3,488 research outputs found
Almost Budget Balanced Mechanisms with Scalar Bids For Allocation of a Divisible Good
This paper is about allocation of an infinitely divisible good to several
rational and strategic agents. The allocation is done by a social planner who
has limited information because the agents' valuation functions are taken to be
private information known only to the respective agents. We allow only a scalar
signal, called a bid, from each agent to the social planner. Yang and Hajek
[Jour. on Selected Areas in Comm., 2007] as well as Johari and Tsitsiklis
[Jour. of Oper. Res., 2009] proposed a scalar strategy Vickrey-Clarke-Groves
(SSVCG) mechanism with efficient Nash equilibria. We consider a setting where
the social planner desires minimal budget surplus. Example situations include
fair sharing of Internet resources and auctioning of certain public goods where
revenue maximization is not a consideration. Under the SSVCG framework, we
propose a mechanism that is efficient and comes close to budget balance by
returning much of the payments back to the agents in the form of rebates. We
identify a design criterion for {\em almost budget balance}, impose feasibility
and voluntary participation constraints, simplify the constraints, and arrive
at a convex optimization problem to identify the parameters of the rebate
functions. The convex optimization problem has a linear objective function and
a continuum of linear constraints. We propose a solution method that involves a
finite number of constraints, and identify the number of samples sufficient for
a good approximation.Comment: Accepted for publication in the European Journal of Operational
Research (EJOR
Nonequilibrium phase transitions in models of adsorption and desorption
The nonequilibrium phase transition in a system of diffusing, coagulating
particles in the presence of a steady input and evaporation of particles is
studied. The system undergoes a transition from a phase in which the average
number of particles is finite to one in which it grows linearly in time. The
exponents characterizing the mass distribution near the critical point are
calculated in all dimensions.Comment: 10 pages, 2 figures (To appear in Phys. Rev. E
A new class of highly efficient exact stochastic simulation algorithms for chemical reaction networks
We introduce an alternative formulation of the exact stochastic simulation
algorithm (SSA) for sampling trajectories of the chemical master equation for a
well-stirred system of coupled chemical reactions. Our formulation is based on
factored-out, partial reaction propensities. This novel exact SSA, called the
partial propensity direct method (PDM), is highly efficient and has a
computational cost that scales at most linearly with the number of chemical
species, irrespective of the degree of coupling of the reaction network. In
addition, we propose a sorting variant, SPDM, which is especially efficient for
multiscale reaction networks.Comment: 23 pages, 3 figures, 4 tables; accepted by J. Chem. Phy
Effect of spatial bias on the nonequilibrium phase transition in a system of coagulating and fragmenting particles
We examine the effect of spatial bias on a nonequilibrium system in which
masses on a lattice evolve through the elementary moves of diffusion,
coagulation and fragmentation. When there is no preferred directionality in the
motion of the masses, the model is known to exhibit a nonequilibrium phase
transition between two different types of steady states, in all dimensions. We
show analytically that introducing a preferred direction in the motion of the
masses inhibits the occurrence of the phase transition in one dimension, in the
thermodynamic limit. A finite size system, however, continues to show a
signature of the original transition, and we characterize the finite size
scaling implications of this. Our analysis is supported by numerical
simulations. In two dimensions, bias is shown to be irrelevant.Comment: 7 pages, 7 figures, revte
A high-resolution flexible tactile imager system based on floating comb electrodes
pre-printFlexible high-resolution contact force imagers are needed in many applications for robotic grippers and gait analysis, but its intrinsic intimate contact requirement often causes breaking of top metallization layers and failure in a short time. The use of floating electrodes has significantly improved the reliability of traditional quad-cell capacitive tactile sensing devices. In this paper we present a new type of high-resolution (676-sensors) flexible pressure/shear imager array based on floating combs. Each sensing cell consists of two sets of orthogonal comb electrodes connected in a differential capacitance configuration. The shear sense direction (+x, -x, +y, -y) is determined by the amount of asymmetric comb overlap. Pressure readouts are obtained from the net capacitance of the cell. The new comb configuration multiplies the shear capacitive signal by the number of combs per cell. The imager is read using a high-speed switched-capacitor circuit with a 12-bit resolution at full frame rates of 100 Hz (~ 0.8Mb/s)
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