Short-range Magnetic interactions in the Spin-Ice compound Ho2_{2}Ti2_{2}O7_{7}

Magnetization and susceptibility studies on single crystals of the pyrochlore Ho$_{2}$Ti$_{2}$O$_{7}$ are reported for the first time. Magnetization isotherms are shown to be qualitatively similar to that predicted by the nearest neighbor spin-ice model. Below the lock-in temperature, $T^{\ast }\simeq 1.97$ K, magnetization is consistent with the locking of spins along [111] directions in a specific two-spins-in, two-spins-out arrangement. Below $T^{\ast}$ the magnetization for $B||[111]$ displays a two step behavior signalling the breaking of the ice rules.Comment: 4 pages, 3 figure

The effects of atmospheric refraction on the accuracy of laser ranging systems

Correction formulas derived by Saastamoinen and Marini, and the ray traces through the refractivity profiles all assume a spherically symmetric refractivity profile. The errors introduced by this assumption were investigated by ray tracing through three-dimensional profiles. The results of this investigation indicate that the difference between ray traces through the spherically symmetric and three-dimensional profiles is approximately three centimeters at 10 deg and decreases to less than one half of a centimeter at 80 deg. If the accuracy desired in future laser ranging systems is less than a few centimeters, Saastamoinen and Marini's formulas must be altered to account for the fact that the refractivity profile is not spherically symmetric

Experimental study of cold-formed ferritic stainless steel hollow sections

Stainless steel is gaining increasing use in construction because of its durability, favorable mechanical properties, and aesthetic appearance, with the austenitic grades being the most commonly used. Austenitic stainless steels have a high nickel content (8–11%), resulting in high initial material cost and significant price fluctuations; this, despite its desirable properties, represents a considerable disadvantage in terms of material selection. Ferritic stainless steels, having no or very low nickel content, may offer a more viable alternative for structural applications, reducing both the level and variability of the initial material cost while maintaining adequate corrosion resistance. There is currently limited information available on the structural performance of this type of stainless steel. Therefore, to overcome this limitation, a series of material, cross section, and member tests have been performed, covering both the standard EN 1.4003 grade (similar to the chromium weldable structural steel 3Cr12) and the EN 1.4509 grade (441), which has improved weldability and corrosion resistance. In total, 20 tensile coupon tests, 16 compressive coupon tests, eight stub column tests, 15 flexural buckling tests, and eight in-plane bending tests were carried out. Precise measurements of the geometric properties of the test specimens, including the local and global geometric imperfections, were also made. The experimental results are used to assess the applicability of the current European (EN 1993-1-4) and North American (SEI/ASCE-8) provisions to ferritic stainless steel structural components. In addition, the relative structural performance of ferritic stainless steel to that of more commonly used stainless steel grades is also presented, showing ferritic stainless steel to be an attractive choice for structural applications

Testing of ferritic stainless steel tubular structural elements.

Stainless steel is gaining increasing usage in construction owing to its durability, favourable mechanical properties and its aesthetic appearance, with the austenitic grades being the most commonly utilised. Austenitic stainless steels have a high nickel content (8%-11%), resulting in high initial material cost and significant price fluctuations; this, despite its desirable properties, represents a considerable disadvantage in terms of material selection. Ferritic stainless steels, having no or very low nickel content, may offer a more viable alternative for structural applications, reducing both the level and variability of the initial material cost. In comparison to the most widely used austenitic grades, the ferritic grades typically have higher yield strengths (250-350 N/mm2) and are easier to machine and work. Furthermore, by varying the chromium content (10.5%-29%), and with additions of other alloying elements, the required corrosion resistance for a wide range of structural applications and operating environments can be achieved. There is currently limited information available on the structural performance of this type of stainless steel. Therefore, to overcome this limitation, a series of material and rosssection tests have been performed, covering both the standard 1.4003 grade and the 1.4509 grade, which has improved weldability and corrosion resistance. The experimental results are reported, analysed and compared to the results of tests performed on other stainless steel grades. Finally, design recommendations suitable for incorporation into Eurocode 3: Part 1.4 (2006) have been proposed

A threshold for a q-sorting methodology for computer-adaptive surveys

© 2017 Proceedings of the 25th European Conference on Information Systems, ECIS 2017. All rights reserved. Computer-Adaptive Surveys (CAS) are multi-dimensional instruments where questions asked of respondents depend on the previous questions asked. Due to the complexity of CAS, little work has been done on developing methods for validating their content and construct validity. We have created a new q-sorting technique where the hierarchies that independent raters develop are transformed into a quantitative form, and that quantitative form is tested to determine the inter-rater reliability of the individual branches in the hierarchy. The hierarchies are then successively transformed to test if they branch in the same way. The objective of this paper is to identify suitable measures and a “good enough” threshold for demonstrating the similarity of two CAS trees. To find suitable measures, we perform a set of bootstrap simulations to measure how various statistics change as a hypothetical CAS deviates from a “true” version. We find that the 3 measures of association, Goodman and Kruskal's Lambda, Cohen's Kappa, and Goodman and Kruskal's Gamma together provide information useful for assessing construct validity in CAS. In future work we are interested in both finding a “good enough” threshold(s) for assessing the overall similarity between tree hierarchies and diagnosing causes of disagreements between the tree hierarchies

A Q-sorting methodology for Computer-Adaptive Surveys - Style "Research"

Computer-Adaptive Surveys (CAS) are multi-dimensional instruments where questions asked of respondents depend on the previous questions asked. Due to the complexity of CAS, little work has been done on developing methods for validating their construct validity. This paper describes the process of using a variant of Q-sorting to validate a CAS item bank. The method and preliminary results are presented. In addition, lessons learned from this study are discussed

Researching creatively with pupils in Assessment for Learning (AfL) classrooms on experiences of participation and consultation

This paper reports on an ESRC TLRP project, Consulting Pupils on the Assessment of their Learning (CPAL). The CPAL project provides an additional theoretical perspective to the ‘educational benefits’ perspective of engaging pupil voice in learning and teaching (Rudduck et al., 2003) through its exploration of pupil rights specifically in relation to assessment issues presently on the policy agenda in the Northern Ireland context – notably Assessment for Learning (AfL). An emergent framework for assessing pupil rights, based on Article 12 of the United Nations Convention on the Rights of the Child (Lundy, 2007), is being used to explore the ways in which AfL classroom practice creates the conditions for increased pupil participation and consultation. Pupil views on their AfL classroom experiences and participation are explored by means of a variety of pupil-centred, creative research methods that engage and stimulate pupils to observe, communicate and analyse their learning and assessment experiences and give meaning to them. This presentation highlights preliminary data based on a sample of 11-14 years pupils' experiences of participation and consultation in classrooms adopting AfL pedagogical principles, and identifies characteristics that support or inhibit pupil participation in their learning and the expression of their views about such matters