CONSERVATION CAPITAL AND SUSTAINABLE ECONOMIC GROWTH

This paper develops an endogenous growth model which links pollution to ineffective input-use, which can be reduced through conservation capital investment. It derives the conditions under which individual preferences for environmental quality and private investment in conservation capital can lead to non-decreasing environmental quality and balanced growth in an unregulated and in a regulated regime. In the absence of regulation, balanced growth can lead to improvement in environmental quality as long as the rate of growth is low. The extent to which the growth rate is low depends upon preference for environmental quality, interest and discount rates, productivity of conservation capital, and price of the polluting input. Under an emissions tax regime, sustainable balanced growth requires the interest rate to lie between the amenity value derived by consumers from environmental improvement and the marginal return to the firm due to the regenerative capacity of the environment. This implies that interest rate must be high enough to encourage consumers to forego consumption but low enough to constrain the productivity of conservation capital and restrain usage of the polluting input. The emissions tax is also shown to be equivalent to a pollution permit system or to a two-instrument scheme composed of a tax on polluting input and a subsidy on conservation capital investment.Environmental Economics and Policy, International Development,

Nanoadhesion of elastic bodies : roughness and temperature effects

We present a simple model which illustrates the nature of the contact between an elastic solid and a hard surface with cosine-corrugation profile. In the continuum limit, the contact mechanics depends only on two dimensionless parameters, namely the ratio between the height and wavelength of the substrate corrugation, and the ratio between a surface energy and an elastic energy. The theory shows that the complete contact state is always a local energy minima (in the zero temperature limit), but for large enough surface roughness the global minima correspond to a partial contact state. We show that at nonzero temperature, the contribution to the free energy from the vibrational entropy is very important, and favors the detached state. Computer simulations results are also presented where we study more complicated roughness geometries and the influence of temperature on the adhesion. Simulation results agrees well with the analytical predictions. (C) 2003 American Institute of Physics

Theory and simulations of squeeze-out dynamics in boundary lubrication

The dynamics of expulsion of the last liquidlike monolayer of molecules confined between two surfaces (measured recently for the first time [J. Chem. Phys. 114, 1831 (2001)]) has been analyzed by solving the two-dimensional Navier-Stokes equation combined with kinetic Monte Carlo simulations. Instabilities in the boundary line of the expelled film produce a rough boundary for all length scales above a critical value. The squeeze-out of liquid is shown to result from the 2D-pressure gradient in the lubrication film in the contact area. The Monte Carlo simulations agrees well with experiments, reproducing most qualitative and quantitative features. In particular it shows the formation of small islands, which (in the absence of pinning mechanism) drift slowly to the periphery of the contact area. We calculate the drift velocity analytically as a function of the distance of the island to the periphery of the contact area. Experiments indicate that some kind of pinning mechanism prevails, trapping fluid pockets for very long times. When including such pinning areas in the simulations, three distinct squeeze phases and time scales were observed: (1) initial fast squeeze of most of the fluid; (2) slower squeeze of unpinned fluid pockets; (3) long term pinning of fluid pockets. We also show that a distribution of small pinning areas may produce a synergistic effect, slowing down the second phase of the squeeze, compared to a small number of big pinning areas. The paper presents a new stochastic numerical approach to problems of moving boundaries which naturally accounts for thermal fluctuations and their effect in unstable dynamics. (C) 2001 American Institute of Physics

Pairs of Bloch electrons and magnetic translation groups

A product of irreducible representations of magnetic translation group is considered. It leads to irreducible representations which were previously rejected as nonphysical. A very simple example indicates a possible application of these representations. In particular, they are important in descriptions of pairs of electrons in a magnetic field and a periodic potential. The periodicity of some properties with respect to the charge of a particle is briefly discussed.Comment: 4 pages, RevTex. Latex2.09, amsfont

NetFPGA - Rapid prototyping of high bandwidth devices in open source

The demand-led growth of datacenter networks has meant that many constituent technologies are beyond the budget of the wider community. In order to make and validate timely and relevant new contributions, the wider community requires accessible evaluation, experimentation and demonstration environments with specification comparable to the subsystems of the most massive datacenter networks. We demonstrate NetFPGA SUME, an open-source FPGA-based PCIe board for rapid prototyping of high bandwidth devices. NetFPGA SUME has I/O capabilities for 100Gbps operation as a networking device, computing unit, or for test and measurement.This work was jointly supported by EPSRC INTERNET Project EP/H040536/1, National Science Foundation under Grant No. CNS-0855268, and Defense Advanced Research Projects Agency (DARPA) and Air Force Research Laboratory (AFRL), under contract FA8750-11-C-0249. The views, opinions, and/or findings contained in this report are those of the authors and should not be interpreted as representing the official views or policies, either expressed or implied, of the National Science Foundation, Defense Advanced Research Projects Agency or the Department of Defense. The Xilinx XUP program has been a long-standing supporter of NetFPGA and the NetFPGA SUME project is only possible with their generous support. We thank the people at Digilent Inc. We thank Micron and Cypress Semiconductor for their generous part donations.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/FPL.2015.729396

NetFPGA: Rapid Prototyping of Networking Devices in Open Source

The demand-led growth of datacenter networks has meant that many constituent technologies are beyond the budget of the wider community. In order to make and validate timely and relevant new contributions, the wider community requires accessible evaluation, experimentation and demonstration environments with specification comparable to the subsystems of the most massive datacenter networks. We demonstrate NetFPGA, an open-source platform for rapid prototyping of networking devices with I/O capabilities up to 100Gbps. NetFPGA offers an integrated environment that enables networking research by users from a wide range of disciplines: from hardware-centric research to formal methods.This work was jointly supported by EPSRC INTERNET Project EP/H040536/1, National Science Foundation under Grant No. CNS-0855268, and Defense Advanced Research Projects Agency (DARPA) and Air Force Research Laboratory (AFRL), under contract FA8750-11-C-0249. The views, opinions, and/or findings contained in this report are those of the authors and should not be interpreted as representing the official views or policies, either expressed or implied, of the National Science Foundation, Defense Advanced Research Projects Agency or the Department of Defense.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1145/2785956.279002

Alternating current driven instability in magnetic junctions

An effect is considered of alternating (high-frequency) current on the spin-valve type magnetic junction configuration. The stability with respect to small fluctuations is investigated in the macrospin approximation. When the current frequency is close to the eigenfrequency (precession frequency) of the free layer, parametric resonance occurs. Both collinear configurations, antiparallel and parallel ones, can become unstable under resonance conditions. The antiparallel configuration can become unstable under non-resonant conditions, also. The threshold current density amplitude is of the order of the dc current density switching the magnetic junction.Comment: 8 page