Parametric Investigation of Seismic Interaction Between Precast Concrete Cladding Systems and Moment Resisting Frames

This paper presents the results of a preliminary numerical investigation into the interaction between precast concrete cladding systems and moment resisting frames. Macro-scale models of cladding systems are implemented in existing lumped plasticity models for moment resisting frames. Different failure mechanisms and various configurations are considered in order to show the effect of the entire cladding system upon a structure’s seismic behavior. Several parameters are varied in order to establish their associated influence on the overall structural response. Results show that it is clearly more advantageous to have a failure mechanism governed by the connection than one governed by either the panel or the frame. An experimental program is now underway building on what has been learnt from the parametric investigation. The authors intend to continue the research to successively develop improved or innovative low-damage cladding-moment resisting frame systems. They also aim to produce simple design tools that provide easy inclusion of the seismic effects of cladding-frame interaction

Wide-Area Imaging of Ultrasonic Fields by Digital Phase-Stepping Shearography

Shearography, introduced in 1973 by both Hung & Taylor [1] and Leendertz & Butters [2], was developed from speckle pattern interferometry. Both methods are full- field optical techniques which generate interference patterns by combining a reference beam with the reflected light from a diffusive surface. However, a significant difference exists between the manner in which these two methods form their resulting interferograms. Shearography is a common path intereferometer; the reference beam is derived from the same beam as that used to probe the object. This distinction has a number of advantages including tolerance to rigid body motions, reduced laser coherence requirements, compact design, convenient sensitivity adjustment, and direct measurement of differential displacement. The advent of modern video cameras has allowed designers to build upon these intrinsic advantages producing a portable low-cost sensor. In this configuration, (electronic) shearography has gained acceptance as a nondestructive inspection technique [3–5], which is commonly used on aerospace structures and materials [6–10]

DynPeak : An algorithm for pulse detection and frequency analysis in hormonal time series

The endocrine control of the reproductive function is often studied from the analysis of luteinizing hormone (LH) pulsatile secretion by the pituitary gland. Whereas measurements in the cavernous sinus cumulate anatomical and technical difficulties, LH levels can be easily assessed from jugular blood. However, plasma levels result from a convolution process due to clearance effects when LH enters the general circulation. Simultaneous measurements comparing LH levels in the cavernous sinus and jugular blood have revealed clear differences in the pulse shape, the amplitude and the baseline. Besides, experimental sampling occurs at a relatively low frequency (typically every 10 min) with respect to LH highest frequency release (one pulse per hour) and the resulting LH measurements are noised by both experimental and assay errors. As a result, the pattern of plasma LH may be not so clearly pulsatile. Yet, reliable information on the InterPulse Intervals (IPI) is a prerequisite to study precisely the steroid feedback exerted on the pituitary level. Hence, there is a real need for robust IPI detection algorithms. In this article, we present an algorithm for the monitoring of LH pulse frequency, basing ourselves both on the available endocrinological knowledge on LH pulse (shape and duration with respect to the frequency regime) and synthetic LH data generated by a simple model. We make use of synthetic data to make clear some basic notions underlying our algorithmic choices. We focus on explaining how the process of sampling affects drastically the original pattern of secretion, and especially the amplitude of the detectable pulses. We then describe the algorithm in details and perform it on different sets of both synthetic and experimental LH time series. We further comment on how to diagnose possible outliers from the series of IPIs which is the main output of the algorithm.Comment: Nombre de pages : 35 ; Nombre de figures : 16 ; Nombre de tableaux :

Entrepreneurship in a Transition Economy: An Examination of Venture Creation in Hungary

This study examines entrepreneurs and new ventures in a transition economy, Hungary, and identifies what variables distinguish between Hungarian entrepreneurs and their new ventures in the pre-1988 transition period from that which followed. The variables that discriminate most strongly are their business strategies. The newer firms had a concentration strategy while the older firms had a new product development strategy. Other variables that discriminated between the groups include reacting to the political environment, satisfaction with firm performance, encouragement from investors, recent investment in building improvement, and family history of entrepreneurship. The newer entrepreneurs had more family role models of entrepreneurship

Electronic behavior of the Zn- and O-polar ZnO surfaces studied using conductive atomic force microscopy

We have used conducting atomic force microscopy (CAFM) to study the morphology and electronic behavior of as-received and air-annealed (0001) Zn- and (0001¯) O-polar surfaces of bulk ZnO. Both polar surfaces exhibit relatively flat morphologies prior to annealing, which rearrange to form well-defined steps upon annealing in air at 1050 °C for 1 h. Long-term exposure to air results in surface layer pitting and the destruction of steps for both the as-received and air-annealed (0001¯)surfaces, indicating its enhanced reactivity relative to the (0001) surface. CAFM I-V spectra for polar surfaces are similar and indicate Ohmic to rectifying behavior that depends on the maximum applied ramp voltage, where higher voltages result in more conducting behavior. These data and force-displacement curves suggest the presence of a physisorbed H2O layer, which is removed at higher voltages and results in higher conduction

Alliances and Networks: Cooperative Strategies for Small Businesses

Research on large firms shows that cooperative strategies have the potential to improve performance by helping firms gain access to necessary resources, enter new markets, and spread the risk over several partners. Interviews with thirty-four small business managers show small firms also can profit from using a cooperative network. Highly-allied small businesses entered alliances to gain resources and based their alliances on a distinctive competence. The highly allied businesses grew more rapidly than the less allied firms. Mutual goals and joint decision making were viewed as critical to the high level of satisfaction achieved