Distributed match-making

In many distributed computing environments, processes are concurrently executed by nodes in a store- and-forward communication network. Distributed control issues as diverse as name server, mutual exclusion, and replicated data management involve making matches between such processes. We propose a formal problem called distributed match-making as the generic paradigm. Algorithms for distributed match-making are developed and the complexity is investigated in terms of messages and in terms of storage needed. Lower bounds on the complexity of distributed match-making are established. Optimal algorithms, or nearly optimal algorithms, are given for particular network topologies

Impact of Higher Harmonics in Searching for Gravitational Waves from Non-Spinning Binary Black Holes

Current searches for gravitational waves from coalescing binary black holes (BBH) use templates that only include the dominant harmonic. In this study we use effective-one-body multipolar waveforms calibrated to numerical-relativity simulations to quantify the effect of neglecting sub-dominant harmonics on the sensitivity of searches. We consider both signal-to-noise ratio (SNR) and the signal-based vetoes that are used to re-weight SNR. We find that neglecting sub-dominant modes when searching for non-spinning BBHs with component masses $3\,M_{\odot} \leq m_1, m_2 \leq 200\,M_{\odot}$ and total mass $M < 360\,M_{\odot}$ in advanced LIGO results in a negligible reduction of the re-weighted SNR at detection thresholds. Sub-dominant modes therefore have no effect on the detection rates predicted for advanced LIGO. Furthermore, we find that if sub-dominant modes are included in templates the sensitivity of the search becomes worse if we use current search priors, due to an increase in false alarm probability. Templates would need to be weighted differently than what is currently done to compensate for the increase in false alarms. If we split the template bank such that sub-dominant modes are only used when $M \gtrsim 100\,M_{\odot}$ and mass ratio $q \gtrsim 4$, we find that the sensitivity does improve for these intermediate mass-ratio BBHs, but the sensitive volume associated with these systems is still small compared to equal-mass systems. Using sub-dominant modes is therefore unlikely to substantially increase the probability of detecting gravitational waves from non-spinning BBH signals unless there is a relatively large population of intermediate mass-ratio BBHs in the universe.Comment: 22 pages, 11 figures. Version approved by journa

The impact of the soccer schedule on TV viewership and stadium attendance : evidence from the Belgian Pro League

In the past decade, television broadcasters have been investing a huge amount of money for the Belgian Pro League broadcasting rights. These companies pursue an audience rating maximization, which depends heavily on the schedule of the league matches. At the same time, clubs try to maximize their home attendance and find themselves affected by the schedule as well. Our paper aims to capture the Belgian soccer fans’ preferences with respect to scheduling options, both for watching matches on TV and in the stadium. We carried out a discrete choice experiment using an online survey questionnaire distributed on a national scale. The choice sets are based on three match characteristics: month, kickoff time, and quality of the opponent. The first part of this survey concerns television broadcasting aspects. The second part includes questions about stadium attendance. The choice data is first analyzed with a conditional logit model which assumes homogenous preferences. Then a mixed logit model is fit to model the heterogeneity among the fans. The estimates are used to calculate the expected utility of watching a Belgian Pro League match for every possible setting, either on TV or in the stadium. These predictions are validated in terms of the real audience rating and home attendance data. Our results can be used to improve the scheduling process of the Belgian Pro League in order to persuade more fans to watch the matches on TV or in a stadium

Uncertainty Propagation and Feature Selection for Loss Estimation in Performance-based Earthquake Engineering

This report presents a new methodology, called moment matching, of propagating the uncertainties in estimating repair costs of a building due to future earthquake excitation, which is required, for example, when assessing a design in performance-based earthquake engineering. Besides excitation uncertainties, other uncertain model variables are considered, including uncertainties in the structural model parameters and in the capacity and repair costs of structural and non-structural components. Using the first few moments of these uncertain variables, moment matching requires only a few well-chosen point estimates to propagate the uncertainties to estimate the first few moments of the repair costs with high accuracy. Furthermore, the use of moment matching to estimate the exceedance probability of the repair costs is also addressed. These examples illustrate that the moment-matching approach is quite general; for example, it can be applied to any decision variable in performance-based earthquake engineering. Two buildings are chosen as illustrative examples to demonstrate the use of moment matching, a hypothetical three-story shear building and a real seven-story hotel building. For these two examples, the assembly-based vulnerability approach is employed when calculating repair costs. It is shown that the moment-matching technique is much more accurate than the well-known First-Order-Second-Moment approach when propagating the first two moments, while the resulting computational cost is of the same order. The repair-cost moments and exceedance probability estimated by the moment-matching technique are also compared with those by Monte Carlo simulation. It is concluded that as long as the order of the moment matching is sufficient, the comparison is satisfactory. Furthermore, the amount of computation for moment matching scales only linearly with the number of uncertain input variables. Last but not least, a procedure for feature selection is presented and illustrated for the second example. The conclusion is that the most important uncertain input variables among the many influencing the uncertainty in future repair costs are, in order of importance, ground-motion spectral acceleration, component capacity, ground-motion details and unit repair costs