The book is written by a group of authors united by application of the same methodology and experience of cooperation for a long time. The contents of the book cover:

1. Methods of generation of noncircular gears by enveloping methods that are similar to those applied for generation of circular gears. However, the motions of the generating tools (rack cutter, shaper, or hob) are nonlinear and must be computerized.

2. Design of noncircular gears to be applied for variation of output speed and generation of functions. Such a design requires determination of mating centrodes that roll over each other.

3. Detailed procedure of design of elliptical gears with spur and helical teeth, oval gears, lobes, eccentric involute gears, and twisted gears (applied for extension of the interval of function generation).

4. Tandem design of planar linkages coupled with noncircular gears for a broader variation range of the output speed.

The authors hope that this book will allow extension of application and design of noncircular gear drives in mechanisms and industry.

Noncircular gears (NCG) have been considered a curiosity and a product of niche applications for a long time because of their design and manufacture complexity. However, thanks to the availability of powerful computers and sophisticated CNC machine tools, the design and manufacturing of NCG became more feasible and their potential in many fields can be more easily exploited.

NCG are used to improve the function, versatility, and simplicity of many mechanical processes. For instance, they allow speed matching on assembly lines, linear motion with quick return, and stop-and-dwell motion. Very recent publications in highly respected scientific journals show that the interest in NCG is still very strong, for both the theoretical and manufacturing challenges involved, especially in today's high-performance automatic machines.

In this context, this book on NCG is very welcome. It covers all the basic issues of NCG and shows how to solve most of the key problems in NCG design and manufacturing. It clearly presents the foundations of this topic, very useful to the beginner, as well as new and advanced concepts of great importance to both scientists involved in research issues and skillful designers facing NCG sizing and manufacturing. In particular, the book represents the most comprehensive and authoritative treatise on NCG available today for scientists and designers. When complemented with a recently published book, Gear Geometry and Applied Theory (2nd ed.) by F. L. Litvin and A. Fuentes (Cambridge University Press, 2004), which provides the fundamentals of all types of gears, the whole field of the theory and applications of gears is covered.

Introduction: government, targets and measurement

The last twenty years have seen the use of performance measurement and performance management mushroom in government departments and agencies in the United Kingdom and elsewhere. A review of the use of performance measurement in various countries can be found in Public Management Reform: A Comparative Analysis, by Pollitt and Bouckaert (2004). Performance measurement is not a new feature of public administration, but it has become much more prominent in the United Kingdom, the United States, New Zealand and some other countries during the last two decades. A positive review of these developments in the United Kingdom was produced by the government's Comptroller and Auditor General in 2001 (National Audit Office, 2001). A rather more critical review can be found in the report produced by the Public Administration Select Committee in 2003 following its extensive discussions (Public Administration Select Committee, 2003).

There are many different aspects of the public sector that could be measured. These include issues of productivity, traditionally the domain of economists, which was the major concern of the Atkinson Review (Office of National Statistics, 2005), set up by the National Statistician “to advance methodologies for the measurement of government output, productivity and associated price indices in the context of the National Accounts …”.