Technique and Qualities of Beams with Expanded Metal Sections

The rotary expander technique can be used for manufacturing Lattice framework from a single strip of sheet metal by integrating expanded metal with solid sheet. This technique can be used to distribute the material in a tubular, or open profile to where it\u27s best needed. Valuable qualities possible to are: - low weight and optimal strength - low energy transmission (noise and heat) - soft deformation and favorable energy absorbing properties - good fatigue resistance - high flexibility in design and product qualities These qualities are useful in applications like: - light and strong steel framing systems for buildings - energy absorbing support structures in road equipment - light vehicles - construction pipes and profiles Manufacturing of expanded metal implies a strain hardening of the mesh. This effect is more obvious in rotary expander manufacturing, due to a forced extension to match the solid metal strips. The use of strain hardened material to make light profiles with high stiffness. In combination with plaiting, it is possible to produce rigid C- and Z-studs

Andrzej Pekalski networks of scientific interests with internal degrees of freedom through self-citation analysis

Old and recent theoretical works by Andrzej Pekalski (APE) are recalled as possible sources of interest for describing network formation and clustering in complex (scientific) communities, through self-organisation and percolation processes. Emphasis is placed on APE self-citation network over four decades. The method is that used for detecting scientists field mobility by focusing on author's self-citation, co-authorships and article topics networks as in [1,2]. It is shown that APE's self-citation patterns reveal important information on APE interest for research topics over time as well as APE engagement on different scientific topics and in different networks of collaboration. Its interesting complexity results from "degrees of freedom" and external fields leading to so called internal shock resistance. It is found that APE network of scientific interests belongs to independent clusters and occurs through rare or drastic events as in irreversible "preferential attachment processes", similar to those found in usual mechanics and thermodynamics phase transitions.Comment: 7 pages, 1 table, 44 references, submitted to Int J Mod Phys

X-ray Observations of the Warm-Hot Intergalactic Medium

We present Chandra observations that provide the most direct evidence to date for the pervasive, moderate density, shock-heated intergalactic medium predicted by leading cosmological scenarios. We also comment briefly on future observations with Constellation-X.Comment: To be published in the proceedings of the conference "IGM/Galaxy Connection- The Distribution of Baryons at z=0". 6 page

Like Day and NIght: On Becoming a Teacher in Two Distinct Professional Cultures in Rural Saskatchewan

Framed within ecological and institutional ethnography perspectives, and situated within a larger study of beginning teachers in the Canadian province of Saskatchewan, this paper focuses on the dramatically different experiences of one beginning teacher who happened to secure half-time contracts in two rural schools within commuting distance of one another. His account of these experiences and how he makes sense of them orient researchers to the broad social, economic, and material conditions that organize the mutually dependent work of parents and teachers. This analysis contributes to beginning teacher research by affirming the value of personal stories of learning to teach, moving beyond studies of individual adaptation to fixed notions of professional success, and opening to scrutiny the shared conditions of early and later career teachers as they are institutionally and discursively organized, thus promoting appreciation of the complexities of learning to teach attuned to variation in local rural circumstances

Differences in Teachers’ Knowledge of Language

Teachers need to expand their understanding of language in order to meet the di-verse language and literacy needs of their students. Students may demonstrate deficits in the domains of language form (phonology, morphology, syntax), con-tent (semantics), and use (pragmatics). However, existing studies have only investigated teachers’ knowledge of language form. Therefore, this study investi-gated 236 preservice and inservice teachers’ knowledge of language form, content, and use as well as the teacher characteristics that may influence this knowledge. Both preservice and inservice teachers were found to have low levels of language knowledge. Experienced teachers, inservice teachers, and inservice teachers taking graduate level courses at a university tended to perform better than preservice teachers with no teaching experience on all three subscales. These findings have implications for teacher training programs and for profes-sionals providing support services to classroom teachers

Autofocus and analysis of geometrical errors within the framework of fast factorized back-projection

This paper describes a Fast Factorized Back-Projection (FFBP) formulation that includes a fully integrated autofocus algorithm, i.e. the Factorized Geometrical Autofocus (FGA) algorithm. The base-two factorization is executed in a horizontal plane, using a Merging (M) and a Range History Preserving (RHP) transform. Six parameters are adopted for each sub-aperture pair, i.e. to establish the geometry stage-by-stage via triangles in 3-dimensional space. If the parameters are derived from navigation data, the algorithm is used as a conventional processing chain. If the parameters on the other hand are varied from a certain factorization step and forward, the algorithm is used as a joint image formation and autofocus strategy. By regulating the geometry at multiple resolution levels, challenging defocusing effects, e.g. residual space-variant Range Cell Migration (RCM), can be corrected. The new formulation also serves another important purpose, i.e. as a parameter characterization scheme. By using the FGA algorithm and its inverse, relations between two arbitrary geometries can be studied, in consequence, this makes it feasible to analyze how errors in navigation data, and topography, affect image focus. The versatility of the factorization procedure is demonstrated successfully on simulated Synthetic Aperture Radar (SAR) data. This is achieved by introducing different GPS/IMU errors and Focus Target Plane (FTP) deviations prior to processing. The characterization scheme is then employed to evaluate the sensitivity, to determine at what step the autofocus function should be activated, and to decide the number of necessary parameters at each step. Resulting FGA images are also compared to a reference image (processed without errors and autofocus) and to a defocused image (processed without autofocus), i.e. to validate the novel approach further

An Efficient Solution to the Factorized Geometrical Autofocus Problem

This paper describes a new search strategy within the scope of factorized geometrical autofocus (FGA) and synthetic-aperture-radar processing. The FGA algorithm is a fast factorized back-projection formulation with six adjustable geometry parameters. By tuning the flight track step by step and maximizing focus quality by means of an object function, a sharp image is formed. We propose an efficient two-stage approach for the geometrical variation. The first stage is a low-order (few parameters) parallel search procedure involving small image areas. The second stage then combines the local hypotheses into one global autofocus solution, without the use of images. This method has been applied successfully on ultrawideband CARABAS II data. Errors due to a constant acceleration are superposed on the measured track prior to processing, giving a 6-D autofocus problem. Image results, including resolution, peak-to-sidelobe ratio and magnitude values for point-like targets, finally confirm the validity of the strategy. The results also verify the prediction that there are several satisfying autofocus solutions for the same radar data

Factorized Geometrical Autofocus for Synthetic Aperture Radar Processing

This paper describes a factorized geometrical autofocus (FGA) algorithm, specifically suitable for ultrawideband synthetic aperture radar. The strategy is integrated in a fast factorized back-projection chain and relies on varying track parameters step by step to obtain a sharp image; focus measures are provided by an object function (intensity correlation). The FGA algorithm has been successfully applied on synthetic and real (Coherent All RAdio BAnd System II) data sets, i.e., with false track parameters introduced prior to processing, to set up constrained problems involving one geometrical quantity. Resolution (3 dB in azimuth and slant range) and peak-to-sidelobe ratio measurements in FGA images are comparable with reference results (within a few percent and tenths of a decibel), demonstrating the capacity to compensate for residual space variant range cell migration. The FGA algorithm is finally also benchmarked (visually) against the phase gradient algorithm to emphasize the advantage of a geometrical autofocus approach