Performance of binary block codes at low signal-to-noise ratios

The performance of general binary block codes on an unquantized additive white Gaussian noise (AWGN) channel at low signal-to-noise ratios is considered. Expressions are derived for both the block error and the bit error probabilities near the point where the bit signal-to-noise ratio is zero. These expressions depend on the global geometric structure of the code, although the minimum distance still seems to play a crucial role. Examples of codes such as orthogonal codes, biorthogonal codes, the (24,12) extended Golay code, and the (15,6) expurgated BCH code are discussed. The asymptotic coding gain at low signal-to-noise ratios is also studied

Analyses of two new electrode configurations for earth resistivity surveying

Two new electrode configurations for the electrical resistivity- surveying are introduced: the A-configuration, consisting of a closely spaced pair of current electrodes separated at larger distance from the closely spaced pair of potential electrodes, and the B-configuration, in which each closely spaced pair consists both current and potential electrode. Because electrode pairs can be carried as units, the new configurations can be applied to continuous resistivity surveying more easily than the Wenner configuration.... Theoretical apparent resistivity values are derived, by Maxwell\u27s theory of images, for the A- and B-configuration over a two layered earth using the depth probe method, and across a vertical fault plane using lateral traversing. These theoretical values are substantiated by measurements of models --Abstract, page ii

Rethinking transfer: Learning from CALL teacher education as consequential transition

Behind CALL teacher education (CTE) there is an unproblematized consensus of transfer, which suggests a positivist and tool-centered view of learning gains that differs from the sociocultural focus of recent teacher education research. Drawing on Beach’s (2003) conceptualization of transfer as consequential transition, this qualitative study seeks a cross-contextual understanding of language teacher learning with digital technology as the teachers in this study moved from a CTE course back to their own teaching contexts. Near the end of a CTE course, 19 in-service language teachers were asked to build connections between their experiences in the course and their teaching by creating a presentation. Four types of connections were identified, including thoughtful action planning, past experience refinement, and limited and reluctant use. In-depth interviews eight months later with four of the teachers found that they could seldom use the tools in the ways they had planned. However, they each experienced consequential transition as they struggled to reflect on their CTE course experience in everyday teaching. These results challenge the view that transfer in CTE must be about using technology. It is suggested that a focus on critical reflection of technology use may encourage teachers to continue reflective engagement in the ever-changing and complicated digital learning and teaching context

A simple model for detection of rare sound events

We propose a simple recurrent model for detecting rare sound events, when the time boundaries of events are available for training. Our model optimizes the combination of an utterance-level loss, which classifies whether an event occurs in an utterance, and a frame-level loss, which classifies whether each frame corresponds to the event when it does occur. The two losses make use of a shared vectorial representation the event, and are connected by an attention mechanism. We demonstrate our model on Task 2 of the DCASE 2017 challenge, and achieve competitive performance.Comment: Accepted by Interspeech 201

The effects of sulphur and copper on hot-workability of pure iron

The independent effects of sulphur, copper and their combinations on the hot-workability of pure iron free from other elements was studied, with special emphasis on the red-short phenomenon. Electrolytic pure iron with the addition of 0.023 cent sulphur, 0.33 per cent copper and 0.024 per cent sulphur plus 0.032 per cent copper along with a heat of only electrolytic pure iron was melted under vacuum, and cast under helium pressure. The specimens machined from the forged bars were tested at various temperatures by the hot twist-test and by the constant energy single blow drop forging test to evaluate the hot-workability and red-shortness. The red-short temperature range starts from not too far above the eutectic point of the iron-sulphur system and extends up to a certain temperature at which the solubility of sulphur in gamma iron is much more than sufficient to absorb all the sulphur content. The red-short range starts and ends gradually rather than suddenly, especially at the upper end of the red short range. The red-short range can be illustrated by the grain boundary strength curve, which dips down to lower than the grain strength at this temperature; this provides an easy way to evaluate the red-short range, by plotting the deformation or torque curve of the iron in question along with that of the normal one. Copper itself proved not to induce any red-shortness nor make the sulphur effect worse at the amount of 0.33 per cent copper content in this investigation, but indicates beneficial effects --Abstract, page 6

Institutional Herding in Bond Markets

Recent research has shown that institutional herding is a relevant phenomenon in stock markets. Do institutional investors also follow each other in bond markets? This paper focuses on the German bond market and uses data from 57 German mutual funds that invest mainly in DM-denominated bonds, which represents 71% of the total market volume. Due to the variety and large number of bonds that exist, we do not expect mutual funds to herd with regard to separate bonds. We believe instead that bonds with the same characteristics such as interest rate, maturity, collateral, or issuer are considered to be equivalent by institutional investors. Consequently, we construct "bond groups" consisting of similar bonds and analyze herding at a "bond group" level. Our results indicate that there is strong evidence of herding, albeit it is weaker than in stock markets. Further analysis suggests that mutual funds do not place an equal weight on different bond characteristics. Nominal interest rates appear to be most important in the bond selection process. --Mutual Funds,Herding,Imitation,Coordination,Behavioral Finance