Behavior of large-scale rectangular columns confined with FRP composites

This paper focuses on axially loaded, large-scale rectangular RC columns confined with fiber-reinforced polymer (FRP) wrapping. Experimental tests are conducted to obtain the stress-strain response and ultimate load for three field-size columns having different aspect ratios and/or corner radii. Effective transverse FRP failure strain and the effect of increasing confining action on the stress-strain behavior are examined. Existing strength models, the majority of which were developed for small-scale specimens, are applied to predict the structural response. Since some of them fail to adequately characterize the test data and others are complex and require significant calculation, a simple design-oriented model is developed. The new model is based on the confinement effectiveness coefficient, an aspect ratio coefficient, and a corner radius coefficient. It accurately predicts the axial ultimate strength of the large-scale columns at hand and, when applied to the small-scale columns studied by other investigators, produces reasonable results

Flight Flutter Testing of Rotary Wing Aircraft Using a Control System Oscillation Technique

A flight flutter testing technique is described in which the rotor controls are oscillated by series actuators to excite the rotor and airframe modes of interest, which are then allowed to decay. The moving block technique is then used to determine the damped frequency and damping variation with rotor speed. The method proved useful for tracking the stability of relatively well damped modes. The results of recently completed flight tests of an experimental soft-in-plane rotor are used to illustrate the technique. Included is a discussion of the application of this technique to investigation of the propeller whirl flutter stability characteristics of the NASA/Army XV-15 VTOL tilt rotor research aircraft

Approach to rapid mission design and planning

Methods and techniques are described for implementation in automated computer systems to assess parametric data, capabilities, requirements and constraints for planning earth orbit missions. Mission planning and design procedures are defined using two types of typical missions as examples. These missions were the high energy Astronomical Observatory Satellite missions, and Small Applications Technology Satellite missions

Electron paramagnetic resonance study of Eu2+ centers in melt-grown CsBr single crystals

The structure of Eu2+ monomer centers in CsBr single crystals is investigated using electron paramagnetic resonance (EPR) spectroscopy. These centers are produced by heating the melt-grown crystals above 600 K in vacuum followed by a rapid quench to room temperature (RT) or 77 K. The angular dependence of their EPR spectrum demonstrates that these centers have cubic symmetry. At RT the EPR spectrum decays by aggregation of the Eu2+ ions. This strongly contrasts with the situation for CsBr:Eu needle image plates synthesized by physical vapor deposition, where the Eu2+-related EPR spectrum was observed to exhibit long-term stability at RT

Lunar targeting study: Lunar and planetary Ephemeris tapes

The Univac 1108 computer tape data formats are documented for the ephermeris tape generated by the Jet Propulsion Laboratory and the ephemeris tape used by the Quick Response Targeting Program (QRTP). Ephermeris tapes are used as the data source for the position and velocity components of those celestial bodies being considered in an integrated trajectory simulation program. The QRTP ephemeris tape has data only for lunar mission simulations. The JPL ephemeris tape has data for the moon and the nine planets. The ephemeris tapes, the data formats, the coordinate systems, and units are defined. The transformation from the mean-of-1950 coordinate system to the nearest mean Besselian year is given

Numerical modelling of the debonding between CFRP strips and concrete in shear tests under static loads using different approaches

The present paper deals with the finite element (FE) analysis of bond slip between concrete and carbon fiber reinforced polymer (CFRP) strips in a single pull-out test under static loads. The commercial software LS-DYNA is used to simulate the test set-up using a plastic damage material model and an elastic material model for the concrete prism and the unidirectional CFRP strip, respectively. The bond interface between the concrete and the CFRP strip is simulated following three different approaches using a perfect bond model, a cohesive bond model and contact algorithms based on recently developed proposed bond slip models. The numerical model is validated based on experimental test results available from literature. The debonding failure mode and the delamination loads of the CFRP strip are predicted. The numerical results show a good agreement with the experimental data using the cohesive bond model. The perfect bond model gives an overestimation of the delamination loads and of the damage distribution in the concrete prism

Creative thinking as an innovative approach to tackle nutrition in times of economic crises

An interactive session ‘Let’s cook something up’ organised by the European Nutrition Leadership Platform (ENLP – www.enlp.eu.com) during the 20th International Congress of Nutrition (ICN) organised in Granada, Spain, showed how an innovative approach to parallel sessions can be a meaningful tool in formulating solutions to current nutritional challenges. The key objective of the session was to provide a proof-of-concept that even in the context of a large conference such as the ICN, with approximately 4250 attendants, one can utilise innovative and active learning techniques to get a message across and work towards solutions rather than using the traditional ‘chalk and talk’ method. There is a huge potential for innovation at these types of conferences in creating an environment that encourages interaction by breaking down the boundaries of authority and placing the focus on sharing knowledge with enjoyment. To provide such a proof-of-concept, the context of nutrition during times of economic crises was chosen to guide the session

Measuring and modelling the energy cost of reconfiguration in sensor networks [forthcoming]

As Wireless Sensor Networks (WSN) must operate for long periods on a limited power budget, estimating the energy cost of software operations is critical. Contemporary reconfiguration approaches for WSN allow for software evolution at various granularities; from reflashing of a complete software image, through replacement of complete applications, to the reconfiguration of individual software components. This paper contributes a generic model for measuring and modelling the energy cost of reconfiguration in WSN. We validate that this model is accurate in the face of different hardware platforms, software stacks and software encapsulation approaches. We have embedded this model in the LooCI middleware, resulting in the first energy aware reconfigurable component model for sensor networks. We evaluate our approach using two real-world WSN applications and demonstrate that our model predicts the energy cost of reconfiguration with 93% accuracy. Using this model we demonstrate that selecting the most appropriate software modularisation approach is key to minimising energy consumption

Reduced-bias estimator of the Conditional Tail Expectation of heavy-tailed distributions

International audienceSeveral risk measures have been proposed in the literature. In this paper, we focus on the estimation of the Conditional Tail Expectation (CTE). Its asymptotic normality has been first established in the literature under the classical assumption that the second moment of the loss variable is finite, this condition being very restrictive in practical applications. Such a result has been extended by Necir {\it et al.} (2010) in the case of infinite second moment. In this framework, we propose a reduced-bias estimator of the CTE. We illustrate the efficiency of our approach on a small simulation study and a real data analysis