Characterization of the mean velocity of a circular jet in a bounded basin

A circular jet has broad and important applications in practical engineering. Most research in this area has focused on a free jet, a wall jet or a vertical jet in a bounded domain. In this study, the mean velocities of circular offset jets were studied for four jet exit Froude numbers (Fr), three offset heights (S) (S/d=1, 2, 3) and three submergence ratios (ht/S) (surface jet, mixed jet, and submerged jet) in a bounded basin. Based on the results, we propose a velocity decay formula for a circular jet. The lateral velocity spread was more consistent with Gaussian and Cauchy–Lorentz distributions than the vertical velocity. Moreover, Fr had little effect on the decay of the mean velocity for a circular jet when Re>1×10⁴. The lateral and vertical spreads showed a quadratic relationship with the streamwise distance for different values of Fr at X/d<10. The positions of maximum mean velocity decay were independent of Fr and S/d when X/d<10. The spread rate was more uniform in the lateral direction than that in the vertical direction in a certain region for different S/d and ht/S. Therefore, the decay, spread, and maximum velocity position of the mean velocity for a circular offset jet can remain stable under different values of Fr, offset height, and submergence ratio.     

Factors affecting the adoption of e-learning systems in Qatar and USA: Extending the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2)

This study examines the major factors that may hinder or enable the adoption of e-learning systems by university students in developing (Qatar) as well as developed (USA) countries. To this end, we used extended Unified Theory of Acceptance and Use of Technology 2 (UTAUT2) with Trust as an external variable. By means of an online survey, data were collected from 833 university students from a university in Qatar and another from USA. Structural equation modelling was employed as the main method of analysis in this study. The results show that performance expectancy, hedonic motivation, habit and trust are significant predictors of behavioural intention (BI) in both samples. However, contrary to our expectation, the relationship between price value and BI is insignificant. Our results also show that effort expectancy and social influence lead to an increase in students’ adoption of e-learning systems in developing countries but not in developed countries. Moreover, facilitating conditions increase e-learning adoption in developed countries which is not the case in developing countries. Overall, the proposed model achieves an acceptable fit and explains its variance for 68% of the Qatari sample and 63% of the USA sample. These results and their implications to both theory and practice are described.     

An Epistemology of Presence and Reconceptualisation in Design Education

In this paper, the idea of coming into presence and an epistemology that recognises the agency of the learner in the construction of knowledge is developed as an organising framework for reconceptualising design education. Design is typically taught as a problem solving exercise based on a representational epistemology. A critique of the representational epistemology is presented. The idea of design as coming into presence is introduced and exemplified though considerations of implicate order, context, and closure. It is suggested that an epistemology of presence provides a better alignment between how people experience the world through design and the ways in which they engage with it both intellectually and practically.     

Didactic and technical considerations when developing e-learning and CME

Several usability issues were encountered during the design of a blended e-learning program for a course in evidence-based medicine for general practice trainers. The program was developed in four steps. We focused in this article on step 2 and 3. Step 2 focused on which educational principles to apply, that is, which learning theories, instructional designs and other theories should influence the program. Step 3 focused on the design elements, namely whether to use hypermedia and/or multimedia, and what screen design and which font to use. This article presents the important issues in designing an e-course and provides an impression of the complexity of designing high quality e-learning in particular for continuing medical education (CME).     

Applications of speech-to-text recognition and computer-aided translation for facilitating cross-cultural learning through a learning activity: issues and their solutions

In this study, 21 university students, who represented thirteen nationalities, participated in an online cross-cultural learning activity. The participants were engaged in interactions and exchanges carried out on Facebook^® and Skype^® platforms, and their multilingual communications were supported by speech-to-text recognition (STR) and computer-aided translation (CAT) systems. The participants spoke in their native languages, and the STR system generated texts from their voice input. The CAT system then simultaneously translated the STR-texts into English. The aim of this study was to examine the accuracy rates of STR and CAT processes for different languages during intercultural communication. We also explored issues associated with these processes and how they were addressed in the study context. In addition, an attempt was made to determine whether or not our learning activity as supported by STR and CAT technologies facilitated cross-cultural learning. Our results showed that the lowest STR accuracy rate was for Belizean English whereas the highest STR accuracy rate was for French and Hindi. The lowest CAT accuracy rate was for Mongolian and Filipino, and the highest was for Spanish, Russian, and French. Seven issues associated with the STR process and ten issues associated with the CAT process were identified. The participants employed ten workarounds to address the STR-related issues and thirteen workarounds to address the CAT-related issues. We refer to a workaround as a method used by the participants to overcome a limitation related to either STR or CAT. Finally, our results demonstrated that cross-cultural learning took place; the participants understood and could explain foreign traditions to others and could also compare foreign traditions with their own. Based on our results, we made several suggestions and provided implications for the teaching and research community.     

Study on the failure mechanism of Ag-Ce contacts in DC level

Nominal contact resistance, minimum erosion and material transfer are required with low cost materials working in a wide currents range for DC relays. Ag-Ni contact materials have low contact resistance, but the erosion and material transfer are large at high current level. Ag-SnO2 contact materials have good anti-welding properties and resistance to arc erosion, but they have large contact resistance during working and are easily block SnO2 from flocking together on the surface at low current level. In this paper, the failure mechanisms of Ag-Ce contact material were studied. The surface morphologies of the contacts after electrical endurance test for Ag-Ce contact material were compared with that of Ag-Ni and Ag-SnO2 contact materials. The effect of Ce on the surface morphologies of the contacts after electrical endurance test was analyzed.     

Challenging teacher beliefs about student engagement in mathematics

This study explored the beliefs about student engagement in mathematics of three Year 5 and 6 teachers, focusing on the shifts that occurred during a 10-week intervention. Data obtained from teacher surveys, interviews, video-recorded workshop observations and artefacts from teachers’ classrooms reveal variations in their reactions to the professional learning experiences. Teacher responses were mediated by personal and contextual elements including teacher efficacy beliefs, teacher confidence in mathematics and their conceptions of student engagement. Theories of teacher conceptual change are used to account for variations to teacher beliefs.     

The paradox of un/making science people: practicing ethico-political hesitations in science education

Over the years neoliberal ideology and discourse have become intricately connected to making science people. Science educators work within a complicated paradox where they are obligated to meet neoliberal demands that reinscribe dominant, hegemonic assumptions for producing a scientific workforce. Whether it is the discourse of school science, processes of being a scientist, or definitions of science particular subjects are made intelligible as others are made unintelligible. This paper resides within the messy entanglements of feminist poststructural and new materialist perspectives to provoke spaces where science educators might enact ethicopolitical hesitations. By turning to and living in theory, the un/making of certain kinds of science people reveals material effects and affects. Practicing ethicopolitical hesitations prompt science educators to consider beginning their work from ontological assumptions that begin with abundance rather than lack.     

Improving the judgment of task difficulties: prospective teachers’ diagnostic competence in the area of functions and graphs

To teach adaptively, teachers should be able to take the students’ level of knowledge into account. Therefore, a key component of pedagogical content knowledge (PCK) is the ability to assume the students’ perspectives. However, due to the so-called expert blind spot, teachers tend to misestimate their students’ knowledge, such as when estimating the difficulty of a given task. This empirically well-documented estimation bias is predicted by Nickerson’s anchoring and adjustment model, which generally explains how people take on other people’s perspectives. In this article, we present an intervention study that aims to improve the accuracy of prospective teachers’ judgments of task difficulty in the area of functional thinking. Two types of treatments are derived from Nickerson’s model. In the first condition (PCK group), participants acquire knowledge about task characteristics and students’ misconceptions. The second condition (sensitizing group) serves to control the idea that potential improvements in the PCK group are not merely based on a pure sensitization of the expert’s estimation bias. Accordingly, these participants are only informed about the general tendency of overestimating task difficulties. The results showed that the PCK group improved both in terms of the accuracy of the estimated solution rates and the accuracy of rank order, whereas the sensitizing group only improved in regard to the former. Thus, the study shows that prospective teachers’ diagnostic judgments can be improved by teaching them relevant PCK in a short amount of time.     

Phenolic compounds participating in mulberry juice sediment formation during storage

The stability of clarified juice is of great importance in the beverage industry and to consumers. Phenolic compounds are considered to be one of the main factors responsible for sediment formation. The aim of this study is to investigate the changes in the phenolic content in clarified mulberry juice during storage. Hence, separation, identification, quantification, and analysis of the changes in the contents of phenolic compounds, both free and bound forms, in the supernatant and sediments of mulberry juice, were carried out using high performance liquid chromatographic system, equipped with a photo-diode array detector (HPLC-PDA) and HPLC coupled with quadrupole-time of flight mass spectrometric (HPLC-QTOF-MS/MS) techniques. There was an increase in the amount of sediment formed over the period of study. Total phenolic content of supernatant, as well as free phenolic content in the extracts of the precipitate decreased, whereas the bound phenolic content in the sediment increased. Quantitative estimation of individual phenolic compounds indicated high degradation of free anthocyanins in the supernatant and sediment from 938.60 to 2.30 mg/L and 235.60 to 1.74 mg/g, respectively. A decrease in flavonoids in the supernatant was also observed, whereas the contents of bound forms of gallic acid, protocatechuic acid, caffeic acid, and rutin in the sediment increased. Anthocyanins were the most abundant form of phenolics in the sediment, and accounted for 67.2% of total phenolics after 8 weeks of storage. These results revealed that phenolic compounds, particularly anthocyanins, were involved in the formation of sediments in mulberry juice during storage.