springer jul 1979 (3 Ergebnisse)

Buch. Zustand: Neu. Neuware - This volume is the product of a conference on the theme 'Development - the Next Twenty-five Years' which the Institute of Social Studies held in Decem ber 1977 to mark its own twenty-fifth anniversaryas a centre of development studies. We felt it appropriate at that point in time to caU together specialists from all over the world in an attempt to assess the 'state of play' in our field as we move into the last quarter of the twentieth century. 1 For several days, therefore, the Institute's new building house d a remarkable concentration of knowledge and experience concerning the problems of the so-calle d less developed countries, drawn from all over the world. Although it was inevitable that the participants should represent the past (and it was several times re marked that, in that sense, there were too few women present), the earnest and sometimes heated discussions looked to the future as much as to what had happened in the last twenty-five years. As the discussions proceeded, three things became apparent. Firstly , although the papers submitted did not fully reveal it, the ongoing debate between radicals and moderates, those who saw possibilities of change only basically through a direct break with existing structures and those who felt change possibIe within them, is by no means at an end.

Buch. Zustand: Neu. Neuware - While general systems research has had a considerable impact on research in the social sciences, this impact has been mainly conceptual and has not served to provide the operational and methodological aids for research which are possible. In addition, many of those systems-oriented directions and results which do impact social science research have developed inde pendently and in piecemeal fashion in recent decades. The main develop ment of this book is a cohesive framework within which to integrate results of general systems research and which provides a means for the organiza tion of data and observations - and operational procedures by which to proceed - in the investigation and study of social and socio-technical systems. The book systematically develops in the first five chapters ail of the basic concepts and aspects which make up the framework, showing wherever possible the main sources of these concepts and placing them in historical perspective. The developments of the first five chapters are pulled together and integrated, in the last chapter, into a conceptual and operational general systems problem solving framework which extends the investiga tive capabilities of researchers of specific systems. The last chapter also contains an example of an overall investigation which utilizes the frame work and which proceeds from system definition through the derivation of explanatory knowledge regarding the object system and which illustrates in detail most of the concepts and elements of the framework.

Taschenbuch. Zustand: Neu. Neuware - Mit dem verstarkten Einsatz des ProzeBrechners in der spanen den Fertigung wachst auch die Forderung, Grenzregelungs (ACC-) Systeme in den Rechner zu integrieren. Diese Aufgabe wurde in der vorliegenden Arbeit in drei Entwicklungsstufen durchge ftihrt. Zunachst wurde die Grenzregelung als Einzelfunktion in einen ProzeBrechner integriert (direkte digitale Grenzregelung) . Ausgehend von der Dynamik der Regelstrecke -Bahnsteuerung, FrasprozeB, Sensor- ergab sich die Abtastperiode ftir dieses DDC-System durch Untersuchung der Bandbreite und des Strecken storverhaltens. Die ermittelten Werte ftir die Abtastperiode dienten als Anhaltswerte ftir die Rechnerbelastung durch den zu entwickelnden Regelalgorithmus. Dieser wurde in Form eines nichtlinearen Kompensationsalgorith mus gefunden, der das System trotz der stark schwankenden Ver starkung des Frasprozesses adaptiv stabilisiert und zudem eine ext rem niedrige Rechnerbelastung bewirkt. Die Programmierung des ACC-programms wurde in Assemblersprache durchgeftihrt. Dabei erweist sich der Befehlsumfang gangiger ProzeBrechner einschlieBlich Mikro-Computer als ausreichend, so fern die Operationen Multiplikation und Division hardware maBig ablaufen. Die Steuerung des Anschnittvorgangs tiber den ProzeBrechner kann auf Grund seiner geringen Interrupt-Reaktionszeit ohne Schwie rigkeiten durchgeftihrt werden. Das entwickelte programm ftir die direkte digitale Grenzregelung beim Frasen kann in seiner vorliegenden Konzeption auch auf an dere ProzeBrechner, insbesondere auch auf Mikro-Computer, tiber tragen werden. In einem zweiten Schritt folgt die Integration des entwickel ten Regelkonzepts in den Steuerungsrechner einer CNC. - 123 - Ausschlaggebend fUr diese Systemlosung war die Moglichkeit der schnittstellennahen Kopplung zwischen ACC- und CNC-Funk tionen innerhalb des Steuerungsrechners und der daraus resul tierende minimale Hardware-Aufwand fUr das ACC-System.