D.J. Smith - Böcker

Aquaculture is rapidly becoming a major source of fish protein used to meet the nutritional needs of humans. As the aquaculture industry grows, exposure of farmed fish to environmental contaminants, and the need for chemical therapeutic agents for fish, will increase. This book is designed to bring together authorities worldwide on the regulation of environmental contaminants and food chemicals and researchers investigating the metabolism and disposition of foreign chemicals (xenobiotics) in fish species.

Until the reign of Queen Anne oxen were widely used for ploughing, and most other jobs on the farm, such as harvesting, were done manually by farm labourers. But at the beginning of the eighteenth century the Agricultural Revolution began. Oxen were displaced by horses for ploughing and the famous heavy breeds of Shires, Clydesdales and Suffolks developed. Horses were more versatile than oxen and came to be used for many tasks other than ploughing. Following the Industrial Revolution the ingenuity of Victorian manufacturers produced an enormous range of horse-drawn agricultural machinery – not just ploughs, but grubbers, cultivators, harrows, rollers, drills, reapers, binders, root lifters, manure spreaders, rakes and many other types – which continued in use until the tractor replaced the horse from the 1930s. In this book the author describes these machines and includes drawings of many of them, as well as photographs.

Aquaculture is rapidly becoming a major source of fish protein used to meet the nutritional needs of humans. As the aquaculture industry grows, exposure of farmed fish to environmental contaminants, and the need for chemical therapeutic agents for fish, will increase. This book is designed to bring together authorities worldwide on the regulation of environmental contaminants and food chemicals and researchers investigating the metabolism and disposition of foreign chemicals (xenobiotics) in fish species.

How to Use This Book The primary purpose of this book is to assist small companies, involved in both hardware and software, to devise and evolve their own quality systems. There are a number of national and now international standards which outline the activities for which procedures and records need to be specified. They are described and compared in Chapter 2, and the subsequent guidance in the book is intended to assist in meeting them. Although, at first sight, the operations of a hardware equipment developer may seem very different from those of a software house, the basic requirements of a quality system, such as the BS 5750 and ISO 1987 series of documents, are the same. For this reason the same standard can be called for in both areas and it will be seen, in Part 2, that suitable procedures can be derived to meet both types of operation. Quality standards (BS 5750, AQAP, ISO 9000 series) distinguish between companies carrying out, on the one hand, both design and manufacturing fixed functions and, on the other hand, those who only manufacture to specifications. In practice, the lesser requirements (those applying to manufacture to fixed specifications) are common to both levels of standard and the additional controls pertaining to design are added to obtain the higher standard. Chapter 2 explains the differences in detail.

The rapid growth in use of programmable technology, in nearly all sectors of Engineering, is a well-known established trend and one which there is every reason to believe will continue into the foreseeable future. The drivers of this trend include cost, flexibility, rich functionality and certain reliability and safety advantages. However, as explained in this book, these advantages have to be carefully weighed against a number of dis­ advantages which, amongst other things, have fundamental implications for reliability and safety. Ideally, a programmable system would be viewed as a fusion of hardware, software and user (or 'skinware'), operating under a set of environmental conditions. To date, such a unifying model does not exist and so hardware, software and human factors are still considered largely as three separate disciplines, albeit with certain interdependencies. Established techniques are available which enable the engineer to develop systems comprising purely hardware components to a prescribed reliability and performance. Software, however, is fundamentally different in a number of ways, and does not lend itself to equivalent analysis. A major problem with software is its poor 'visibility', and consequently the great difficulty in understanding and predicting its behaviour in all cir­ cumstances. This results in the ever-present software design flaws, or 'bugs', which have plagued the software industry from its beginnings.