Active design of tooth profiles using parabolic curve as the line of action

This paper proposes a method for the design of gear tooth profiles using parabolic curve as its line of action. A mathematical model, including the equation of the line of action, the equation of the tooth profile, and the equation of the conjugate tooth profile, is developed based on the meshing theory. The equation of undercutting condition is derived from the model. The influences of the two design parameters, that present the size (or shape) of the parabolic curve relative to the gear size, on the shape of tooth profiles and on the contact ratio are also studied through the design of an example drive. The strength, including the contact and the bending stresses, of the gear drive designed by using the proposed method is analyzed by an FEA simulation. A comparison of the above characteristics of the gear drive designed with the involute gear drive is also carried out in this work. The results confirm that the proposed design method is more flexible to control the shape of the tooth profile by changing the parameters of the parabola.

The potential for neighbourhood regeneration in a period of austerity: changing forms of neighbourhood governance in two cities

Localism is an active political strategy, developed in a period of austerity by the UK's coalition government as a justification for the restructuring of state-civil society relationships. The deprived neighbourhood has long been a site for service delivery and a scale for intervention and action, giving rise to a variety of forms of neighbourhood governance. Prior international comparative research indicated convergence with the US given the rise of the self-help conjuncture and the decline of neighbourhood governance as a medium of regeneration. The subsequent shift in the UK paradigm from ‘big’ to ‘small state’ localism and deficit-reducing cuts to public expenditure confirm these trends, raising questions about the forms of neighbourhood governance currently being established, the role being played by local and central government, and the implications for neighbourhood regeneration. Two emerging forms of neighbourhood governance are examined in two urban local authorities and compared with prior forms examined in earlier research in the case study sites. The emerging forms differ significantly in their design and purpose, but as both are voluntary and receive no additional funding, better organised and more affluent communities are more likely to pursue their development. While it is still rather early to assess the capacity of these forms to promote neighbourhood regeneration, the potential in a period of austerity appears limited. Reduced funding for local services increases the imperative to self-help, while rights to local voice remain limited and the emerging forms provide little scope to influence (declining) local services and (still centralised) planning decisions, especially in neighbourhoods with regeneration needs which are likely to lack the requisite capacities, particularly stores of linking social capital. Initial conclusions suggest greater polarity and the further containment of deprived neighbourhoods.