20,172 research outputs found

    Keynote address

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    Approved and projected probe mission strategies for the outer planet exploration programs are briefly outlined

    Hypersonic Research Vehicle (HRV) real-time flight test support feasibility and requirements study. Part 2: Remote computation support for flight systems functions

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    The requirements are assessed for the use of remote computation to support HRV flight testing. First, remote computational requirements were developed to support functions that will eventually be performed onboard operational vehicles of this type. These functions which either cannot be performed onboard in the time frame of initial HRV flight test programs because the technology of airborne computers will not be sufficiently advanced to support the computational loads required, or it is not desirable to perform the functions onboard in the flight test program for other reasons. Second, remote computational support either required or highly desirable to conduct flight testing itself was addressed. The use is proposed of an Automated Flight Management System which is described in conceptual detail. Third, autonomous operations is discussed and finally, unmanned operations

    The generic task toolset: High level languages for the construction of planning and problem solving systems

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    The current generation of languages for the construction of knowledge-based systems as being at too low a level of abstraction is criticized, and the need for higher level languages for building problem solving systems is advanced. A notion of generic information processing tasks in knowledge-based problem solving is introduced. A toolset which can be used to build expert systems in a way that enhances intelligibility and productivity in knowledge acquistion and system construction is described. The power of these ideas is illustrated by paying special attention to a high level language called DSPL. A description is given of how it was used in the construction of a system called MPA, which assists with planning in the domain of offensive counter air missions

    The impact of trade liberalisation on South African agricultural productivity

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    This study attempts to examine the empirical relationship between trade and total factor productivity (TFP) in the agricultural sector using both cross -sectiona, (across nine agricultural commodities), and time -series analysis. The Error Correction Model of ordinary least square (OLS) results from the cross -sectional analysis confirm that export shares and capital formation were found to be positive and significant; whereas, import shares and real exchange rate were found to be related negatively. However, the net effect of export and import shares had a positive effect. This implies that trade liberalisation causes productivity gains. Moreover, the time -series analysis goes in the same direction as the cross -sectional results, showing that there is a robust relationship among TFP, degree of openness, and capital formation. Whereas, debt was found to be inversely related, this implies that agricultural industries / farmers lack debt management skills.TFP, OLS, Trade liberalization or degree of openness, capital formation, International Relations/Trade,

    Water markets an alternative for central water allocation?

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    South Africa is entering a whole new era in water management. In the face of efforts to curtail runaway government spending and protect the environment, water institutions must foster the conservation and efficient allocation of existing supplies. They must also take water's growing recreational and environmental value into account. The crucial question is, can the current water institutions meet today's requirements? Despite the resulting inefficiency and waste, traditional resource economists continue to identify taxes, regulations, subsidies, and governmental allocation as solutions to today's water problems. Internationally, there is enough evidence to prove that central allocation with almost any resource gave rise to gross inefficiency. The main reason is the distortions on the value placed on resources within such a centralised planning environment. Resources are either valued to high or to low. What is the value of freshwater and how can water be allocated in such a way as to reflect the scarcity value of water? A non-linear spatial equilibrium model was developed to simulate the impact of a potential water market in the Upper-Berg River: Western Cape. This paper explores water markets as an alternative to central water allocation decisionsResource /Energy Economics and Policy,
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