196,945 research outputs found
Data for: Screening of Different Iranian Ecotypes of Cannabis under Water Deficit Stress
No full textIncludes; analysis of correlation between indices, The dry weight of all ecotypes, which includes male and female plants In two replicates which includes water deficit stress and control treatment
Molecular identification of two phytoplasma strains associated with the gladiolus virescence disease in Iran
No full textSevere symptoms of virescence in gladiolus flowers were observed in the Chaharmahal-Bakhtiari province of Iran in 2023. In the areas surveyed the disease incidence ranged from 5% to 40% and has a substantial economic impact, posing a serious threat to gladiolus cut flower production. Given that these disease symptoms have been reported to be associated with the presence of phytoplasmas, verifying the presence and identity of these bacteria is essential for a focused disease management. Sequence analyses of the 16S rRNA, ribosomal protein (rp), and tuf genes confirmed the presence of 'Candidatus Phytoplasma asteris' and 'Ca. P. tritici' strains in the symptomatic plants. Restriction fragment length polymorphism indicated that the phytoplasmas in the 30 symptomatic gladiolus plant samples examined belong to subgroups 16SrI-F and 16SrI-R. These results were also confirmed through phylogenetic analysis on the three studied genes in which the two strains resulted closely related to phytoplasmas in the 16SrI-R and 16SrI-F subgroups, respectively. This is the first report of 16SrI-R and 16SrI-F phytoplasmas associated with the virescence disease in gladiolus plants
A new basic unit for cascaded multilevel inverters with reduced number of power electronic devices
No full textIn this paper, a new topology for asymmetrical cascaded multilevel inverter is proposed. The proposed topology consists of series connection of several basic units. Reduction of number of power switches, driver circuits, IGBTs and dc voltage sources are some advantages of the proposed topology in comparison with the conventional cascaded multilevel inverters. In order to generate all output voltage levels, a new algorithm to determine the magnitudes of dc voltage sources is proposed. Finally, to verify the performance of the proposed inverter, the simulation results by using PSCAD/EMTDC software on a 33-level single-phase inverter are used
Assessment of critical buckling load of bi-directional functionally graded truncated conical micro-shells using modified couple stress theory and Ritz method
No full textThe present investigation has analyzed the buckling of bi-directional functionally graded conical micro-shells bearing axial loading. The dominant equations serve on the basis of the theory of first-order shear deformation in the modified couple stress theory (MCST). The Ritz technique is used so as to solve the governing equations. Bi-directional functionally graded material is the material used to construct the shell, and in a predefined composition profile, the volume fractions pertaining to the constituent materials constantly vary through the conical edge directions and thickness. The model predictions are compared and successfully validated using the ones available in the literature. According to the results, in comparison with the classical theory, the micro-shell buckling load is higher in the MCST. In addition, the contribution of a number of geometrical and mechanical parameters, for example, radius-to-thickness ratio, thickness-to-length scale ratio, length-to-radius ratio, semi-vertex angle, homogenization schemes, and material gradient indexes, to the buckling performance of conical micro-shells has been investigated. It is noteworthy that this investigation is the first effort to present a buckling analysis for the purpose of bi-directional functionally graded truncated conical micro-shells in accordance with the MCST
Hygrothermal modeling of the buckling behavior of sandwich plates with nanocomposite face sheets resting on a Pasternak foundation
No full textIn this work we investigate the buckling response of sandwich plates with a polymeric core and two face sheets reinforced by carbon nanotubes (CNTs). The problem is tackled analytically by means of a higher-order sandwich plate theory, where the face sheets are modeled according to a classical plate theory and modified strain gradient theory with temperature-dependent and moisture-dependent material properties. A Mori–Tanaka method is applied to determine the mechanical properties associated with the face sheets, while considering the agglomeration effect of CNTs. The governing equations of the problem are derived from the Hamilton’s principle, whose solutions are recovered by means of a Navier–Stokes method. A thorough sensitivity study of the structural response to different parameters includes the agglomeration and volume fraction of CNTs, the material length scale parameter, the side and aspect ratios, together with the temperature variation and humidity conditions. The sandwich plates are assumed to be immersed within an orthotropic Pasternak foundation, whose normal and shear moduli can affect the overall buckling response of the structure. Numerical experiments show that sandwich plates with nanocomposite face sheets, resting on orthotropic elastic foundations, feature an increased stiffness, where the proposed formulation yields accurate results, due to the possibility of considering the variation in temperature, humidity and agglomeration of the reinforcing CNTs within the solution
The Influence of GPL Reinforcements on the Post-Buckling Behavior of FG Porous Rings Subjected to an External Pressure
No full textThe work focuses on the post- buckling behavior of functionally graded graphene platelet (FG-GPL)-reinforced porous thick rings with open-cell internal cavities under a uniform external pressure. The generalized rule of mixture and the modified Halpin–Tsai model are here used to evaluate the effective mechanical properties of the ring. Three types of porosity patterns are assumed together with five different GPL distributions as reinforcement across the ring thickness. The theoretical formulation relies on a 2D-plane stress linear elasticity theory and Green strain field in conjunction a virtual work principle to derive the nonlinear governing equations of the postbuckling problem. Unlike the simple ring models, 2D elasticity considers the thickness stretching. The finite element model combined with an iterative Newton–Raphson algorithm is used to obtain the post-buckling path of the ring up to the collapse. A systematic investigation evaluates the effect of the weight fraction of nanofillers, the coefficient of porosity, porosity distribution, and the GPLs distribution on the deep post-buckling path of the ring. Based on the results, it is found that the buckling value and post-buckling strength increase considerably (by approximately 80%) by increasing the weight fraction of the nanofiller of about 1%
Free Vibration Analysis of Thick Annular Functionally Graded Plate Integrated with Piezo-Magneto-Electro-Elastic Layers in a Hygrothermal Environment
No full textThe present work aims at investigating the hygrothermal effect on the natural frequencies of functionally graded (FG) annular plates integrated with piezo-magneto-electro-elastic layers resting on a Pasternak elastic foundation. The formulation is based on a layer-wise (LW) theory, where the Hamiltonian principle is used to obtain the governing equation of the problem involving temperature- and moisture-dependent material properties. The differential quadrature method (DQM) is applied here as a numerical strategy to solve the governing equations for different boundary conditions. The material properties of FG annular plates are varied along the thickness based on a power law function. The accuracy of the proposed method is, first, validated for a limit-case example. A sensitivity study of the free vibration response is, thus, performed for different input parameters, such as temperature and moisture variations, elastic foundation, boundary conditions, electric and magnetic potential of piezo-magneto-electro-elastic layers and geometrical ratios, with useful insights from a design standpoint
Photogrammetric Reconstruction of a Stolen Statue
No full textIn this paper, we propose a method to reconstruct a digital 3D model of a stolen/damaged statue using photogrammetric methods. This task is challenging because the number of available photos for a stolen statue is in general very limited – especially the side/back view photos. Besides using standard structure-from-motion and multi-view stereo methods, we match image pairs with low overlap using sliding windows and maximize the normalized cross-correlation (NCC) based patch-consistency so that the image pairs can be well aligned into a complete model to build the 3D mesh surface. Our method is based on the prior of the planar side on the statue’s pedestal, which can cover a large range of statues. We hope this work will motivate more research efforts for the reconstruction of those stolen/damaged statues and heritage preservation.Mechatronic DesignEmerging Material
Occurrence and identification of a phytoplasma associated with Pinus brutia witches’ broom disease in Isfahan, Iran
No full textBetween 2016 and 2017, symptoms of witches’ broom, proliferation, drying of twigs and ball-like structures formation were observed in Pinus brutia in urban green areas and parks in Isfahan (Iran). All samples from affected P. brutia trees resulted positive in nested-PCR using primer pairs targeting the phytoplasma 16S rRNA gene. Amplicons were obtained only from all the symptomatic pine tree samples and RFLP analyses of R16F2n/R16R2 amplicons with KpnI, AluI, HaeIII, HhaI, HpaII, MseI, RsaI,ThaI, BfaI and TaqI restriction enzymes showed the presence of phytoplasmas enclosed in the 16SrVI group. Four amplicons were sequenced and showed 100% identity to each other. One of these sequences was deposited in the GenBank database (accession number MK158098) and the virtual RFLP pattern was identical (similarity coefficient 1.00) to the reference pattern of 16Sr group VI, subgroup A confirming that the phytoplasma detected in pine is a member of 16SrVI-A subgroup. This is the first report of a 16SrVI-A phytoplasma strain associated with pine tree witches’ broom (P. brutia) disease
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