On-Line Practices of Data Base Producers

This Working Paper reports on a study undertaken by us as a private venture for the Commission of the European Communities. The subject-matter is however closely related to the sub-task, International Data Exchange, included in the 1977 research plan of the Computer Science Group: one of the main areas of international data exchange at the scientific and technical level is the interactive interrogation of computer bibliographic and fact databases. During the present decade this has grown from insignificant levels to become an international business in North America and Europe with a total utilization of several hundred thousand hours of terminal connections per year. At a Workshop on International Data Exchange held by IIASA at Toronto in August 1977, to identify the critical issues for research in this general field, economic issues scored the highest individual rating, and it is evident that such problems may have a determining effect on future growth-rates, particularly outside the industrialized regions. The study reported here was essentially a fact-finding exercise on one aspect of the economics of scientific and technical information flows, that of the relation between charges to users and charges levied by the producers of scientific and technical information databases for the use of computerized versions of their products. Other important aspects remain open, in particular the influence of the changing policies of international carriers and telecommunication administrations on total user costs, the economies of scale to be obtained from multi database operators etc

The Aggregation of the Agricultural Supply Utilisation Accounts

It is our hope that the publication of this paper will satisfy a number of requests, some of which stem from the very distant past, to provide detailed information about the data aggregation done by the FAP at IIASA. The Supply Utilisation Accounts on Agricultural Products (SUA), published by the FAO, have been the starting point for the aggregation of agricultural commodities and the time series available for the FAP commodity lists, as well as the basis for the FAP Data Bank. The SUA and its aggregates have been widely used in the FAP Modeling work, at IIASA and at the collaborating institutions. This paper gives first some general explanations concerning the original SUA, and concentrates then mainly on the "aggregation-logic", for general cases and for special cases. The last section deals with the computerization of the aggregation, as this constituted the main effort and seems to be a very valuable idea for similar types of calculations. The appendixes, a large part of this paper, go into greater detail for the interested reader and for the users of the accounts

Priorities and Pay Function Routing for a Packet Switching Network

In every network there arises the problem of choosing a path for a message so that it reaches its destination. If there are many users requesting the same channel it could be occupied and another would have to be chosen, provided that it would also be a good path and free, otherwise the message would have to queue up. The choice of an objective function for the selection procedure of a path is part of the decision process when constructing the routing algorithm. The selection is carried out with respect to an objective function which is maximized (or minimized). There exist some useful objective functions commonly used for routing in a computer network: minimization of distance, minimization of delay or cumulative costs, maximization of throughput or reliability, etc

Communication Audit for IIASA Phase I: External Communications

In early 1977 an analysis was conducted of external communication mechanisms currently in use at IIASA. This analysis was based on a six-month sample of the communication traffic via ten different media (telephone, telegrams, night letters, European telex, Non-European telex, travel by IIASA staff, visitors to IIASA, workshops, mail, and IIASA publications). By condensing the data for telegrams, nightletters, European telex, and Non-European telex into one mode an analysis of seven general modes was then conducted. The analysis did not include local telephone traffic (i.e. non-long-distance) nor did it cover incoming messages via mail, telex/telegram or telephone or internal seminars. While this study has helped to clarify a portion of the current communication traffic at IIASA, it does not answer the question regarding the justification for high-speed data channels. That answer will evolve, but in the meantime this report can provide useful data on what now exists. Even so, this is a snapshot of the situation several months ago and even now data traffic for telexes, as an example, is increasing

The Impact of the X.25 on the Efficiency of the Communications Subnetwork

The acceptance of the X.25 international standards requires a virtual call procedure, which imposes some restriction on the usage of communication resources, namely a fixed route for the whole duration of the session. In an example of network simulation, datagram and virtual call methods are compared, producing the result that the datagram gives a better performance with regard to delivery time. The difference between these two methods is greater when the load, the number of packets per message, and the size of the network is increased

User's Guide to SLIMFORP

The work of the INterindustry FORecasting at the University of Maryland (INFORUM) has gradually expanded and similar work is now underway at over fifteen institutes around the world. SLIMFORP, the basic computer programming system for the forecasting models of INFORUM, makes the modeling efforts of the many institutes a practical reality. A strong attempt has been made to make the programs portable. The solutions to several problems encountered while transporting the programs from computer to computer now lay hidden in the code. Since unit numbers for specific data files may not be possible on all machines, I wish to call your specific attention to Appendix 2 where the linkage between data files and unit numbers is presented especially well. The guide has the strength that it was not written by the original programmer of the model but rather by one, like many of you, who had to implement the model and adapt it to another machine. Thus, I believe, more of the questions asked by the newcomers to the programs are answered and probably in a better way than if I had written this manual

A cultivated planet in 2010 – Part 2: The global gridded agricultural-production maps

Data on global agricultural production are usually available as statistics at administrative units, which does not give any diversity and spatial patterns; thus they are less informative for subsequent spatially explicit agricultural and environmental analyses. In the second part of the two-paper series, we introduce SPAM2010 – the latest global spatially explicit datasets on agricultural production circa 2010 – and elaborate on the improvement of the SPAM (Spatial Production Allocation Model) dataset family since 2000. SPAM2010 adds further methodological and data enhancements to the available crop downscaling modeling, which mainly include the update of base year, the extension of crop list, and the expansion of subnational administrative-unit coverage. Specifically, it not only applies the latest global synergy cropland layer (see Lu et al., submitted to the current journal) and other relevant data but also expands the estimates of crop area, yield, and production from 20 to 42 major crops under four farming systems across a global 5 arcmin grid. All the SPAM maps are freely available at the MapSPAM website (http://mapspam.info/, last access: 11 December 2020), which not only acts as a tool for validating and improving the performance of the SPAM maps by collecting feedback from users but is also a platform providing archived global agricultural-production maps for better targeting the Sustainable Development Goals. In particular, SPAM2010 can be downloaded via an open-data repository (DOI: https://doi.org/10.7910/DVN/PRFF8V; IFPRI, 2019)