10,103 research outputs found
Similarity Measure Development for Case-Based Reasoning- A Data-driven Approach
In this paper, we demonstrate a data-driven methodology for modelling the
local similarity measures of various attributes in a dataset. We analyse the
spread in the numerical attributes and estimate their distribution using
polynomial function to showcase an approach for deriving strong initial value
ranges of numerical attributes and use a non-overlapping distribution for
categorical attributes such that the entire similarity range [0,1] is utilized.
We use an open source dataset for demonstrating modelling and development of
the similarity measures and will present a case-based reasoning (CBR) system
that can be used to search for the most relevant similar cases
Scattering length for helium atom-diatom collision
We present results on the scattering lengths of ^4He--^4He_2 and ^3He--^4He_2
collisions. We also study the consequence of varying the coupling constant of
the atom-atom interaction.Comment: Contribution to Proceedings of the International Workshop ``Critical
Stability of Few-Body Quantum Systems'' (Dresden, October 17--22, 2005
Variabilitas Suhu Permukaan Laut Dan Klorofil-a Kaitannya Dengan El Nino Southern Oscillation (Enso) Dan Indian Ocean Dipole (Iod) Pada Periode Upwelling 2010-2014 Di Lautan Hindia (Perairan Cilacap)
Perairan Cilacap merupakan salah satu perairan selatan Jawa yang memiliki variabilitas suhu permukaan laut (SPL) dan kesuburan perairan (konsentrasi klorofil-a) karena adanya pengaruh variabilitas iklim. Tujuan dari penelitian ini adalah mengkaji variabilitas SPL dan klorofil-a pada variasi tahunan (pengaruh angin monsun) dan antar tahunan (pengaruh ENSO dan IOD) di Perairan Cilacap. Data yang digunakan dalam penelitian ini meliputi data arus laut insitu, data SPL insitu, data SPL dan klorofil-a citra MODIS level 3, data angin dan arus BMKG Cilacap, data sea surface temperature (SST) di NINO3,4 dan data dipole mode index (DMI). Variabilitas nilai SPL dan klorofil-a secara tahunan menunjukkan bahwa pada bulan September selama tahun 2010-2014 didapatkan rerata SPL terendah yaitu sebesar 26,35 0C dan rerata konsentrasi klorofil-a tertinggi yaitu sebesar 1,16 mg/m3. Variabilitas nilai SPL dan klorofil-a antar tahunan menunjukkan rerata SPL terendah pada tahun 2011 yaitu sebesar 26,35 0C, sedangkan klorofil-a terdistribusi secara spasial mencapai titik koordinat 80 15' 0” LS (62 km dari garis pantai). Kondisi ini bertepatan dengan terjadinya La Nina sedang dan IOD positif (+) dengan durasi selama 5 bulan. Pada tahun 2012 didapatkan rerata konsentrasi klorofil-a tertinggi yaitu sebesar 0,974 mg/m3 namun hanya terdistribusi secara spasial pada titik koordinat 80 12' 9,3” LS (57 km dari garis pantai). Kondisi ini bertepatan dengan terjadinya fenomena El Nino lemah dan IOD(+) dengan durasi selama 3 bulan
Cake Cutting Algorithms for Piecewise Constant and Piecewise Uniform Valuations
Cake cutting is one of the most fundamental settings in fair division and
mechanism design without money. In this paper, we consider different levels of
three fundamental goals in cake cutting: fairness, Pareto optimality, and
strategyproofness. In particular, we present robust versions of envy-freeness
and proportionality that are not only stronger than their standard
counter-parts but also have less information requirements. We then focus on
cake cutting with piecewise constant valuations and present three desirable
algorithms: CCEA (Controlled Cake Eating Algorithm), MEA (Market Equilibrium
Algorithm) and CSD (Constrained Serial Dictatorship). CCEA is polynomial-time,
robust envy-free, and non-wasteful. It relies on parametric network flows and
recent generalizations of the probabilistic serial algorithm. For the subdomain
of piecewise uniform valuations, we show that it is also group-strategyproof.
Then, we show that there exists an algorithm (MEA) that is polynomial-time,
envy-free, proportional, and Pareto optimal. MEA is based on computing a
market-based equilibrium via a convex program and relies on the results of
Reijnierse and Potters [24] and Devanur et al. [15]. Moreover, we show that MEA
and CCEA are equivalent to mechanism 1 of Chen et. al. [12] for piecewise
uniform valuations. We then present an algorithm CSD and a way to implement it
via randomization that satisfies strategyproofness in expectation, robust
proportionality, and unanimity for piecewise constant valuations. For the case
of two agents, it is robust envy-free, robust proportional, strategyproof, and
polynomial-time. Many of our results extend to more general settings in cake
cutting that allow for variable claims and initial endowments. We also show a
few impossibility results to complement our algorithms.Comment: 39 page
Social Welfare in One-Sided Matching Mechanisms
We study the Price of Anarchy of mechanisms for the well-known problem of
one-sided matching, or house allocation, with respect to the social welfare
objective. We consider both ordinal mechanisms, where agents submit preference
lists over the items, and cardinal mechanisms, where agents may submit
numerical values for the items being allocated. We present a general lower
bound of on the Price of Anarchy, which applies to all
mechanisms. We show that two well-known mechanisms, Probabilistic Serial, and
Random Priority, achieve a matching upper bound. We extend our lower bound to
the Price of Stability of a large class of mechanisms that satisfy a common
proportionality property, and show stronger bounds on the Price of Anarchy of
all deterministic mechanisms
Pareto Optimal Matchings in Many-to-Many Markets with Ties
We consider Pareto-optimal matchings (POMs) in a many-to-many market of
applicants and courses where applicants have preferences, which may include
ties, over individual courses and lexicographic preferences over sets of
courses. Since this is the most general setting examined so far in the
literature, our work unifies and generalizes several known results.
Specifically, we characterize POMs and introduce the \emph{Generalized Serial
Dictatorship Mechanism with Ties (GSDT)} that effectively handles ties via
properties of network flows. We show that GSDT can generate all POMs using
different priority orderings over the applicants, but it satisfies truthfulness
only for certain such orderings. This shortcoming is not specific to our
mechanism; we show that any mechanism generating all POMs in our setting is
prone to strategic manipulation. This is in contrast to the one-to-one case
(with or without ties), for which truthful mechanisms generating all POMs do
exist
Progress in Monte Carlo calculations of Fermi systems: normal liquid 3He
The application of the diffusion Monte Carlo method to a strongly interacting
Fermi system as normal liquid He is explored. We show that the fixed-node
method together with the released-node technique and a systematic method to
analytically improve the nodal surface constitute an efficient strategy to
improve the calculation up to a desired accuracy. This methodology shows
unambiguously that backflow correlations, when properly optimized, are enough
to generate an equation of state of liquid He in excellent agreement with
experimental data from equilibrium up to freezing.Comment: 14 pages, 3 eps figure
Ultra-low energy scattering of a He atom off a He dimer
We present a new, mathematically rigorous, method suitable for bound state
and scattering processes calculations for various three atomic or molecular
systems where the underlying forces are of a hard-core nature. We employed this
method to calculate the binding energies and the ultra-low energy scattering
phase shifts below as well as above the break-up threshold for the three
He-atom system. The method is proved to be highly successful and suitable for
solving the three-body bound state and scattering problem in configuration
space and thus it paves the way to study various three-atomic systems, and to
calculate important quantities such as the cross-sections, recombination rates
etc.Comment: LaTeX, RevTeX and amssymb styles, 7 pages (25 Kb), 3 table
High-quality variational wave functions for small 4He clusters
We report a variational calculation of ground state energies and radii for
4He_N droplets (3 \leq N \leq 40), using the atom-atom interaction HFD-B(HE).
The trial wave function has a simple structure, combining two- and three-body
correlation functions coming from a translationally invariant
configuration-interaction description, and Jastrow-type short-range
correlations. The calculated ground state energies differ by around 2% from the
diffusion Monte Carlo results.Comment: 5 pages, 1 ps figure, REVTeX, submitted to Phys. Rev.
How to observe the Efimov effect
We propose to observe the Efimov effect experimentally by applying an
external electric field on atomic three-body systems. We first derive the
lowest order effective two-body interaction for two spin zero atoms in the
field. Then we solve the three-body problem and search for the extreme
spatially extended Efimov states. We use helium trimers as an illustrative
numerical example and estimate the necessary field strength to be less than 2.7
V/angstrom.Comment: 4 pages, 2 postscript figures, psfig.sty, revte
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