Measurement and evaluation of swirl-type flow in labyrinth seals of conventional turbine stages

The effects of load factor and rotor eccentricity were determined on flow conditions in test series for two stages. The results indicate that swirl-type entry flow follows the rules of potential swirl. Within the labyrinth cavities two spatial separated flow areas are considered. A dominating flow in periphera direction nearly fills the space between the sealing strips and the ceiling of the cavity. Below this flow, an area of axial mass transport is situated, with a slight peripheral component, limited on the nearest surroundings of the seals gap and the rotor surface. Between both flows, an exchange of energy takes place. Within the gaps, flow direction depends on axial velocity and therefore on variable flow contraction. A balance of energy within the seal and the cavities interprets the results of lateral force measurements as an influence of friction at the sealing strips surface and the rotating shaft surface. Stages with their blades put together in buckets by means of shrouding segments are particularly influenced by the rotating speed of the shrouding

Metacognitive knowledge, metacognitive strategies, and CALL

CALL Research Perspectives creates a foundation for the study and practice of computer-assisted language learning and provides an overview of ways to conceptualize and to conduct research in CALL. Its core assumptions are that all approaches to research have a place, and that researchers, teachers, and students all have a role to play in the study of computer-enhanced language learning. This is not a how-to-do-research text. Written by top researchers in the field, it offers an open-ended view of what educators need to know and be able to do to answer questions that they have. It is intended to be easy to read, to provide resources for readers to explore the ideas further, and to be non-prescriptive in presenting suggestions for CALL research. The text explores problems with current CALL research and suggests ways that teachers and other researchers can avoid such problems; presents both commonly known and less explored theories that provide a foundation for CALL and language research; and addresses other issues and ideas that affect research outcomes

On the Fence

Over a hundred years ago, my great-great grandmother fled Germany by herself to come to the United States to escape the abuse of her father. She had no connections in this country and nowhere to go. That same century my ancestors from Ireland crossed the Atlantic to make a better life in America. They were discriminated against for their religion and for their nationality. Ana* and her husband, two hardworking Mexicans, paid a coyote to help them cross the Rio Grande into the United States ten years ago. They saw no future for their two young girls in Mexico and could not make ends meet. The family has struggled with racial profiling and prejudices since they arrived. On the surface there are no differences in these stories. With other opportunities exhausted, these determined people uprooted their lives and moved to an unknown country, where the language, religion, and customs are different and friends or family are limited. [excerpt

Owning Up To The Age Old Excuse

A few days ago, I was having a conversation with an older gentleman. He was friendly and very interested in my studies, but every now and then he would interject some racist slur or joke. He insistently referred to undocumented individuals as illegals because, according to him, “that’s exactly what they are.” He also made a few comments about Aryan dominance yet claimed that he wasn’t racist because he discriminates against all non-Aryans equally. The man clearly expected me to laugh along with him, especially with those last remarks, as if it were completely normal to utter them in an everyday conversation. He justified his words by saying “that’s just how it used to be”, ”I’m old-school”, and “everyone’s overly sensitive these days.” [excerpt

Fearless: Emily Hauck

Beginning with an interest in Spanish language that led her to Argentina and Spain, Emily decided to use the language skills she acquired during her gap year after high school and time spent studying abroad to get herself connected to the Latino community in Adams County. Volunteering with different organizations and programs like the LIU #12 Migrant Education Programs, Casa de la Cultura, and El Centro, Emily started seeing the big picture—making connections between the immigration stories, people she was meeting, and the greater national dialogue on immigration issues. [excerpt

Exploring the link between language anxiety and learner self-management in open language learning contexts

The Department of Languages at the Open University/UK was set up in 1991 and presented its first course in French for lower intermediate learners[1] in 1995. Intensive course production over a number of years has resulted in a portfolio of courses from beginner to degree level in French, German and Spanish. Language learning resources are varied and include print, video and audio materials as well as ICT components such as, for example, course websites. All students are individually assigned a tutor who advises on learning, marks coursework and holds tutorials. Until recently all tutorials took place face-to-face in the Open University's regional centres throughout the UK and Continental Western Europe, but since 2002 tutorials for some courses have been conducted online using Lyceum, an Internet-based conferencing system originally developed by the university's Knowledge Media Institute which provides multiple synchronous audio channels as well as synchronous text chat and several shared graphic interfaces (for a more detailed description of the tool see Hauck & Hampel, 2005). As a result of the continuing success of this tutorial mode the Department of Languages now offers a choice of face-to-face or Lyceum-based tuition to all students. This paper seeks to enhance our understanding of the interrelationship between affective issues, language anxiety in particular, and successful learner self-management in these learning environments. The findings are based on two phenomenographic studies, with the first one on language anxiety prompting the second one which explores the role of successful learner self-management. After some background information about the Open University's approach to distance education in general and the Department of Languages' approach to teaching languages at a distance in particular, this article looks at the theory underpinning the phenomena of language anxiety and learner self-management. This is followed by a presentation of the aforementioned studies, a discussion of their results and some preliminary conclusions

Electromagnetic Waves in a Rotating Frame of Reference

We discuss the electromagnetic measurements of rotating observers and study the propagation of electromagnetic waves in a uniformly rotating frame of reference. The phenomenon of helicity-rotation coupling is elucidated and some of the observational consequences of the coupling of the spin of a particle with the rotation of a gravitational source are briefly examined.Comment: LaTeX file, 2 PS figures, 18 pages, a few minor corrections, accepted for publication in Annalen der Physik, in pres

Departures from cost-effectiveness recommendations: The impact of health system constraints on priority setting

The methods and application of cost-effectiveness analysis have reached an advanced stage of development. Many decision makers consider cost-effectiveness analysis to be a valid and feasible approach towards setting health priorities, and it has been extensively applied in evaluating interventions and developing evidence based clinical guidelines. However, the recommendations arising from cost-effectiveness analysis are often not implemented as intended. A fundamental reason for the failure to implement is that CEA assumes a single constraint, in the form of the budget constraint, whilst in reality decision-makers may be faced with numerous other constraints. The objective of this paper is to develop a typology of constraints that may act as barriers to implementation of cost-effectiveness recommendations. Six categories of constraints are considered: the design of the health system; costs of implementing change; system interactions between interventions; uncertainty in estimates of costs and benefits; weak governance; and political constraints. Where possible -and if applicable- for each class of constraint, the paper discusses ways in which these constraints can be taken into account by a decision maker wishing to pursue the principles of cost-effectiveness