Investigation of skewing effects on the vibration reduction of three-phase switched reluctance motors

Switched reluctance motors (SRMs) are gaining in popularity because of their robustness, low cost, and excellent high-speed characteristics. However, they are known to cause vibration and noise primarily due to the radial pulsating force resulting from their double-saliency structure. This paper investigates the effect of skewing the stator and/or rotor on the vibration reduction of the three-phase SRMs by developing four 12/8-pole SRMs, including a conventional SRM, a skewed rotor-SRM (SR-SRM), a skewed stator-SRM (SS-SRM), and a skewed stator and rotor-SRM (SSR-SRM). The radial force distributed on the stator yoke under different skewing angles is extensively studied by the finite-element method and experimental tests on the four prototypes. The inductance and torque characteristics of the four motors are also compared, and a control strategy by modulating the turn-ON and turn-OFF angles for the SR-SRM and the SS-SRM are also presented. Furthermore, experimental results validate the numerical models and the effectiveness of the skewing in reducing the motor vibration. Test results also suggest that skewing the stator is more effective than skewing the rotor in the SRMs.

Outer rotor mechanical and dynamic performance analysis for high-speed machine

Due to high-speed rotation, the problems about rotor mechanics and dynamics for outer rotor high-speed machine are more serious than conventional ones, in view of above problems the mechanical and dynamics analysis for an outer rotor high-speed permanent magnet claw pole motor are carried out. The rotor stress analytical calculation model was derived, then the stress distribution is calculated by finite element method also, which is coincided with that calculated by analytical model. In addition, the stress distribution of outer rotor yoke and PMs considering centrifugal force and temperature effect has been calculated, some influence factors on rotor stress distribution have been analyzed such as pole-arc coefficient and speed. The rotor natural frequency and critical speed were calculated by vibration mode analysis, and its dynamics characteristics influenced by gyroscope effect were analyzed based on Campbell diagram. Based on the analysis results above an outer rotor permanent magnet high-speed claw pole motor is design and verified.

Análisis del proceso productivo en la fabricación de muebles en la ciudad de Cuenca y propuesta de un plan de optimización del área de producción de la fábrica Vitae Muebles. Periodo 2015

El presente trabajo de titulación fue elaborado en la Fábrica Vitae Muebles en el área de producción donde se realizó el estudio de la filosofía empresarial. Se analizaron las herramientas de Lean Manufacturing como: Justo a tiempo, 5 S, Kaizen, Kanban y Poke Yoke lo que permitió decidir que la mejor alternativa para el área de producción de la fábrica es la metodología 5 S. Se efectuó un análisis de la producción de muebles en la ciudad de Cuenca, además se realizó una comparación de los niveles de producción con empresas que tienen mayor trayectoria en el mercado nacional. Para describir el proceso concerniente a la fabricación de muebles se realizaron visitas diarias durante un período de tiempo de 2 meses y para su respectivo análisis se realizó un check–list lo que permitió comprobar las dificultades que se presentan en las diferentes secciones de producción donde se encontraron problemas relacionados con la acumulación de materiales, desorganización, falta de limpieza e indisciplina. . Se elaboró la propuesta del plan de optimización usando los 5 pilares fundamentales que comprende Seiri (clasificación), Seiton (organización), Seiso (limpieza), Seiketsu (estandarización), Shitsuke (disciplina), los cuales brindarán beneficios en obtener una mejor imagen en la planta de trabajo, cambios de hábitos en los operarios e incremento de su seguridad laboral. Por último se realizaron las conclusiones y recomendaciones de este trabajo de titulación.

La letteratura escatologica ebraica tra XI e XIII secolo: aspettative messianiche e di redenzione alla luce delle persecuzioni del periodo delle crociate

Questo lavoro prende in analisi le aspettative messianiche e di redenzione ebraiche nel periodo delle crociate, ossia tra l’XI e il XIII secolo. Fu, questa, un’epoca di importanti persecuzioni nei confronti delle comunità ebraiche – stanziate soprattutto in Germania –, sottoposte ad attacchi e a conversioni forzate da parte dei crociati diretti a Gerusalemme. In quel periodo venne copiato e rielaborato un gran numero di testi di carattere apocalittico-escatologico, il cui scopo, secondo la mia ricostruzione, era quello di infondere speranza negli ebrei oppressi e di consolarli in merito all’imminente liberazione dal giogo straniero che l’era messianica avrebbe comportato. Nella prima parte del lavoro ricostruisco il quadro storico in cui tali testi circolavano, mentre nella seconda propongo un’edizione e una traduzione italiana degli scritti più rilevanti per la discussione.