68,688 research outputs found
Equidistribution and Counting for orbits of geometrically finite hyperbolic groups
Let G be the identity component of SO(n,1), acting linearly on a finite
dimensional real vector space V. Consider a vector w_0 in V such that the
stabilizer of w_0 is a symmetric subgroup of G or the stabilizer of the line
Rw_0 is a parabolic subgroup of G. For any non-elementary discrete subgroup
Gamma of G with w_0Gamma discrete, we compute an asymptotic formula for the
number of points in w_0Gamma of norm at most T, provided that the
Bowen-Margulis-Sullivan measure on the associated hyperbolic manifold and the
Gamma skinning size of w_0 are finite.
The main ergodic ingredient in our approach is the description for the
limiting distribution of the orthogonal translates of a totally geodesically
immersed closed submanifold of Gamma\H^n. We also give a criterion on the
finiteness of the Gamma skinning size of w_0 for Gamma geometrically finite.Comment: Extensions of Equidistribution results to G/Gamma are obtained for
Gamma Zariski dense, and Much more precise description on the structure of
cuspidal neighborhoods of parabolic points is obtained for Gamma
geometrically finite. 63 pages (with 1 figure
Hypervolume-based Multi-objective Bayesian Optimization with Student-t Processes
Student- processes have recently been proposed as an appealing alternative
non-parameteric function prior. They feature enhanced flexibility and
predictive variance. In this work the use of Student- processes are explored
for multi-objective Bayesian optimization. In particular, an analytical
expression for the hypervolume-based probability of improvement is developed
for independent Student- process priors of the objectives. Its effectiveness
is shown on a multi-objective optimization problem which is known to be
difficult with traditional Gaussian processes.Comment: 5 pages, 3 figure
Student-t Processes as Alternatives to Gaussian Processes
We investigate the Student-t process as an alternative to the Gaussian
process as a nonparametric prior over functions. We derive closed form
expressions for the marginal likelihood and predictive distribution of a
Student-t process, by integrating away an inverse Wishart process prior over
the covariance kernel of a Gaussian process model. We show surprising
equivalences between different hierarchical Gaussian process models leading to
Student-t processes, and derive a new sampling scheme for the inverse Wishart
process, which helps elucidate these equivalences. Overall, we show that a
Student-t process can retain the attractive properties of a Gaussian process --
a nonparametric representation, analytic marginal and predictive distributions,
and easy model selection through covariance kernels -- but has enhanced
flexibility, and predictive covariances that, unlike a Gaussian process,
explicitly depend on the values of training observations. We verify empirically
that a Student-t process is especially useful in situations where there are
changes in covariance structure, or in applications like Bayesian optimization,
where accurate predictive covariances are critical for good performance. These
advantages come at no additional computational cost over Gaussian processes.Comment: 13 pages, 6 figures, 1 table. To appear in "The Seventeenth
International Conference on Artificial Intelligence and Statistics (AISTATS),
2014.
An Inventory Model for Deteriorating Commodity under Stock Dependent Selling Rate
Economic order quantity (EOQ) is one of the most important inventory policy that have to be decided
in managing an inventory system. The problem addressed in this paper concerns with the decision of the optimal
replenishment time for ordering an EOQ to a supplier. This Model is captured the affect of stock dependent
selling rate and varying price. We developed an inventory model under varying of demand-deterioration-price of
commodity when the relationship of supplier-grocery-consumer at stochastic environment. The replenishment
assumed instantaneous with zero lead time. The commodity will decay of quality according to the original
condition with randomize characteristics. First, the model is addressed to solve a problem phenomenon how long
is the optimum length of cycle time. Then, an EOQ of commodity to be ordered by will be determined by model.
To solve this problem, the first step is developed a mathematical model based on reference’s model, and then
solve the model analytically. Finally, an inventory model for deteriorating commodity under stock dependent
selling rate and considering selling price was derived by this research.
Keywords: deterioration commodity, expected profit, optimal replenishment time stock dependent selling rate
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A general method for calculation of flow boiling and flow condensation heat transfer coefficients in minichannels
This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Flow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena, however their description with a single correlation has yet to be suggested. In the case of flow boiling in minichannels there is mostly encountered the annular flow structure, where bubble generation is not present. Similar picture holds for inside tube condensation, where annular flow structure predominates. In such case the heat transfer coefficient is primarily dependent on the convective mechanism. In the paper a method developed earlier by D. Mikielewicz et al. (2007) is applied to calculations of heat transfer coefficient for inside tube condensation. Satisfactory consistency with well established correlations for condensation has been found
Pedaling out of poverty: Social impact of a manual irrigation technology in South Asia.
Irrigation management / Treadle pump / Treadle pump technology / Technology transfer / Manual pumps / Water lifting / Low lift pumps / Aquifers / Poverty / Irrigated farming / Social impact / Income / Marketing / Pricing / South Asia / India / Bangladesh / Nepal
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