Reasoning about relationships among design constraints can facilitate objective and effective decision making at various stages of engineering design. Exploiting dominance among constraints is one particularly strong approach to simplifying design problems and to focusing designers' attention on critical design issues. Three distinct approaches to constraint dominance identification have been reported in the literature. We lay down the basic principles of these approaches with simple examples, and we apply these methods to a practical linear electric actuator design problem. With the help of the design problem we demonstrate strategies to synergistically employ the dominance identification methods. Specifically, we present an approach that utilizes the transitive nature of the dominance relation. The identification of dominance provides insight into the design of linear actuators, which leads to effective decisions at the conceptual stage of the design. We show that the dominance determination methods can be synergistically employed with other constraint reasoning methods such as interval propagation methods and monotonicity analysis to achieve an optimal solution for a particular design configuration of the linear actuator. The dominance determination methods and strategies for their employment are amenable for automation and can be part of a suite of tools available to assist the designer in detailed as well as conceptual design.

In current commercial feature modeling systems, support for direct manipulation of features is not commonly available. This is partly due to the strong reliance of such systems on constraints, but also to the lack of speed of current constraint solvers. In this paper, an approach to the optimization of geometric constraint solving for direct manipulation of feature dimensions, orientation, and position is described. Details are provided on how this approach was successfully implemented in the Spiff feature modeling system.

The problem investigated in this research is that engineering design decision making can be complicated and made difficult by highly coupled design parameters and the vast number of design parameters. This complication often hinders the full exploration of a design solution space in order to generate optimal design solution. These hindrances result in inferior or unfit design solutions generated for a given design problem due to a lack of understanding of both the problem and the solution space. This research introduces a computational framework of a new algebraic constraint-based design approach aimed at providing a deeper understanding of the design problem and enabling the designers to gain insights to the dynamic solution space and the problem. This will enable designers to make informed decisions based on the insights derived from parameter relationships extracted. This paper also describes an enhanced understanding of an engineering design process as a constraint centered design. It argues that with more effort and appreciation of the benefits derived from this constraint-based design approach, engineering design can be advanced significantly by first generating a more quantitative product design specification and then using these quantitative statements as the basis for constraint-based rigorous design. The approach has been investigated in the context of whole product life-cycle design and multidisciplinary design, aiming to derive a generic constraint-based design approach that can cope with life-cycle design and different engineering disciplines. A prototype system has been implemented based on a constraint-based system architecture. The paper gives details of the constraint-based design process through illustrating a worked real design example. The successful application of the approach in two highly coupled engineering design problems and the evaluation undertaken by a group of experienced designers show that the approach does provide the designers with insights for better exploration, enabled by the algebraic constraint solver. The approach thus provides a significant step towards fuller scale constraint-based scientific design.

In constraint-based design, components are modeled by variables describing their properties and subject to physical or mechanical constraints. However, some other constraints are difficult to represent, like comfort or user satisfaction. Partially defined constraints can be used to model the incomplete knowledge of a concept or a relation. Instead of only computing with the known part of the constraint, we propose to complete its definition by using machine-learning techniques. Because constraints are actively used during solving for pruning domains, building a classifier for instances is not enough: we need a solver able to reduce variable domains. Our technique is composed of two steps: first we learn a classifier for the constraint's projections and then we transform the classifier into a propagator. We show that our technique not only has good learning performances but also yields a very efficient solver for the learned constraint.

In this paper, we present the development and application of a technical feasibility model used in preliminary design to determine whether a set of desired product specifications obtained from marketing is feasible in the engineering domain. This model is developed by integrating the capabilities of a multiobjective design problem, a multicriteria design optimization tool, a Pareto frontier gap analyzer, metamodeling methods, and use of the Pareto frontier as a constraint for feasibility assessment. Although the tools are independent of the domain, their application is illustrated using two examples: a simple three-objective mathematical problem and a five-objective passenger vehicle design problem. The feasibility of the desired product specifications is determined with respect to the problem's Pareto frontier, which is considered to be the necessary constraint to satisfy.

This study examined the impact of Computer Assisted Language Learning (CALL) on Korean TAFE (Technical and Further Education) college students in an English as a Foreign Language (EFL) reading classroom in terms of their perceptions of learning environment and their reading performance. The study compared CALL and traditional reading classes over one semester by measuring students’ reading performance. A group of 74 first year English major students were divided evenly into two classes. Both groups were taught by the same teacher and covered the same topics in their weekly two-hour reading lessons. A reading comprehension test was given at the beginning and the end of the semester to measure the students’ performance. A written survey was also administered at the end of the semester. Classroom observations and group interviews with students supplemented the data obtained from the surveys. Analysis of Covariance (ANCOVA) was used for the performance test to explore the differences between the two classes while statistically controlling for the pre-test (covariate). The questionnaires were analyzed by a principle component factor analysis, a repeated-measure ANOVA and a discriminant analysis whereas the interviews with students were analyzed by a content analysis. Students’ performances in the pre-test and the post-test were not significantly different between the two classes. However, the students in the CALL-based English class were more positive in their perceptions of their learning environment than were those in the traditional English class. This study shows that computer technology had a positive impact on students’ perceptions of their learning environment, especially in relation to learning materials and tasks, and with regard to interaction and collaboration with the tutor and other students.

ReCALL Vol 17(2) November 2005Please note that due to a misunderstanding the affiliation of the paper entitled “Can it be as effective? Distance versus blended learning in a web-based EAP programme” on page 197 was incorrectly cited.The correct citation should have been: Mihye Harker and Dimitra Koutsantoni Division of Language and Communication, LBSUniversity of Luton, Luton LU1 3JU, UK(e-mail: mihyeharker@yahoo.co.uk, dkoutsantoni@yahoo.com).

This paper describes an English language listening test intended as computer-based testing material for secondary school students in Hong Kong, where considerable attention is being invested in online and computer-based testing. As well as providing a school-based testing facility, the study aims to contribute to the knowledge base regarding the efficacy and reliability of computer-based testing. The paper describes the construction of an item bank of over 400 short listening items calibrated on item response theory principles. Items from this bank were used to form a traditional paper-based listening test, and an adaptive computer-based test. Both forms of the test were administered to two Hong Kong Grade 11 and Grade 12 classes. Descriptive test statistics indicated that both test types discriminated effectively between school grades. In terms of comparability between test types, there was significant difference between the Grade 11 classes’ performance although not with that of Grade 12. Test takers generally performed better on the computer-based test than on the paper-based test, confirming earlier research. Interviews with test takers after taking both tests indicated an even split in terms of preference, with boys opting for the computer-based test and girls the paper-based test. Correlations between test takers’ performance on the two test types were high enough to indicate the computer-based test’s potential as a low-stakes test (its intended purpose as a school-based testing facility), although not as a high-stakes test (for example, as a territory-wide test replacing a traditional paper-based test).

This article presents findings from an exploratory pilot project which aimed at fostering electronic and professional literacy skills of preservice language teachers through computer-mediated peer collaboration. The research context is a qualitative case study involving cooperation via the email and chat functions of FirstClass among preservice teachers at the Justus-Liebig Universität in Giessen and the Pädagogische Hochschule Heidelberg in Germany. The author investigates participants’ prior experiences with regard to computer skills, Internet proficiency, and technology-based language learning and teaching. Next, she discusses benefits and challenges for preservice teachers with respect to collaborating via computers (computer-mediated communication or CMC) with their transatlantic partners. In collecting and analyzing preservice teachers’ reflections, a Grounded Theory approach (Strauss & Corbin, 1998) was used. Instances of electronic and professional literacies were identified and triangulated with data from pre-course questionnaires, post-course self-assessments, logs, email and chat transcripts, and field notes. The author discusses benefits and challenges which preservice teachers encountered through the collaboration. Findings include preservice teachers’ differing levels of electronic literacy skills, tolerance for ambiguity, institutional constraints, peer feedback, and perception of the final product. Based on her findings, the author stresses the need to encourage preservice teachers’ meta-level reflections on the challenges of the collaboration and suggests conducting longitudinal follow-up studies in order to investigate if and how in-service teachers apply the knowledge they gained from their teacher education program to their own teaching.

This issue of ReCALL represents something of a watershed in the journalÕs history, for a number of reasons. First of all I have to report that Professor Graham Chesters has decided that he wishes to step down as co-editor, and I would like to thank him here for all his work for the journal over the years. Back in 1990 when Graham and I were involved with the Computers in Teaching Initiative Centre for Modern Languages (CTICML) at the University of Hull, funded by the UK Higher Education Funding Council, one of the required ‘deliverables’ was a regular Newsletter, designed to inform university language lecturers about developments in the use of new technologies in language learning. It soon became apparent that some of the material that was being submitted for publication was far too substantial for a Newsletter, yet merited dissemination among our readers. It was Graham who saw the potential need for a new academic journal in this field, and thus ReCALL was born. I still blush to see my attempts at desk-top publishing in those early issues!

Intercultural competence has acquired an important role in the foreign language classroom. However, we must also come to terms with assessing this highly complex construct if we consider it as a superordinate learning objective. Therefore the components of intercultural communicative competence that go beyond knowledge, especially attitudes, deserve closer attention. On the basis of Byram’s (1997) model of Intercultural Communicative Competence (ICC), an attempt has been made to trace the development of attitudes as part of ICC in computer-mediated intercultural communication. Data was drawn from three e-mail projects that took place between 2001 and 2002. Three different upper-secondary classes at a vocational school in Mainz, Germany (n=64) exchanged e-mails with two groups of US-American undergraduate students in Ohio (n=57) and one group of undergraduate students of English from Tokyo (n=30). Preliminary findings from a telecollaborative seminar with US-American undergraduate teacher students at a German teacher training institution were used to support the data. The main question addressed in the paper is whether attitudinal components of ICC can be measured quantitatively in telecollaborative environments. To do this, specifications and implementation of learning objectives for attitudes as put forward by Byram (1997) are applied to different instruments within the framework of the e-mail projects, including a triangulation of instruments. Instruments include e-mails, critical incidents, essays and interaction journals. When data was ambiguous or incomplete, follow-up interviews were conducted with pupils. Results of the study suggest that it is not possible to measure attitudes with the instruments described, but that they can help teachers to describe evidences of attitudes in interaction and trace developments to provide a basis for feedback.

This study in the field of Second Language Acquisition (SLA) was conducted in a Spanish as a foreign language classroom. The study investigates dyadic face-to-face collaborative dialogue at the computer from a sociocultural perspective. Protocols for analysis were obtained by the transcription of audio recordings of twelve dyads/triads completing three tasks in two mediums of implementation, computer and non-computer-based. By comparing learners’ activity in the two mediums through microgenetic analysis (i.e., developmental analysis), we were able to study some specific ways in which the computer influenced the course of interaction. Specifically, the aim of the study was to investigate the value of the tasks as pedagogical instruments to support collaborative activity in the foreign language classroom; the value of collaborative activity as a source for possible restructuring of interlanguage (i.e., microgenesis); and the impact of the computer as a mediational tool in the processes of collaborative activity. Results confirm: (1) the three tasks support high degrees of collaborative activity– albeit qualitatively different; (2) language can – sometimes simultaneously– be deployed by learners both as a means of communication and as a cognitive tool to achieve linguistic development; (3) the presence of the computer seems to change the nature of collaborative activity.

Following work of Ehrhard and Regnier, we introduce the notion of a differential category: an additive symmetric monoidal category with a comonad (a ‘coalgebra modality’) and a differential combinator satisfying a number of coherence conditions. In such a category one should imagine the morphisms in the base category as being linear maps and the morphisms in the coKleisli category as being smooth (infinitely differentiable). Although such categories do not necessarily arise from models of linear logic, one should think of this as replacing the usual dichotomy of linear vs. stable maps established for coherence spaces.

After establishing the basic axioms, we give a number of examples. The most important example arises from a general construction, a comonad $S_\infty$ on the category of vector spaces. This comonad and associated differential operators fully capture the usual notion of derivatives of smooth maps. Finally, we derive additional properties of differential categories in certain special cases, especially when the comonad is a storage modality, as in linear logic. In particular, we introduce the notion of a categorical model of the differential calculus, and show that it captures the not-necessarily-closed fragment of Ehrhard–Regnier differential $\lambda$-calculus.

Iterative theories, which were introduced by Calvin Elgot, formalise potentially infinite computations as unique solutions of recursive equations. One of the main results of Elgot and his coauthors is a description of a free iterative theory as the theory of all rational trees. Their algebraic proof of this fact is extremely complicated. In our paper we show that by starting with ‘iterative algebras’, that is, algebras admitting a unique solution of all systems of flat recursive equations, a free iterative theory is obtained as the theory of free iterative algebras. The (coalgebraic) proof we present is dramatically simpler than the original algebraic one. Despite this, our result is much more general: we describe a free iterative theory on any finitary endofunctor of every locally presentable category $\cal{A}$.

Reportedly, a blow from the welterweight boxer Norman Selby, also known as Kid McCoy, left one victim proclaiming,

‘It's the real McCoy!’.