Resolvable designs with large blocks

Resolvable designs with two blocks per replicate are studied from an optimality perspective. Because in practice the number of replicates is typically less than the number of treatments, arguments can be based on the dual of the information matrix and consequently given in terms of block concurrences. Equalizing block concurrences for given block sizes is often, but not always, the best strategy. Sufficient conditions are established for various strong optimalities and a detailed study of E-optimality is offered, including a characterization of the E-optimal class. Optimal designs are found to correspond to balanced arrays and an affine-like generalization.Comment: Published at http://dx.doi.org/10.1214/009053606000001253 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Venus Lander Design

The students designed an Entry, Descent, and Landing (EDL) system for a lander to reach the surface of Venus. The students used a combination of 3D modelling and programming to design the EDL within given constraints under specific tolerances. An EDL takes into consideration entry flight dynamics, aeroheating, and landing systems. The EDL was divided into three stages (see below). The separation of stages was designed to address unique challenges found at different points throughout the EDL. The primary objective of the first stage was to minimize the heat associated with the entry velocity to the payload. The second stage implemented a parachute to reduce velocity such that the descent time criteria could be met. The third stage involved landing design. Through the use of six simultaneous differential equations, the flight of the vehicle was determined. The system was optimized by modifying craft parameters and initial conditions to meet objectives. After optimization, the revised values of position and velocity were obtained at every time step during descent. The vehicle velocity was used to calculate the heat rate to the heat shield of the entry vehicle. Through the use of a parachute, drag was increased to extend the time of flight and to slow the vehicle for landing. Designs were implemented to minimize impact force to the lander and maintain proper orientation during landing.https://scholarscompass.vcu.edu/capstone/1204/thumbnail.jp

Applied linguistics and mathematics education: More than words and numbers

The preceding set of papers has explored various aspects of the role of language in mathematics education. The papers reflect the work of individual contributors. An important part of our collaboration, however, has been the conversation between us. This paper reflects aspects of that conversation, as we draw together some of the themes that have emerged during our work. In particular, we discuss some of the implications of our analyses for theory, policy, practice and inter-disciplinarity in mathematics education and applied linguistics

BECOMING A CRITICAL LANGUAGE TEACHER: a reflexive journey

Com base num projeto colaborativo com colegas brasileiros, o autor reflete sobre sua compreensão do escopo e fundamento do trabalho crítico no Ensino de Língua Inglesa (ELT). Com esse objetivo, examina e debate a distinção terminológica entre pedagogias críticas (ex.: modernismo emancipatório, PENNYCOOK, 2001) e letramentos críticos (ex.: problematização de pressupostos, cf. PENNYCOOK, 2001) como sugerido por alguns teóricos brasileiros (ex.: MENEZES DE SOUZA 2011; JORDÃO, no prelo).  Inspirado nesse debate, o autor analisa sua própria formação inicial como educador crítico no Instituto Sichuan de Língua Estrangeira em Chongqing, República Popular da China. O artigo discute os desafios da aplicação de teorias críticas do ocidente em ambientes chineses, sequenciado por uma aula específica em ELT crítico ministrado pelo autor. A parte final do artigo explora as implicações dessa aula em relação aos vários entendimentos de criticidade na prática de ensino de língua

Identity presentation: The construction of identity in asynchronous discussion

This study examines the use of e-mail as a tool for long term discussion between teachers and grade six students. E-mail messages between grade six students and teachers were collected over the course of one academic year. Methods of conversation analysis within a framework of social practice are used to examine the data. While identity is more readily constructed and more fully developed in contexts which allow for physical embodiment such as face-to-face discussion, this analysis found that identity can be constructed in a context that does not provide for the physical embodiment of identity: Identity was constructed using the social, cultural, and technological tools provided and supported by e-mail to develop social practices germane to the e-mail discussion. This study has implications for further understanding the relation between identity, goals, constraints and affordances, and the collaborative creation of social practices in asynchronous computer mediated communication. © 2008 FQS