An exact formula for the maximum VCO sweep rate of a PLL

In many phase-locked loop (PLL) applications, the natural pull-in mechanism is too slow and unreliable, and it must be accelerated. By adding an externally-generated ramp to its control voltage input, the PLL voltage controlled oscillator (VCO) frequency can be swept towards the input reference frequency in an attempt to speed up the pull-in process. This popular acquisition aid has a significant limitation when it is used in a second-order, Type II PLL. If the applied ramp voltage has a slope magnitude greater than (alternatively, less than) some value R_m, the PLL state can (alternatively, cannot) sweep past the desired lock point, resulting in a phase lock failure (alternatively, success). In general, the maximum sweep rate magnitude R_m can be computed by using a numerical integration-and-search procedure that is described in the PLL literature. A special case exists for a second-order, Type II PLL that incorporates a triangular-characteristic phase detector (with logic-level binary input signals). For this case, it is possible to develop an exact, closed-form expression for R_m, the main result of this paper. For a range of loop parameters most often used in applications, R_m values are computed by using the exact formula, and these are used in two ways. First, they are used to validate the previously-mentioned numerical integration-and-search procedure. Second, they are compared to maximum sweep rate values computed for a PLL that utilizes a sinusoidal phase detector to show that the triangular-phase-detector PLL can be swept significantly faster than the sinusoidal-phase-detector loop.     

Linking Physical and Numerical Modelling in Hydrogeology using Sand Tank Experiments and COMSOL Multiphysics

Visualising subsurface processes in hydrogeology and building intuition for how these processes are controlled by changes in forcing is hard for many undergraduate students. While numerical modelling is one way to help undergraduate students explore outcomes of multiple scenarios, many codes are not user‐friendly with respect to defining domains, boundary conditions, and coupling processes, and numerical modelling exercises are also often disconnected from systems that the students understand, limiting their ability to extrapolate what they have learned for other situations. Here, we test the hypothesis that hydrogeology students will better estimate rates of groundwater flow and contaminant transport and the magnitudes of the parameters that control flow and transport by linking physical and numerical models. We present an exercise that links physical and numerical modelling of fluid flow and solute transport using 2‐D ‘ant farm’ sand tanks with parallel models in COMSOL Multiphysics. The sand tank exercises provide students with a way to visualise subsurface flow and transport processes, while COMSOL allows them to explicitly pull apart the mathematics associated with these systems and build intuition for their solutions. Given coupled experimentation and numerical exercises, we find that students will connect processes that they see in the laboratory with the outcomes of numerical models, and the post‐exercise tests indicate that they have an improved understanding of: (1) the magnitude and importance of properties and parameters that control flow and transport and (2) the simplifications made in numerical models of physical systems.     

Promoting interculturalism in primary school children through the development of encountering skills: a case study in two Finnish schools

The present article introduces diversity (educational, social and multicultural) of children as a resource in language teaching. Two English teachers with a total of 105 children of their language classes participated in the teaching experiment that was part of a nationwide research and development project in Finland. The aim was to develop conceptions and practices of intercultural language education and transform language curricula based on them. With the support of university researchers, the teachers experimented, reflected on, evaluated and developed such pedagogic action – pedagogy of intercultural encounters – through which they could meet the challenges of diversity in their classrooms. Good practices in teaching intercultural encountering skills were developed and seen essential for promoting identity development in language learning. Based on regular seminars where teachers' reports on their progress were discussed, reflected on and theoretically analysed, the teachers and researchers suggested justified improvements for language curricula.     

Public Versus Private Colleges: Political Participation of College Graduates

Using data from the Baccalaureate and Beyond Longitudinal Study (B&B:93/03) of College Graduates, we use structural equation modeling to model the relationships between college major, values held in college, collegiate community service participation, and the post-college political participation of college graduates by public versus private institutions. We use Holland’s Theory of person-environment fit as lens to understand differences in political participation across majors and institutional contexts. Over a 10-year period immediately after receiving the baccalaureate, we find that choice of major and individual values are differentially associated with post-college political participation for private institution graduates when compared to the counterparts at public institutions. We relate our findings to extant literature that highlights the differences in institutional characteristics between public and private colleges and socialization patterns of undergraduates that may inform differences in post-college political participation. Implications for future research are also offered.     

A cross-level moderating effect of team trust on the relationship between transformational leadership and cohesion

ABSTRACT

We draw on the concept of the shared mental model to explain the cross-level direct and moderating effects of team trust on the relationship between coach transformational leadership and cohesion. Using hierarchical linear modelling, we analysed 597 national level high school and university volleyball players to test our research model. Our results revealed that, (a) at the individual level, coach transformational leadership has a positive effect on athletes’ perceptions on cohesion and (b) team trust, a group-level construct, is positively related to social cohesion and moderates the coach transformational leadership-cohesion relationship. The moderating effect demonstrates that the positive effect of coach transformational leadership on cohesion could be enhanced when high levels of team trust are shared within the group. Implications for coach education and sport psychology in terms of theory and research are discussed.     

The automation of curriculum development using the Authoring Instructional Materials (AIM) system

The Authoring Instructional Materials (AIM) program is a set of software tools for curriculum design and maintenance for use in the Navy. Several Navy test sites are conducting cooperative development and testing of the AIM software. This paper describes the rationale for the AIM system, the development process and products, and some possibilities for further development.     

Teacher education matters: Finnish teacher educators’ concerns,beliefs, and values

The professional development of teacher educators is gaining increasing interest globally. However, not so many studies have been carried out in the Finnish context, which is somewhat surprising considering that the Finnish education system and teacher education has gained so much interest worldwide. This study investigates Finnish teacher educators’ concerns, beliefs and values. The results show that teacher educators experienced a variety of concerns in their work, in the beginning mainly dealing with the position and being a novice, and later they became more concerned with heavy workloads and practical teaching-related matters. The teacher educators studied considered the students’ education to be the most important aspect of their work. The research-based nature of teacher education was also felt to be very important, along with its community aspects, and their own specialization. In general, Finnish teacher educators considered their work to be important.