The measurement of heats of solution of high melting metallic systems in an electromagnetic levitation field

A method was tested for measuring the enthalpies of mixing of liquid metallic alloying systems, involving the combination of two samples in the electromagnetic field of an induction coil. The heat of solution is calculated from the pyrometrically measured temperature effect, the heat capacity of the alloy, and the heat content of the added sample. The usefulness of the method was tested experimentally with iron-copper and niobium-silicon systems. This method should be especially applicable to high-melting alloys, for which conventional measurements have failed

Simplified National Models - The Condensed Version of the Food and Agriculture Model System of the International Institute for Applied Systems Analysis

The aim of this paper is to give a concise description of the simplified national models as they were developed in the Food and Agriculture Program (FAP) at the International Institute for Applied Systems Analysis (IIASA). The work on these models was begun in September 1978 and by late summer 1979 the models had reached a preliminary working stage. The reasons for building such a simplified model system are manifold. First of all, it became apparent that the disaggregated and detailed models of all originally selected countries could not be completed by the end of the program. To provide a self-contained product the simplified version was set up at that time. This system is consistent with the detailed one, but works with a more condensed product list (10 commodity aggregates instead of the 19 envisaged for the detailed version), with a smaller set of countries and with substantially simplified supply and demand components. After completion, the more detailed and sophisticated models can be substituted for this simplified version and, therefore, the system will become more and more realistic. Although we are fully aware of the shortcomings of the simplified version, we hope that it will prove to be a useful demonstration tool. As such, the model will help to make the methodology used more understandable and to stress both its advantages and shortcomings. It also should be possible to indicate what kind of questions the FAP system will be able to answer. And finally, it should enable those modeling groups who complete their work in advance of other teams to link their model with the condensed version and thus test its performance. The paper is organized in the following way: Chapter 2 contains a description of those countries which are included in the simplified version. In Chapter 3 a brief explanation of the overall structure of the model system is given and the basic requirements for linking the system are outlined. Data sources and aggregation procedures are explained in Chapter 4. Chapter 5 contains a description of the production module used in this system; input levels in agriculture and the allocation model are explained, followed by a discussion of nonagricultural production. Finally, in Chapter 6 some remarks on the exchange module are made, particularly on the Expenditure Share System used for modeling national demand

Hunger: Beyond the Reach of the Invisible Hand

The work described in this report differs from many others in that the analysis of policies is based on a common integrated framework. It shows why hunger persists, why many policies advanced in popular literature do not work, and what kind of policies can work. Although based on analyses using a quantitative, sophisticated system of models, the book is addressed to the nontechnical layman and to the general reader. The arguments go beyond economic and technical analysis and deal with political and moral aspects. The authors show that solutions that rely only on the market mechanism do not work to eliminate hunger rapidly enough. This analysis shows that even policies that try to intervene, modify, and distort the market do not help to reduce hunger effectively if they rely on the market mechanism

Towards Free Trade in Agriculture

Agriculture seems to be a difficult sector to manage for most governments. Developing countries face tough dilemmas in deciding on appropriate price policies to stimulate food production and maintain stable, preferably low, prices for poor consumers. Governments in developed countries face similar difficult decisions. They are called upon to give income guarantees to farmers whose incomes are unstable and relatively low when compared to those in the nonagricultural sector. These guarantees often lead to ever-increasing budgetary outlays and unwanted agricultural surpluses. High prices make new investments and the application of new technologies more attractive than world prices warrant, and a process is set in motion where technological innovation attains a momentum of its own, in turn requiring price policies that maintain their rates of return. Surpluses are disposed of with subsidies in domestic markets or in the international market. Price competition reduces the market share of other exporters, who may be efficient producers, unless they are willing to engage in subsidy competition. This lowers export earnings and farm incomes or depletes the public resources of developing countries that export competing products. Retaliatory measures have led to frictions and further distortions of world prices. Every so often the major agricultural exporters -- the USA, the EC, Australia, or Canada -- accuse one another of unfair intervention. Though they have agreed to discuss agricultural trade liberalization under GATT negotiations, if anything, the expenditure on farm support has continued to increase in both the EC and the USA. Some developing countries do benefit from the subsidized disposal of surplus cereals on the world market. This, however, might be only a short-term gain. Low prices are a disincentive to their own producers and lead, in the long run, to an unsustainable dependence on imports, as appears to be the case in many parts of Africa. Also, these benefits of cheap cereals may not offset the loss of markets, such as the sugar market, which is important to a large number of developing countries. Against that background and in the light of the fact that many countries have agreed to discuss agricultural trade liberalization under GATT, it is important to assess the consequences of agricultural trade liberalization. It should increase efficiency at the global level as countries adjust their production more in line with their comparative advantages. However, in the absence of compensating transfers, some countries may lose under liberalization. An assessment of efficiency gains at the global level and gains and losses of countries can provide some insight into the degree to which their own production and trade have become distorted and how large the adjustment costs may be. Several questions are relevant here: what if the developed market economies remove border protection? But also: what consequences can be expected from the removal of border protection by developing countries only? (This is an issue that can be usefully analyzed as it belongs to the regular package of adjustment policies recommended by the World Bank and the IMF.) What would be the impact of simultaneous liberalization by all market economies? Who would gain and who would lose? This book reports on a study that explored these questions using a system of empirically estimated national agricultural policy models linked together through trade and capital transfers. A general equilibrium approach is followed for both the national models and the international linkage. Thus, behavioral responses of consumers and producers, as well as the responses of government policies to changes in world market conditions, are accounted for. We call this system of models the Basic Linked System (BLS). It consists of 18 national models, two models of regions -- namely, the EC and the Council for Mutual Economic Assistance (CMEA) -- and 14 somewhat similar models of groups of countries. Together these cover all the nations of the world. We believe that the BLS is particularly suited -- at least, better than any other existing analytic tool -- for the analysis of issues related to agricultural trade liberalization and self-sufficiency. The present study differs from other available studies on trade liberalization in combining all the following features: a general equilibrium approach is applied to both the national and international levels; most of the parameters are empirically estimated; a number of agricultural commodities are distinguished; nations are distinguished; and a rich variety of policy instruments for national governments is permitted, including tariffs, trade, quotas, taxes, transfers, and stock operations. The existence of these features can significantly alter policy conclusions derived from the analysis

Bringing Agriculture into the GATT: Assessing the Benefits of Trade Liberalization

International Relations/Trade,

Atomic Transport in Dense, Multi-Component Metallic Liquids

Pd43Ni10Cu27P0 has been investigated in its equilibrium liquid state with incoherent, inelastic neutron scattering. As compared to simple liquids, liquid PdNiCuP is characterized by a dense packing with a packing fraction above 0.5. The intermediate scattering function exhibits a fast relaxation process that precedes structural relaxation. Structural relaxation obeys a time-temperature superposition that extends over a temperature range of 540K. The mode-coupling theory of the liquid to glass transition (MCT) gives a consistent description of the dynamics which governs the mass transport in liquid PdNiCuP alloys. MCT scaling laws extrapolate to a critical temperature Tc at about 20% below the liquidus temperature. Diffusivities derived from the mean relaxation times compare well with Co diffusivities from recent tracer diffusion measurements and diffsuivities calculated from viscosity via the Stokes-Einstein relation. In contrast to simple metallic liquids, the atomic transport in dense, liquid PdNiCuP is characterized by a drastical slowing down of dynamics on cooling, a q^{-2} dependence of the mean relaxation times at intermediate q and a vanishing isotope effect as a result of a highly collective transport mechanism. At temperatures as high as 2Tc diffusion in liquid PdNiCuP is as fast as in simple liquids at the melting point. However, the difference in the underlying atomic transport mechanism indicates that the diffusion mechanism in liquids is not controlled by the value of the diffusivity but rather by that of the packing fraction