278,197 research outputs found
INDIRECT SAMPLING in the CONTEXT of DUAL FRAME SURVEYS
No full textUnder-coverage is one of the most common problems of sampling frames. To reduce the impact of coverage error on survey estimates several frames can be combined in order to achieve a complete (or nearly complete) coverage of the target population. Multiple frame estimators have been developed to be used in the context of multiple frame surveys. Sampling frames may overlap which is the case when a single unit of the sampling frame is related with more than one element of the target population. Indirect sampling (Lavallée, 1995) is an alternative approach to classical sampling theory in dealing with the overlapping problem of sampling frames on survey estimates. Not infrequently a survey may need more than one sampling frame in order to improve coverage and simultaneously the sampling frame overlap. In this paper a new class of estimators is presented which is the result from merging multiple frames estimators (only the particular case of dual frames will be presented) with indirect sampling estimators in order to bring together in a single estimator the effect of several frames on survey estimates.Indirect Sampling, Generalized Weight Share Method, Dual Frame Surveys
Governing Low Profile Issues: A Frame Analysis of Drug Addiction in a Local Setting
No full textFrame analysis was developed by Erving Goffman as a sociological concept, used for understanding how individual actors relate themselves to the world, creating coherent frames out of individual social experiences. We apply frame analysis in the emergent field of sociology of governance, using the example of low profile public issue of drug addiction in a specific local social and political context of a municipality in Bosnia and Herzegovina, in order to understand the roles of governance actors and their social interactions in the attribution of meaning. We focus on mental organization of governance experiences related to drug addiction and the strategic involvement of different governance actors which use given frames. We discuss the importance of frame coherence and ways in which it can be achieved for the low profile issues.Frame Analysis, Sociology of Governance, Low Profile Issues, Frame Coherence
New Stationary Frame Control Scheme for Three Phase PWM Rectifiers Under Unbalanced Voltage Dips Conditions
No full textA new stationary frame control scheme for three-phase pulsewidth-modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage ripple. This paper's novelty is the development of a new current-reference generator implemented directly in stationary reference frame. This allows using proportional sinusoidal signal integrator (P-SSI) controllers for simultaneous compensation of both positive and negative current sequence components. No phase-locked loop (PLL) strategies and coordinate transformations are needed for the proposed current-reference generator. Experimental results are presented for a 20-kV A alternative current (ac)/direct current (dc) converter prototype to demonstrate the effectiveness of the proposed control scheme. A comparison with two other existing control techniques is also performed. Fast dynamic performance with small dc-link voltage ripple and input sinusoidal currents are obtained with this control scheme, even under severe voltage dips operating condition
Frame catcher adaptation for guardrail extruder terminal
No full textApparatus and methods for preventing penetration of vehicles by causing the guardrail extruder terminal to contact and engage the frame or chassis of vehicles in a collision. In preferred embodiments, a guardrail extruder terminal end treatment is adapted for improved operation during impacts by attachment of a frame catcher penetration guard. The frame catcher adaptation extends below the usual lower edge of the impact head of the guardrail extruder terminal design in order to contact portions of the chassis of a vehicle during an impact at the guardrail end. In several embodiments, the impact head of a guardrail extruder terminal includes a substantially rigid downwardly extending portion which presents an expanded contact area, the location of which approximates the location of a portion of the vehicle's chassis. The frame catcher devices may be retrofitted onto existing guardrail extruder terminal impact heads.U
The role of Scene Type and Priming in the processing and selection of a spatial frame of reference
No full textJohannsen K, de Ruiter J. The role of Scene Type and Priming in the processing and selection of a spatial frame of reference. Frontiers in Psychology. 2013;4:182.The selection and processing of a spatial frame of reference (FOR) in interpreting verbal scene descriptions is of great interest to psycholinguistics. In this study, we focus on the choice between the relative and the intrinsic FOR, addressing two questions: (a) does the presence or absence of a background in the scene influence the selection of a FOR, and (b) what is the effect of a previously selected FOR on the subsequent processing of a different FOR. Our results show that if a scene includes a realistic background, this will make the selection of the relative FOR more likely. We attribute this effect to the facilitation of mental simulation, which enhances the relation between the viewer and the objects. With respect to the response accuracy, we found both a higher (with the same FOR) and a lower accuracy (with a different FOR), while for the response latencies, we only found a delay effect with a different FOR
Hysteretic Characteristics of Wood-Frame Structures Under Seismic Motions
No full textIn order to develop seismic codes that can effectively mitigate damage to wood-frame construction under seismic activity, the dynamic characteristics of wood-frame buildings must be well understood. Funding of full-scale structure experimental tests can be costly and may not be a true replica of real life scenarios. Therefore, data interpretation projects focusing on dynamic behavior of low-rise wooden shearwall buildings under large seismic motions have become increasingly important. Procedures include determining the modal parameters and extracting hysteretic characteristics from the available records. The results help extend the understanding of wood-frame structures and update building codes. Furthermore, the amount of information extracted can help evaluate the effectiveness of the current instrumentation program.
This work focuses on the seismic records from wood-frame structures during the 2004 Parkfield Earthquake. Studies involve verifying the amplitude dependence of modal parameters and retrieving pinching hysteresis curves that are common in wood-frame structures. Modal parameters are identified with a robust routine called MODE-ID. Equivalent viscous damping estimates in wood-frame buildings can range from 5% - 10% in largely linear behavior and 10% - 20% in significant nonlinear behavior. The discrepancies of damping estimates reported in the past are a result of inappropriate comparisons without understanding 1) the degree of nonlinear response and 2) the system identification methods used for the studies. By studying the hysteretic curves, insights can be obtained to reveal and to resolve the damping estimate discrepancies. Since displacement time histories of structures are not typically measured, the hysteretic curves are extracted from acceleration time histories. The proposed process accounts for inherent double integration errors and phase delay through filtering. It is still being debated that if the double integration can provide meaningful structural relative displacement time histories. In a laboratory setting with unilateral ground motion, the extraction process provides accurate hysteretic curves. However, this dissertation demonstrates that if the building experiences bi-directional ground motions, the nonlinear behavior of the diaphragm tampers with this process.
The results from modal identification and hysteresis curves serve as a basis for creating numerical models. Direct and gradient search methods were used for model updating. Bayesian updating and model selection provided the best results for dealing with hysteretic structural models. This probabilistic framework demonstrates potential benefits in a seamless integration with a seismic database. The selected hysteretic model showed great resemblance to the measured responses and had evidence of pinching hysteresis. Insights on the structure’s deformations and dissipation of energy can be inferred from the model.</p
Frame of frames
No full textIn this project I take begin from two points: the frame, and a particular site in Bucharest, Romania. The specific site is the territory surrounding the House of the People, whose construction started in 1986. this building is the third largest building on earth, and built as part of a project for a new civic centre, for which the preparations and construction resulted in the destruction of a third of the old urban fabric of the city. this project ended with the revolution in 1989, and left the site a mixture of old city fabric, late communist blocks, and unused, abandoned and overgrown lots. The frame is that which separates. In mthis project, I detach the frame from what it is, and focus instead on what it does. the frame separates and distinguishes something from its surroundings, and thus creates a condition of inclusion/exclusion. the frame permeates all aspects of this project, from theory to urbanism to strategy to landscape to detail to the very process of design and production itself. From these starting points, my investigation was guided by four questions: What are the mechanisms of framing? How can the frame provide a tool for understanding and intervening in a contested landscape immanently? How can a landscape architecture project be framed into a landscape? How can landscape architecture elaborate landscape in both a critical and open ended way?Landscape architectureArchitecture and The Built Environmen
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