14,010 research outputs found
Exploration vs Exploitation vs Safety: Risk-averse Multi-Armed Bandits
Motivated by applications in energy management, this paper presents the
Multi-Armed Risk-Aware Bandit (MARAB) algorithm. With the goal of limiting the
exploration of risky arms, MARAB takes as arm quality its conditional value at
risk. When the user-supplied risk level goes to 0, the arm quality tends toward
the essential infimum of the arm distribution density, and MARAB tends toward
the MIN multi-armed bandit algorithm, aimed at the arm with maximal minimal
value. As a first contribution, this paper presents a theoretical analysis of
the MIN algorithm under mild assumptions, establishing its robustness
comparatively to UCB. The analysis is supported by extensive experimental
validation of MIN and MARAB compared to UCB and state-of-art risk-aware MAB
algorithms on artificial and real-world problems.Comment: 16 page
Response-surface-model-based system sizing for nearly/net zero energy buildings under uncertainty
Properly treating uncertainty is critical for robust system sizing of nearly/net zero energy buildings (ZEBs). To treat uncertainty, the conventional method conducts Monte Carlo simulations for thousands of possible design options, which inevitably leads to computation load that is heavy or even impossible to handle. In order to reduce the number of Monte Carlo simulations, this study proposes a response-surface-model-based system sizing method. The response surface models of design criteria (i.e., the annual energy match ratio, self-consumption ratio and initial investment) are established based on Monte Carlo simulations for 29 specific design points which are determined by Box-Behnken design. With the response surface models, the overall performances (i.e., the weighted performance of the design criteria) of all design options (i.e., sizing combinations of photovoltaic, wind turbine and electric storage) are evaluated, and the design option with the maximal overall performance is finally selected. Cases studies with 1331 design options have validated the proposed method for 10,000 randomly produced decision scenarios (i.e., users’ preferences to the design criteria). The results show that the established response surface models reasonably predict the design criteria with errors no greater than 3.5% at a cumulative probability of 95%. The proposed method reduces the number of Monte Carlos simulations by 97.8%, and robustly sorts out top 1.1% design options in expectation. With the largely reduced Monte Carlo simulations and high overall performance of the selected design option, the proposed method provides a practical and efficient means for system sizing of nearly/net ZEBs under uncertainty
Measuring voting power in convex policy spaces
Classical power index analysis considers the individual's ability to
influence the aggregated group decision by changing its own vote, where all
decisions and votes are assumed to be binary. In many practical applications we
have more options than either "yes" or "no". Here we generalize three important
power indices to continuous convex policy spaces. This allows the analysis of a
collection of economic problems like e.g. tax rates or spending that otherwise
would not be covered in binary models.Comment: 31 pages, 9 table
The Bacterial Chemotactic Response Reflects a Compromise Between Transient and Steady State Behavior
Swimming bacteria detect chemical gradients by performing temporal
comparisons of recent measurements of chemical concentration. These comparisons
are described quantitatively by the chemotactic response function, which we
expect to optimize chemotactic behavioral performance. We identify two
independent chemotactic performance criteria: in the short run, a favorable
response function should move bacteria up chemoattractant gradients, while in
the long run, bacteria should aggregate at peaks of chemoattractant
concentration. Surprisingly, these two criteria conflict, so that when one
performance criterion is most favorable, the other is unfavorable. Since both
types of behavior are biologically relevant, we include both behaviors in a
composite optimization that yields a response function that closely resembles
experimental measurements. Our work suggests that the bacterial chemotactic
response function can be derived from simple behavioral considerations, and
sheds light on how the response function contributes to chemotactic
performance.Comment: 19 pages, 5 figure
Reactor Neutrino Flux Uncertainty Suppression on Multiple Detector Experiments
This publication provides a coherent treatment for the reactor neutrino flux
uncertainties suppression, specially focussed on the latest
measurement. The treatment starts with single detector in single reactor site,
most relevant for all reactor experiments beyond . We demonstrate
there is no trivial error cancellation, thus the flux systematic error can
remain dominant even after the adoption of multi-detector configurations.
However, three mechanisms for flux error suppression have been identified and
calculated in the context of Double Chooz, Daya Bay and RENO sites. Our
analysis computes the error {\it suppression fraction} using simplified
scenarios to maximise relative comparison among experiments. We have validated
the only mechanism exploited so far by experiments to improve the precision of
the published . The other two newly identified mechanisms could
lead to total error flux cancellation under specific conditions and are
expected to have major implications on the global knowledge
today. First, Double Chooz, in its final configuration, is the only experiment
benefiting from a negligible reactor flux error due to a 90\% geometrical
suppression. Second, Daya Bay and RENO could benefit from their partial
geometrical cancellation, yielding a potential 50\% error suppression,
thus significantly improving the global precision today. And
third, we illustrate the rationale behind further error suppression upon the
exploitation of the inter-reactor error correlations, so far neglected. So, our
publication is a key step forward in the context of high precision neutrino
reactor experiments providing insight on the suppression of their intrinsic
flux error uncertainty, thus affecting past and current experimental results,
as well as the design of future experiments
- …