Roll forming process is used for manufacturing sheet metal parts by successive bending and creating the final shape with gradual deformation. In this article, deformation of a pre-punched sheet due to the roll forming process was studied. Two main defects in the roll forming process are ovality of holes and bow defect. The ovality of the hole is influenced by the process parameters including sheet strength, thickness, initial hole diameter and distance of hole center to lateral edge. Due to the roll forming process, the sheet undesirably bent along longitudinal direction to a slight curved part which called bow defect. Also, the magnitude of product’ s curvature along longitudinal direction (bow defect) was measured. The experimental tests were conducted on ASTM 230, 275 and 340 galvanized steels. The results showed that increase in the yield strength elongates the hole along rolling direction and shortened the hole perpendicular to rolling dimension. Therefore, the ovality of hole increases by increasing the yield strength. Also, similar trends were observed by increasing the thickness and the distance between hole center and lateral edge. The results showed that the bow defect decreases by increasing the material yield strength, while with increase in the sheet thickness, initial hole diameter and hole distance from lateral edge the bow defect was increased.

Mesquite (Prosopis farcta) is a perennial weed that propagates by seeds and rhizomes. P. farcta became widespread in arid zones of Iran. During 2009-2010, the studies indicated that Stator limbatus feeds on seeds of P. farcta and the larvae can destroy up to 60% of the Mesquite seeds. Biological characteristics of S. limbatus were assessed in various temperatures ranging from 25. 39 ± 0. 5 to 21. 17 ± 0. 55 ° C day: night, RH= 37. 78 ± 1. 38% and LD=11: 13 hours. Some infected fruits were collected from Meibod. Infected seeds were retained in the breeding box until the larva transformed into the adult insects. Incubation period lasted an average of 8. 85 ± 0. 59 days. Eggs were laid individually on fruits. Each female insect laid an average of 47. 57 ± 4. 47 eggs on seeds. The roaches in Yazd climatic conditions had more than three generations in each year and overwintering of the insect is in the form of larvae and pupae inside the seeds and remained fruits on the host plant. The insect pupates and transform into the adult stage in late spring and early summer, coinciding with the start of Kahourak fruiting. After mating, adult females begin hatching on pods. Upon completion of the embryonic period, the larva enters to seed directly from egg shell. Only one larva grows in each seed and after feeding from all the internal parts come out and become white pupates in cocoons. In these conditions, the duration of a complete generation from egg to adult was 39 ± 1. 04 days. The values for larva and pupa periods were 21. 2 ± 0. 7 and 8. 8 ± 0. 38 days, respectively. Mean adult longevity without feeding was 26. 36 ± 2. 06 days and over this period an average value of females lying was 47. 57 ± 4. 47 eggs. Data showed that in average 83. 52± 5. 071% of the eggs were hatched. Therefore, this insect can be a suitable agent for biological control of this weed in Yazd province. In nature the pest larvae are attacked by big black wasps from Braconidae family.

The scope of this paper is to consider two-dimensional flows in a rotor-stator blade rows and to analyze their effects on each other. The control volume approach based on Jameson's technique is used to solve two-dimensional unsteady compressible Euler equations in a stage of an axial flow turbine. The computational speed. At the intersection of the domains, a slip grid technique is used. The equations are solved simultaneously for both domains. The method is used in this paper for slipping of the grid has some advantages over the other slipping techniques with regard to the accuracy and CUP time. In this technique, transferring the information from the moving mesh to the stationary mesh is done by using some imaginary cells. The cubic spline interpolation is employed in such a way that the conservation laws to be satisfied. The results obtained for an axial flow turbine in this work, are compared with other's results and good agreement is obtained. Finally, the effects of row spacing between the stator and rotor blades are considered and analyzed.

The air-gap of electrical machines may become non-uniform due to low accuracy of the manufacturing machinery, in assembling processes, or by aging. Detection and monitoring of this phenomenon is very important and of interest. There are several methods to model non-uniform air-gaps and to detect them by monitoring systems. One of the most widely used methods is by the analysis of the line currents. In this paper a new, simple and comprehensive method is presented to model and detect non-uniform air-gaps in synchronous generators with skewed rotors. The influence of non-uniform air-gaps on the harmonics of the induced voltage of the stator is investigated by the proposed method. Simulations are performed for three cases: uniform air-gap, static rotor eccentricity, and stator ovality in a two phase generator. The experimental results are also presented. The good correspondence between the simulation and the experimental results clearly validates the theoretical findings put forward in this paper.

The seed beetle, Stafor limbatus (Horn) (Col.: Bruchidae), collected from Bushehr and Yazd provinces, Iran, on Acasia sp. and Prosopis farcta, is newly recorded from Iran. It is native to southwestern United States but distributed in various parts of the world. The beetle was identified by Delobel from France.

In the present study, the effect of stator dynamics on the chaotic behavior of a rotor-diskbearing system with rub-impact between disk and stator is investigated. The governing equations of motion are derived using Jeffcott model and Newton’s second law and then are made dimensionless. In the beginning, the system is modeled regardless of stator dynamics, and then the stator dynamics is also considered in the modeling of the system. In both cases, the system behavior is studied by bifurcation diagrams, time series diagrams, phase plane diagrams, power spectrum diagrams, Poincaré maps, and maximum Lyapunov exponent, respectively. The obtained results show that the type of stator dynamics modeling has a significant effect on the prediction of the response of a disk-bearing system with rubimpact between disk and stator. In other words, the results show the system has a chaotic behavior without considering the dynamics of the stator in mathematical modeling, while in the case of considering the stator dynamics and using the suitable values for the stator stiffness, the motion behavior of the system can be changed from the chaotic to the regular and periodic motion.

This paper reviews the current state of the double-stator permanent magnet vernier (DS-PMV) machine technology. At first, the recent advances in PMV machines are presented. In the following, the classification of various PMV machines' configuration is elucidated. In general, this review covers the principle of better understanding of the novel PMV machines' topologies using different windings configurations, flux modulation poles and stator/rotor structures.

This paper presents a design and optimization procedure for a dual-stator machine with a diametrically magnetized PM to improve the electromagnetic performance. First, analytical design equations are presented based on MEC analysis,they are used to design a basic dual-stator machine. Then, by applying an artificial intelligence algorithm, the machine is optimized to achieve high efficiency and torque density, and low pulsating torque for direct-drive applications. A quantitative comparison is performed between the optimized new machine and conventional dual-stator machines to evaluate the performances and improvements of the understudy machine. The machine performance, including air-gap flux density distribution, back electromotive force, electromagnetic torque, cogging torque, and torque ripple are analyzed by the finite element method. The analysis results have demonstrated that benefiting from its topology, the optimized dual-stator machine with diametrically magnetized PM has the comprehensively better performance, including higher torque density, higher efficiency, and lower torque ripple and cogging torque compared to conventional dual-stator machines.

Stator fault detection may be done with different methods. However, If the stator current sensor is to be installed for protection and controlling of an induction motor, signature and FFT analyses are the mostly used for on-line stator fault detection. Also, winding function method is an effective procedure for modeling motors in unbalance conditions. Simulation results with this method are used in this paper for detection of the turn-to-turn, coil-to-coil and phase-to-phase faults. The FFT analysis of line current, interrupting motor power supply; negative sequence currents and R.M.S value of speed are all important criteria for fault diagnosis. Simulation and Experimental results confirm that the FFT analyses and interruption of motor from supply and R.M.S value of the speed are the effective methods for the fault detection. Experimental results are presented to verify the accuracy of the simulation results

This study aimed to provide the analytical design, optimization, and three-dimensional (3D) simulation through finite element method of a coreless stator axial field flux-switching motor (AFFSM). The motor consists of two indented rotors with a coreless stator between them consisting of a magnet and winding. First of the motor electrical and magnetic design was performed and its basic parameters were calculated. Then, the optimization of the machine was evaluated implementing the Taguchi algorithm in order to minimize the motor cogging torque. Some of the basic motor dimensions, such as the magnet length and width, the rotor tooth width and height, and the back iron thickness, were selected as optimization variables, and the best combination of these variables was obtained by changing them in a certain range to achieve the desired objective. Then, the accuracy of analytical design and optimization was evaluated through forming a 3D finite element method (FEM) of the motor and investigating its performance. Comparison of the optimized and primary motor revealed that the optimal design had a better performance than the initial. Finally, a prototype of the proposed motor was fabricated and tested, which indicated that the experimental results were largely similar to the analytical results.