Radio Frequency Association of Efimov Trimers

The quantum-mechanical three-body problem is one of the fundamental challenges of few-body physics. When the two-body interactions become resonant, an infinite series of universal three-body bound states is predicted to occur, whose properties are determined by the strength of the two-body interactions. We report on the association and direct observation of a trimer state consisting of three distinguishable fermions using radio-frequency (RF) spectroscopy. The measurements of its binding energy are consistent with theoretical predictions which include non-universal corrections.Comment: 12 pages, 6 figure

A methodology for the design of robust rollover prevention controllers for automotive vehicles: Part 2-Active steering

In this paper we apply recent results from robust control to the problem of rollover prevention in automotive vehicles. Specifically, we exploit the results of Pancake, Corless and Brockman, which provide controllers to robustly guarantee that the peak magnitudes of the performance outputs of an uncertain system do not exceed certain values.We use the dynamic Load Transfer Ratio LTRd as a performance output for rollover prevention, and design active-steering based rollover controllers to keep the magnitude of this quantity below a certain level, while we use control input u as an additional performance output to limit the maximum amount of control effort. We present numerical simulations to demonstrate the efficacy of our controllers

On the Kalman-Yakubovich-Popov lemma and common Lyapunov solutions for matrices with regular inertia

In this paper we extend the classical Lefschetz version of the Kalman-Yacubovich-Popov (KYP) lemma to the case of matrices with general regular inertia. We then use this result to derive an easily verifiable spectral condition for a pair of matrices with the same regular inertia to have a common Lyapunov solution (CLS), extending a recent result on CLS existence for pairs of Hurwitz matrices

Opal-A rich additives used in ancient lime mortars

Ancient stone and brick masonry mortars from three monuments in Konya, Central Anatolia dated to the Anatolian Selçuk Period (12th and 13th centuries AD) were examined for their raw material composition and durability characteristics to understand some characteristics of medieval mortar technology. Optical microscopy, XRD, SEM, EDX, FTIR and TGA analyses revealed that the mortars contained high percentage of lime binder totally carbonated into micritic calcite. Coarse and medium aggregates were mainly composed of sandstone and metamorphic rock fragments, quartz, feldspar and mica minerals. Opal-A was found in considerable amounts in the fine aggregates, likely not derived from the coarser ones but added separately. Pozzolanic activity of the fine aggregates was determined by conductometric measurements. Their ability to form C-S-H was observed by treating them with saturated Ca(OH)2 solution. Bulk density and total porosity measurements showed that the mortars were highly porous due to the use of high amount of lime. On the other hand, they possessed sufficient mechanical strength. Mechanical properties were determined by point load tests and ultrasonic pulse velocity measurements. They were expressed as uniaxial compressive strength (UCS) and modulus of elasticity (Emod) in MPa. The results were also discussed in terms of durability characteristics of the mortars. They were expressed with the use of uniaxial compressive strengths in dry and wet states, and total porosity values. The mortars were considered to have high durability to wetting and drying cycles but had poor durability to the crystallization of water-soluble salts

A methodology for the design of robust rollover prevention controllers for automotive vehicles: Part 1-Differential Braking

In this paper we apply recent results from robust control to the problem of rollover prevention in automotive vehicles. Specifically, we exploit the results of Pancake, Corless and Brockman, which provide controllers to robustly guarantee that the peak values of the performance outputs of an uncertain system do not exceed certain values. We introduce a new measure of performance for rollover prevention, the Load Transfer Ratio LTRd , and design differential-braking based rollover controllers to keep the value of this quantity below a certain level; we also obtain controllers which yield robustness to variations in vehicle speed. We present numerical simulations to demonstrate the efficacy of our controllers

Adaptive Rollover Prevention for Automotive Vehicles with Differential Braking

In this paper we present an adaptive controller implementation based on the multiple models, switching, and tuning (MMST) paradigm for preventing untripped rollover in automotive vehicles. Our approach relies on differential-braking to keep the value of the Load Transfer Ratio (LTR) below a threshold. We first employ multiple models to infer the unknown center of gravity height and the suspension parameters of the vehicle, which are subsequently used to switch to the corresponding rollover controller. The proposed multicontroller switched scheme is shown via numerical simulations to result in better performance than its fixed robust counterpart

General Inertia and Circle Criterion

In this paper we extend the well known Kalman-Yacubovic-Popov (KYP) lemma to the case of matrices with general regular inertia. We show that the version of the lemma that was derived for the case of pairs of stable matrices whose rank difference is one, extends to the more general case of matrices with regular inertia and in companion form. We then use this result to derive an easily verifiable spectral condition for a pair of matrices with the same regular inertia to have a common Lyapunov solution (CLS), extending a recent result on CLS existence for pairs of Hurwitz matrices that can be considered as a time-domain interpretation of the famous circle criterion