Optimizing low-order controllers for haptic systems under delayed feedback

Cataloged from PDF version of article.In this paper, a PD controller design for haptic systems under delayed feedback is considered. More precisely, a complete stability analysis of a haptic system where local dynamics are described by some second-order mechanical dynamics is presented. Next, using two optimization techniques (H∞ and stability, margin optimization) an optimal choice for the controller gains is proposed. The derived results are tested on a three degree-of-freedom real-time experimental platform to illustrate the theoretical results. © 2013 Elsevier Ltd

On dwell time minimization for switched delay systems: Free-weighting matrices method

In this paper, we present a quasi-convex minimization method to calculate an upper bound of dwell-time for stability of switched delay systems. Piecewise Lyapunov-Krasovskii functionals are introduced and the upper bound for the derivative of Lyapunov functionals are estimated by free weighting matrices method to investigate non-switching stability of each candidate subsystems. Then, a sufficient condition for dwell-time is derived to guarantee the asymptotic stability of the switched delay system. Once these conditions are represented by a set of linear matrix inequalities (LMIs), dwell time optimization problem can be formulated as a standard quasi-convex optimization problem. Numerical examples are given to illustrate improvements over previously obtained dwell-time bounds. © 2014 IEEE

On Dwell Time Minimization for Switched Delay Systems: Time-Scheduled Lyapunov Functions

In the present paper, dwell time stability conditions of the switched delay systems are derived using scheduled Lyapunov-Krasovskii functions. The derivative of the Lyapunov functions are guaranteed to be negative semidefinite using free weighting matrices method. After representing the dwell time in terms of linear matrix inequalities, the upper bound of the dwell time is minimized using a bisection algorithm. Some numerical examples are given to illustrate effectiveness of the proposed method, and its performance is compared with the existing approaches. The yielding values of dwell time via the proposed technique show that the novel approach outperforms the previous ones. © 201

Two Higgs Doublet Model and Lepton Polarization in the B -> K tau+ tau- Decay

The decay width, forward-backward asymmetry and tau lepton longitudinal and transversal polarization for the exclusive (B -> K tau^+ tau^-) decay in a two Higgs doublet model are computed. It is shown that the forward-backward asymmetry and longitudinal polarization of the tau lepton are very effective tools for establishing new physics.Comment: 25 pages, 20 figures, LaTeX formatte

Low-order controller design for haptic systems under delayed feedback

In this paper, we consider PD controller design for haptic systems under delayed feedback. More precisely, we present a complete stability analysis of a haptic system where local dynamics are described by some second-order mechanical dynamics. Next, using two optimization techniques (H ∞ and stability margin optimization) we propose an optimal choice for the controller gains. The derived results are tested on a three degree of freedom real-time experimental platform to illustrate the theoretical results. © 2012 IFAC

Rare B -> K^* l^+ l^- decay, two Higgs doublet model, and light cone QCD sum rules

The decay width, forward-backward asymmetry and lepton longitudinal and transversal polarization for the exclusive K^* -> l^+ l^- decay in a two Higgs doublet model are computed. It is shown that all these quantities are very effective tools for establishing new physics.Comment: 18 pages, 7 figures, LaTeX formatte

Quality assurance for the query and distribution systems of the RCSB Protein Data Bank

The RCSB Protein Data Bank (RCSB PDB, www.pdb.org) is a key online resource for structural biology and related scientific disciplines. The website is used on average by 165 000 unique visitors per month, and more than 2000 other websites link to it. The amount and complexity of PDB data as well as the expectations on its usage are growing rapidly. Therefore, ensuring the reliability and robustness of the RCSB PDB query and distribution systems are crucially important and increasingly challenging. This article describes quality assurance for the RCSB PDB website at several distinct levels, including: (i) hardware redundancy and failover, (ii) testing protocols for weekly database updates, (iii) testing and release procedures for major software updates and (iv) miscellaneous monitoring and troubleshooting tools and practices. As such it provides suggestions for how other websites might be operated

Light cone QCD sum rule analysis of B -> K l(+) l(-) decay

We calculate the transition formfactors for the B -> K l(+) l(-) decay in the framework of the light cone QCD sum rules. The invariant dilepton mass distribution and the final lepton longitudinal polarization asymmetry are investigated. The comparison analysis of our results with traditional sum rules method predictions on the formfactors is performed.Comment: 18 pages, 3 figures, LaTeX formatte

The Effect of Tax Treaties on Multinational Firms: New Evidence from Microdata

This paper uses affiliate level data from Swedish multinationals to examine the impact of tax treaties on both overall affiliate sales and the composition of those sales. In line with previous results, we find little evidence for an effect of treaties on the level of total sales. We do, however, find that a tax treaty increases the probability of investment by a firm in a given country. In addition, we find that a treaty reduces exports to the parent but increases imports of intermediate inputs from the parent. This is consistent with treaties increasing the effective host tax. This suggests that tax treaties impact the behavior of multinationals along some dimensions but not along others