The Palapa Space Communication System

Indonesian social development has depended greatly upon the PALAPA space communication system since 1976 as one major component in the creation of a national infrastructure to enhance business development and the dissemination of national cultural information. The success of the first two satellites in serving telephone and television and in setving the Asean region has made it necessary to assure the continuity of these operations through the 1980\u27s and beyond. Replacement Bl and B2 satellites have been contracted for delivery in early 1983. The uncertainties of placing these two new satellites in their chosen geosynchronous orbit locations has presented some unique problems of management particularly in respect to the choice of launch vehicles due to launch uncertainties , and the assessment of the risk of potential launch failure on ongoing telecommunication system operations. Planning for recovery from the many contingencies presented as potential catastophies in the path to successful replenishment of the present space system has necessitated consideration of a number of strategies involving launch schedule for alternate vehicles , launch insurance, relaunch costs, as well as component production delays and launch slot availability for space flight operations.The objective of these management considerations have been to minimize costs to the Indonesian government while providing a high degree of assurance that the required communication capacity of the satellite system will be maintained in support of the national telecommunication system

Breeding a barley resistant to leaf disease

In the last few years the Department of Agriculture has begun a programme to produce brley varieties resistant to the leaf diseases, scald and net blotch. These diseases cause substantial losses that may not be apparent to an individual farmer

Keeping ahead of powdery mildew in barley

Powdery mildew is one of the world\u27s most significant barley diseases. In Australia, and more particularly Western Australia, its importance has been under-rated, and only recently has interest in this disease emerged. Powdery mildew was widespread throughout Western Australia\u27s southern cereal growing areas in 1983. Only a prolonged dry period in August and early September of that year prevented possible large-scale crop losses. Similar outbreaks occurred in 1984. While some barley varieties are resistant to infection, the use of fungicides, particularly seed dressings, can minimise further infection

Barley staining

GRAIN discolouration or staining is a quality defect in W.A. barley which substantially reduces the marketable value oi the crop. It also causes heavy losses to individual growers whose grain is docked or rejected

One-dimensional Ising ferromagnet frustrated by long-range interactions at finite temperatures

We consider a one-dimensional lattice of Ising-type variables where the ferromagnetic exchange interaction J between neighboring sites is frustrated by a long-ranged anti-ferromagnetic interaction of strength g between the sites i and j, decaying as |i-j|^-alpha, with alpha>1. For alpha smaller than a certain threshold alpha_0, which is larger than 2 and depends on the ratio J/g, the ground state consists of an ordered sequence of segments with equal length and alternating magnetization. The width of the segments depends on both alpha and the ratio J/g. Our Monte Carlo study shows that the on-site magnetization vanishes at finite temperatures and finds no indication of any phase transition. Yet, the modulation present in the ground state is recovered at finite temperatures in the two-point correlation function, which oscillates in space with a characteristic spatial period: The latter depends on alpha and J/g and decreases smoothly from the ground-state value as the temperature is increased. Such an oscillation of the correlation function is exponentially damped over a characteristic spatial scale, the correlation length, which asymptotically diverges roughly as the inverse of the temperature as T=0 is approached. This suggests that the long-range interaction causes the Ising chain to fall into a universality class consistent with an underlying continuous symmetry. The e^(Delta/T)-temperature dependence of the correlation length and the uniform ferromagnetic ground state, characteristic of the g=0 discrete Ising symmetry, are recovered for alpha > alpha_0.Comment: 12 pages, 7 figure

The local content of all pure two-qubit states

The (non-)local content in the sense of Elitzur, Popescu, and Rohrlich (EPR2) [Phys. Lett. A 162, 25 (1992)] is a natural measure for the (non-)locality of quantum states. Its computation is in general difficult, even in low dimensions, and is one of the few open questions about pure two-qubit states. We present a complete solution to this long-lasting problem.Comment: 9 pages, 3 figure

P-SCOR: Integration of Constraint Programming Orchestration and Programmable Data Plane

In this manuscript we present an original implementation of network management functions in the context of Software Defined Networking. We demonstrate a full integration of an artificial intelligence driven management, an SDN control plane, and a programmable data plane. Constraint Programming is used to implement a management operating system that accepts high level specifications, via a northbound interface, in terms of operational objective and directives. These are translated in technology-specific constraints and directives for the SDN control plane, leveraging the programmable data plane, which is enriched with functionalities suited to feed data that enable the most effective operation of the “intelligent” control plane, by exploiting the language