Coupled Extensional-Torsional Vibration Frequency of Hoisting Rope in Tower-Type Friction Drive Hoist System
In order to avoid resonance, and to enhance safety of hoisting system and monitoring reliability, an impact mechanical model of mine hoisting rope for friction drive hoist system was built. According to Hamilton principle and considering the effect of oriented pulley and hoisting rope string, coupled extensional-torsional and extensional only mathematical models of hoisting rope were deduced. Mode shape and transcendental equation of angular frequency were obtained based on the hypothesis that the wave of vibration propagated with sine shape. With numerical calculation, results show that the frequency considering the effect of oriented pulley and hoisting rope string was slightly lower comparing with the frequency ignoring the effect at the bottom of shaft, but much different at the mouth; and there is significant difference between coupled frequency and extensional vibration only. Thereby, to make the design and monitoring of mine hoisting much more reliably, it is suggested that the extensional-torsional coupled vibration of hoisting rope, oriented pulley and hoisting rope string should be considered.
Effect of Hoisting Load on Transverse Vibrations of Hoisting Catenaries in Floor Type Multirope Friction Mine Hoists
The effect of hoisting load on transverse vibrations of hoisting catenaries during lifting in coal mines was investigated in this study. Firstly, dynamic analyses of the vertical hoisting rope were performed. The results show that transverse vibration plays the dominating role in the coupled dynamics of the vertical rope subjected to external excitation induced by axial fluctuations of head sheave, and the rope tension can be approximated by the quasistatic tension. Secondly, employing dynamic simulations, the effect of hoisting load on the transverse vibrations of hoisting catenaries was discussed. The results show that, under the second-order excitation frequency, a discrepant large transverse amplitude will be excited when the hoisting load ranges from 0 to 5000 kg, leading to collision between the two adjacent catenaries and accelerating the rupture of rope. To solve this problem, according to simulation curves, the self-weight of conveyance (preload) can be optimized from 39500 kg to 49500 kg. Eventually, on-site measurements were performed on the studied machine, validating the accuracy of the effect of hoisting load on transverse vibrations of hoisting catenaries. This investigation will greatly support facility maintenance, machine design, and even engineering optimization for floor type multirope friction mine hoists.
Child psychiatry curricula in undergraduate medical education.
OBJECTIVE
To review the literature describing the content and time allocated to undergraduate medical education curricula in child and adolescent psychiatry and make recommendations about child and adolescent psychiatry teaching goals and curricula content.


METHOD
A literature search from 1970 to February 2007 using the key words undergraduate, curriculum, teaching, education, psychiatry, child, adolescent, and medical school, was conducted using PubMed, PsycINFO, and Web of Science.


RESULTS
There is limited agreement about curricula content for undergraduate child and adolescent psychiatry teaching programs in medical schools, with a wide range of objectives identified by different programs. On average, the time allowed for teaching child and adolescent psychiatry is small. There is also great variation in the time allocated by different medical schools. In many countries, the number of child and adolescent psychiatrists with academic appointments is limited, and child and adolescent psychiatry programs are developed and taught by a small number of teaching staff at each medical school.


CONCLUSIONS
Medical schools should reconsider the relatively low priority given to teaching child and adolescent psychiatry to medical students. The child and adolescent psychiatry profession must identify clear learning goals for a longitudinal developmentally appropriate model of child and adolescent psychiatry education commencing at an undergraduate level in medical schools and continuing through residency and fellowships. There is a need to promote national and international standards for teaching in this area and to encourage stronger collaborations between teaching staff across different medical schools.