摘要:

AbstractThis paper reviews the biological problem of crop protection from a systems analysis point of view, and discusses the commonalities in the biological and mathematical form of the population models used to describe the interactions between trophic levels (e.g. herbivore–plant). The historical development of the mathematical models is presented. The uses of these models in crop production are discusse

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02243.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02244.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe state–variable approach to systems analysis and dynamic simulation is based on the assumption that the state of each system at any moment may be quantitatively characterized and that changes in state may be described by mathematical equations.The basic distinction between state, rate and driving variables in this approach is illustrated by examplesThe conflict resulting from the large number of state variables that may be distinguished in any ecological system and the small number that can be handled in simulation models is treated and attention is given to the distinction between unique and recurring systems, especially with reference to the problem of model evaluatio

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02245.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02246.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractIn this paper multiple regression models are compared with fundamental models in the context of the plant disease system. The value of the regression technique for analysing the pathogen–host–environment complex and for prediction is discussed. Although there are limitations to the use and interpretation of multiple regression equations, their underlying simplicity can be of advantage for the solution of many practical problems in disease management. Despite the empirical nature of multiple regression, it can be used to advantage in the construction of hybrid models of the deductive–inductive type which combine the summary of experience with the fundamental principles of disease mecha

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02247.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02248.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractWhen faced with a model to be simulated on a computer, one is in general faced with a series of problems, to which answers are quite often difficult to find. These problems include:1) Can we construct a mathematical approximation of the model in such a way that the resulting formulation can be implemented as a computer for simulation purposes ? 2) Will the above mathematical formulation guarantee a result on an ideal (perfect) machine ? 3) Will the chosen method of simulation withstand the non–ideal characteristics of an actual machine ? 4) Will it be possible to compute results to the computing sequence that is created for the simulation ? 5) How does one choose the right language that is to be the programming vehicle for the simulation ? 6) Can one describe every simulation problem in any of the languages for specific classes of problems ?This paper tries to give an insight into the possible answers to these questions and endeavours to provide the reader with some basic knowledge about the possibilities available and the problems to look for when setting up simulation experiments by programming them with simulation languages for digital computer

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02249.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02250.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractCROPS is a GASP IV based simulation language which emphasizes the development of the equations which model crop physiology. The CROPS philosophy of physiology is to first divide the crop into constituents (carbon, nitrogen, phosphorus, potassium and water) and then partition the crop into compartments (leaves, grain, stems, and roots). Flows of constituents between compartments are illustrated by system dynamics diagrams. A crop model consists of the equations which describe these constituent flows and which are totally user–specified in separate FORTRAN functions.The CROPS coding (which is a specially written set of GASP IV user routines) accomplishes all other tasks normally required in a crop simulation. CROPS automatically processes weather data, collects and reports statistics on crop growth rates and relative growth rates, and prints status reports on simulated crop conditions. In addition, all GASP IV support routines (plots, histograms, etc.) are available to the CROPS user. A reference manual, which provides complete documentation, and a mini–tutorial, which introduces the reader to using CROPS, are also availa

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02251.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1979.tb02252.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY