No abstract

Fluctuating asymmetry measures random deviations from bilateral symmetry, and thus estimates developmental instability, the loss of ability by an organism to regulate its development. There have been few rigorous tests of this proposition. Regulation of bilateral symmetry must involve either feedback between the sides or independent regulation toward a symmetric set point. Either kind of regulation should decrease asymmetry over time, but only right–left feedback produces compensatory growth across sides, seen as antipersistent growth following perturbation. Here, we describe the developmental trajectories of perturbed and unperturbed leaves of pumpkin, Cucurbita pepo L., grown at three densities. Covering one side of a leaf with aluminium foil for 24 h perturbed leaf growth. Reduced growth on the perturbed side caused leaves to become more asymmetrical than unperturbed controls. After the treatment the size‐corrected asymmetry decreased over time. In addition, rescaled range analysis showed that asymmetry was antipersistent rather than random, i.e. fluctuation in one direction was likely to be followed by fluctuations in the opposite direction. Development involves right–left feedback. This feedback reduced size‐corrected asymmetry over time most strongly in the lowest density treatment suggesting that developmental instability results from a lack of resilience rather than resistance.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 27–41.

This paper is the first in a series dedicated to investigating the airflow and thermal management of electrical machines. Due to the temperature dependent resistive losses in the machine"s windings, any improvement in cooling provides a direct reduction in losses and an increase in efficiency. This paper focuses on the airflow which is intrinsically linked to the thermal behaviour of the machine as well as the windage power consumed to drive the air through the machine. A full CFD model has been used to analyse the airflow around all major components of the machine. Results have been experimentally validated and investigated. At synchronous speed the experimentally tested mass flow rate and windage torque were under predicted by 4% and 7% respectively by the CFD. A break-down of torque by component shows that the fan consumes approximately 87% of the windage torque.

No abstract

This paper is the first in a series dedicated to investigating the airflow and thermal management of electrical machines. Due to the temperature dependent resistive losses in the machine"s windings, any improvement in cooling provides a direct reduction in losses and an increase in efficiency. This paper focuses on the airflow which is intrinsically linked to the thermal behaviour of the machine as well as the windage power consumed to drive the air through the machine. A full CFD model has been used to analyse the airflow around all major components of the machine. Results have been experimentally validated and investigated. At synchronous speed the experimentally tested mass flow rate and windage torque were under predicted by 4% and 7% respectively by the CFD. A breakdown of torque by component shows that the fan consumes approximately 87% of the windage torque.