Index tuning, i.e., selecting the indexes appropriate for a workload, is a crucial problem in database system tuning. In this paper, we solve index tuning for large problem instances that are common in practice, e.g., thousands of queries in the workload, thousands of candidate indexes and several hard and soft constraints. Our work is the first to reveal that the index tuning problem has a wel...

We propose two modeling approaches of AIMD congestion control mechanisms. The first separates the increase and decrease parts where as the second describes the rate evolution as a continuous process governed by a differential equation. We relate the approaches and show that the second one is an averaged approximation of the first one. The objective of this paper is twofold: model a class of (st...

Flow velocity in rivers has a major impact on residence time of water and thus on high and low water as well as on water quality. For global scale hydrological modeling only very limited information is available for simulating flow velocity. Based on the Manning-Strickler equation, a simple algorithm to model temporally and spatially variable flow velocity was developed with the objective of im...

We study the self-tuning of general brane junctions and brane networks on the 6-dimensional space-time. For the general brane junctions, there may exist one fine-tuning among the brane tensions. For the brane networks, similar to the 5-dimensional self-tuning brane models, the brane tensions can be set arbitrarily and there exists the singularity for the metric and bulk scalar. And if we want t...

David A. Powell,1,* Mikhail Lapine,2,1 Maxim V. Gorkunov,3 Ilya V. Shadrivov,1 and Yuri S. Kivshar1 1Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200, Australia 2Department Electronics and Electromagnetics, Faculty of Physics, University of Seville, Avda. Reina Mercedes s/n, 41015 Seville, Spain 3A....

Programming parallel/distributed applications is a difficult task that requires a high degree of knowledge and expertise, especially to achieve the potential performance offered by HPC. Analysis and tuning tools can be helpful for automatically improving applications performance. In particular, dynamic analysis and tuning tools are necessary for applications that vary their behaviour at executi...

In this project, we use recent findings from electrophysiological recordings and a previous model of the cellular properties of barrel cortical neurons to explore their implications on the dynamic properties of directional tuning in barrel cortex. We find that directional tuning is influenced by the frequency and speed of whisker directions, even in the low frequency range of natural whisking. ...

International Journal of Control Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t713393989 Dahlin minimum variance self-tuning controller Lamya A. Al-Chalabi a; Fouad F. Khalil b a Department of Control and Systems Engineering, University of Technology, Baghdad, Iraq b Department of Electrical Engineering, Uni...

The PI control of first-order linear passive systems through a delayed communication channel is revisited in light of the relative stability concept called σ-stability. Treating the delayed communication channel as a transport PDE, the passivity of the overall control-loop is guaranteed, resulting in a closed-loop system of neutral nature. Spectral methods are then applied to the system to obta...

Recent progress in string theory moduli stabilization has motivated a mixed modulus–anomaly mediated supersymmetry breaking scenario, also dubbed ‘mirage mediation’. This scenario has a number of phenomenologically attractive features, in particular with respect to the cosmological gravitino/moduli problem. In this note, we investigate the issues of fine–tuning associated with obtaining the cor...