energy injected into the system), and the frequency of the pivot. The Lagrange equation governs this phenomenon. The proposed solution methods include the modified midpoint, along with fourth-order Runge-Kutta, to check the conditions for probable instability. The total value of the energy of the system is in the form of initial kinetic and potential energies. All numerical evaluations of the mathematical equations were coded. To investigate the chaotic behavior, a three dimensional phase space diagram for characteristic parameters of the system was constructed. The energy of chaos onset for each value of the pivot frequency was obtained utilizing three procedures: 1) The Poincare map, which is a special section in the three-dimensional diagram of phase space, in which one of the system parameters is constant (the angle of the first pendulum with a vertical line is zero). For a regular system (not chaotic), points in the Poincare map are located in an imaginary circle with limited radius, and they do not exceed this circle, even at very large times, 2) Lyapunov characteristic exponents, which are the average exponential separation between the nearby phase space trajectories of system motion. A system with one or more positive Lyapunov characteristic exponents is known as chaotic, and 3) The bifurcation diagram for characteristic parameters that shows the period doubling of chaos. It is a form of transition from periodicity to chaos. From this diagram, the onset of chaos is detected. The results are obtained using three methods, which depict good agreement with each other. They indicate that the more the frequency of the moving pivot, the less the initial energy required by that system to become chaotic. Initial energy decrease, which is due to frequency increase, follows a regular style, except for the natural frequency of the system. It was found that the moving pivot of the double pendulum has a dominant effect on chaos onset under certain circumstances.

Identification and transfer of desirable genes from wild relatives to crop species is one of the breeding solutions for producing resistance to pathogens and pests. This study was conducted to evaluate crossability and the response to Pythium ultimum in three species of the genus Carthamus. To assess response to the pathogen, eight cultivated safflower (Carthamus tinctorius L.) genotypes, two ecotypes of wild species C. oxyacanthus collected from Tehran and Isfahan, and one ecotype of wild species C. lanatus collected from Golestan province as sub factor were cultured on pathogen-free and infested medium with zoospore suspension of P. ultimum as main factor in a split plot design with 4 replications. Suspension of 105 zoospore per milliliter was used for inoculation. At the pathogen-free media, seed germination of cultivated and C. lanatus genotypes was higher than 90%, but at the infested media just cultivated genotypes had germination to this extent. The crossability experiment shows that, success in interspecific hybrid seed production is highly depended on choosing the seed producing parent. In the cross of cultivated species with C. oxyacanthus; more hybrid seed was obtained when C. oxyacanthus was female parent. Produced seeds on the cross of cultivated species and C. oxyacanthus had enough germination ability, but it was nothing for seeds obtained from cross of cultivated species and C. lanatus. Resistance of C. oxyacanthus to the pathogen Pythium and success in hybrid seed production show the potential of this species for transferring of resistance and other favorable traits to cultivated safflower.

This research uses computational modeling to explore another method to increase diesel engine performance while maintaining low pollutant emission levels. Previous studies have shown that injection-rate profiles and injector configurations play important roles on the performance and emissions of particulate and NOx in DI diesel engines. Since the most important engine design parameters, including filling efficiency, flame stability, performance and pollutant formation depend on the local flow field in inlet port and then in cylinder, the ability to accurately predict these more details is a key requirement for successful application of computational fluid dynamics techniques to design and optimization engines. In this work which is done at Motorsazan.Co in order to optimize inlet port shape, a procedure is outlined for producing a computational mesh for intake port and in-cylinder geometry on 135TI diesel engine at various intake port shapes. After modeling the combustion chamber with inlet port, AVL FIRE software has been employed for grid generation and numerical simulation in an open cycle mode. The numerical results are validated by corresponding experimental data for base line engine. Concerning the design limitations, two new helical ports are introduced and simulated using the same solver, boundary and initial conditions. Final performance and pollutant emission results, obtained from new models are compared with those of the base model and the model with the best results is introduced as the optimum among all. This work demonstrates that multidimensional modeling at an open cycle can now be used to gain insight into the combustion process and provide direction to explore new engine concepts.