Modeling Urbanization and Economic Growth

The past quarter century has witnessed unprecedented economic progress in the Third World. Yet major problems have arisen, some of which are the consequences of the progress itself and may become serious constraints on future development. City growth is one such problem. Pessimists stress the developing countries' inability to cope with the resource and social systems requirements of rapid urban growth, thus prompting the term "over-urbanization". Optimists minimize the negative externalities and view urban growth as the key to raising average labor productivity and living standards. All of this experience has taken place under conditions of "population explosions". This paper presents a general equilibrium economic-demographic model which highlights various aspects of urbanization. Attention is focused on the determinants and consequences of rural-urban migration, on the resource demands of housing associated with rapid urbanization, on optimal land use between urban and rural activities, and on the allocation of investments to education and labor force training. The economic model is designed to be "representative" of a large group of developing countries, and it will eventually contain a fully elaborated demographic component. The model will be tested with Third World growth experience since the 1950s. It will then be used to analyze the sources of migration and urbanization, and to explore their interaction with distribution, accumulation and growth

Modeling Growing Economies in Equilibrium and Disequilibrium

The papers in this volume were presented and discussed at a meeting held at IIASA. The meeting's goals were to stimulate interaction and collaboration, and to encourage setting research priorities for the future. Indeed, it is in this latter area where the meeting appeared to yield some of its greatest benefits. It became clear from the deliberations that much needs to be done to better specify the microfoundations of general equilibrium models. More realistic specifications of "conflict resolution" in resource allocation, in both market and nonmarket economies, need to be developed. Equally importantly, much work is required to explore the role of economic disequilibrium in economic growth and development. "Equilibrium" and "disequilibrium" are positive, not normative concepts; neither view is right or wrong; neither will necessarily yield desired social outcomes at all stages of development, or across all regions. Rather, they yield quite different outcomes, which themselves should be subjects for scientific inquiry. The meeting pointed out the potential for expanding the conceptions of general equilibrium modeling to incorporate elements of disequilibrium analysis, so that this framework may not only be increasingly relevant to Eastern countries, but so that the possibilities of East-West interaction on critical aspects of resource allocation and economic growth can be enhanced

A conservative control strategy for variable-speed stall-regulated wind turbines

Simulation models of a variable-speed, fixed-pitch wind turbine were investigated to evaluate the feasibility of constraining rotor speed and power output without the benefit of active aerodynamic control devices. A strategy was postulated to control rotational speed by specifying the demanded generator torque. By controlling rotor speed in relation to wind speed, the aerodynamic power extracted by the blades from the wind was manipulated. Specifically, the blades were caused to stall in high winds. In low and moderate winds, the demanded generator torque and the resulting rotor speed were controlled to cause the wind turbine to operate near maximum efficiency. Using the developed models, simulations were conducted of operation in turbulent winds. Results indicated that rotor speed and power output were well regulated. Preliminary investigations of system dynamics showed that, compared to fixed-speed operation, variable-speed operation caused cyclic loading amplitude to be reduced for the turbine blades and low-speed shaft and slightly increased for the tower loads. This result suggests a favorable impact on fatigue life from implementation of the proposed control strategy

When prosocials act like proselfs in a commons dilemma

important that previous research has also shown that the motivation to preserve a common pool is not equally strong for everybody. Although people who seek to maximize collective outcomes (i.e., prosocials) carefully adapt their behavior to an imminent resource shortage by cutting down their consumption, people who seek to maximize own outcomes or differences in outcomes (i.e., proselfs) keep up their high consumption as if resources were still abundant (see Kramer, McClintock, & Messick, 1986). The Kramer et al. (1986) findings illuminate that motivations are relevant to solving the social dilemma at its most important moment—when the common pool is close to being depleted. That is, differences between prosocial and proself motives seem most important when the dilemma is most pronounced and the collec-tive consequences most severe. At the same time, exper-iments examining the effects of personality differences on individual resource consumption have always been conducted in a “perfect world. ” Participants were usu-ally able to realize their intended consumption without any limitations; that is, they could fully translate thei

EDGeS: a bridge between desktop grids and service grids

Desktop grids and service grids widely used by their different users communities as efficient solutions for making full use of computing power and achieving loads balances across Intranet or Internet. Nevertheless,little work has been done to combine these two grids technologies together to establish a seamless and vast grid resources pool. In this paper we will present a new European FP7 infrastructure project:EDGeS (enabling desktop grids for e-science), which aim to build technological bridges to facilitate interoperability between desktop grid and service grid. We give also a taxonomy of existing grid systems: desktop grids such as BONIC and XtremWeb, service grids such as EGEE. Then we describe furtherly our solution for identifying translation technologies for porting applications between desktop grids and service grids, and vice versa. There are three themes in our solution, which discuss actual popular bridging technologies, user access issues, and distributed data issues about deployment and application development

Green function techniques in the treatment of quantum transport at the molecular scale

The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics

On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes

The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic